equine American Edition | May 2016 veterinary education

in this issue:

Fun, engagement help ambulatory practice win owner education events Cervical spondylosis deformans in two Quarter Horses The official journal of the American Association of A modified surgical technique for penile amputation and preputial ablation Equine Practitioners, produced in the horse in partnership with BEVA. COMPLEX LAMENESS CASE ?

DON’T BE LEFT IN THE DARK, CONSIDER STANDING EQUINE MRI

www.hallmarq.net Standing Equine MRI equine veterinary education American Edition May 2016 • Volume 28 • Number 5

AAEP News: In this issue contents Fun, engagement help ambulatory practice win owner education events ...... III

Equine upper airway expert Dr. Norm Ducharme to deliver 2016 Milne Lecture ...... IV

Expand your repro skills at summer Focus meeting ...... V

Highlights of Recent Clinically Relevant Papers S. WRIGHT ...... 239

Case Reports Resuscitation attempts in a foal with sudden cardiac arrest in the early recovery period K. HOPSTER, J. TÜENSMEYER and S. B. R. KÄSTNER ...... 241

Cervical spondylosis deformans in two Quarter Horses A. C. E. DRAPER and C. J. FINNO ...... 248

Diagnostic imaging, surgical treatment and histopathological findings of a vascular hamartoma in a 2-year-old horse B. MUSTERLE, R. HAGEN, P. GREST and J. KÜMMERLE ...... 253

Lameness caused by plate-like osteoma cutis in a Thoroughbred colt S. K. LEE, B-H. KIM, E. SEO, C. J. KWON, J-B. LEE and J-I. HAN ...... 259

Severe supracondylar lysis of the third metatarsal bone due to intra-articular haemorrhage with similarities to human pigmented villonodular synovitis: A differential diagnosis to intra-articular neoplasia G. J. HINNIGAN, R. PAPOULA-PEREIRA, U. HETZEL and E. R. SINGER ...... 262

Clinical Commentaries Cardiopulmonary resuscitation: A waste of time? G. D. HALLOWELL ...... 245

Cervical spondylosis deformans L. JEFFCOTT ...... 252

Original Article A modified surgical technique for penile amputation and preputial ablation in the horse C. E. WYLIE and R. J. PAYNE ...... 269

Review Articles Equine laryngeal dysplasia S. Z. BARAKZAI ...... 276

Evaluation of poor performance in competition horses: A musculoskeletal perspective. Part 1: Clinical assessment S. DYSON ...... 284

Advertisers’ Index ...... 251

Cover photo by Dr. Jorge Colón. Equine veterinary education American Association of Equine Practitioners American Edition 4033 Iron Works Parkway Lexington, KY 40511 0D\‡9ROXPH‡1XPEHU  5&-


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 FAX (859) 233-1968 E-MAIL [email protected] Editor (UK) Assistant Editors www.aaep.org T. S. Mair, BVSc, PhD, DEIM, DESTS, F. Andrews J.-P. Lavoie DipECEIM, MRCVS D. Archer S. Love To access our website, go to www.aaep.org, F.T. Bain M.L. Macpherson click on Members, select LOGIN, then enter your Editors (USA) A.R.S. Barr M.J. Martinelli e-mail and password or, for first-time visitors, N. A. White II, DVM A. Blikslager I.G. Mayhew enter your e-mail as your Username and your W. D. Wilson, MRCVS M. Bowen M. Mazan member number with the letter ‘a’ in front as N. Cohen C.W. McIlwraith your Password. Deputy Editors V. Coudry B. McKenzie Published monthly. Deadlines are the A. Dart R. Moore P.R. Morresey seventh of the preceding month. J.-M. Denoix M. Oosterlinck P.A. Wilkins T. Divers A. Parks 2016 AAEP Officers P. Dixon S. Puchalski Management Group Kathleen Anderson, DVM, President W. Duckett C. Riggs D. Foley B. Dunkel H. Schott R. Reynolds Cowles, DVM, President-Elect T. S. Mair S. Dyson J. Schumacher Margo Macpherson, DVM, Vice President N. A. White Y. Elce S. Semevelos Jack Easley, DVM, Treasurer W. D. Wilson T. Fischer J. Slater G. Kent Carter, DVM, Immediate Past President J. L. N. Wood D. Freeman B. Sponseller T. Greet C. Sweeney AAEP Staff Management Board R. Hanson H. Tremaine David Foley, CAE, Executive Director A. R. S. Barr S. E. Palmer P. Harris S. Weese [email protected] D. Foley N. A. White (US Editor) M. Hillyer R. Weller M. Holmes C. Yao Lori Rawls, Director of Finance & Operations P. Harris S. White [email protected] T. S. Mair (Editor) W. D. Wilson (US Editor) N. Hudson P.O. E. Mueller J. L. N. Wood (Chairman) P. Johnson Ex-officio Sally J. Baker, APR, Director of Marketing P.T. Khambatta J. Cooney & Public Relations
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TCBLFS!BBFQPSH Keith Kleine, Director of Industry Relations [email protected] Equine Veterinary Education is a refereed educational journal designed to keep the practicing veterinarian up to Nick Altwies, Director of Membership date with developments in equine medicine and surgery. Submitted case reports are accompanied by invited reviews [email protected] of the subject (satellite articles) and clinical quizzes. Tutorial articles, both invited and submitted, provide in-depth coverage of issues in equine practice. Sue Stivers, Executive Assistant [email protected] Equine Veterinary Education (American Edition ISSN 1525-8769) is published monthly by the American Association of Equine Practitioners, an international membership organization of equine veterinarians. Office of Carey Ross, Scientific Publications Coordinator publication is 4033 Iron Works Parkway, Lexington, KY 40511. Periodicals Postage paid at Lexington, KY and [email protected] additional mailing office. POSTMASTER: Send address changes to: Equine Veterinary Education, 4033 Iron Works Amity Brannock, Communications Coordinator Parkway, Lexington, KY 40511. [email protected] Communications regarding editorial matters should be addressed to: The Editor, Equine Veterinary Education, Dana Kirkland, Sponsorship and Advertising Mulberry House, 31 Market Street, Fordham, Ely, Cambridgeshire CB7 5LQ, UK. Telephone: 44 (0) 1638 720250, Coordinator
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ELJSLMBOE!BBFQPSH Fax: 44 (0) 1638 721868, E-mail: [email protected]. Deborah Miles, CMP, Meetings Coordinator All manuscript submissions for the journal should be submitted online at http://mc.manuscriptcentral.com/eve. Full [email protected] instructions and support are available on the site and a user ID and password can be obtained on the first visit. If you require assistance, click the Get Help Now link that appears at the top right of every ScholarOne Manuscripts page. Elaine Young, Student Programs Coordinator [email protected] All subscription inquiries should be addressed to: Subscriptions Department, AAEP, 4033 Iron Works Parkway, Pam Shook, Foundation Programs Coordinator Lexington, KY 40511, Telephone: (859) 233-0147, E-mail: [email protected]. Subscription rates: AAEP annual [email protected] membership dues include $40 for a subscription to Equine Veterinary Education. Other subscriptions at $151.80. Single copies $37.50. Cynthia Hinkle, Office Manager [email protected] Canadian Subscriptions: Canada Post Corporation Number 40965005. Send change address information and blocks of undeliverable copies to IBC, 7485 Bath Road, Mississauga, ON L4T 4C1, Canada. John Cooney, Publications Coordinator [email protected] © World copyright by Equine Veterinary Journal Ltd 2016. Jodie Bingham, Foundation Development Coordinator [email protected] The authors, editors and publishers do not accept responsibility for any loss or damage arising from actions or decisions based or relying on information contained in this publication. Responsibility for the treatment of horses Chelsea Smith, Member Engagement Coordinator under medical or surgical care and interpretation of published material lies with the veterinarian. This is an aca- [email protected] demic publication and should not be used or interpreted as a source of practical advice or instruction.

Megan Gray, Database Services Coordinator The American Association of Equine Practitioners cannot accept responsibility for the quality of products or ser- [email protected] vices advertised in this journal or any claim made in relation thereto. Every reasonable precaution is taken before Kristin Walker, Member Relations advertisements are accepted, but such acceptance does not imply any form of recommendation or approval. [email protected] All companies wishing to advertise in Equine Veterinary Education, American edition, must be current AAEP exhibitors. Bailey McCallum, Communications Manager, AAEP retains the right, in its sole discretion, to determine the circumstances under which an exhibitor may advertise in this Equine Disease Communication Center journal. While all advertisers must comply with applicable legal guidelines, Compounding Pharmacies are specifically [email protected] directed to limit themselves to pharmacy practices as dictated by the FDA Center for Veterinarian Medicine, Compliance Policy Guideline (www.fda.gov/ora/compliance_ref/cpg/cpgvet/cpg608-400.html). Advertising any complete or partial All advertising inquiries should be addressed to: mimicry of drugs and dosage forms of FDA approved formulations will not be accepted. Compounding Pharmacies, or any Dana Kirkland (859) 233-0147 other exhibitors/advertisers who violate this rule in any fashion, will render their advertising contract null and void. [email protected] As a private organization, the AAEP reserves the right to exclude any company from advertising in Equine AAEP Mission Statement: To improve the Veterinary Education, American edition, for any reason. The signing and delivery of the advertising contract shall health and welfare of the horse, to further the constitute an offer subject to acceptance by the AAEP. In its sole and absolute discretion, the AAEP may revoke its professional development of its members, acceptance of the advertising contract or may terminate any contract by delivery of written notice, in which event and to provide resources and leadership for the AAEP shall have no liability to the advertiser for damages for any other remedy. the benefit of the equine industry. Printed by: Cadmus Professional Communications, Lancaster Division, Lancaster, PA. EQUINE VETERINARY EDUCATION / AE / NOVEMBERMAY 2016 2015 III

Fun, engagement help ambulatory practice win owner education events

“A long-term investment” is how Dr. Jay Joyce, owner of Total Equine Veterinary Associates (TEVA), a two-doctor

ambulatory practice in Leesburg, Va., summed up his 10 Dr. Jay Joyce years of hosting owner education seminars. Through per- sistence, feedback and adjustment, however, practice seminars have blossomed from discouraging audiences of the same 10 or 20 people to an encouraging mix of 60 or more current and prospective clients, largely newer female owners of one to three horses.

“You can’t wake up one day and hope you’re going to have 60 people sitting in front of you—it has to gain momentum over the years,” he said. “Even before that, you have to really believe that owner education is a priority, one of your foundations, and it’s something you demonstrate every day all day long.”

TEVA hosts five two-hour seminars annually at the Morven Park Equestrian Center, where Dr. Joyce estab- lished a business office in 2014. A series of three Thursday evening seminars is held in a large classroom during the winter when the practice is a little slower and horse owners aren’t so distracted. A pair of summer seminars, also on Thursday evenings, are held outdoors in TEVA associate Dr. Sallie Hyman demonstrates proper leg what Dr. Joyce describes as hands-on clinics where live bandaging with a willing volunteer. horses are enlisted for demonstrations such as interactive lameness workups or bandaging practice. All seminars are free. “It’s been a boon for the business because now we’re drawing people who aren’t our regular clients whereas “If you just stand up there and lecture for two for the first few years it was more or less our own people, and it’s hard to grow that way,” said Dr. Joyce. “Now hours, no one is ever going to come back.” that we’ve tapped these other businesses and groups, they’re feeding us people who know nothing about us. We always acknowledge their efforts to support us.” Fostering a fun, casual and engaging atmosphere has been essential to the growing popularity of TEVA Dr. Joyce mentions prices when demonstrating or seminars, which feature PowerPoint presentations, videos, discussing various procedures in order to “add perspec- photos, demonstrations, chalkboard sessions and plenty tive and take some of the mystery out of veterinary care,” of audience participation. It’s not uncommon for Dr. like when reinforcing the long-term cost benefit of main- Joyce to spotlight a client taking excellent care of their taining soundness as opposed to trying to fix a lame horses with a short guest feature. In addition, each horse. seminar has an underlying but often unrelated theme. For instance, John Denver night included pictures and music Seminar expenses run between $200 and $300, primarily clips of the acclaimed acoustic singer-songwriter. for food, beer and wine. Sometimes the cost is recouped from pharmaceutical reps, who often have a small stipend “We make it fun,” said Dr. Joyce. “If you just stand up for practice education; but Dr. Joyce doesn’t necessarily there and lecture for two hours, no one is ever going to view the seminar cost as an expense he needs to recover. come back.” Planning begins about five months in advance in order to Helping drive prospective client attendance has been market the events adequately since print publication TEVA’s relationships with equine service providers in the deadlines can be a couple of months out. In addition to area such as farriers and saddle fitters, some of whom the organic assist from the area’s equine service providers, have participated in prior seminars. continued on page IV IV EQUINE VETERINARY EDUCATION / AE / MAY 2016

Equine upper airway expert Dr. Norm Ducharme to deliver 2016 Milne Lecture

Renowned airway surgeon and airway physiology at exercise. This encompasses flow and pioneer in laryngeal procedures pressure mechanics, neuromuscular assessment of the Dr. Norm Ducharme will help neural control of airway patency, characterization of practitioners recognize, diagnose health status and disease (respiratory), and their influence and treat the variety of perfor- on modifying or developing new surgical diagnosis and mance-limiting upper airway treatments. Dr. Ducharme has published more than 150 problems when he delivers the peer-reviewed manuscripts and 37 book chapters 2016 Frank J. Milne State-of-the- Art Lecture on Dec. 4 during the Dr. Ducharme received his veterinary degree from the AAEP’s 62nd Annual Convention University of Montreal in 1979. After completing his in Orlando, Fla. residency in large animal surgery at Cornell in 1982, he served on faculty at the University of Guelph until 1986, Dr. Norm Ducharme Dr. Ducharme’s lecture, titled when he joined the faculty at Cornell. He is a diplomate “Equine Upper Airways: of the American College of Veterinary Surgeons and Intersection of Evidence-Based Data, Emerging served on the ACVS board of regents from 1997 to 2000 Discoveries and the ‘Veterinary Art’,” will focus on and from 2004 to 2007. He served as president of the clinical applications of various upper airway problems ACVS in 2006 and as chair of its board of regents in through examination of current research and emerging 2007. Additionally, he has served on the executive diagnostics and treatments. Included in his presentation committee of the World Equine Airways Symposium will be unpublished data on management of complica- since 1997. tions as well as advances in standing laryngoplasty. The convention lecture, sponsored by Platinum Dr. Ducharme is the James Law Professor of Surgery, Performance, is named for AAEP past president and dis- Section of Large Animal Surgery, at Cornell University tinguished life member Dr. Frank J. Milne. College of Veterinary Medicine. He served as medical director of the equine and large animal hospitals at The AAEP’s 62nd Annual Convention Cornell from 1990 to 2014, when the Cornell Ruffian will be held at Orlando’s Orange County Equine Specialists Clinic opened near Belmont Park in Convention Center, Dec. 3-7, 2016. Elmont, N.Y. Registration will open during the summer at www.aaep.org. His clinical and research interests center on sports medicine with an emphasis on equine upper respiratory

Fun, engagement help ambulatory practice win owner education events, continued upcoming seminars are mentioned on every invoice and upwards of 12 hours—the return on investment is well document that leaves the practice, and flyers are distribut- worth it. ed at client barns. Much of the marketing, however, is focused on social media and e-mail. One-third of attendees “We’ve gotten at least one new client out of almost every discover the seminars via Facebook, according to feedback seminar, which to me is a success,” he said. “The seminars forms submitted at the end of seminars and entered in a have also raised our profile in the community and raffle drawing to encourage submission. Feedback forms provided owners with an educational and entertaining also help determine future seminar topics. evening from which they take something out of.”

“What I want as a topic is almost never what my clients Editor’s Note: The AAEP offers its members complimen- want,” said Dr. Joyce. “I haven’t done a seminar in three tary client education PowerPoint presentations on core years that’s originated with me. It’s been based on equine health topics. Access presentations at www.aaep. popularity and feedback from attendees.” org/info/client-education.

While Dr. Joyce admits that seminar preparation can be a pain—creating a PowerPoint from scratch can take EQUINE VETERINARY EDUCATION / AE / MAY 2016 V

Expand your repro skills at summer Focus meeting

July 25-27, 2016 New Orleans, Louisiana

Broodmare subfertility is the No. 1 cause of economic loss in equine reproduction. This places added emphasis on your ability to successfully produce a live foal from mares that may have difficulty breeding, becoming pregnant or carrying a foal. Who’s who: Focus on the Breeding Shed will feature a select team of board-certified theriogenologists from academia and Whether you’re an experienced theriogenologist or a new private practice, including the current president of the practitioner seeking to add or expand reproductive American College of Theriogenologists: services in your practice, the AAEP’s Focus on the Breeding Shed will dispense the information you need to Dr. Ryan Ferris Dr. Semira Mancill improve the efficiency and success of client reproductive Dr. Sara Lyle Dr. Charlie Scoggin programs. Practical sessions and case-based discussions (2016 president, ACT) will help you improve success rates through effective treatment of subfertility in mares and stallions utilizing Next steps: Focus on the Breeding Shed will be held July proper facility design and appropriate resources, 25-27 at the Hilton Riverside in New Orleans, La. The early including assisted reproductive techniques (ART). registration deadline is June 30, and the early registration rate for AAEP members is $495. Register at www.aaep.org/ Meeting topics will include: info/focus-breeding. r
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Mid-Atlantic Equine Medical Center founder Dr. Peter Bousum dies

Dr. Peter Bousum, founding partner and president of The Mid-Atlantic Equine Medical Center in Ringoes, N.J., passed away March 26 following a long battle with prostate cancer. He was 74.

A 1969 graduate of the University of Pennsylvania School of Veterinary Medicine, Dr. Bousum traveled extensively with the U.S. and Canadian Equestrian Teams prior to founding The Mid-Atlantic Equine Medical Center in 1986. He also lectured locally and nationally on the topics of lameness and pre-purchase exams.

Dr. Bousum joined the AAEP in 1973 and served on its board of directors from 2009-2011. He also volunteered as a member of the Finance, Insurance, Owner Education, Performance Horse, Purchase Dr. Peter Bousum Exam and Sports Medicine committees. VI EQUINE VETERINARY EDUCATION / AE / MAY 2016

Thoroughbred racing fatalities decline 14% in 2015

The fatality rate for Thoroughbreds racing in the United States and Canada declined 14% from 1.89 per 1,000 starts in 2014 to 1.62 per 1,000 starts in 2015, according to statistics maintained in the Equine Injury Database and Dr. Scott Palmer recently released by The Jockey Club.

The overall fatality rate of 1.62 is the lowest since the Equine Injury Database began publishing statistics in 2009. The statistics are based on injuries that resulted in fatalities within 72 hours from the date of the race and reflect 299,121 starts made in the U.S. and Canada last year.

The 2015 fatality rates associated with each racing surface (with comparable 2014 rate in parentheses) were:

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Touch Point: Use client profiles to understand differences in service needs

A client’s age, gender, number of horses owned and type of horses owned all should affect the way vet- erinarians approach relationship and communication issues, according to AAEP market research.

The client who owns English sport horses values different things in veterinary service than the client with a single pleasure horse. The savvy and insightful veterinarian tailors his or her approach with each client based on the client’s individual needs and demographic profile. One size truly does not fit all.

The AAEP Touch program offers 13 different client profiles to help you better understand the individual needs of your future clients. You can view all profiles at client type can yield the blueprint for customizing your http://touch.aaep.org/-i-13.html. approach within your equine practice.

Although the top priorities for relationship attributes and Touch is exclusively available to AAEP members at services are consistent across all demographic groups, touch.aaep.org. You can log in using the same username paying attention to the subtle differences between each and password that you use for aaep.org. EQUINE VETERINARY EDUCATION / AE / MAYNOVEMBER 2016 2015 VII

Reinforce relationships, aid equine welfare with tribute gifts

The passing of a horse is an emotional time for your clients. Beyond offering sympathies, you can express your Our Hoofbeats Were Many, appreciation of the relationship through an Equine but Our Hearts Beat as One. Memorial Program donation in the deceased horse’s name —Author Unknown to the AAEP Foundation.

Upon receipt of an equine memorial contribution, the Foundation mails a sympathy card to the horse owner or designated contact. An empathic letter on the inside of the card conveys the donation in the horse’s name (amount not disclosed) and expresses the commitment of the Foundation and program partner Zoetis to supporting the mission of improving the welfare of horses.

“A number of years ago we made a practice decision to memorialize the horses that either passed away or had to be euthanized under our care via a donation to the AAEP The front of the equine memorial sympathy card received Foundation,” said Dr. Mitchell Rode, founder and owner by owners. of Clarke Equine Wellness and Performance in Berryville, Va. “I can’t begin to tell you how many clients have reached out to us with thanks for remembering their $25,000 annually, enabling participants to double the horses in this fashion or express the degree of heartfelt impact of their contributions. Since inception of the emotion in their letters. Many have been moved to make matching program in December 2008, Zoetis has contributions of their own upon learning of the nature of provided $175,000 in added funds. the Foundation. For us, it has been rewarding both for the practice—giving back to equine healthcare, welfare If you or your practice and research—and for our clients’ peace of mind during a would like to participate difficult time.” in the Equine Memorial Program, simply visit In 2015, the Foundation received 1,141 equine memorial www.aaepfoundation.org gifts totaling $64,372 from 232 donors and practices. and select the “Memorial Giving” option from the AAEP Educational Partner Zoetis generously matches “How to Help” drop-down menu. Equine Memorial Program donations up to a cumulative

AAEP Media Partner Profile: EQUUS and EquiManagement

EQUUS and EquiManagement magazines are proud to be AAEP Media Partners from Active Interest Media’s Equine Network. EQUUS is a monthly publication committed to helping horse owners understand the nature and needs of their horses. EQUUS works with AAEP to provide accurate, up-to-date information about horse care, and serves as a bridge between horse owners and veterinarians by presenting technical information in accessible, concise language.

EquiManagement is a publication and website dedicated to the business side of equine veterinary medicine, and it is polybagged with EQUUS and delivered quarterly to AAEP members and student members, as well as AAEVT members.

EQUUS has enjoyed a long partnership with the AAEP, and EquiManagement is a growing partner in the veterinary industry’s business education arena. Thank you for allowing our publications into your practices and making them valuable educational resources for you and your clients. VIII EQUINE VETERINARY EDUCATION / AE / MAY 2016

Experts from 35 countries gather for infectious diseases conference in Argentina AAEP Foundation sponsors Practitioners’ Day session By Jenny Evans

More than 400 attendees from 35 countries convened at the 10th International Equine Infectious Diseases

Conference, April 4-8 in Buenos Aires, Argentina, to Jenny Evans present and discuss the latest topics and trends of infectious diseases in all species of equids.

Held every four years in a different country, the conference focuses on emerging, re-emerging and other frequently-encountered infectious diseases that afflict many equine populations throughout the world.

The conference kicked off with a Practitioners’ Day, AAEP member Dr. Peter Timoney presents at the conference. sponsored by the AAEP Foundation, and was followed by a second Practitioners’ Day session and the beginning of is a lot more unknown and more studies are needed the “full conference” with the first day of oral abstract moving forward. presentations. Oral and poster presentations focused on 10 topic areas: biosecurity, diagnostics, emerging and re- The proceedings of abstracts from the conference are emerging diseases, gastrointestinal, neurological, other available via Open Access at www.sciencedirect.com/ system diseases, parasitology, reproduction, respiratory science/journal/07370806/39/supp/S. The proceedings do and working equids. The conference also included a not include the Practitioners’ Day talks. special session on the international movement of horses, Plans for the next conference, including the location, will chaired by Dr. Peter Timoney. be announced by the end of 2016. The Practitioners’ Day sessions offered a broad overview Jenny Evans, MFA, is the interim executive director of the and featured talks from the topic areas. A common theme UK Gluck Equine Research Foundation and marketing/ throughout the presentations was that while there is a lot promotion specialist senior of the UK Gluck Equine known in the realm of infectious diseases research, there Research Center.

Last chance to nominate a deserving colleague for an AAEP award Nomination deadline is June 1

Honor a colleague or group for their substantial contri- butions to the equine veterinary profession or well-being of horses with a nomination for an AAEP award.

Nominations are being accepted until June 1 for the following awards: AAEP Research Award Distinguished Educator – Academic Award Distinguished Educator – Mentor Award Distinguished Service Award George Stubbs Award Sage Kester Beyond the Call Award Dr. John W. Lee Jr., right, receives the 2015 Distinguished Educator – Mentor Award from 2015 AAEP President Dr. G. The Lavin Cup (The Equine Welfare Award) Kent Carter at the 61st Annual Convention in Las Vegas, Nev. A description of each award, list of past recipients and a Award recipients will be honored at the AAEP’s 62nd link to the nomination form is accessible at www.aaep. Annual Convention, which will be held Dec. 3-7 in org/info/aaep-annual-awards. A nomination form is also Orlando, Fla., at a new location—the Orange County available by contacting Sue Stivers at (859) 233-0147 or Convention Center. [email protected]. Time to Renew Your AAEP Membership !

Education

AAEP is a primary source for innovative CE, professional development and ethical standards.

Advocacy

AAEP is a respected source of information for influencing public policy.

AAEP Touch

AAEP is delivering tools and resources to strengthen the veterinarian-client relationship through AAEP Touch (touch.aaep.org).

Win a Free Convention Registration!

Renew your membership before midnight EDT on May 31 and be eligible to win one complimentary registration to the 62nd Annual Convention to be held Dec. 3-7, 2016, in Orlando, Fla.

Renew today at www.aaep.org/info/renew-membership X EQUINE VETERINARY EDUCATION / AE / MAY 2016

Chip in for equine welfare when renewing your AAEP membership As an AAEP member, and relief; equine advocacy and unwanted horses; you provide exceptional Equitarian programs, humanitarian efforts that help care to your clients’ working equids in underdeveloped nations; equine horses. Expand your community programs, including professional and youth healing touch and make development; and other benevolence programs. a difference in the lives of horses and their caretakers around the world with a Whether renewing your AAEP membership online or by voluntary contribution to the AAEP Foundation when mail or fax, you select the amount you want to contribute. renewing your AAEP membership in the coming weeks. Contributions are tax deductible where allowed by law, and your entire donation goes toward improving the Now in its 22nd year as the charitable arm of the AAEP to welfare of the horse because Foundation operating improve the welfare of the horse, the AAEP Foundation expenses are absorbed entirely by the AAEP. provides essential funds for scholarships and continuing education for students; equine research, with particular To learn more about the AAEP Foundation and how you emphasis on the study of laminitis; disaster preparedness can help us help horses, visit www.aaepfoundation.org.

The AAEP welcomes new members and congratulates recent graduates

New Members: James H. Tilley, DVM, Bonnerdale, AR Peter Agnew, DVM, Belli Park, Australia Jessie Ziegler, DVM, San Jose, CA Sheri Keele, DVM, Winona, TX Jeffrey Mahany, DVM, Savannah, GA Recent Graduates: Hoyt Rees, DVM, Jerome, ID Stephanie Campbell-Heron, DVM PhD, Dunnville, ON, Harumi Sano, DVM, Hokkaido, Japan Canada Gard Skaar, DVM, Tonsberg, Norway Samuelle Coulombe, DVM, Otterburn Park, QC, Canada Christopher C. Sumner, DVM, Rocky Mount, VA Marianne Joergensen, DVM, Brandon, FL

Opportunity Knocks!

Expanding Kentucky practice seeks associate Rapidly growing mixed animal practice with an extensive, Base salary based on experience, but will be Pro-Sal—so established client base. Our practice is expanding with a the sky is the limit. Additional bonus pay for emergency new construction veterinary hospital to include medical appointments and after hours surgery (i.e. colic surgery). and surgical services for equine, small animals, and small Competitive vacation/CE/medical insurance allowances. ruminants. Project to be completed May 2016. We have All licensure and liability expenses paid by the practice. an amazing location, facility, staff, and all of the “tools/ On-site housing available on a short-term basis if needed toys” to practice high-quality medicine and surgery. Our (less than 6 months). NO small animal emergency call, team is optimistic, hardworking (we play hard too) and rotating Equine call. we all still love what we do! Would prefer seasoned practitioner but will consider new What we are looking for: A veterinarian who isn’t content graduates. Equine experience, acupuncture certification or with mediocre care; someone who wants to be awesome chiropractic training are bonus qualities, but are on a daily basis. You should be confident in your skills absolutely not required for this position. Must be eligible and client communication abilities and enjoy the routine for Kentucky licensure. of preventative/wellness appointments as well as surgery and emergency/critical care. The right applicant is a good Please send resume to [email protected]; leader and self-motivator. phone (502) 938-4894. Website: Bannonwoodsvet.com EQUINE VETERINARY EDUCATION / AE / MAY 2016 XI

AAEP Media Partner Profile: The Horse: Your Guide To Equine Health Care

The Horse is dedicated to providing hands-on participants in the horse industry with reliable horse health information based on scientific research that experts explain. AAEP member veterinarians are important partners in this process, acting as invaluable idea generators, trusted sources, and respected reviewers. The Horse encourages productive dialogue between horse owner and veterinarian, ultimately promoting a positive veterinarian-client relationship and optimal equine health care practices.

All pages on TheHorse.com link to AAEP.org. The Horse magazine promotes AAEP and its missions through the AAEP Forum and a branding page in each issue. An editorial advisory board made up of AAEP members reviews content for each issue, helping staff ensure the material is accurate, up-to-date, and relevant to today’s horse owner.

The Horse offers a special discount on gift subscriptions given by AAEP members. Contact [email protected] for this discount.

Updated ‘Internal Parasites’ PowerPoint presentation available Your AAEP membership provides access to ready-made client education PowerPoint presentations on topics fundamental to equine health, including a newly updated presentation on internal parasites that incorporates recent revisions to the AAEP parasite control guidelines accessible at www.aaep.org/info/guidelines. Recommendations in the internal parasites guidelines and PowerPoint are based on: r
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parasite infection and more at risk for developing disease. The Internal Parasites PowerPoint presentation may be downloaded from www.aaep.org/info/client-education. Contact Dana Kirkland, sponsorship and advertising coordinator, for additional information at [email protected].

Member in the News

Dr. Lynn Criner appointed to Texas veterinary board Dr. Lynn Criner, owner of Texas Equine and Pet in Missouri City, Texas, has been appointed by Texas Governor Greg Abbott to a five-year term on the State Board of Veterinary Medical Examiners. The board’s mission is to establish and enforce policies to ensure the best possible quality of veterinary and equine dental provider services for the people of Texas.

Dr. Criner received her veterinary degree from Texas A&M University in 1995, and she holds a category II accreditation from the USDA Animal and Plant Health Inspection Service. Her board position will expire in August 2021. Dr. Lynn Criner XII EQUINE VETERINARY EDUCATION / AE / MAY 2016

AAEP Meetings and Continuing Education

June 19-22, 2016 July 25-27, 2016 July 25-27, 2016 December 3-7, 2016 360° Pain in the Neck – Focus on the Breeding Shed Focus on Soft Tissue 62nd Annual What’s the Story from New Orleans, Louisiana Lameness in the Convention Anatomy to Treatment Performance Horse Orlando, Florida Fort Collins, Colorado New Orleans, Louisiana (Sold Out) ForFor moremore infinformation,ormation ccontactontactt thee AAEPP officeoffice atat (859)) 233233-0147 01477 oror (800)) 443443-0177 01777 oror oonlinenline aatt www.aaep.org.www aaep org

Membership Benefits

AAEP Rounds a convenient forum to discuss specific veterinary topics

“For me, one of the most Rounds are e-mail communi- important AAEP member ties centered on a specific benefits is my ability to consult topic and are an ideal way with colleagues, both general to exchange ideas and share practitioners like myself as well expertise with AAEP as experts in our profession, members around the world. through the various AAEP Rounds. To be able to post a You can subscribe to the following Rounds: question on a case, including Business Education Parenting diagnostic images, and then Complementary & Podiatry benefit within hours or less Alternative (Integrative) Public Auction from the experience and Medicine Purchase Exam knowledge of others is a Dentistry Racing Dr. Harry W. Werner tremendous advantage for the Disease Alerts (new) Reproduction/Perinatology practitioner and, most English Sport Horse Solo Practitioner important, facilitates the best possible care for the sick or Equitarian Student injured horse. Well done, AAEP!” Infectious Disease Western Performance Horse —Harry W. Werner, VMD, North Granby, Conn. New Practitioners You don’t have to work through the challenges of equine In addition, you may also join the AAEP’s General veterinary practice alone. You can get answers and advice Discussion List, which is open to a wide variety of topics of from your fellow AAEP members by joining the interac- interest to AAEP members. For more information or to join tive discussion taking place year-round in any of 17 a Round, log into www.aaep.org and click the “My AAEP” AAEP Rounds. button.

AAEP group purchasing program qualifies your practice for substantial savings

As an AAEP member, you are eligible for substantial Participation in the group purchasing program is free with savings on supplies and services to operate your your AAEP membership. Depending on usage, savings veterinary practice. The AAEP and The Veterinary Club could exceed the annual cost of your AAEP membership. have partnered to provide all AAEP members with access to the industry’s most robust catalog To participate, AAEP members must register of contracts offering substantial, at www.theveterinaryclub.com. quantifiable savings. Discounts For more information about this are available at such companies membership benefit, contact as Verizon, Sprint, UPS, FedEx, Nick Altwies, membership services Staples, Office Depot and Sherwin-Williams. coordinator, at [email protected]. ”I recommend ColiCare for all of my patients, and my own horses are enrolled, too!”

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SmartPak.com/ColiCare | 1-800-461-8898 6:7/6:Ž JSVKYVUH[LPUQLJ[PVU Bisphosphonate For use in horses only. Brief Summary (For Full Prescribing Information, see package insert) CAUTION: Federal (USA) law restricts this drug to use by or on the order of a licensed veterinarian. DESCRIPTION: Clodronate disodium is a non-amino, chloro- containing bisphosphonate. Chemically, clodronate disodium is (dichloromethylene) diphosphonic acid disodium salt and is manufactured from the tetrahydrate form. INDICATION: For the control of clinical signs associated with navicular syndrome in horses. A stride forward CONTRAINDICATIONS: Horses with hypersensitivity to clodronate disodium should not receive OSPHOS. for Navicular Syndrome WARNINGS: Do not use in horses intended for human consumption. HUMAN WARNINGS: Not for human use. Keep this and all drugs out of the reach of children. Consult a physician in case of accidental Introducing OSPHOS, the new human exposure. PRECAUTIONS: As a class, bisphosphonates may be associated with gastrointestinal and renal toxicity. Sensitivity to drug FDA approved intramuscular associated adverse reactions varies with the individual patient. Renal and gastrointestinal adverse reactions may be associated with plasma concentrations of the drug. Bisphosphonates are bisphosphonate injection from excreted by the kidney; therefore, conditions causing renal impairment may increase plasma bisphosphonate concentrations resulting in an increased risk for adverse reactions. Concurrent Dechra Veterinary Products administration of other potentially nephrotoxic drugs should be approached with caution and renal function should be monitored. Use of bisphosphonates in patients with conditions or diseases affecting renal function is not recommended. Administration of bisphosphonates has been associated with abdominal pain (colic), discomfort, and agitation in horses. Clinical signs usually occur shortly after drug administration and may be associated with alterations in intestinal motility. In horses treated with OSPHOS these clinical signs usually Easily administered began within 2 hours of treatment. Horses should be monitored for at least 2 hours following administration of OSPHOS. via intramuscular Bisphosphonates affect plasma concentrations of some minerals and injection electrolytes such as calcium, magnesium and potassium, immedi- ately post-treatment, with effects lasting up to several hours. Caution should be used when administering bisphosphonates to horses with conditions affecting mineral or electrolyte homeostasis (e.g. hyper- kalemic periodic paralysis, hypocalcemia, etc.). Well tolerated* Proven efficacy* No The safe use of OSPHOS has not been evaluated in horses less than 4 years of age. The effect of bisphosphonates on the skeleton of in clinical trials at 6 months Reconstitution growing horses has not been studied; however, bisphosphonates post treatment required inhibit osteoclast activity which impacts bone turnover and may affect bone growth. Bisphosphonates should not be used in pregnant or lactating mares, or mares intended for breeding. The safe use of OSPHOS has not been evaluated in breeding horses or pregnant or lactating mares. Bisphosphonates are incorporated into the bone matrix, from where OSPHOS contains clodronate disodium, a bisphosphonate indicated they are gradually released over periods of months to years. The extent of bisphosphonate incorporation into adult bone, and hence, for the control of clinical signs associated with navicular syndrome the amount available for release back into the systemic circulation, is in horses. OSPHOS is the only FDA-approved bisphosphonate directly related to the total dose and duration of bisphosphonate use. Bisphosphonates have been shown to cause fetal developmental for use in horses that is labeled for intramuscular injection. abnormalities in laboratory animals. The uptake of bisphosphonates into fetal bone may be greater than into maternal bone creating a In a clinical trial evaluating OSPHOS in 86 horses, lameness possible risk for skeletal or other abnormalities in the fetus. Many drugs, including bisphosphonates, may be excreted in milk and may improved in 74.7% of horses by at least one grade 56 days be absorbed by nursing animals. after treatment. Only 9% of horses displayed clinical signs of Increased bone fragility has been observed in animals treated being uncomfortable, nervous, colicky and or pawing with bisphosphonates at high doses or for long periods of time. Bisphosphonates inhibit bone resorption and decrease bone turnover after receiving OSPHOS. Less than 1% of horses which may lead to an inability to repair micro damage within the bone. In humans, atypical femur fractures have been reported in patients experienced colic requiring treatment. on long term bisphosphonate therapy; however, a causal relationship has not been established. WITH OSPHOS THE BENEFITS ARE CLEAR . . . ADVERSE REACTIONS: The most common adverse reactions reported in the field study were clinical signs of discomfort or nervousness, colic and/or pawing. Other signs reported were lip licking, yawning, head shaking, injection site swelling, and hives/pruritus. Learn more online Call our 24 hour Tech Support www.dechra-us.com (866) 933-2472 www.equinelameness.com www.osphos.com

+PZ[YPI\[LKI`! As with all drugs, side effects may occur. In field studies, the most common side effects reported were signs of discomfort +LJOYH=L[LYPUHY`7YVK\J[Z or nervousness, colic, and/or pawing. OSPHOS should not be used in pregnant or lactating mares, or mares intended for *VSSLNL)V\SL]HYK:\P[L 6]LYSHUK7HYR2: breeding. Use of OSPHOS in patients with conditions affecting renal function or mineral or electrolyte homeostasis is not   recommended. Refer to the prescribing information for complete details or visit www.dechra-us.com. +LJOYH3[K CAUTION: Federal law restricts this drug to use by or on the order of licensed veterinarian. 6:7/6:PZHYLNPZ[LYLK [YHKLTHYRVM+LJOYH3[K * Freedom of Information Summary, Original New Animal Drug Application, NADA 141-427, for OSPHOS. April 28, 2014. (SSYPNO[ZYLZLY]LK 5(+( (WWYV]LKI`-+( EQUINE VETERINARY EDUCATION / AE / MAY 2016 239

Highlights of recent clinically relevant papers . Predicting grass sickness survival The authors preferred the LCP and would recommend use of a LCP for ventral stabilisation of selected cases of vertebral This retrospective observational study by Rachel Jago and fractures. colleagues in the UK aimed to determine whether bodyweight change can provide an objective predictor of survival in chronic equine grass sickness. Corneal grafting The records of 213 cases were reviewed: minimum weight, time from first weight to minimum weight, duration of disease In this retrospective study, Laura Mancuso and colleagues in on admission and duration of hospitalisation were compared in the USA describe the clinical course, outcomes, and both survivor (n = 114, 53.5%) and nonsurvivor (n = 99, 46.5%) complications associated with the use of commercially groups. The most common indication for euthanasia was available porcine urinary bladder extracellular matrix (ECM) recumbency and inability to stand. There was no significant grafts in equids with keratomalacia, and evaluate the fi difference in age or duration of disease prior to hospitalisation ef cacy of ECM grafts as a viable alternative to other between survivors and nonsurvivors: 50% of nonsurvivors were biomaterials for corneal grafting in equids. euthanased by 21 days and 75% by 32 days from disease Medical records were reviewed to identify equids with (i) onset. Survivors were hospitalised for longer than nonsurvivors, diagnosis with keratomalacia severe enough to warrant with 50% being discharged by Day 42. surgical repair and (ii) surgical repair with an extracellular Survivors had lower maximum bodyweight loss (as matrix graft. The inclusion criteria was met by 16 horses and percentage of initial weight) compared with nonsurvivors. one donkey (17 eyes). Survivors also had a significantly earlier day of minimum Twelve of 17 eyes (71%) were considered infected based weight and lower weight loss than nonsurvivors at all time on either corneal cytology (10/17, 59%) or corneal culture points. All nonsurvivors lost weight during hospitalisation, (12/17, 71%) positive for bacteria (8/17, 47%) or fungi (9/17, whereas some survivors rapidly reached their lowest weight 53%). Sixteen eyes (94%) were visual at the time topical with some even gaining weight during hospitalisation. The medications were discontinued. One operated eye ruptured greatest percentage bodyweight loss occurred between 0 5 days post operatively and was enucleated. Keratouveitis and 7 days of hospitalisation in both groups. This figure was developed approximately 2 weeks post operatively in all 14 similar in individuals from both groups, indicating that cases eyes that underwent regular examinations; this responded to fl can survive despite significant weight loss and that this systemic nonsteroidal anti-in ammatory drug therapy. alone is not an indicator for euthanasia. Survival prediction Extracellular matrix grafts may be a viable alternative to curves were compiled which enable survival rate to be other biomaterials for corneal grafting in equids. Advantages predicted by comparing a change in bodyweight between include commercial availability and shelf storage. any time intervals. The authors concluded that bodyweight fi change is a signi cant predictor of survival in chronic grass EHV-5 and pulmonary fibrosis sickness. In this study, Nicola Pusterla and colleagues in the USA assessed quantitative polymerase chain reaction (qPCR) for Internal fixation of cervical fractures equine herpesvirus-5 (EHV-5) in blood, nasal secretions and This case report by Fabrice Rossignol and colleagues in bronchoalveolar lavage (BAL) fluid for the laboratory France describes the surgical treatment outcome of cervical diagnosis of equine multinodular pulmonary fibrosis (EMPF). fractures in three horses. The diagnosis of EMPF requires histological examination of Three client-owned horses were referred for neck stiffness, lung tissue, obtained either by percutaneous lung biopsy or pain and ataxia after a cervical trauma caused by a fall. at post mortem examination. Due to the potential risks of lung Radiographic examination showed an oblique displaced biopsy, a positive result for EHV-5 in respiratory secretions fracture of the caudal aspect of the body of the second detected by qPCR is often used to support diagnosis. This cervical vertebra (C2) in Horse 1, an oblique displaced study aimed to determine the prevalence of EHV-5 detection fracture of the caudal aspect of C4 involving the disc in respiratory samples from confirmed cases of EMPF, cases between C4 and C5 in Horse 2, and a displaced transverse with other lung pathology and normal horses. Seventy adult fracture of the body of the axis (C2) extending to the lateral horses of varying ages and breeds were included. Based on arches and involving the vertebral canal in Horse 3. The clinical findings, BAL cytology, thoracic imaging and fracture in Horse 1 was reduced and stabilised using a histopathology of lung tissue, the horses were divided into 4 14-hole narrow dynamic compression plate (DCP), applied groups: EMPF, inflammatory airway disease (IAD), non-EMPF ventrally, and fixed with cancellous screws. A cervical fusion interstitial lung disease and the control (horses euthanased for was performed. Fracture fixation in Horses 2 and 3 was reasons not related to respiratory disease). Blood, nasal swabs performed using a 5-hole narrow locking compression plate and BAL fluid samples were tested for the presence of EHV-5 (LCP) and 5 mm locking screws. All horses showed and the viral load by qPCR. improvement and returned to full activity. The fracture The highest rate of detection of EHV-5 was in the EMPF healed in all horses. group in which 91% of blood samples, 82% of nasal swabs Internal fixation of cervical fracture in these horses was and 92% of BAL samples were positive. Viral loads in blood associated with minimal complications, and was associated were significantly higher in the EMPF group compared with with healing and a highly functional outcome in all horses. other groups. The viral load in nasal secretions was

© 2016 EVJ Ltd 240 EQUINE VETERINARY EDUCATION / AE / MAY 2016

significantly higher in EMPF cases than in the two other lung Multi-drug resistance was found in 47% of bacterial isolates. disease groups. After the EMPF group, the control group had Variables that significantly impacted survival included the highest rate of detection in nasal swabs (72%). The high haemorrhagic nasal discharge, laminitis, and thoracic rate of detection in the control group may be reflective of radiographs with a sharp demarcation between marked that population, or indicate a wider prevalence of latent caudal pulmonary alveolar infiltration and more normal- infection in healthy horses. When both blood and nasal appearing caudodorsal lung. secretions were EHV-5 positive (regardless of viral load), the The authors concluded that Klebsiella spp. should be sensitivity for that horse having EMPF was 90% and the considered as a differential diagnosis for horses presenting specificity 89.8%. with haemorrhagic pneumonia and for horses developing One horse in the IAD group was positive for EHV-5 on BAL pneumonia after mechanical ventilation. Multi-drug fluid, with all other positive BAL samples being in the EMPF resistance is common. Prognosis for survival generally is fair, group. Therefore the presence of EHV-5 in BAL fluid is a but is guarded for adult horses in which K. pneumoniae is consistent finding in EMPF. isolated as the primary organism. Detection of EHV-5 by qPCR in BAL samples, or EHV-5 detection in the combination of blood and nasal secretions Systemic pain assessment are consistent with EMPF in suspected clinical cases. This article by Janny de Grauw and Thijs van Loon from Nephrosplenic space obliteration using Utrecht University, the Netherlands, reviews systemic pain prosthetic mesh assessment in horses. Accurate recognition and quantification of pain in horses In this retrospective study, Megan Burke and Eric Parente is imperative for adequate pain management. This review report surgical complications, occurrence of post-obliteration describes parameters that can be used to detect pain in colic, long-term outcome, and return to previous function for horses, provides an overview of the various pain scales horses treated with prosthetic mesh obliteration of the developed (visual analogue scales, simple descriptive scales, nephrosplenic space. numerical rating scales, time budget analysis, composite pain This study included 26 horses undergoing nephrosplenic scales and grimace scales), and highlights their strengths and space obliteration using prosthetic mesh. A ProxplastTM mesh weaknesses for potential clinical implementation. The authors was secured to the nephrosplenic space with titanium helical discuss the available literature on the use of each pain coils in standing horses using laparoscopic technique. assessment tool in specific equine pain states (laminitis, All 26 horses undergoing mesh obliteration during the lameness, acute synovitis, post-castration, acute colic and study period survived to discharge. Long-term follow-up was post-abdominal surgery), including any problems with available for 25 horses, with 23 returning to their previous level sensitivity, reliability or scale validation as well as translation of of function, and 21 alive at the time of follow-up. Cause of results to other clinical pain states. This review also considers death was not associated with the surgical procedure in any future development and further refinement of currently case. Geldings and Warmbloods were overrepresented available equine pain scoring systems. compared to the hospital colic population. Ten horses (38%) demonstrated colic after mesh obliteration. All 10 horses were S. WRIGHT examined by a veterinarian and none were diagnosed with EVE Editorial Office recurrence of nephrosplenic entrapment. The authors concluded that mesh obliteration of the References nephrosplenic space is an effective alternative to suture closure for preventing nephrosplenic entrapment of the large Burke, M.J. and Parente, E.J. (2016) Prosthetic mesh for obliteration of the nephrosplenic space in horses: 26 clinical cases. Vet. Surg. 45, colon in horses. No complications related to mesh obliteration 201-207. were reported in this study population. Estell, K.E., Young, A., Kozikowski, T., Swain, E.A., Byrne, B.A., Reilly, C.M., Kass, P.H. and Aleman, M. (2016) Pneumonia caused by Klebsiella pneumonia Klebsiella spp. in 46 horses. J. Vet. Intern. Med. 30, 314-321. de Grauw, J.C. and van Loon, J.P.A.M. (2016) Systemic pain Klebsiella spp. are implicated as a common cause of assessment in horses. Vet. J. 209, 14-22. bacterial pneumonia in horses. In this retrospective study, Jago, R.C., Handel, I., Hahn, C.N., Pirie, R.S., Keen, J.A., Waggett, B.E. Krista Estell and colleagues in the USA describe the clinical and McGorum, B.C. (2016) Bodyweight change aids prediction of presentation and disease progression. survival in chronic equine grass sickness. Equine Vet. J. Epub Medical records were reviewed and 46 horses from which ahead of print doi/10.1111/evj.12551. Klebsiella spp. was isolated from the lower respiratory tract Mancuso, L.A., Lassaline, M. and Scherrer, N.M. (2016) Porcine urinary bladder extracellular matrix grafts (ACell Vetâ Corneal Discs) for were identified. Exact logistic regression was performed to keratomalacia in 17 equids (2012–2013). Vet. Ophthalmol. 19, 3-10. determine whether any variables were associated with Pusterla, N., Magdesian, K.G., Mapes, S.M., Zavodovskaya, R. and survival to hospital discharge. Kass, P.H. (2016) Assessment of quantitative polymerase chain Survival in horses <1 year old was 73% and overall survival reaction for equine herpesvirus-5 in blood, nasal secretions and in adults was 63%. For adults in which Klebsiella pneumoniae bronchoalveolar lavage fluid for the laboratory diagnosis of was the primary isolate, survival was 52%. In 11 horses equine multinodular pulmonary fibrosis. Equine Vet. J. Epub ahead of print doi/10.1111/evj.12545. mechanical ventilation preceded development of pneumonia. Complications occurred in 25/46 horses, with Rossignol, F., Brandenberger, O. and Mespoulhes-Riviere, C. (2016) Internal fixation of cervical fractures in three horses. Vet. Surg. 45, thrombophlebitis and laminitis occurring most frequently. 104-109.

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Case Report Resuscitation attempts in a foal with sudden cardiac arrest in the early recovery period K. Hopster*, J. Tüensmeyer† and S. B. R. Kästner Clinic for Horses and †Clinic for Small Animals, University of Veterinary Medicine Hannover, Germany. *Corresponding author email: [email protected]

Keywords: horse; foal; resuscitation; biphasic electrical defibrillation; ulna fracture; anaesthesia

Summary infants vs. older children (Meaney et al. 2006). Therefore, A 3-month-old female Warmblood foal, weighing 150 kg, was prognosis for successful resuscitation may be better in foals presented to the Equine Clinic of the University of Hannover compared to adult horses due to their smaller size and higher with a fracture of the ulna (type 5 fracture of the olecranon). chest wall compliance. Anaesthesia was induced with midazolam and ketamine after sedation with xylazine and maintained with isoflurane. Case details Anaesthesia was uneventful until cardiac arrest occurred in the A 3-month-old Warmblood, female foal, weighing 150 kg, was early recovery period. Cardiopulmonary resuscitation (CPR) presented to the Clinic for Horses of the University of Hannover was performed with chest compressions and electrical with a type 5 fracture of the olecranon of the left ulna. defibrillation. During resuscitation palpebral reflexes and spontaneous breathing returned but ventricular fibrillation Anaesthetic technique could not be converted to sinus rhythm by transthoracic defibrillation of the heart by electrical shock. The foal was presented with a severe lameness of the left front limb after trauma which had occurred a few hours previously. Radiographic examination showed an oblique fracture of the Introduction left olecranon (type 5) and fracture repair under general Cardiac arrest represents the most serious cardiovascular anaesthesia was performed. complication. The results of the confidential enquiry into The clinical examination and complete blood cell count perioperative equine fatalities (CEPEF) revealed that with blood chemistry showed no abnormal findings. The animal approximately one-third of unexpected deaths are a was premedicated with penicillin (Penicillin Grünenthal)1 consequence of cardiac arrest (Johnston et al. 2002, 2004). and flunixin meglumine (Flunidol)2 and sedated using This occurs most commonly during the maintenance phase of 0.5 mg/kg bwt xylazine (Xylazin 2%)2 and 0.03 mg/kg anaesthesia (78%) and with a lower incidence at induction butorphanol (Alvegesic)2. Anaesthesia was induced with (13%) or recovery (8%). midazolam (Midazolam-ratiopharm)3 (0.05 mg/kg bwt) and In some cases, the cause of cardiac arrest can be ketamine (Narketan)4 (2.2 mg/kg bwt) and maintained with determined, for example due to severe hyperkalaemia or isoflurane (Isofluran CP)2 in 100% oxygen. The foal was placed massive blood loss, but in most cases it occurs unexpectedly in right lateral recumbency and connected to a large and without warning, even in horses being adequately animal circle breathing system. Dobutamine (Dobutamin- monitored (Kellagher and Watney 1986; McGoldrick et al. ratiopharm 250 mg)3 was administered to effect with a 1998). rate of 0.1–1.3 μg/kg bwt/min to maintain a mean arterial Cardiac arrest is the cessation of functional circulation of blood pressure (MAP) above 70 mmHg. During anaesthesia, blood due to failure of the heart to contract effectively. The lactated Ringer’s solution (Ringer-Laktat-Lösung)5 and treatment for cardiac arrest is CPR to provide circulatory hydroxyethylstarch (Tetraspan 10%)5 were given with 10 ml/kg support, followed by defibrillation if a shockable rhythm is bwt/h and 1 ml/kg bwt/h, respectively. present. The goal of CPR is to restore blood flow to the organs The transverse facial artery was cannulated for invasive that cannot tolerate oxygen deprivation, most importantly the blood pressure monitoring and arterial blood sampling. Arterial brain and myocardium. In addition, if some blood flow can be blood pressure, heart rate (HR), respiratory rate (RR), end tidal maintained, there is a chance of delivering cardiovascular carbon dioxide partial pressure (ETCO2), inspired oxygen stimulants to the myocardium and vascular beds (Hubbell fraction (FIO2) and expiratory isoflurane concentration were et al. 1993). monitored with an anaesthetic multi-parameter monitor Performing CPR in an adult horse is not successful in most (Cardiocap/5)6. cases, but there are reports of successful outcome (Kellagher Total anaesthesia time was 3 h and was uneventful with a and Watney 1986; McGoldrick et al. 1998) when the arrest was stable cardiovascular status and preserved palpebral and recognised early and treated aggressively. One reason corneal reflex, ventromedial rotation of the eye. Spontaneous discussed for the poor outcome in horses is the large size of breathing was maintained with a frequency of 6–8 these patients and decreased elasticity of the chest, breaths/min and arterial carbon dioxide partial pressure did especially in adult horses. Chest compressions lead to higher not increase over 58 mmHg. End-tidal CO2 partial pressure cardiac output in infants and immature animals compared to ranged between 38 and 51 mmHg and ETCO2-PaCO2 older individuals (Dean et al. 1990) and this could be the cause differences were always between 5 and 10 mmHg. Arterial for better outcomes from so-called in-hospital cardiac arrest in blood gases (ABL800 Flex)7 and electrolytes (Na+,K+,Cl−,Ca2+,

© 2014 EVJ Ltd 242 EQUINE VETERINARY EDUCATION / AE / MAY 2016

glucose level) were checked every 20 min. Arterial oxygen vessels explaining the haemothorax or defects of relevant partial pressure ranged between 380 and 450 mmHg and no nerves were identified on necropsy. abnormalities in electrolyte status or blood glucose level were found. Mean arterial blood pressure ranged between 70 and Discussion 90 mmHg, requiring 0.5 μg/kg bwt/min dobutamine. Heart rate The reported case demonstrates that thoracic compressions ranged between 30 and 38 beats/min and no abnormal at a rate of 40–60 compressions/min in a 3-month-old foal findings in ECG were observed. After successful surgery the under general anaesthesia were successful in achieving foal was disconnected from the anaesthetic machine and sufficient blood flow to the brain to regain spontaneous monitor. Thereafter, the foal’s legs were hobbled, the hoist respiration and palpebral reflexes, despite the fact that we attached and the foal suspended upside down while were unable to convert cardiac rhythm to a sinus rhythm. transported into the recovery box and placed in right lateral Unexpected cardiac arrest in anaesthetised horses has recumbency. been previously reported (Kellagher and Watney 1986; McGoldrick et al. 1998). There are many reasons for cardiac arrest such as congestive heart failure, cardiac dysrhythmias, Cardiopulmonary resuscitation increased vagal tone, electrolyte imbalances, e.g. Immediately after reaching the recovery box, the foal stopped hyperkalaemia, disturbance of the acid-base-status, massive breathing for about 1 min. Intermittent pressure ventilation with blood loss, overdose of anaesthetic drugs with overly deep 100% oxygen by means of a demand valve (Resuscitation plane of anaesthesia, resulting in severe hypovolaemia and/or Demand Valve Equine)8 with a frequency of 4 breaths/min hypoxia. was initiated immediately. No heart sounds were audible In the post operative period cardiac arrest can occur and no pulse was palpable indicating cardiac arrest. Chest when horses are moved or are hoisted with positional compressions were initiated with a frequency of 40–60 changes. The aetiology is unknown but may be related to compressions/min and the foal was connected to a circle redistribution of blood volume. Sudden cardiac arrest has also rebreathing system and a capnograph (Cardiocap/5)6. been attributed to vagal stimulation (Hale and Chambers Measurement of ETCO2 showed values between 12 and 1989). Due to the fact that monitoring is limited during the 16 mmHg and 1.5 mg adrenaline (Suprarenin)9 (0.01 mg/kg transport from the surgery theatre to the recovery box the bwt) and 1.5 mg atropine (atropinum sulfuricum)10 redistribution of blood leading to severe hypotension as well as (0.01 mg/kg bwt) were injected i.v. and infusion of an isotonic a massive vagal stimulation leading to severe bradycardia or crystalloid (Ringer-Laktat-Lösung)5 started. A lead II ECG cardiac arrest can happen without immediate recognition. (Cardiocap/5)9 showed asystole and the adrenaline dose was The heart is innervated by vagal and sympathetic fibres repeated while external thoracic compressions were forming the cardiac plexus. The right vagus nerve primarily continued. Ventricular fibrillation subsequently occurred and innervates the SA node, whereas the left vagus innervates the transthoracic electrical defibrillation (cardiolife TEC 5521)11 AV node; however, there can be significant overlap in the (270 joule) was attempted without achieving a sinus rhythm. anatomical distribution. In horses, the sympathetic fibres Defibrillation was performed with a biphasic defibrillator and innervating the heart come from the cervicothoracic ganglion one defibrillator paddle was placed between the front legs (ganglion stellatum) (Schummer and Habermehl 1996). The left while the other one was placed on the left chest wall over the and right ganglia are located near the trachea and the longus area of the apex of the left heart. The hair over the colli muscle in the first intercostal space. It cannot be ruled out defibrillation sides was clipped and a conductive electrode that the trauma which led to the fracture of the ulna also gel applied to the paddles. Chest compressions were resumed caused damage or irritation of the nerves or ganglia within the immediately after the shock and administration of adrenaline thoracic cavity innervating the heart, although there was no and electrical defibrillation (270 joule) were repeated, without morphological evidence for this on post mortem examination. leading to sinus rhythm. Twenty minutes after starting chest In adult horses limited cardiac output is achievable using compressions, palpebral reflexes returned and the foal started closed chest cardiopulmonary resuscitation due to the large breathing spontaneously with a regular rate of 8–10 size and low chest compliance (Hubbell et al. 1993). In man breaths/min and an ETCO2 ranging from 16–20 mmHg. When and small animals, size and age of the patient influence compressions were stopped, no peripheral pulse was the outcome of resuscitation giving a better prognosis for detectable and ECG still showed venticular fibrillation. After small and/or young individuals (Dean et al. 1990; Meaney stopping the chest compressions, the foal went into apnoea et al. 2006). Therefore we assume that performing cardiac and palpebral reflexes disappeared. Thoracic compression resuscitation in a 3-month-old foal increases the possibility was restarted and spontaneous breathing and palpebral of achievement of sufficient myocardial and pulmonary reflexes reoccurred. No peripheral pulse was detected. A third perfusion compared to case reports describing resuscitation in dose of 1.5 mg adrenaline was given and because of the adult horses (Kellagher and Watney 1986; McGoldrick et al. presence of ventricular fibrillation further attempts of 1998). extrathoracic electrical defibrillation (270 joule) were made In the present case CPR was performed immediately after without success. After stopping thoracic compression, the foal diagnosing cardiac arrest. A high success rate described in an stopped spontaneous breathing within a minute. Fifty minutes experimental trial with ponies was attributed to early after detection of cardiac arrest a transthoracic ultrasound recognition of the problem, small size of the patient and was performed and no cardiac action could be detected. relatively short duration of cardiopulmonary resuscitation The decision to open the chest was made and a haemothorax leading to success (Frauenfelder et al. 1981). In our case, was diagnosed. Cardiopulmonary resuscitation was stopped cardiac arrest was recognised at least within 3–4 min, which on the owners’ request. A post mortem examination was was the time between leaving theatre and reaching the performed and no fractures of the ribs, rupture of any large recovery box. Frauenfelder et al. (1981) noted that periods

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between cardiac arrest and beginning resuscitation longer defibrillator was used instead of a monophasic one, because than 2 min made the prognosis worse. Ventilation with oxygen this multiple direction current lowers the threshold for and thoracic compressions were started immediately after successful defibrillation (Jones et al. 1990; Schneider et al. recognising cardiac arrest. The European Resuscitation 2000). In man and small animals a successful threshold for Council (ERC) states that chest compression is the most biphasic electrical defibrillation is 2–4 joule/kg (Gliner et al. important action in resuscitation (Anon 2005). The 1995; Schneider et al. 2000; Egger 2007). Due to limitations of recommended chest compression rate in man indicates that a the available defibrillator maximum energy for electrical compression rate of higher than 100 compressions/min is better defibrillation was 270 joule resulting in an energy ratio of at than less than 80 compressions/min with a ratio of compression least 1.8 joule/kg. This might explain why transthoracic to decompression of 1:1 (Kern et al. 1992) to maintain best defibrillation was unsuccessful. possible peripheral perfusion and cardiac output. In one case report a compression rate of 20 compressions/min led to a Conclusion mean systolic blood pressure of only 58 mmHg in ponies Cardiopulmonary resuscitation with chest compressions at a (Frauenfelder et al. 1981). Therefore, we tried to achieve a rate of 40–60 compressions/min in a 150 kg foal were able to high compression rate. In addition to compression rate, obtain sufficient blood flow resulting in return of palpebral and compression force is also important. A high rate with sufficient corneal reflexes and spontaneous breathing. Biphasic force is hard to achieve in large size patients. transthoracic electrical defibrillations were not able to convert The RECOVER effort states that open chest CPR leads to ventricular fibrillation to sinus rhythm. greater survival, perfusion pressures and organ blood flow in comparison to closed-chest CPR (Hopper et al. 2012). In our foal, closed chest compression resulted in blood flow Authors’ declaration of interests conditions sufficient to result in return of palpebral and corneal No competing interests have been declared. reflexes and spontaneous breathing 20 min after initiating resuscitation indicating a sufficient perfusion. Therefore we Manufacturers’ addresses decided initially not to open the chest for cardiac massage. 1Grünenthal GmbH, Aachen, Germany. Advanced life support includes repeated doses of 2CP-Pharma GmbH, Burgdorf, Germany. adrenaline. Adrenaline increases coronary and cerebral 3Ratiopharm GmbH, Ulm, Germany. perfusion pressure by increasing vessel tone and 4Vétoquinol GmbH, Ravensburg, Germany. vasoconstriction. However, adrenaline also leads to an 5B. Braun, Melsungen AG, Germany. increased myocardial oxygen consumption which is 6Datex-Ohmeda GmbH, Duisburg, Germany. contraindicated in cardiac arrest. Vasopressin has been shown 7Radiometer GmbH, Willich, Germany. to be effective in various laboratories and was associated with 8ASS Medical, Oxfordshire, UK. superior survival compared to adrenaline (Lindner et al. 1995; 9Sanifia-Aventis GmbH, Frankfurt am Main, Germany. Wenzel et al. 1999). Atropine is given in man at initiation of 10Eifelfango GmbH & Co. KG, Bad Neuenahr-Ahrweiler, Germany. 11 resuscitation in cases with pulseless electrical activity of the Nihon Corporation, Rosbach, Germany. heart or asystole (Stueven et al. 1984) because both can be precipitated or exacerbated by excessive vagal tone. References However, studies in man found no difference in outcome when Anon (2005) Principles of training in resuscitation. European high or low dose atropine was given as the initial resuscitation Resuscitation Council Guidelines for Resuscitation http://www medication (Coon et al. 1981), or even if the standard dose .erc.edu/index.php/guidelines_download_2005/en/. was given or a placebo (DeBehnke et al. 1995). European Blecic, S., Chaskis, C. and Vincent, J.L. (1992) Atropine administration in experimental electromechanical dissociation. Am. J. Emerg. Med. Resuscitation Council Guidelines for Resuscitation states 10, 515-518. ‘Atropine is no longer recommended for routine use in asystole Coon, G.A., Clinton, J.E. and Ruiz, E. (1981) Use of atropine for or pulseless electrical activity (PEA)’. In contrast to these bradyasystolic prehospital cardiac arrest. Ann. Emerg. Med. 10, findings in an experimental study with dogs, a complete loss of 462-467. vagal tone improved the rate of return of spontaneous Dean, J.M., Koehler, R.C., Schleien, C.L., Berkowitz, I., Michael, J.R., circulation (Blecic et al. 1992). Due to the fact that increased Atchison, D., Rogers, M.C. and Traystman, R.J. (1990) Age-related vagal tone could not be excluded we decided to add effects of compression rate and duration in cardiopulmonary atropine to medical resuscitation. resuscitation. J. Appl. Physiol. 68, 554-560. Following the administration of adrenaline ventricular Debehnke, D.J., Swart, G.L., Spreng, D. and Aufderheide, T.P. (1995) Standard and higher doses of atropine in a canine model of fibrillation occurred and therefore electrical defibrillation was pulseless electrical activity. Acad. Emerg. Med. 2, 1034-1041. performed. The American Heart Association (AHA) defines Egger, C. (2007) Anaesthetic complications, accidents and defibrillation as a process in which an electronic device emergencies. In: BSAVA Manual of Canine and Feline Anaesthesia (defibrillator) gives an electric shock to the heart to re-establish and Analgesia, 2nd edn., Eds: C. Seymour and T. Duke-Novakovski, normal contraction rhythms in a heart having dangerous British Small Animal Veterinary Association, Gloucester. pp 310-332. arrhythmia or in cardiac arrest. Defibrillators can be mono- or Frauenfelder, H.C., Fessler, J.F., Latshaw, H.S., Moore, A.B. and Bottoms, biphasic. Whereas monophasic waveforms vary in the speed G.D. (1981) External cardiovascular resuscitation of the anesthetized pony. J. Am. Vet. Med. Ass. 179, 673-676. with which the waveform returns to the zero voltage point, either gradually (damped sinusoidal) or instantaneously Gliner, B.E., Lyster, T.E., Dillion, S.M. and Bardy, G.H. (1995) Transthoracic defibrillation of swine with monophasic and biphasic waveforms. (truncated exponential), biphasic waveforms deliver current Circulation 92, 1634-1643. that first flows in a positive direction for a specified duration. In Hale, G.J. and Chambers, J.P. (1989) Bradycardia and asystole the second phase the device reverses the direction of current following attempted arterial cannulation in a horse under general so that it flows in a negative direction. In our case a biphasic anaesthesia. J. Ass. Vet. Anaesth. 16, 10-11.

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Clinical Commentary Cardiopulmonary resuscitation: A waste of time? G. D. Hallowell School of Veterinary and Medicine and Science, University of Nottingham, Sutton Bonington, Leicestershire, UK. Corresponding author email: [email protected]

For many equine practitioners, the thought of one of their whereby changes in thoracic volume promote forward blood cases arresting fills them with a two-pronged dread. The first is flow (Haas et al. 2003). In order to achieve this, horses should being unsure how to approach this quite unusual emergency be positioned on a hard surface in lateral recumbency and and the second is the thought that whatever effort is invested hands should be placed over the widest portion of the chest is likely to be futile as was the case in the report published by wall (caudodorsally) and the chest should be depressed to Hopster et al. (2016) in this issue. approximately 30–50% of its width (Fletcher et al. 2012), with We have little evidence regarding the best approach to a 1:1 compression to relaxation rate at 100 compressions/min cardiopulmonary arrest in our equine cases, but there is a (Palmer 2007), which correlates to the underlying beat of plethora of evidence that can be extrapolated from human ‘Staying Alive’, written and sung by the Bee Gees and used and small animal cases. In fact the Veterinary Emergency to promote the British Heart Foundation Hands-only CPR and Critical Care Society published the RECOVER guidelines Campaign. The RECOVER guidelines suggested that this chest in 2012 are largely applicable to foals and I would compression rate may be too low, and as such may be recommend anyone interested in further information to read revised in the future (Hopper et al. 2012). ‘Push hard, push these recommendations (Fletcher et al. 2012), in addition to fast’ (Travers et al. 2010) needs to be the approach in these an extremely valuable, albeit slightly older review specifically cases and even then cardiac output will only be 25–30% of aimed at the foal (Palmer 2007). the normal resting amount (Cave et al. 2010). The chest There is excellent evidence in other species, including compression rate in the Hopster et al. (2016) case report was man, that certain factors increase the chances of success significantly less than this, which will have compromised and these include having an area or at least a collection of coronary artery blood flow. The other fact to bear in mind equipment ready for when disaster happens and having when performing CPR is how physically as well as mentally appropriately trained staff. When did you last go through a tiring it is. The authors (Hopster et al. 2016) did not discuss how simulated arrest in your practice? If you anaesthetise or many people were involved in resuscitating this foal, but the hospitalise brood mares or foals, this should probably be recommendations are to change the person performing done in the preparation phase to the foaling season when chest compressions every 2–3 min as they fatigue and other preparations are underway. Also many of us have a perform substandard compressions, both reducing the resuscitation box of drugs, but is all the equipment you need amount of thoracic compression and rate. in one place with it? A resuscitation simulation allows staff to Assessment of success of chest compressions is best be familiar with what will happen and what their role is likely measured using end-tidal carbon dioxide (ETCO2). It is to be, as well as identifying any missing or broken equipment accepted that 12–18 mmHg suggests adequate cardiac or out of date drugs. output in this situation and was achieved in the case When horses arrest under anaesthesia, all of the reported by Hopster et al. (2016). However this can be equipment we are likely to need will be available and in most transiently artefactually increased with epinephrine circumstances the animal will be intubated making airway administration. In nonintubated animals or if ETCO2 is management and breathing much easier. Human unavailable, pupil size can be monitored to help to assess cardiopulmonary resuscitation (CPR) guidelines were effectiveness of chest compressions. When blood flow to the overhauled approximately 5 years ago, when chest brain is substandard, pupils will become markedly dilated, compressions for out-of-hospital arrest were elevated above whereas with adequate flow pupils will be neutral in size. airway and breathing for adults so the Airway, Breathing, Both of these techniques provide timely information to the Circulation and Drugs became Circulation (Drugs), Airway person performing chest compressions, allowing them to and Breathing as most adults usually sustain cardiac arrest. change depth and rate. Palpation of peripheral pulses The guidelines for paediatric patients remained Airway, wastes time and provides minimal information. Chest Breathing, Circulation and Drugs and are probably more compressions should not be stopped for more than 10 sec appropriate for foals, particularly those at or around birth. every 2 min for intervention and to check the Anaesthetic deaths may be either primarily respiratory or electrocardiogram. cardiac in origin. However, time is of the essence...the sooner If foals are intubated, there is no need for coordination resuscitation is implemented, the more likely a favourable between compressions and breaths, whereas if breaths are outcome will occur and thus chest compressions should begin given using a self-inflating bag valve device, some whilst equipment and drugs are being located if this does not coordination is required. One fast breath every 10 sec should occur in theatre. The potential time reported to implement be given. There is no evidence to suggest that 100% oxygen CPR from possible arrest (3–4 min) in Hopster et al. (2016) may is better than room air (Hopper et al. 2012). If at all possible, have contributed to the adverse outcome in this case. having someone accurately timing the whole procedure, Chest compressions to aid circulation in foals or mature both from the start of CPR as well as when breaths should be equine cases involves using the ‘thoracic pump’ method administered is extremely helpful.

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For many, the focus of CPR is all about pharmacological Doxopram does not feature in any of the resuscitation agents. However, the evidence for the value of these agents guidelines for human or small animal patients and has no is either completely lacking or weak (Kattwinkel et al. 2010; place in large animal resuscitation either. The two main Neumar et al. 2010). Drugs for resuscitation should be disadvantages of using this drug is that it is used instead of administered intravenously as they were in the case by providing appropriate airway management and also Hopster et al. (2016). Absorption from sublingual and increases cerebral oxygen demand, which in the face of intratracheal administration is poor at best. The hypoxia will increase the likelihood of neurological diseases recommendations now are that these drugs should not be such as perinatal asphyxia syndrome. administered into the heart – the detrimental effects far In conclusion, the best approach to cardiopulmonary outweigh any benefits. In terms of the drugs administered, resuscitation is to make every effort to prevent it and institute low dose adrenaline (or vasopressin if you have it) are the CPR when ETCO2 begins to fall or bradycardia and reduced mainstay for management of cardiac arrest. Magnesium respiratory rate are detected. Every effort should be made to sulphate and lidocaine may also be of value with pulseless observe patients in at risk periods so that CPR can be ventricular tachycardia (Fig 1). As Hopster et al. (2016) state, initiated as quickly as possible. As soon as an animal arrests, atropine is no longer recommended in human guidelines and chest compressions should be started at 100/min and probably has minimal place in veterinary resuscitation, unless ventilation (one fast breath every 10 sec) implemented. a likely vagal event has triggered the arrest. Vascular access should then be made available and low

Arrest or impending arrest

Initiate chest compressions 100 per minute

Establish an airway Ventilate 1 fast breath every 10 seconds

Establish venous access – intravenous or intra-osseous

Low dose epinephrine (0.01 mg/kg) every 3 to 5 minutes

Place ECG and check rhythm Do not stop chest compressions for more than 10 seconds Attach capnograph

SHOCKABLE RHYTHM NON - SHOCKABLE RHYTHM

Ventricular fibrillation Asystole or pulseless electrical Pulseless ventricular tachycardia activity

Defibrillation if available (<200 Kg) Chest compressions 100 per minute Chest compressions Check rhythm after 2 minutes 100 per minute Check cardiac rhythm after 2 Low dose epinephrine (0.01 mg/kg) minutes every 3 to 5 minutes Check cardiac rhythm after 2 SHOCKABLE RHYTHM minutes Epinephrine 0.01 mg/kg Lidocaine 1 mg/kg – maximum 3 doses Magnesium sulphate 20 mg/kg – Fig 1: Schematic diagram adapted maximum 5 doses from Palmer (2007) showing a logical approach to cardiopulmonary Defibrillation if available (<200 Kg) resuscitation in arrest or impending arrest.

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dose adrenaline (0.01 mg/kg bwt) administered. Monitoring mechanism during cardiopulmonary resuscitation. Resuscitation 58, including electrocardiogram should be attached whilst CPR 113-116.

continues (Fig 1). ETCO2 or pupil size should be used to assess Hopper, K., Epstein, S.E., Fletcher, D.J., Boller, M. and RECOVER Basic effectiveness of chest compressions. Having all of the Life Support Domain Worksheet Authors (2012) RECOVER evidence and knowledge gap analysis on veterinary CPR. Part 3: basic life equipment and drugs readily available with trained staff will support. J. Vet. Emerg. Crit. Care (San Antonio) 22, Suppl. 1, improve likely outcome, depending on the underlying cause. S26-S43. In summary, CPR is not a waste of time, and success, Hopster, K., Tuensmeyer,€ J. and Kastner,€ S.B.R. (2016) Resuscitation particularly in neonates is achievable, but not in every case. attempts in a foal with sudden cardiac arrest in the early recovery We all need to ensure that the reason for failure of CPR was period. Equine Vet. Educ. 28, 241-244. the underlying disease process and not an iatrogenic cause Kattwinkel, J., Perlman, J.M., Aziz, K., Colby, C., Fairchild, K., Gallagher, or poor CPR technique. J., Hazinski, M.F., Halamek, L.P., Kumar, P., Little, G., McGowan, J.E., Nightengale, B., Ramirez, M.M., Ringer, S., Simon, W.M., Weiner, G.M., Wyckoff, M., Zaichkin, J. and American Heart Association (2010) Neonatal resuscitation: 2010 American Heart Association References Guidelines for cardiopulmonary resuscitation and emergency Cave, D.M., Gazmuri, R.J., Otto, C.W., Nadkarni, V.M., Cheng, A., cardiovascular care. Pediatrics 126, e1400-e1413. Brooks, S.C., Daya, M., Sutton, R.M., Branson, R. and Hazinski, M.F. Neumar, R.W., Otto, C.W., Link, M.S., Kronick, S.L., Shuster, M., (2010) Part 7: CPR techniques and devices: 2010 American Heart Callaway, C.W., Kudenchuk, P.J., Ornato, J.P., McNally, B., Silvers, Association Guidelines for cardiopulmonary resuscitation and S.M., Passman, R.S., White, R.D., Hess, E.P., Tang, W., Davis, D., Sinz, emergency cardiovascular care. Circulation 122,18Suppl. 3, S720- E. and Morrison, L.J. (2010) Part 8: adult advanced cardiovascular S728. life support: 2010 American Heart Association Guidelines for Fletcher, D.J., Boller, M., Brainard, B.M., Haskins, S.C., Hopper, K., cardiopulmonary resuscitation and emergency cardiovascular McMichael, M.A., Rozanski, E.A., Rush, J.E., Smarick, S.D. and care. Circulation 122,18Suppl. 3, S729-S767. American College of Veterinary Medicine and Veterinary Palmer, J.E. (2007) Neonatal foal resuscitation. Vet. Clin. N. Am.: Emergency and Critical Care Society. (2012) RECOVER evidence Equine Pract. 23, 159-182. and knowledge gap analysis on veterinary CPR. Part 7: clinical Travers, A.H., Rea, T.D., Bobrow, B.J., Edelson, D.P., Berg, R.A., Sayre, guidelines. J. Vet. Emerg. Crit. Care (San Antonio) 22, Suppl. 1, M.R., Berg, M.D., Chameides, L., O’Connor, R.E. and Swor, R.A. S102-S131. (2010) Part 4: CPR overview: 2010 American Heart Association Haas, T., Voelckel, W.G., Wenzel, V., Antretter, H., Dessl, A. and Guidelines for cardiopulmonary resuscitation and emergency Lindner, K.H. (2003) Revisiting the cardiac versus thoracic pump cardiovascular care. Circulation 122,18Suppl. 3, S676-S684.

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Hopper, K., Epstein, S.E., Fletcher, D.J., Boller, M. and RECOVER Basic Life McGoldrick, T.M., Bowen, I.M. and Clarke, K.W. (1998) Sudden cardiac Support Domain Worksheet Authors (2012) RECOVER evidence and arrest in an anaesthetised horse associated with low venous oxygen knowledge gap analysis on veterinary CPR. Part 3: basic life support. tensions. Vet. Rec. 142, 610-611. J. Vet. Emerg. Crit. Care 22, 26-43. Meaney, P.A., Nadkarni, V.M., Cook, E.F., Testa, M., Helfaer, M., Kaye, W., Hubbell, A.E., Muir, W.W. and Gaynor, J.S. (1993) Cardiovascular effects Larkin, G.L. and Berg, R.A. (2006) Higher survival rates among of thoracic compression in horses subjected to euthanasia. Equine younger patients after pediatric intensive care unit cardiac arrests. Vet. J. 25, 282-284. Pediatrics 118, 2424-2433. Johnston, G.M., Eastment, J.K., Taylor, P.M. and Wood, J.L.N. (2004) Is Schneider, T., Martens, P.R., Paschen, H., Kuisma, M., Wolcke, B., Gliner, isoflurane safer than halothane in equine anaesthesia? Results from B.E., Russell, J.K., Weaver, W.D., Bossaert, L. and Chamberlain, D. a prospective multicentre randomised controlled trial. Equine Vet. J. (2000) Multicenter, randomized, controlled trial of 150-J biphasic 36, 64-71. shocks compared with 200- to 360-J monophasic shocks in the Johnston, G.M., Eastment, J.K., Wood, J.L.N. and Taylor, P.M. (2002) The resuscitation of out-of-hospital cardiac arrest victims. Optimized confidential enquiry into perioperative equine fatalities (CEPEF): Response to Cardiac Arrest (ORCA) Investigators. Circulation 102, mortality results of phases 1 and 2. Vet. Anaesth. Analg. 29, 159-170. 1780-1787. Jones, J.L., Swartz, J.F., Jones, R.E. and Fletcher, R. (1990) Increasing Schummer, A. and Habermehl, K.H. (1996) Reizbildungs – und fibrillation duration enhances relative asymmetrical biphasic versus Erregungsbildungssysteme des Herzens. In: Nickel Schummer Seiferle monophasic defibrillator waveform efficacy. Circ. Res. 67, 376-384. Lehrbuch Der Anatomie Der Haustiere Band 3, 3 edn., Eds: K.H. Kellagher, R.E. and Watney, G.C. (1986) Cardiac arrest during Habermehl, B. Vermerhaus, H. Wilkens and H. Waibl, Paul Paray anaesthesia in two horses. Vet. Rec. 119, 347-349. Verlag, Berlin. pp 36-38. Kern, K.B., Sanders, A.B., Raife, J., Milander, M.M., Otto, C.W. and Ewy, Stueven, H.A., Tonsfeldt, D.J., Thompson, B.M., Whitcomb, J., Kastenson, G.A. (1992) A study of chest compression rates during E. and Aprahamian, C. (1984) Atropine in asystole: human studies. cardiopulmonary resuscitation in humans. The importance of Ann. Emerg. Med. 13, 815-817. rate-directed chest compressions. Arch. Intern. Med. 152, 145-149. Wenzel, V., Lindner, K.H., Krismer, A.C., Miller, E.A., Voelckel, W.G. and Lindner, K.H., Prengel, A.W., Pfenninger, E.G., Lindner, I.M., Strohmenger, Lingnau, W. (1999) Repeated administration of vasopressin but not H.U., Georgieff, M. and Lurie, K.G. (1995) Vasopressin improves vital epinephrine maintains coronary perfusion pressure after early and organ blood flow during closed-chest cardiopulmonary late administration during prolonged cardiopulmonary resuscitation resuscitation in pigs. Circulation 91, 215-221. in pigs. Circulation 99, 1379-1384.

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Case Report Cervical spondylosis deformans in two Quarter Horses A. C. E. Draper* and C. J. Finno Department of Veterinary Population Medicine, University of Minnesota, St Paul, USA. *Corresponding author email: [email protected]

Keywords: horse; cervical spondylosis deformans; bridging; neck stiffness

Summary This case series describes the diagnosis of bridging SD of the This case report describes 2 Quarter Horses diagnosed with cervical vertebrae, resulting in clinical signs of reduced neck severe bridging spondylosis deformans of the cervical spine. mobility, in 2 Quarter Horses. Clinical signs in both horses included severe neck stiffness, reduced mobility and issues with grazing normally. Both were Case details diagnosed with cervical radiographs. Ataxia was noted in one Case 1 horse. One horse has shown progressively worsening signs Case 1, an 18-year-old Quarter Horse gelding, was presented over 4 years. Where severe neck stiffness and reduced to the University of Minnesota Equine Centre with a 4-year mobility are noted in a horse, cervical spondylosis deformans history of progressive neck stiffness. The gelding initially should be considered as a differential diagnosis. demonstrated a reduced range of motion and difficulty when lowering his head to eat. Muscle relaxants (methocarbamol; 50 mg/kg bwt per os q. 12 h) were prescribed, but had no Introduction noticeable effect. The gelding’s difficulty in lowering his head Spondylosis deformans (SD) is a condition of ageing and, in continued to worsen and, 3–4 months prior to presentation, veterinary medicine, is most commonly diagnosed in moderate atrophy of the cervical musculature was noted. The companion animals (de Lahunta and Glass 2009a; gelding was not in regular ridden exercise, but had previously Kranenburg et al. 2011; 2012). The condition results from been used for Western Pleasure competitions. Upon degeneration of the intervertebral discs (IVD), with little presentation, the horse was bright, alert and responsive with change to radiographic IVD spaces (Denoix 2007). normal vital parameters. The gelding held its head in a neutral Periarticular osteophytes (bone spurs) form and ankylose the position and was not able to lift its head past the level of the adjacent intervertebral bodies, thus affording greater stability withers. Bilateral lateral flexion of the neck was limited to poll to that joint (Haussler 1999). The exact aetiology for the rotation and neck ventroflexion was limited to the level of the production of the osteophytes is not known; however they are brisket. There was moderate symmetrical atrophy of the postulated to form from stress and strain applied to the cervical musculature and strap muscles (sternohyoideus, peripheral fibres of the intervertebral disc attachment and the thyroideus and cephalicus). Deep palpation of C4–C7 ventral longitudinal ligament (Denoix 2007; Meehan et al. induced a painful response and spasm of the strap muscles 2009). bilaterally. A complete neurological examination was The incidence of SD, as defined by having at least one unremarkable. Given the chronicity of the limited neck intervertebral space affected, in dogs, cats and horses in the mobility and moderate muscle atrophy, cervical radiographs UK has been reported as 62.8%, 68% and 3.4%, respectively were performed. (Morgan et al. 1967; Read and Smith 1968; Meehan et al. These revealed extensive bridging ankylosing SD affecting 2009). Most reports of spondylosis in dogs and horses involve C2 extending to T1 (Fig 1). Thoracolumbar radiographs did not the thoracolumbar spine. As the condition is a degenerative reveal any SD lesions. A final diagnosis of idiopathic cervical process, rather than inflammatory, affected cases are often ankylosing SD was made. Cervical tuberculous osteomyelitis without clinical signs (Jeffcott 1980; de Lahunta and Glass was considered, but deemed unlikely due to the lack of 2009a; Meehan et al. 2009; Kranenburg et al. 2011). In horses, evidence for systemic inflammation (Wurtz et al. 1993). The radiographic spondylosis lesions are graded from 0–5, with cervical muscle atrophy was attributed to a radiculopathy Grade 0 showing no evidence of osteophytes and Grade 5 from impingement of the spinal nerve roots from the SD. demonstrating osteophytes that have completely spanned Management changes were discussed with the owners, the intervertebral space, thus fusing the vertebral bodies including feeding and watering from a height, providing large together (Meehan et al. 2009). As the osteophytes grow, stalls to turn around in, limiting turnout and no riding. impingement of the local nerve roots is possible and rarely, Anti-inflammatory medication was prescribed to try and direct spinal cord compression can occur (Haussler 1999). reduce perineuronal inflammation. A tapering 4-week Although back pain and spasm, reduced thoracolumbar phenylbutazone (1.1–2.2 mg/kg bwt per os q. 12 h) trial, spine mobility, exercise intolerance and ataxia have all been reportedly, made little clinical improvement. Supplementation attributed to thoracolumbar spondylosis in horses, the majority with RRR-α-tocopherol (5 iu/kg bwt per os q. 24 h) was also of affected horses are without clinical signs (Jeffcott 1980; advised. Long-term prognosis was deemed guarded, and the Eskonen et al. 2007; Meehan et al. 2009). horse was discharged. One year post discharge (time of Although primarily described in the thoracolumbar spine, reporting) the horse reportedly showed progression of the cases of cervical SD in the horse appear to be extremely rare. neck stiffness, such that all its food and water had to be

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a) mentation and the vital parameters were within normal limits. C1 There was extreme stiffness of the neck, the head and neck were held below the wither level, and there was an inability to flex dorsally and laterally. Ventral flexion of the neck was possible but not for extended periods. The cervical musculature was contracted and painful on palpation. Neurological examination revealed a symmetric ataxia (forelimb grade 3.5/5 and hindlimb grade 3/5) (Lunn and Mayhew 1989). Mentation, cranial nerve function, reflexes, tail and anal tone were within normal limits. Haematological and biochemical analyses were unremarkable, with the exception C2 of elevations in muscle enzymes (creatine kinase: 3909 u/l, reference range: 82–303 u/l; aspartate transaminase: 326 u/l, reference range: 162–316 u/l). These elevations were attributed to the recent trauma. b) Based on the history of falling, neck stiffness, and C3 neuro-anatomical localisation of the ataxia to the C1–C7 region of the spinal cord, radiographs of the cervical spine were taken. These revealed extensive bridging ankylosing SD C4 affecting C3–C7 (Fig 2). Moderate osteoarthrosis was noted in the articular facet joints of C5-C6 and C6-C7. The ataxia was attributed to acute exacerbation of facet joint osteoarthrosis at the base of the neck. It was postulated that the recent falling episodes could have been precipitated by an underlying ataxia. Without further diagnostic investigation it was not possible to rule out direct spinal cord impingement from the SD. With the acute spinal cord trauma, anti-inflammatory (dexamethasone; 0.08 mg/kg bwt i.v. q. 24 h), free radical scavenging (dimethylsulfoxide; 1 g/kg bwt i.v. q. 24 h), and muscle relaxant (methocarbamol; 50 mg/kg bwt per os q. 12 h) medications were administered. The mare c) was hospitalised. After 24 h, there was no improvement C5 observed in the neurological deficits and cervical pain so the C6 mare was subjected to euthanasia. The owners declined a post mortem examination. Discussion To the authors’ knowledge, this is the first case series of cervical bridging SD in horses. Cervical SD is rarely reported in veterinary species (Seawright and English 1964, 1967; Fry 1968; De Lahunta and Glass 2009a,b; Kranenburg et al. 2011), but is seen in human patients with some frequency (McDonnell and Lucas 2012). In dogs and man, SD is most often associated with type II disc disease, whereby the anulus fibrosus tears (Kranenburg et al. 2011). Degenerative disc disease could have been present in both horses’ cervical spines and been Fig 1: Case 1; Right lateral standing cervical radiographs. the inciting cause for the spondylosis. However, cervical disc a) C1–C3. b) C2–C5. c) C4–C7. Extensive spondylosis deformans herniation has been reported in horses without evidence of notable, grade 4; C3–C4, C4–C5, C5–C6 and C6–C7 and grade 5; spondylosis (Foss et al. 1983) and conversely thoracolumbar SD C2–C3. in dogs is reported without disc disease (Levine et al. 2006; Kranenburg et al. 2011). Hypervitaminosis A can lead to deforming cervical spondylosis in cats, without evidence of elevated. In addition, the muscle atrophy had progressed but disc disease, as the toxic vitamin A levels directly induce no neurological deficits had developed. generalised bony exostosis formation (Seawright and English 1964, 1967; Fry 1968). Vitamin A toxicity has been Case 2 demonstrated to affect bone development in horses (Hintz Case 2, a 17-year-old Quarter Horse mare, was presented to and Schryver 1976); however, cervical spondylosis has not the University of Minnesota Equine Centre with a history of been attributed to this toxicity and the lesion locations were acute onset ataxia. Over the 2 days prior to presentation, the distinctly different between the 2 species (Seawright and mare fell whilst lungeing, twice. The mare received flunixin English 1967). meglumine prior to referral (1.1 mg/kg bwt i.v.) and had Radiography is commonly utilised to diagnose SD in horses recently been retired from Western Pleasure competitions. (Seawright and English 1964, 1967; Meehan et al. 2009; Upon presentation, the mare appeared to have normal Kranenburg et al. 2011) and nuclear scintigraphy can be

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a) helpful in identifying ‘active’ SD (Meehan et al. 2009). C3 Spondylosis deformans is typically identified from T10–T14 and, rarely, the lumbar spine in horses. The region of T10–T14 is under the largest lateral motion and axial rotation of the equine C4 spine, thus exposing the anulus fibrosus to disproportionate strain (Meehan et al. 2009). These large forces are speculated to result in osteophyte formation at the sites of attachment and perpetuate spondylosis formation (Townsend et al. 1983; Denoix 1999). Treatment in dogs and man includes analgesics (nonsteroidal anti-inflammatory drugs etc. or analgesics for chronic pain relief), potent anti-inflammatory medications (corticosteroids) in acute situations, or surgical intervention to reduce bony exostosis (de Lahunta and Glass 2009a; b) McDonnell and Lucas 2012). Western Pleasure horses are encouraged to have a low head and neck carriage. Given the older age of both horses, C5 and the years spent within this discipline, it is possible that additional strain was applied to the lower cervical joints. Perpetuation of disc disease from this may have stimulated a severe SD. Case 1 demonstrated symmetrical atrophy of the neck muscles and, with the extensive nature of the SD, neurogenic atrophy secondary to a radiculopathy induced by infringement of the spinal nerve root exiting the intervertebral foramen was likely. Impingement on the spinal nerve root could also explain the intermittent muscle spasms noted during physical examination of Case 1. c) Regrettably, the ante and post mortem diagnostic C6 work-ups associated with ataxia exhibited by Case 2 were incomplete. The acute ataxia was associated with severe neck stiffness. The marked bridging SD, cervical muscle spasm and pain (from the recent trauma) explained the limited neck mobility and the latter 2 issues were probably the reasons for Case 2 having limited ventroflexion, whilst Case 1 demonstrated severely limited dorsiflexion. The ataxia could have resulted from cervical spinal cord compression due to cervical facet joint osteoarthrosis, diskospondylitis or impingement by the dorsal osteophytes from the spondylosis. Alternatively, the recent trauma may have exacerbated ongoing spinal cord compression. Spondylosis deformans has been reported to be the cause of thoracolumbar spinal cord d) compression in horses only rarely (Eskonen et al. 2007), C6 whereas osteoarthritis of the cervical articular facets is a commonly reported cause of compression (de Lahunta and Glass 2009a). Human patients who develop cervical C7 spondylosis also rarely report direct spinal cord compression related to the spondylosis (McDonnell and Lucas 2012). Additional diagnostics would have been necessary to definitively rule out other possible causes of ataxia. Neuroborreliosis has been reported to cause neck stiffness and low head carriage in some affected horses (Burgess and Mattison 1987; Fritz and Kjemtrup 2003; James et al. 2010; Imai et al. 2011). All of these cases showed a combination of additional signs, including ataxia, arthritis of the appendicular skeleton/synovitis, pyrexia, muscle atrophy and fasciculations, hyperaesthesia, and cranial nerve deficits. Although mild muscle atrophy and fasciculations were seen with Case 1 and ataxia in Case 2, the remainder of the history and clinical signs Fig 2: Case 2; Left lateral standing cervical radiographs. a) C2–C5. were not consistent with chronic neuroborreliosis (James et al. b) C3–C7. c) C5–C7. d) C6–C7. Extensive spondylosis deformans 2010; Imai et al. 2011). notable, grade 1; C2–C3, grade 3; C5–C6 and grade 4; C3–C4 and In conclusion, cervical bridging SD should be considered C4–C5. There is also arthritis of the articular facet joints noticeable where a horse demonstrates progressive or severe neck at C5–C6, C6–C7. stiffness with or without cervical muscle atrophy. Further

© 2014 EVJ Ltd EQUINE VETERINARY EDUCATION / AE / MAY 2016 251

investigations are necessary to characterise the underlying Jeffcott, L.B. (1980) Disorders of the thoracolumbar spine of the horse – pathology, disc-health and neurological implications fully. a survey of 443 cases. Equine Vet. J. 12, 197-210. Kranenburg, H.C., Meij, B.P., Van Hofwegen, E.M., Voorhout, G., Authors’ declaration of interests Slingerland, L.I., Picavet, P. and Hazewinkel, H.A. (2012) Prevalence No conflicts of interest have been declared. of spondylosis deformans in the feline spine and correlation with owner-perceived behavioural changes. Vet. Comp. Orthop. References Traumatol. 25, 217-223. Burgess, E.C. and Mattison, M. (1987) Encephalitis associated with Kranenburg, H.C., Voorhout, G., Grinwis, G.C., Hazewinkel, H.A. and Borrelia burgdorferi infection in a horse. J. Am. Vet. Med. Ass. 191, Meij, B.P. (2011) Diffuse idiopathic skeletal hyperostosis (DISH) and 1457-1458. spondylosis deformans in purebred dogs: a retrospective radiographic study. Vet. J. 190, 84-90. De Lahunta, A. and Glass, E. (2009a) Small animal spinal cord disease. In: Veterinary Neuroanatomy and Clinical Neurology, 3rd edn., Eds: Levine, G.J., Levine, J.M., Walker, M.A., Pool, R.R. and Fosgate, G.T. A. De Lahunta and E. Glass, W.B. Saunders, St Louis. pp 264-265. (2006) Evaluation of the association between spondylosis De Lahunta, A. and Glass, E. (2009b) Large animal spinal cord disease. deformans and clinical signs of intervertebral disk disease in dogs: In: Veterinary Neuroanatomy and Clinical Neurology, 3rd edn., Eds: 172 cases (1999–2000). J. Am. Vet. Med. Ass. 228, 96-100. A. De Lahunta and E. Glass, W.B. Saunders, St Louis. pp 293-294. Lunn, D.P. and Mayhew, I.G.J. (1989) The neurological evaluation of Denoix, J.M. (1999) Spinal biomechanics and functional anatomy. Vet. horses. Equine Vet. Educ. 1, 94-101. Clin. N. Am.: Equine Pract. 15, 27-60. McDonnell, M. and Lucas, P. (2012) Cervical spondylosis, stenosis, and Denoix, J.M. (2007) Discovertebral pathology in horses. Equine Vet. rheumatoid arthritis. Med. Health R. I. 95, 105-109. Educ. 19, 72-73. Meehan, L., Dyson, S. and Murray, R. (2009) Radiographic and Eskonen, T., Ruohoniemi, R. and Karkamo, V. (2007) Spondylosis in the scintigraphic evaluation of spondylosis in the equine thoracolumbar equine cranial thoracic spine – case report. Suom. Elainlaakarilehti spine: a retrospective study. Equine Vet. J. 41, 800-807. 113, 251-255. Morgan, J.P., Ljunggren, G. and Read, R. (1967) Spondylosis deformans Foss, R., Genetzky, R., Reidesel, E. and Graham, C. (1983) Cervical (vertebral osteophytosis) in the dog. A radiographic study from intervertebral disc protrusion in 2 horses. Can. Vet. J. 24, 188-191. England, Sweden and U.S.A. J. Small Anim. Pract. 8, 57-66. Fritz, C.L. and Kjemtrup, A.M. (2003) Lyme borreliosis. J. Am. Vet. Med. Ass. 223, 1261-1270. Read, R.M. and Smith, R.N. (1968) A comparison of spondylosis deformans in the English and Swedish cat and in the English dog. Fry, P.D. (1968) Cervical spondylosis in the cat. J. Small Anim. Pract. 9, J. Small Anim. Pract. 9, 159-166. 59-61. Seawright, A.A. and English, P.B. (1964) Deforming cervical spondylosis Haussler, K. (1999) Anatomy of the thoracolumbar vertebral region. Vet. in the cat. J. Pathol. Bacteriol. 88, 503-509. Clin. N. Am.: Equine Pract. 15, 13-26. Hintz, H.F. and Schryver, H.F. (1976) Nutrition and bone development in Seawright, A.A. and English, P.B. (1967) Hypervitaminosis A and horses. J. Am. Vet. Med. Ass. 168, 39-44. deforming cervical spondylosis of the cat. J. Comp. Pathol. 77, 29-39. Imai, D.M., Barr, B.C., Daft, B., Bertone, J.J., Feng, S., Hodzic, E., Johnston, J.M., Olsen, K.J. and Barthold, S.W. (2011) Lyme neuroborreliosis in 2 Townsend, H.G., Leach, D.H. and Fretz, P.B. (1983) Kinematics of the horses. Vet. Pathol. 48, 1151-1157. equine thoracolumbar spine. Equine Vet. J. 15, 117-122. James, F.M., Engiles, J.B. and Beech, J. (2010) Meningitis, cranial neuritis, Wurtz, R., Quader, Z., Simon, D. and Langer, B. (1993) Cervical and radiculoneuritis associated with Borrelia burgdorferi infection in tuberculous vertebral osteomyelitis: case report and discussion of a horse. J. Am. Vet. Med. Ass. 237, 1180-1185. the literature. Clin. Infect. Dis. 16, 806-808.

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Clinical Commentary Cervical spondylosis deformans L. Jeffcott University Veterinary Teaching Hospital, University of Sydney, Camden, New South Wales, Australia. Corresponding author email: [email protected]

There are an awful lot of horses with stiff necks out in with marked cervical muscular atrophy. The authors’ practice, but there is little in the literature to assist clinicians speculation was that degenerative disc disease may have with understanding their underlying pathogenesis. The been the cause, but this is very rare in the horse. The other situation is redressed to some extent in the well presented possibility is a more generalised osteoarthritis, but unfortunately case report in this issue (Draper and Finno 2016) of severe no other parts of the axial skeleton were imaged. It would have spondylosis deformans in two older, but not geriatric, horses. been nice if the horses had undergone nuclear scintigraphy to Most of the literature on the cervical spine concentrates evaluate the thoracolumbar spine, or to have done ultrasound on diagnosis and treatment of cervical vertebral examination of the articular processes of the caudal thoracic malformation (wobbler disease), and one of these horses and lumbar vertebrae. The authors mentioned the possibility of exhibited signs of grade 3 ataxia. In my clinical experience of tubercular osteomyelitis, but the radiological changes would almost 50 years working with performance horses, many not have fitted these two cases. Why the cervical spine is cases go undiagnosed. This report demonstrates that in really predisposed to tuberculosis is not known. The other condition chronic cases the radiological changes may be spectacular. that can cause widespread new bone proliferation and It is amazing to me that they have not been reported spondylosis around the cervical and thoracolumbar spine is previously (and hopefully will not go undiagnosed in the Marie’s disease (hypertrophic osteoarthropathy), but this also future). seems unlikely. Hypervitaminosis A and Bran disease There are a number of clinical comments that I would like (secondary nutritional hyperthyroidism) would not seem to fit to make about this interesting paper. Firstly, the imaging the clinical or pathological findings. carried out was certainly adequate to demonstrate the Finally, the lack of post mortem evidence to appreciate extensive bony changes to the cervical spine from C2 to C7. the full extent of cervical damage and the specific cause of The severe spondylosis mainly involved the ventral aspect of vertebral stenosis was a great pity, and clearly prevented us the spine, causing ankylosis of the intervertebral joints and having any clear idea of pathogenesis. I suspect that more therefore complete rigidity of the neck. The articular facet general osteoarthritis of the thoracolumbar spine would have joints were more severely affected in Case 2, particularly C5– been present despite the lack of clinical signs. Nevertheless, C7. This was probably the site of vertebral stenosis either from the recording for the first time of two cases and the the arthropathy or a synovial cyst at that level. The fact that associated picture was well worth publishing. the ataxia (grade 3/5) was as severe in the forelimbs as the hindlimbs was surprising. I would have expected the hindlimbs Author’s declaration of interests to be more severely involved. The intriguing thing about these two cases was to No conflicts of interest have been declared. appreciate the likely pathogenesis of such dramatic changes. It would probably not be due to trauma and there was no Reference evidence of any old fractures noted, although the muscle- derived enzymes (CK and AST) were mildly elevated in Case 2. Draper, A.C.E. and Finno, C.J. (2016) Cervical spondylosis deformans - It is not surprising that both horses were in considerable pain in two Quarter Horses. Equine Vet. Educ. 28, 248 251.

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Case Report Diagnostic imaging, surgical treatment and histopathological findings of a vascular hamartoma in a 2-year-old horse B. Musterle, R. Hagen†,P.Grest‡ and J. Kümmerle* Equine Hospital, †Diagnostic Imaging and ‡Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Switzerland. *Corresponding author email: [email protected]

Keywords: horse; hamartoma; haemangioma; tarsus

Summary description of histopathological findings and substantiates the We describe a case of a 2-year-old mare that presented with specification as a hamartoma based on a critical review of a large firm swelling on the lateral aspect of the right tarsus. classification systems found in the existing literature. Diagnostic ultrasound demonstrated a fluid filled cavernous mass that was not clearly demarcated from the surrounding Case history subcutaneous tissue. Contrast radiography with intralesional A 2-year-old Swiss Warmblood filly (body weight 480 kg) was injection of contrast medium showed accumulation of the presented to the Equine Hospital at the University of Zurich with medium in the caverns of the mass and in the saphenous vein. a large tissue mass on the lateral aspect of the right tarsus. The Contrast enhanced computed tomography demonstrated 2 owner had discovered this mass 8 months previously and vascular meshes, one deep and one more superficially, reported continuous growth since then. The horse had never closely associated with the mass. Surgical excision of the mass shown any lameness and no treatment had been initiated was performed and a vascular hamartoma was diagnosed prior to referral to the hospital. based on histopathology. The horse showed no signs of recurrence 7 months after surgery. Clinical findings At time of presentation a prominent soft tissue mass was Introduction obvious at the lateral and dorsolateral aspect of the right tarsus (Fig 1), approximately 25 cm long, 12 cm wide and Vascular proliferations of the skin are infrequently reported in 4–6 cm thick. This mass was mostly firm on palpation but there the horse and can be a diagnostic and therapeutic challenge because it is often difficult to determine if the lesion represents a malformation or a neoplasm. Vascular malformations such as hamartomas result from an error in morphogenesis and are characterised by an excessive focal overgrowth of mature normal tissue (Hargis and McElwain 1984). Their growth rate is usually slower than in masses of neoplastic origin (Johnson et al. 1996; Colbourne et al. 1997; Zafra et al. 2012). Haemangiomas are benign expansively growing vascular neoplasms and consist of proliferating vascular channels lined by flattened endothelial cells and separated by a collagenous stroma. Congenital forms of vascular neoplasms of the skin have been reported (Johnson et al. 1996) and might be difficult to differentiate from hamartomas (Ginn et al. 2007). Malignant vascular neoplasms are usually characterised by a meshwork of variably sized and anastomosing blood filled channels that are lined by atypical endothelial cells. Cutaneous haemangiosarcomas are supposed to be less malignant than visceral or multicentric forms (Lempe et al. 2008); however, frequent recurrence and formation of metastases have been reported (Johns et al. 2005; Lempe et al. 2008). In the equine literature, there are few reviews or case reports on vascular proliferations. Hamartomas as well as haemangiomas and haemangiosarcomas are reported to occur in young horses (Hargis and McElwain 1984; Johnstone 1987; Platt 1987; Johnson et al. 1996; Johns et al. 2005; Saifzadeh et al. 2006; Lempe et al. 2008). However, description and nomenclature seem to be inconsistent and often it is unclear if the lesions are neoplastic or not. This report presents a case of a vascular mass with a variety Fig 1: Soft tissue mass at the lateral and dorsolateral aspect of the of diagnostic imaging modalities applied, gives a detailed right tarsus at time of presentation.

© 2014 EVJ Ltd 254 EQUINE VETERINARY EDUCATION / AE / MAY 2016

seemed to be fluctuant areas within the mass. The entire surface was covered with normal skin and there was no heat or pain on palpation. None of the adjacent synovial structures showed signs of effusion. On lameness examination, a slightly irregular gait of the right hindlimb of grade 1/5 (Ross 2003) was visible in the trot with the horse showing a decelerated swinging phase in the affected limb.

Diagnosis Radiographic examination I Four standard projections (lateromedial, dorsoplantar, dorsomedial-plantarolateral oblique and dorsolateral- plantaromedial oblique) of the right tarsus were obtained. The osseous structures were within normal limits apart from a slightly rough contour of the craniodistal aspect of the tibial cortex. However, a very large soft tissue swelling with subtle granular structures with mineralised opacity superimposed on its most distal part was noted over the dorsolateral aspect of the tarsus.

Needle aspiration and cytology Fine needle aspiration revealed a sanguinous fluid with a packed cell volume of 24% and a total leucocyte count of 5.625 × 109 cells/l consistent with blood contamination or acute haemorrhage. No abnormal cells were visible microscopically.

Radiographic examination II In the standing, sedated patient 100 ml of iodinated contrast medium (CM; Ultravist 370 mg/ml)1 were injected intralesionally. Positive contrast radiographs showed that the mass consisted of a network of communicating small caverns Fig 2: Lateromedial projection of the right tarsus after intralesional that accumulated CM (Fig 2). Proximally, the saphenous vein injection of contrast medium. Note the size of the swelling and the also showed accumulation of CM. On the lateromedial cavernous architecture that accumulates radiopaque contrast projection, a network of vessels could be seen dorsal to the medium. Proximal to the swelling contrast medium is seen filling a tubular structure with valves, most likely the saphenous vein. tarsal bones. No sign of communication to tarsal synovial Caudal to the tibia and plantar to the calcaneus, the soft tissue structures could be detected, i.e. no contrast material was swelling shows as increased opacity. found to outline the synovial cavities.

Sonographic examination multi-row CT scanner Somatom Sensation Open; 120 kV, Diagnostic ultrasound demonstrated a cavernous mass 300mAs)2 of the right tarsus was performed with the horse in containing highly echogenic fluid. The mass was not clearly left lateral recumbency. After a plain study was obtained, demarcated from the surrounding subcutaneous tissue. The a contrast study was acquired with injection of 100 ml caverns appeared to communicate with one another, which of iodinated CM (Telebrix 350 mg/ml)3 into the saphenous could be demonstrated by fluid movement caused by varying vein with a tourniquet applied proximally. Images were transducer pressure. Multiple round structures were found in reconstructed in a bone and soft tissue algorithm. the dependent parts of the larger fluid filled caverns, some of Hyperattenuating CM delineated 2 heterogenic vascular which showed sonographic signs of mineralisation. Examining meshes, one deep and one more superficial. Vena saphena the right tarsus, depiction of the normal anatomical structures medialis, V. tibialis cranialis and an anastomosing branch was hampered by the presence of the large mass, creating accumulated CM as well as several vessels entering the tissue extra tissue for the ultrasound beam to travel through and mass (Fig 4). Retrograde injection of CM into the saphenous consequently limiting imaging of the deeper structures. The vein did not fill all the caverns of the mass, so the tourniquet lateral collateral tarsal ligaments were directly adjacent to the was removed and the mass was injected with 100 ml of CM abnormal tissue; however, they were of normal structure and and the tarsus was imaged again. This allowed for creation of showed regular parallel fibre arrangement. The long and short the 3-dimensional reconstruction of the tarsus including the lateral collateral ligaments were imaged (Fig 3). The wall of the mass, which demonstrated that there was no significant tarsocrural synovial cavity was smooth and the joint fluid was drainage to the saphenous vein. anechoic. These findings were consistent with a very well vascularised In the abnormal tissue several small focal mineralisations mass with intimate connections to the surrounding venous were visible. The saphenous vein and a parallel vein running network, and a neoplasm of vascular origin such as a more deeply could be seen. A horizontal branch of the vein haemangioma, haemangiosarcoma or vascular hamartoma. with several divergent vessels continued into the mass.

Computed tomography Treatment The horse was anaesthetised and contrast enhanced After CT examination the horse was moved directly into computed tomography (CT; Single-slice, third-generation the surgical theatre for resection of the mass. In left lateral

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a)

b)

Fig 4: A dorsomedial view of a 3-dimensional computed tomography reconstruction of the right tarsus after intravenous angiography. Note the vascular ramifications that wrap around and enter the mass located on the dorsolateral and lateral aspect of the limb (arrow labels the saphenous vein).

resected and finally the wound was closed primarily in 2 layers. Fig 3: a) Longitudinal sonographic image of the lateral long collateral ligament (CL) of the tarsocrural joint. In the near field an A full-limb bandage was applied and the horse recovered approximately 3 cm thick layer of strongly heterogeneous from general anaesthesia uneventfully. The excised mass was unstructured abnormal tissue covers the normally much closer submitted for histological examination. Post operatively, imaged CL. Due to the increased depth (approximately 4 cm), the phenylbutazone (Equipalazone)4 was administered for 8 days ligament boundaries are not as well depicted as normally. There (2.2 mg/kg bwt b.i.d. for 2 days followed by 1.1 mg/kg bwt are small hyperechoic foci with acoustic shadowing, compatible s.i.d. for 6 days, respectively). with focal mineralisations. However, normal ligamentous structure can be demonstrated. b) Longitudinal image of one of the 3 parts of the lateral short CL of the tarsocrural joint, deep to Outcome approximately 3 cm of abnormal heterogeneous tissue. The CL Two days after surgery the horse did not show any signs of shows normal parallel fibre arrangement and the contours are still lameness at the walk. The bandage was changed and the definable. drains removed 48 h after surgery. The bandage was changed every 4 days and the skin sutures removed 15 days after recumbency, a longitudinal, curvilinear incision of surgery. Three weeks after surgery, progressive swelling of the approximately 20 cm length was made directly over the mass limb, a slight lameness at the walk and accumulation of on the lateral side of the right tarsus. Intraoperatively, the mass bloody-purulent fluid in the wound was noted. A wound was found to be located subcutaneously and in close revision performed under general anaesthesia revealed proximity to anatomical structures including the lateral granulation like tissue in the wound cavity of a brownish colour malleolus and the long digital extensor tendon but did not and of a very friable quality, which was removed and tissue infiltrate them. The deep aspect of the mass also extended to samples were collected for histopathology. The wound the surface of the lateral collateral tarsal ligaments but, since was debrided and the drainage holes re-established. The the deep part of the mass was located superficially to the short tissue samples were classified as granulation tissue on part and dorsally to the long part of these ligaments, it did not histopathological examination. Purulent discharge from the extend into these structures. A thin capsule encased the wound continued for several days and a swab was taken for lateral aspect of the mass; however, this capsule was ill bacteriological examination and the wound flushed with defined proximally, distally and medially where it faded into iodine solution. Coagulase-positive staphylococci and intima-like tissue. Therefore, this tissue was resected together Pseudomonas aeruginosa could be detected, none of them with the mass using scissors and a monopolar electro scalpel. multiresistant. Wound infection was presumed to be mainly The mass with its capsule and adjacent intima-like tissue, due to inadequate drainage. Therefore, no antibiotic therapy respectively, was excised almost in one piece. All visible – apart from routine perioperative systemic antibiosis with remaining abnormal tissue was then removed separately. cefquinom (Cobactan)4 i.v. 2.2 mg/kg bwt once before After lavage with lactated Ringer’s solution, 2 passive silicone induction of each general anaesthesia – was initiated. drains were placed via separate incisions. Excessive skin was Eighteen days after the second surgery the horse was

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200 μm

Fig 6: Hamartoma composed of variably sized vascular structures (asterisk) lined by flat endothelial cells (arrows) with interspersed broad collagen bundles. Haematoxylin and eosin ×4.

haemangiosarcomas. However, often it remains unclear if a true neoplasm or a malformation is present. Here we present a case with a thorough histopathological examination including immunohistochemistry revealing features more consistent with a hamartoma than with a haemangioma. Hamartomas are composed of mature tissue elements corresponding to the site of origin but growing in a disorganised manner (Ginn et al. 2007). Haemangiomas are benign neoplasms of endothelium forming vascular Fig 5: Right tarsus of the horse 19 weeks after surgery; the wound is channels lined by a single layer of flat endothelial cells and completely healed and the swelling abated. separated by collagenous stroma (Ginn et al. 2007). Haemangiosarcomas are infiltrative malignant neoplasms discharged from the hospital with mild secretion from the composed of a network of vascular channels that are not wound and a firm but regressive swelling over the right tarsus. uniformly closed, form an anastomosing network and are lined Six weeks after discharge from the hospital, the owner was by endothelial cells with atypical cells (Gross et al. 2005) interviewed via telephone. He reported that the wounds were Histopathology and immunohistochemistry may assist in nearly closed and the swelling still abating with no signs of differentiating neoplasia from malformation. An important relapse. Nineteen weeks after surgery, the horse was visited on criterion is the normal organisation of the vessel wall. In cases the farm and did not show any signs of lameness in any gait of malformations, the vascular architecture remains largely and was getting started under saddle. Only a mild firm residual intact while neoplastic changes are characterised by partial swelling was present at the operated area (Fig 5). loss of specific layers of the vascular wall. The diagnosis of hamartoma is based on the finding of a proliferation Histopathology composed of variably sized vessels lined by monotonous The mass consisted of numerous irregularly formed cavities that endothelial cells and with walls of variable thickness that contained small numbers of erythrocytes and thrombi. predominantly feature elements of normal vessel walls (Gross Papillary projections with a core of connective tissue et al. 2005). Haemangiomas are usually characterised by protruded into these cavities. The cells lining the mass were proliferating vascular channels lined by endothelial cells that monomorphous endothelial-like cells. The cavities were are aligned on collagenous tissue (Gross et al. 2005). In cases separated by connective tissue with broad collagen bundles of undifferentiated forms with minimal or no formation of and interspersed clusters of variably sized regularly formed vascular channels the endothelial nature of the proliferating vessels (Fig 6). Immunohistochemistry revealed a strong cells is confirmed with specific staining methods. In the case positive reaction of the cells for factor VIII confirming their described in this report, a malignant vascular proliferation was endothelial origin and revealed a variably thick rim of cells excluded based on the presence of uniformly closed and positive for smooth muscle actin around every vascular highly differentiated vascular channels with no atypical cells structure (Fig 7). In the samples used for histopathology, no among lining endothelial cells. Since immunohistochemistry clear excisional margins of the mass could be verified. demonstrated a normal structural architecture of the vascular walls, a hamartoma was diagnosed. Discussion Saifzadeh et al. (2006) described a hamartoma composed Vascular proliferations are described in young horses and of many vessels separated by connective tissue with scattered are often referred to as hamartomas, haemangiomas or fibroblasts and inflammatory cells. Some of the vessels had

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a) differed because they presented as alopecic plaques rather than firm swellings under intact skin. In conclusion, there seems to be a significant variability in macroscopic appearance which makes a specific diagnosis based on clinical presentation impossible. Radiology is commonly performed to rule out bony involvement and evaluate mineralisation of a mass. In our case, standard radiographic examination of the bony structures was mainly within normal limits. In an attempt to rule out other reasons for a local swelling, fine-needle aspiration can be performed. However, in vascular proliferations cytology often reveals normal blood (Colbourne et al. 1997; Johns et al. 2005; Saifzadeh et al. 2006; Lempe et al. 2008). This is in accordance with the known poor exfoliation rate of proliferating endothelial cells (Tyler et al. 1999) that often causes nondiagnostic cytological samples (Colbourne et al. 1997; Johns et al. 2005; Saifzadeh et al. 2006; Lempe et al. 5050 μm 2008). Usually, histopathological examination of a biopsy is required to get a definitive diagnosis in cases of vascular b) malformations or vascular tumours (Johns et al. 2005). Due to the risk of bleeding, it may be favourable to remove the mass en bloc and submit it for histopathology rather than taking biopsies in advance. Radiographic examination and CT with iodinated contrast medium can play a key role for planning the surgical therapy. Vascular anomalies such as varices or an aneurysm can be ruled out. The precise 3-dimensional illustration of the mass and its associated vasculature facilitates planning the surgical procedure and can prevent excessive bleeding during surgery – a complication mentioned by Lempe et al. (2008) and Saifzadeh et al. (2006). Treatment of vascular proliferations is based on surgical excision (Hargis and McElwain 1984). Use of the monopolar electro scalpel was helpful to reduce bleeding, maintain a clear view throughout surgery and effectuate marginal resection. Generally, the prognosis following surgical resection 50 μm is good. However, complicating factors such as infection, recurrent haemorrhage and incomplete removal play a major Fig 7: a) Vascular proliferations lined by flat endothelial cells that stained strongly for factor VIII. Immunohistochemistry, ×20. role in negative outcome. One case of a hamartoma recurred b) Vascular proliferations with a rim of variable thickness consisting repeatedly and led to euthanasia (Colbourne et al. 1997). of smooth muscle cells that stained strongly for smooth muscle Hargis and McElwain (1984) and Johns et al. (2005) also actin. Immunohistochemistry, ×20. reported euthanasia of horses; 2 horses with haemangiomas were subjected to euthanasia due to the size of the mass, neither of these cases underwent any treatment. Johns et al. only a thin layer of endothelial cells while others had a thick (2005) questioned the surgical excision in the case of muscular wall (Saifzadeh et al. 2006). Three additional cases haemangiosarcomas, as 6 of 11 horses had to be subjected to have been reported in young horses and were described as euthanasia, 2 of them due to recurrence. Biological behaviour aggregations of vascular channels with walls of variable of the proliferating cells is another important factor as thickness, lined by endothelial cells and separated by variable malignant neoplasias such as haemangiosarcomas tend to amounts of collagenous stroma (Colbourne et al. 1997). No have a higher rate of recurrence and can lead to metastatic immunohistochemistry was performed and therefore it remains disease (Johns et al. 2005). For this reason histopathological unclear if the proliferating vessels exhibited a normal examination is of prognostic significance. However, organisation. information in the literature is confusing and this seems to be Most vascular proliferations occur on the extremities (Hargis mainly due to inconsistent terminology and imprecise and McElwain 1984; Johnstone 1987; Platt 1987; Johnson et al. histopathological diagnoses. Location of the mass may 1996; Colbourne et al. 1997; Saifzadeh et al. 2006; Lempe et al. preclude resection with clean margins and promote local 2008; Zafra et al. 2012) but other locations in the skin have also recurrence in the case of benign as well as malignant vascular been described (Hargis and McElwain 1984; Platt 1987; proliferations. Adjunctive therapy such as topical liquid Johnson et al. 1996). Compared with the literature, the clinical nitrogen (cryotherapy), local chemotherapy or radiation appearance of our case was similar to a haemangiosarcoma therapy might be conducted to prevent relapse. Local presented by Lempe et al. (2008) as well as hamartomas cryotherapy was attempted unsuccessfully in one case of described by Colbourne et al. (1997) and Saifzadeh et al. hamartoma (Colbourne et al. 1997), while, in a case of (2006). The haemangiomas presented by Zafra et al. (2012) haemangiosarcoma (Johns et al. 2005), repeated surgical

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excision in conjunction with cryotherapy and topical 4MSD Animal Health GmbH, Luzern, Switzerland. 5-fluorouracil led to resolution. A haemangioma in a References one-year-old horse recurred after surgical excision and cryotherapy but regressed completely after radiation therapy Colbourne, C.M., Yovich, J.V., Richards, R.B., Rose, K.J. and Huxtable, C.R. (1997) Vascular hamartomas of the dorsal carpal region in three (Platt 1987). young thoroughbred horses. Aust. Vet. J. 1, 20-23. In cases where tumours recurred, recurrence was rapid Ginn, P.E., Mansell, J.E.K.L. and Rakich, P.M. (2007) Neoplastic and and obvious (Platt 1987; Colbourne et al. 1997; Johns et al. reactive diseases of the skin and mammary glands. In: Jubb, 2005). However, the reported recurrence of a hamartoma Kennedy, and Palmer’s Pathology of Domestic Animals, 5th edn., described by Colbourne et al. (1997) seems questionable Ed: M.G. Maxie, Elsevier Saunders, Edinburgh. pp 746-781. since the authors mention that their histological diagnosis was Gross, T.L., Ihrke, P.J., Walder, E.J. and Affolter, V.K. (2005) Part II Mesenchymal neoplasms and other tumors; vascular tumors. In: Skin unclear because they could not clearly differentiate it from a Diseases of the Dog and Cat, 2nd edn., Blackwell Science, Ames. haemangioma. In our case, there are no signs of recurrence 10 pp 735-758. months after therapy and, because a benign proliferation was Hargis, A.M. and McElwain, T.F. (1984) Vascular neoplasia in the skin of diagnosed, we would consider the prognosis to be good, horses. J. Am. Vet. Med. Ass. 9, 1121-1124. although a complete resection could not be proved Johns, I., Stephen, J.O., Del Piero, F., Richardson, D.W. and Wilkins, P.A. histopathologically. Vascular neoplasms and malformations of (2005) Haemangiosarcoma in 11 young horses. J. Vet. Intern. Med. 4, the skin are rather uncommon in the equine patient but 564-570. represent an important differential diagnosis for locally Johnson, G.C., Miller, M.A., Floss, J.L. and Turk, J.R. (1996) Histologic and immunohistochemical characterization of haemangiomas in the growing masses, especially in young horses. A thorough skin of seven young horses. Vet. Pathol. 2, 142-149. diagnostic work-up is recommended to facilitate complete Johnstone, A.C. (1987) Congenital vascular tumours in the skin of horses. surgical excision of the mass. A precise histopathological J. Comp. Pathol. 3, 365-368. examination helps to achieve a correct diagnosis and provide Lempe, A., Ludewig, E., Reischauer, A. and Scharner, D. (2008) reliable information of the nature of vascular proliferations to Erfolgreiche operative Entfernung eines Hämangiosarkoms bei contribute to the equine literature. einem Fohlen. Pferdeheilkunde 5, 680-687. Platt, H. (1987) Vascular malformations and angiomatous lesions in horses: a review of 10 cases. Equine Vet. J. 6, 500-504. Authors’ declaration of interests Ross, M.W. (2003) Diagnosis of lameness – movement. In: Diagnosis and No conflicts of interest have been declared. Management of Lameness in the Horse, 2nd edn., Eds: M.W. Ross and S.J. Dyson, Elsevier Saunders, St Louis. pp 60-73. Saifzadeh, S., Derakhshanfar, A., Shokouhi, F., Hashemi, M. and Acknowledgements Mazaheri, R. (2006) Vascular hamartoma as the cause of hind limb lameness in a horse. J. Vet. Med. A Physiol. Pathol. Clin. Med. 4, We would like to thank Dr Martin Kummer and Dr Beat 202-204. Wampfler for referral of the case. Tyler, R., Cowell, R.L. and Meinkoth, J.H. (1999) Cutaneous and subcutaneous lesions. In: Diagnostic Cytology and Hematology Manufacturers’ addresses of the Dog and Cat, 2nd edn., Mosby Elsevier, St Louis. pp 20-51. 1 Bayer (Schweiz) AG, Zurich, Switzerland. Zafra, R., Estepa, J.C., Aguilera-Tejero, E., Jaber, J.R., Bautista, M.J., 2 Siemens AG, Medical Solutions, Erlangen, Germany. Pacheco, I. and Perez, J. (2012) Clinicopathological features of 3Guerbet AG, Zurich, Switzerland. haemangioma in two young horses. J. Equine Vet. Sci. 11, 767-769.

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Rose, P.L. (1988) Villonodular synovitis in horses. Comp. Cont. Educ. van der Horst, H., van der Hage, M., Wolvekamp, P. and Lumej, J.T. Pract. Vet. 10, 649-655. (1996) Synovial cell sarcoma in a sulphur-crested cockatoo Ross, M.W. (2003) Movement. In: Diagnosis and Management of (Cacatua galerita). Avian Pathol. 25, 179-186. Lameness in the Horse, 1st edn., Eds: M.W. Ross and S.J. Dyson, W.B. White, N.A. (1990) Synovial pad proliferation in the Saunders, St Louis. pp 60-73. metacarpophalangeal joint. In: Current Practice of Equine Surgery, Szendroi, M. and Deodhar, A. (2000) Synovial neoformations and Eds: N.A. White and J.N. Moore, Lipincott, Philadelphia. pp 555- tumours. Baillieres Best Pract. Res. Clin. Rheumatol. 14, 363-383. 558.

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INDICATION: BetaVet ® is indicated for the control of pain and inflammation of clinical signs of laminitis, glucocorticoids should be used with caution in horses associated with osteoarthritis in horses. with a history of laminitis, or horses otherwise at a higher risk for laminitis. Use IMPORTANT SAFETY INFORMATION with caution in horses with chronic nephritis, equine pituitary pars intermedia dysfunction (PPID), and congestive heart failure. Concurrent use of other For Intra-Articular (I.A.) Use in Horses. anti-inflammatory drugs, such as NSAIDs or other corticosteroids, should be CONTRAINDICATIONS: BetaVet ® is contraindicated in horses with hypersensitivity approached with caution. Due to the potential for systemic exposure, concomitant to betamethasone. Intra-articular injection of corticosteroids for local effect is use of NSAIDs and corticosteroids may increase the risk of gastrointestinal, renal, contraindicated in the presence of septic arthritis. and other toxicity. Consider appropriate wash out times prior to administering additional NSAIDs or corticosteroids. WARNINGS: Do not use in horses intended for human consumption. Clinical and experimental data have demonstrated that corticosteroids administered orally or ADVERSE REACTIONS: Adverse reactions reported during a field study of 239 parenterally to animals may induce the first stage of parturition when administered horses of various breeds which had been administered either BetaVet ® (n=119) or during the last trimester of pregnancy and may precipitate premature parturition a saline control (n=120) at five percent (5%) and above were: acute joint effusion followed by dystocia, fetal death, retained placenta, and metritis. Additionally, and/or local injection site swelling (within 2 days of injection), 15% BetaVet ® and corticosteroids administered to dogs, rabbits and rodents during pregnancy have 13% saline control; increased lameness (within the first 5 days), 6.7% BetaVet ® resulted in cleft palate in offspring and in other congenital anomalies including and 8.3% saline control; loose stool, 5.9% BetaVet ® and 8.3% saline control; deformed forelegs, phocomelia and anasarca. Therefore, before use of increased heat in joint, 2.5% BetaVet ® and 5% saline control; and depression, corticosteroids in pregnant animals, the possible benefits to the pregnant animal 5.9% BetaVet ® and 1.6% saline control. should be weighed against potential hazards to its developing embryo or fetus. DOSAGE AND ADMINISTRATION: Shake well immediately before use. Use Human Warnings: Not for use in humans. For use in animals only. Keep this and immediately after opening, then discard any remaining contents. all medications out of the reach of children. Consult a physician in the case of accidental human exposure. RX ONLY PRECAUTIONS: Corticosteroids, including BetaVet ®, administered intra-articularly References: 1. Houdeshell, JW. Field trials of a new long-acting corticosteroid on the treatment are systemically absorbed. Do not use in horses with acute infections. Acute of equine arthropathies. Vet Med Small Anim Clin. Sept. 1969: 782-784. 2. Trotter GW. Intra-articular corticosteroids. In: McIlwraith CW, Trotter GW, eds. Joint Disease in the Horse. moderate to severe exacerbation of pain, further loss of joint motion, fever, or Philadelphia, PA: W.B. Saunders, 1996;237–256. malaise within several days following intra-articular injection may indicate a septic process. Because of the anti-inflammatory action of corticosteroids, signs of infection in the treated joint may be masked. Due to the potential for exacerbation BetaVet ® is a registered trademark of Luitpold Pharmaceuticals, Inc. © Luitpold Animal Health, LUITPOLD division of Luitpold Pharmaceuticals, Inc. 2015. ANIMAL HEALTH BVT003 Iss. 7/2015 increased lameness (within the first 5 days), 6.7% BetaVet® and 8.3% saline control; loose stool, 5.9% BetaVet® and 8.3% saline control; increased heat in joint, 2.5% BetaVet® and 5% saline control; depression, 5.9% BetaVet® and 1.6% saline control; agitation/anxiety, 4.2% BetaVet® and 2.5% saline control; delayed swelling of treated joint (5 or more days after injection), 2.5% BetaVet® and 3.3% saline control; inappetance, 3.4% BetaVet® and 2.5% saline BRIEF SUMMARY OF PRESCRIBING INFORMATION control; dry stool, 1.7% BetaVet® and 0% saline control; excessive sweating, ® (Betamethasone Sodium Phosphate and Betamethasone Acetate Injectable 0.8% BetaVet and 0% saline control; acute non-weight bearing lameness, 0.8% ® ® Suspension) 6 mg betamethasone per mL BetaVet and 0% saline control; and laminitis, 0.8% BetaVet and 0% saline control. For Intra-Articular (I.A.) Use in Horses CLINICAL PHARMACOLOGY: Betamethasone is a potent glucocorticoid steroid CAUTION: Federal law restricts this drug to use by or on the order of a with anti-inflammatory and immunosuppressive properties. Depending upon their licensed veterinarian. physico-chemical properties, drugs administered intra-articularly may enter the

® general circulation because the synovial joint cavity is in direct equilibrium with the DESCRIPTION: ® BetaVet is a sterile aqueous suspension of betamethasone surrounding blood supply. After the intra-articular administration of 9 mg BetaVet acetate in betamethasone sodium phosphate injection. The combined in horses, there were quantifiable concentrations of betamethasone (above betamethasone content of the suspension is 6 mg/mL where each mL contains 1.0 ng/mL) in the plasma. 3.15 mg betamethasone (as betamethasone sodium phosphate); 2.85 mg betamethasone (as betamethasone acetate); 7.1 mg dibasic sodium phosphate; EFFECTIVENESS: A negative control, randomized, masked field study provided ® 3.4 mg monobasic sodium phosphate; 0.1 mg edetate disodium; and 0.2 mg data to evaluate the effectiveness of BetaVet administered at 1.5 mL benzalkonium chloride, as a preservative in water for injection. The pH is adjusted (9 mg betamethasone) once intra-articularly for the control of pain and to between 6.8 and 7.2. inflammation associated with osteoarthritis in horses. Clinical success was defined

® as improvement in one lameness grade according to the AAEP lameness scoring INDICATION: ® BetaVet is indicated for the control of pain and inflammation system on Day 5 following treatment. The success rate for horses in the BetaVet associated with osteoarthritis in horses. group was statistically significantly different (p=0.0061) than that in the saline DOSAGE AND ADMINISTRATION: Shake well immediately before use. Using group, with success rates of 75.73% and 52.52%, respectively (back-transformed strict aseptic technique, administer 1.5 mL BetaVet® (9 mg total betamethasone) from the logistic regression). ® per joint by intra-articular injection. BetaVet may be administered concurrently ANIMAL SAFETY: A 3-week target animal safety (TAS) study was conducted in up to 2 joints per horse. Use immediately after opening, then discard any ® to evaluate the safety of BetaVet in mature, healthy horses. Treatment groups remaining contents. included a control (isotonic saline at a volume equivalent to the 4x group); 1X CONTRAINDICATIONS: BetaVet® is contraindicated in horses with hypersensitivity (0.0225 mg betamethasone per pound bodyweight; BetaVet®); 2X (0.045 to betamethasone. Intra-articular injection of corticosteroids for local effect is mg betamethasone per pound bodyweight; BetaVet®) and 4X (0.09 mg contraindicated in the presence of septic arthritis. betamethasone per pound bodyweight; BetaVet®). Treatments were administered WARNINGS: Do not use in horses intended for human consumption. by intra-articular injection into the left middle carpal joint once every 5-days for Clinical and experimental data have demonstrated that corticosteroids 3 treatments. Injection site reactions were the most common observations in all administered orally or parenterally to animals may induce the first stage of treatment groups. Injection site reactions were observed within 1 hour of dosing parturition when administered during the last trimester of pregnancy and may and included swelling at the injection site, lameness/stiffness of the left front limb, precipitate premature parturition followed by dystocia, fetal death, retained and flexing the left front knee at rest. The injection site reactions ranged from slight placenta, and metritis. Additionally, corticosteroids administered to dogs, swelling (in many horses on multiple days in all treatment groups) to excessive rabbits and rodents during pregnancy have resulted in cleft palate in offspring. fluid with swelling, pain, and lameness (4x group only). Injection site reactions Corticosteroids administered to dogs during pregnancy have also resulted in other were observed most commonly on treatment days, and generally decreased congenital anomalies including deformed forelegs, phocomelia and anasarca. in number and severity over subsequent days. The incidence of injection site Therefore, before use of corticosteroids in pregnant animals, the possible benefits reactions increased after the second and third injection (number of abnormalities noted on day 10 > day 5 > day 0). In the BetaVet® treated groups the number to the pregnant animal should be weighed against potential hazards to its ® developing embryo or fetus. Human Warnings: Not for use in humans. For use in and severity of the injection site reactions were dose dependent. The 4X BetaVet animals only. Keep this and all medications out of the reach of children. Consult a group had the highest overall incidence of and severity of injection site reactions, physician in the case of accidental human exposure. which included heat, swelling, pain, bleeding, and holding the limb up at rest. The control group and 4X group (which received similar injection volumes) had a ® PRECAUTIONS: Corticosteroids, including BetaVet , administered intra-articularly similar incidence of injection site reactions; however, the severity of reactions was are systemically absorbed. Do not use in horses with acute infections. Acute greater in the 4X group. Absolute neutrophils were statistically significantly higher moderate to severe exacerbation of pain, further loss of joint motion, fever, or in the BetaVet® treated groups as compared to the control group. Trends toward malaise within several days following intra-articular injection may indicate a a decrease in lymphocytes and eosinophils, and an increase in monocytes were septic process. Because of the anti-inflammatory action of corticosteroids, signs identified in the BetaVet® treated groups after the initial dose of BetaVet®. Individual of infection in the treated joint may be masked. Appropriate examination of joint animal values for white blood cells generally remained within the reference range. fluid is necessary to exclude a septic process. If a bacterial infection is present, BetaVet® treated horses also had a trend toward increased blood glucose after appropriate antibacterial therapy should be instituted immediately. Additional the initial dose. Some individual animals showed mild increases in blood glucose doses of corticosteroids should not be administered until joint sepsis has been above the reference range. definitively ruled out. Due to the potential for exacerbation of clinical signs of STORAGE CONDITIONS laminitis, glucocorticoids should be used with caution in horses with a history of laminitis, or horses otherwise at a higher risk for laminitis. Use with caution in Store at 20° to 25°C (68° to 77°F) (See USP Controlled Room Temperature). Protect from light. horses with chronic nephritis, equine pituitary pars intermedia dysfunction (PPID), Use carton to protect contents from light until used. and congestive heart failure. Concurrent use of other anti-inflammatory drugs, HOW SUPPLIED such as NSAIDs or other corticosteroids, should be approached with caution. BetaVet®, One 5 mL vial containing 30 mg betamethasone; Due to the potential for systemic exposure, concomitant use of NSAIDs and packaged in boxes of 1. corticosteroids may increase the risk of gastrointestinal, renal, and other toxicity. SHAKE WELL BEFORE USING Consider appropriate wash out times prior to administering additional NSAIDs or NADA 141-418, Approved by FDA corticosteroids. ADVERSE REACTIONS: Adverse reactions reported during a field study of 239 horses of various breeds which had been administered either BetaVet® (n=119) or a saline control (n=120) were: acute joint effusion and/or local injection site A Division of Luitpold Pharmaceuticals, Inc. ® swelling (within 2 days of injection), 15% BetaVet and 13% saline control; One Luitpold Drive | P.O. Box 9001 | Shirley, NY 11967 EQUINE VETERINARY EDUCATION / AE / MAY 2016 259

Case Report Lameness caused by plate-like osteoma cutis in a Thoroughbred colt S. K. Lee, B-H. Kim, E. Seo, C. J. Kwon, J-B. Lee and J-I. Han*† Korea Racing Authority, Gwacheon, Korea; and †College of Veterinary Medicine, Chungbuk National University, Cheongju, Korea. *Corresponding author email: [email protected]

Keywords: horse; lameness; subcutaneous mass; skin idiopathic; osteoma cutis

Summary This report describes a case of osteoma cutis diagnosed by physical examination, surgery and histopathological examination. A 2-year-old Thoroughbred colt with hindlimb lameness was brought to our facility. Physical examination showed a well-circumscribed, large plate-like mass covered with normal haired skin in the right thigh region. Ultrasonography revealed a subcutaneous linear mass. After surgical removal, histopathological examination showed thin mature bone surrounded by fibrocollagenous tissues. To the authors’ knowledge, this is the first report of spontaneous idiopathic osteoma cutis in horses.

Introduction Osteoma cutis is a cutaneous condition characterised by the presence of bone within the skin or subcutis in the absence of Fig 1: Photograph of the lesion in the horse. The mass is localised in a pre-existing or associated lesion in human patients and the right lateral area of the thigh and the overlaying skin is animals. Based on the presence of underlying causes such as damaged. inflammation, trauma, appendage calcification or fibrous were noted just before presentation. Upon physical proliferation, the condition is classified into 2 groups: primary examination, the horse was alert and responsive and the vital and secondary osteoma cutis (Douri and Shawaf 2006). parameters were within the normal range. The mass was According to literature, primary osteoma cutis is divided into 4 localised in the right lateral area of the thigh and the subtypes in man: isolated osteoma, widespread osteoma, overlaying skin was damaged because the horse had rubbed multiple miliary osteoma of the face and plate-like osteoma the area (Fig 1). On palpation, the mass was well (Al-Ajmi et al. 2004). Two hypotheses have been proposed for circumscribed in the subcutaneous area and had a thin formation of osteoma cutis: 1) a disordered embryogenic plate-like appearance. No change in the local temperature process whereby normal mesenchymal cells that are destined was observed. to differentiate into osteoblasts migrate to the wrong site and 2) a metaplastic process, in which extraskeletal mesenchymal Diagnosis cells are activated to become osteoblasts (Douri and Shawaf During the spavin test, the horse displayed discomfort when 2006; Martin et al. 2006). the mass was touched. Lameness, which was graded as 2/5 In man, Burgdorf and Nasemann (1977) reported that only (American Association of Equine Practitioners scale), was 35 out of 20,000 cases (0.175%) that had calcified skin lesions present in the right hindlimb. Laboratory examinations were histopathologically diagnosed as osteoma cutis. including a complete blood count, serum biochemistry profiles Osteoma cutis is extremely rare in dogs, although osseous and electrolytes showed no abnormalities. Radiographic metaplasia has been reported infrequently in association with examination on the anterior posterior view showed a chronic calcinosis cutis or circumscripta (Martin et al. 2006). homogenous radiopaque mass in the subcutaneous tissue Presently, fewer than 10 cases of either solitary or multiple (Fig 2). Ultrasonography revealed that the mass was located forms have been reported. In horses, osteoma has rarely been at a depth of approximately 3.5 mm from the skin surface and described in the head (Brower 2013), including the paranasal had a hyperechoic linear contour. The biceps femoris muscle, sinuses (Steinman et al. 2002; Cilliers et al. 2008) and the maxilla which was located under the mass, showed no abnormal (Kold et al. 1982). However, no official report has described change. Based on these observations, the mass was osteoma cutis in the horse. tentatively diagnosed as subcutaneous mineralisation forming bone-like materials. Case history and clinical findings A 2-year-old Thoroughbred colt was brought to Busan Korea Treatment and outcome Racing Authority Equine Hospital with a mass in the right thigh Surgical removal was indicated because the large size of the region and ipsilateral hindlimb lameness. The clinical signs mass caused gait disturbance. Preoperatively, penicillin G

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Fig 4: Photograph showing the excised mass, which measured approximately 16 × 8 × 0.3 cm.

Fig 2: Radiograph of the lesion showing the thin plate-like material in the subcutaneous area (arrows).

Fig 5: Histopathological examination reveals the structure of mature bone bordered by a thin layer resembling periosteum. Fibrocollagenous tissue surrounds the bone.

mass, which was approximately 16 × 8 × 0.3 cm (Fig 4), was submitted for histopathological examination.

Histopathological examination Fig 3: Photograph showing that the mass is located in the After routine tissue processing, standard haematoxylin subcutaneous area and has hard and thin plate-like appearance. and eosin staining was performed for examination. On histopathology, the thin, plate-like mass exhibited the structure of mature bone. The bone was within normal limits and (25,000 iu/kg bwt, i.m.) and flunixin meglumine (1.1 mg/kg bwt, was bordered by a thin layer resembling periosteum. i.v.) were administered. The horse was sedated with Fibrocollagenous tissue surrounded the bone. Inflammation detomidine (0.02 mg/kg bwt, i.v.). Induction of general and neoplasia were absent (Fig 5). Finally, the mass was anaesthesia was performed with diazepam (0.03 mg/kg bwt, diagnosed as subcutaneous osteoma cutis. i.v.) and ketamine (2 mg/kg bwt, i.v.), and anaesthesia was maintained with isoflurane in 100% oxygen. The horse was Follow-up positioned in the left lateral recumbent position. After routine The horse did not exhibit lameness at a routine check-up 3 surgical preparation, a C-shape incision (length, 20 cm) months after surgery. A residual mass or an uncomfortable around the caudal margin of the mass was made through the posture was not observed upon palpation or performance of skin in order to expose the margin of the mass. The mass had a the spavin test, respectively. The horse returned to its intended hard and thin plate-like appearance with an irregular surface use. and shape (Fig 3). The mass was separated from the overlying skin and surrounding soft tissues because it had no connection with the epidermis or fascia behind the gluteal muscle. The Discussion overlaying skin was closed routinely with USP 0 polyglactin This report describes a case of osteoma cutis in a horse that (Vicryl) and USP 0 polypropylene (Prolene) sutures. The excised was confirmed by laboratory examination, surgical removal

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Case Report Severe supracondylar lysis of the third metatarsal bone due to intra-articular haemorrhage with similarities to human pigmented villonodular synovitis: A differential diagnosis to intra-articular neoplasia G. J. Hinnigan*, R. Papoula-Pereira†, U. Hetzel† and E. R. Singer‡ School of Veterinary Science, Faculty of Health and Life Sciences, University of Liverpool, Leahurst Campus, UK; †Department of Veterinary Pathology, School of Veterinary Science, Liverpool, UK; ‡Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool, Leahurst Campus, UK. *Corresponding author email: [email protected]

Keywords: horse; metatarsophalangeal; synovitis; haemarthrosis; supracondylar lysis

Summary Case details This report describes a case of severe supracondylar lysis of History and clinical signs the third metatarsal bone of a mature Cob gelding. The A 10-year-old Cob gelding was presented for assessment of gelding presented with moderate to severe lameness and soft lameness associated with a swelling of the distal metatarsal tissue swelling in the distal metatarsal region. A mass was region of the right hindlimb (RH). Right hindlimb lameness and present plantar to the third metatarsal bone and dorsal to swelling had been noted 2 weeks prior to presentation, and the suspensory ligament branches. The mass was removed had not responded to rest and oral phenylbutazone therapy. surgically, and was found to be a large blood coagulum Abnormalities on clinical examination were confined to within an enlargement of the plantar pouch of the the RH. A firm, painful soft tissue swelling approximately metatarsophalangeal joint. The mass was pedunculated and 10 cm in width, was present between the suspensory ligament attached to a region of abnormal synovium. This synovium was branches and the plantar aspect of the third metatarsal bone identified histologically as being an area of villonodular (MtIII; Fig 1). There was a palpable concavity in the contour of synovitis. The lesion had similarities with human pigmented the plantar aspect of MtIII with firm protuberant swellings on villonodular synovitis. Removal of the abnormal tissue resulted the medial and lateral aspects of the bone. There was no in resolution of the lameness and of the lysis of the third palpable fetlock joint or digital flexor tendon sheath effusion metatarsal bone. Haemarthrosis should be considered in the and the suspensory ligament branches and flexor tendons list of differential diagnoses for focally mineralised soft tissue were palpably normal. Initially, the gelding was 7/10 lame masses found within an articulation, and may be associated (Ross 2003) in the RH when walked out, with the lameness with pigmented villonodular synovitis. improving to 3/10 after several strides. Due to the severity of the lameness and the abnormal bone contour of MtIII, the gelding was not examined at trot. Introduction Diagnostic imaging Palmar supracondylar lysis (SCL) is a term used to describe a reduction in cortical bone thickness of the distal third Radiography metacarpal bone (McIII) immediately proximal and palmar to Lateromedial, dorsoplantar, dorsal 45° lateral-plantaromedial the metacarpal condyles. This is a recognised radiographic oblique and dorsal 45° medial-plantarolateral oblique abnormality affecting the metacarpophalangeal joint (MCPJ) projections of the RH limb were attained using a computed (Haynes et al. 1981; McIlwraith 2002). Supracondylar lysis is radiography system (Directview Classic CR)1. Radiographs reported to occur secondary to chronic synovitis and revealed a smooth-margined convex area of bone loss of the osteoarthritis (OA) of the MCPJ. Bone resorption of the metaphysis of MtIII (Fig 2), which appeared as a depression in supracondylar region of McIII is induced by chronic osteoclastic the plantar cortex of the bone with a sclerotic margin. At the activity provoked by hyperaemia and inflammatory mediators deepest point of the depression, MtIII dorsoplantar depth was released in the palmar pouch of the MCPJ (Pool and Meagher decreased by approximately 30% relative to the normal proximal 1990). This report describes the clinical presentation, diagnostic diaphyseal bone. Plantar to the area of bone resorption were imaging findings and treatment of a case of severe plantar SCL multiple, irregularly shaped mineralised opacities measuring in the metatarsophalangeal joint (MTPJ) of a Cob gelding. This approximately 2–6 mm in size. The distal extremity of the second was an unusual case for several reasons: the severity of the SCL, metatarsal bone was displaced medially. the hindlimb involvement, the absence of any signs of OA and the presence of a large intra-articular blood coagulum, Ultrasonography appearing clinically as a solitary soft tissue mass within the Ultrasonographic examination of the distal metatarsal and plantar pouch of the MTPJ. fetlock region of the RH was performed with an 8–12 MHz linear

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Fig 2: Lateromedial radiograph of the fetlock region of the right hindlimb. A smooth-margined convex area of bone loss is evident in the distal plantar metaphysis of the third metatarsal bone with a sclerotic margin. Multifocal areas of radiopacity, consistent with mineralisation, are seen plantar to the area of bone lysis.

evident immediately plantar to the distal MtIII on the sagittal images. Although the signal intensity was heterogeneous it was generally of high intensity, consistent with soft tissue or fluid. On the fat suppressed STIR FSE images, the mass was of high signal intensity at the margins. The plantar cortex of MtIII was concave in outline and was markedly reduced in thickness adjacent to the mass (Fig 3). The cortex of plantar Fig 1: Photograph of the plantar aspect of the distal right hindlimb MtIII measured approximately 2 mm at the thinnest point. acquired prior to surgery. The soft tissue swelling can be seen There was a focal area of increased signal intensity in the distorting the skin on both the medial and lateral aspects of the plantaromedial aspect of MtIII on T1W GRE, T2*W GRE (Fig 4) limb immediately proximal to the fetlock. and STIR transverse images. There was no evidence that the mass was invading the plantar cortex of the third metatarsal array transducer (Vivid-i)2. A heterogenous mass of mixed bone as it appeared as a discreet structure in all images. echogenicity was evident between the suspensory ligament The clinical and imaging findings to this point suggested and plantar MtIII. The mass was predominantly of soft tissue that a multifocally mineralised soft tissue mass was present echogenicity with hyperechogenic foci evident, particularly adjacent to the plantar aspect MtIII. The mass probably on the lateral aspect. The hyperechogenic foci cast an caused lysis of the adjacent bone and was likely to be acoustic shadow, and were consistent with the mineralised responsible for the lameness. A decision was made to attempt opacities identified on radiography. There were small focal to resect the mass in toto, which would be both therapeutic anechoic regions surrounding the tissue mass, thought to and diagnostic. represent fluid. The suspensory ligament body, branches and their insertions onto the proximal sesamoid bones appeared Treatment normal. There was an irregular hyperechogenic appearance Surgery to the periosteum of the abaxial margins of MtIII consistent with A 12 gauge polytetraflouroethylene catheter (Intraflon 2)4 periosteal new bone and the firm swellings felt on palpation. was placed in the left jugular vein. Prior to anaesthesia, phenylbutazone (4.4 mg/kg bwt i.v.) and crystalline sodium Magnetic resonance imaging penicillin (10 mg/kg bwt i.v.) were administered. The gelding Magnetic resonance imaging (MRI) was performed with a 0.27 was premedicated with acepromazine maleate (0.03 mg/kg Tesla magnet standing MRI system (Hallmarq)3. MRI was bwt i.v.) and morphine sulfate (0.1 mg/kg bwt i.v.), followed by performed to classify the mass further, to assess the integrity of romifidine hydrochloride (100 mg/kg bwt i.v.). Anaesthesia was MtIII and to assist with surgical planning. T1 weighted gradient induced with ketamine hydrochloride (2.2 mg/kg bwt i.v.) and echo (T1W GRE), T2 star weighted gradient echo (T2*W GRE) diazepam (0.05 mg/kg bwt i.v.) and was maintained with and short tau inversion recovery fast spin echo (STIR FSE) inhaled oxygen and halothane. sagittal and transverse scans were acquired of the distal The gelding was placed in dorsal recumbency with an metatarsal region of the RH. A large smooth oval structure was Esmarch bandage placed on the RH. An approximately 10 cm

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Fig 5: Intraoperative photograph of the mass reflected from the plantar pouch of the metatarsophalangeal joint. The mass is still attached to the plantar synovial membrane of the joint via a small peduncle. The large proximal out-pouching of the plantar pouch of the metatarsophalangeal joint can be seen above the mass.

curvilinear incision was made on the lateral aspect of the distal Fig 3: Transverse T1W GRE magnetic resonance image of the distal metatarsus. This was centred over the mass with the convex metatarsus of the right hindlimb, lateral is to the left. The mass of high side of the incision plantar. The skin and subcutaneous tissues signal intensity (white arrow) can be seen occupying the entire area between the third metatarsal bone and the suspensory ligament were dissected free from the underlying mass using a branches. The reduction in thickness of the plantar cortex of the third combination of sharp and blunt dissection, with the flap then metatarsal bone is visible, particularly close to the midline. reflected dorsally. A thick fibrous tissue capsule was identified, which was closely adherent to MtIII dorsally. A second, similar curvilinear incision was made on the medial aspect of the limb. Two incisions were made to maximise visualisation of the dissected area. Upon attempting to free the mass from the third metatarsal bone, penetration of the fibrous capsule occurred, releasing a viscous fluid which was synovial in nature. On further examination, it became obvious that the fibrous capsule was the fetlock joint capsule. Further dissection revealed an approximately 7 ¥ 4 ¥ 2 cm dark red mass, with the appearance of a large blood clot, adjacent to the plantar cortex of MtIII. The mass was within a large proximal out-pouching of the MTPJ and was attached to the synovial membrane via a small peduncle (Fig 5). The pedunculated mass and a 1 cm margin of the thickened synovial membrane were removed. The medial dissection was discontinued and the lateral wound was closed by suturing the joint capsule to the connective tissue on the periosteal surface of MtII with interrupted horizontal mattress sutures of 3 metric braided lactomer (Polysorb)5. The subcutaneous tissue was sutured with a continuous horizontal mattress pattern of 3 metric Polysorb on both the medial and lateral aspects of the limb. The skin was opposed with stainless steel staples (Skin Stapler W)6.A distal limb cast was placed from the foot to the proximal metatarsus for recovery from anaesthesia, which was rope assisted. Recovery from anaesthesia was uneventful.

Histopathology Fig 4: Transverse T2*W GRE magnetic resonance image of the distal The entire mass and the adjacent resected synovial metatarsal region of the right hindlimb, lateral is to the left. This membrane (Fig 6) were fixed in 10% neutral buffered formalin. image was acquired further proximal to Figure 3, immediately distal to the body of the suspensory ligament. There is an area of The submitted tissues were embedded in paraffin in the routine increased signal intensity in the plantaromedial cortex of the third manner. Paraffin sections were stained with haematoxylin and metatarsal bone (white arrow). The mass of high signal intensity eosin, periodic acid-Schiff/alcian blue, Masson trichrome, can be seen between the plantar aspect of the third metatarsal Perl’s and van Kossa stains. The sections were examined under bone and the suspensory ligament branches. a light microscope.

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a) b)

c) d)

e) f)

g) h)

Fig 6: Photomicrographs of the intra-articular mass. (a,b) Villo-nodular appearance of the synovial membrane (asterisks) with moderate diffuse subsynovial fibrosis and focal hyperaemia (a: haematoxylin and eosin [H&E] ¥20, b: Masson trichrome ¥20). (c,d,e) Higher magnification of the villonodular synovium with large numbers of macrophages (c: H&E, ¥100), partly containing iron (blue staining in d: Prussian blue ¥200) and a fibrous to myxoid, alcian blue positive extracellular matrix (e: alcian blue/periodic acid Schiff, ¥200). (f,g,h) The major component of the intra-articular mass is represented by acute haemorrhage. Acute haemorrhage arranged in a lamellar fashion (f: H&E ¥40). A later stage of haemorrhage with fibrin and fibroblast proliferation (g: H&E ¥100). Chronic haemorrhage with resorption and haemosiderophages with brown intracytoplasmic granular material (asterisk), demarcated by a fibroblast rich tissue (h: H&E ¥200).

The mass was unilaterally demarcated by a partly smooth, erythrocytes indicating recurrent intra-articular haemorrhages. partly villonodular vascularised myxoid connective tissue partly Multifocally, there were also areas of mineralisation. Where covered by synoviocytes (inner joint capsule with synovium). present, the synovium showed moderate hyperplasia and The mass itself was composed of lamellarly arranged hypertrophy. The subsynovial tissue was characterised by amorphous eosinophilic, proteinaceous material containing fibroblasts, embedded into a myxoid and collagen rich necrotic cellular debris and leucocytes alternating with extracellular matrix with focally mild lympho-plasmacytic

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(Haynes et al. 1981). Thinning of the palmar cortex of McIII in cases of SCL is caused by chronic osteoclastic activity, provoked by hyperaemia and inflammatory mediators released from the synovium of joints chronically affected by OA (Pool and Meagher 1990). It has been proposed that the SCL lesion itself is of no clinical significance but is simply a clinical sign of chronic OA. In contrast to other reported cases of SCL, there was no radiographic or MRI evidence of OA of the MTPJ in the case presented. The SCL of MtIII in this case was severe and extended significantly further proximally than other reported cases (Haynes et al. 1981). This was probably due to the reorganising haemarthrosis causing significant proximal stretching of the plantar MTPJ capsule with consecutive osteoclastic activity being induced over a larger area, and hence a more extensive SCL lesion developing. Synovial masses, both neoplastic and non-neoplastic, Fig 7: Lateromedial radiograph taken 6 months following surgery have been extensively reported in man (Szendroi and (left image) and the original lateromedial radiograph taken at presentation (right image). The third metatarsal bone has Deodhar 2000). Synovial neoplasia has been reported rarely in modelled significantly towards the normal shape of the bone, with the horse, with reports of synovial sarcomas (Cheli and Zaraga approximately 50% of the dorsoplantar depth being replaced 1977; Edens et al. 2001) and a lipoma (Hammer et al. 2002) in when compared to the original radiograph. the literature. Synovial sarcomas present similarly to the case reported here, as a soft tissue mass adjacent to a joint (Edens infiltration and areas of macrophages with foamy vacuolated et al. 2001). Radiographic signs of synovial sarcomas include cytoplasm, containing granular pale cream, Perl’s positive periosteal reaction, mineralisation of the mass and lysis of material consistent with haemosiderosis. the adjacent bone (van der Horst et al. 1996); however, it is The morphological histological diagnosis was of recurrent rare for a synovial sarcoma to occur within a joint capsule. The reorganising intra-articular haemorrhages (haemarthrosis) with histological appearance of a synovial sarcoma is also vastly consecutive pigmented villonodular synovial hyperplasia in different from that of the case presented here, with a highly the plantar aspect of the MTPJ. cellular mass of pleomorphic cells being a typical appearance (McGlennon et al. 1988). Non-neoplastic masses within synovial structures have Post operative management also been reported in the horse. A single case of suspected The distal limb cast was removed 24 h following surgery and synovial osteochondromatosis involving the extensor carpi the limb was placed in a support bandage. The gelding was radialis tendon sheath has been described (Newell et al. administered a course of oral phenylbutazone (2.2 mg/kg bwt 1996). Synovial hamartomas, non-neoplastic masses derived b.i.d. per os) for 5 days. Trimethoprim sulfadiazine (30 mg/kg from vascular tissues, have also been described associated bwt b.i.d. per os) was administered for 10 days, as there was with the tendon sheaths of the dorsal carpus (Colbourne et al. some drainage of synovial fluid from the incision for 5 days 1997). Pigmented villonodular synovitis in man is an uncommon following surgery. The distal limb swelling reduced and the non-neoplastic condition that often affects the knee joint gelding was 1/10 lame on the RH at walk by the time of (Mankin et al. 2011). The morphological findings in the case discharge from the hospital, 10 days following surgery. The presented are comparable to human PVNS, arising on the gelding was box rested with an ascending walking exercise synovial surface. Human PVNS is characterised by a programme for 8 weeks, before being re-introduced to small villonodular synovial component with the presence of paddock turnout for a further 4 weeks. monocytes, giant cells, lipocytes, histiocytes and fibroblasts. Although the intra-articular behaviour can be aggressive, the Follow-up lesion is interpreted as a benign disorder (Mankin et al. 2011). Six months following surgery, the gelding was sound at The term pigmented relates to the presence of haemosiderosis walk and trot in a straight line and was in light work. Repeat of the lesion, as was seen in the case presented here. radiographs showed approximately 50% of the dorsoplantar Haemarthrosis is also common in PVNS and is seen in 75% of depth of the defect in the plantar MtIII cortex had been cases (Myers et al. 1980). modelled, partially restoring the normal shape of MtIII (Fig 7). The condition seen in this case has to be distinguished from the most widely reported intra-articular mass in the horse, Discussion proliferation of the normal synovial pad of the MCPJ (Nickels This report describes a case of extensive SCL of MtIII secondary et al. 1976; Rose 1988; Dabareiner et al. 1996; Murphy and to chronic, recurrent reorganising haemarthrosis with Nixon 2001). Proliferation of the synovial pad is a condition that villonodular synovial hyperplasia of the plantar MTPJ. This is reported to affect the forelimb MCPJ exclusively and is condition demonstrates morphological similarities to the entity predominantly seen in horses used for racing (Dabareiner et al. of articular pigmented villonodular synovitis (PVNS) in man. 1996). The condition is characterised by a proliferation of the There are no previous reports that document a reorganising normal synovial pad or plica in the dorsoproximal recess of the haemarthrosis as the cause of bone resorption, in the form of MCPJ. This pad is composed of fibrous connective tissue and is SCL in horses. thought to act as a cushion between the proximal phalanx Supracondylar lysis is thought to occur secondary to and McIII during maximal extension (White 1990). Repetitive chronic synovitis and fibrosis of the palmar pouch of the MCPJ trauma due to repeated hyperextension, as is seen in the

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racehorse, is thought to cause hypertrophy and thickening of plantar pouch of an equine MTPJ associated with PVNS, which the pad due to chronic fibrosis (White 1990; Dabareiner was responsible for significant lameness and extensive SCL et al. 1996). Clinically, the condition presents with swelling of of the adjacent MtIII. Surgical resection was curative and the dorsal aspect of the fetlock, synovitis, synovial effusion resulted in resolution of the lameness and the bone lysis. In and varying degrees of lameness (Murphy and Nixon 2001). conclusion, haemarthrosis should be considered in the list of Radiographic evaluation often reveals lysis of the dorsal differential diagnoses for focally mineralised soft tissue masses aspect of McIII adjacent to the synovial pad proliferation found within an articulation, and may be associated with (Dabareiner et al. 1996). Synovial pad proliferation was PVNS. originally termed villonodular synovitis but has since been reclassified, as the mass is a proliferation of the normal fibrous Authors’ declaration of interests connective tissue and haemosiderosis is not seen (White 1990). No conflicts of interest have been declared. Although a traumatic aetiology for the condition was suspected from the histological findings of the joint capsule, no other evidence of trauma was identified in the case presented Manufacturers’ addresses here. There was no known history of a traumatic event, no 1Kodak UK, Hemel Hempstead, Hertfordshire, UK. external wound or scar and no evidence of injury to adjacent 2GE Healthcare, Chalfont St Giles, Buckinghamshire, UK. structures. The intrasynovial pathology and associated bone 3Hallmarq Veterinary Imaging Ltd, Guildford, Surrey, UK. lysis may have been initiated by an overextension injury 4Arnolds Veterinary Products Ltd, Shrewsbury, Shropshire, UK. tearing the plantar joint capsule, although this cannot be 5Covidien Plc, Dublin, Ireland. 6 proven. The authors’ hypothesis is that recurrent haemorrhage Henry Schein Inc., Melville, New York, USA. from the associated villonodular synovitis in the plantar aspect of the MTPJ led to osteoclastic resorption of MtIII and caused References the extensive bone lysis identified on radiography and MRI. Booth, T.M., Dart, A.J. and Watkins, J.P. (2003) Equine limb casts: The effects of the villonodular synovitis and organised classification and indications. Comp. Cont. Educ. Pract. Vet. 25, haemarthrosis appeared to be limited to enlargement of the 701-706. plantar pouch of the MTPJ and significant SCL of MtIII. The Cheli, R. and Zaraga, L. (1977) Synovioma of the (large proximal) aetiology of human PVNS also remains unknown, with no sesamoid bones in a horse. Clin. Vet., Milano 100, 280-283. apparent association with trauma and no familial or genetic Colbourne, C.M., Yovich, J.V., Richards, R.B., Rose, K.J. and Huxtable, C.R. (1997) Vascular hamartomas of the dorsal carpal region in three origin (Mankin et al. 2011). young Thoroughbred horses. Aust. Vet. J. 75, 20-23. Magnetic resonance imaging added valuable diagnostic Dabareiner, R.M., White, N.A. and Sullins, K.E. (1996) information by demonstrating that the plantar cortex of MtIII Metacarpophalangeal joint synovial pad fibrotic proliferation in 63 was markedly thinner than normal near the midline, which horses. Vet. Surg. 25, 199-206. could not be appreciated fully on radiography. The area of Edens, M.S., Gaughan, E.M., Allen, D. and Andrews, G.A. (2001) Synovial hyperintense signal in the plantaromedial cortex of MtIII was cell sarcoma in two horses. Irish Vet. J. 54, 289-292. visible in all image weightings indicating bone oedema, Hammer, E.J., Chope, K., Lemire, T.D. and Reef, V.B. (2002) A lipoma of necrosis, fibrosis or inflammation at this level adjacent to the the extensor tendon sheaths in a horse. Vet. Radiol. Ultrasound 43, mass (Murray et al. 2006). This abnormal signal raised further 63-65. concerns regarding the integrity of MtIII; therefore, the gelding Haynes, P.F., Root, C.R., Clabough, D.L. and Roberts, E.D. (1981) Palmar supracondylar lysis of the 3rd metacarpal bone. Proc. Am. Ass. was recovered from anaesthesia in a distal limb cast in order Equine Practnrs. 27, 185-193. to decrease the risk of fracture (Booth et al. 2003). Magnetic Mankin, H., Trahan, C. and Hornicek, F. (2011) Pigmented villonodular resonance imaging also confirmed that the mass was soft synovitis of joints. J. Surg. Oncol. 103, 386-389. tissue in origin due to its homogenous hyperintense signal, McGlennon, N.J., Houlton, J.E.F. and Gorman, N.T. (1988) Synovial rather than a mass originating from the bone. sarcoma in the dog. A review. J. Small Anim. Pract. 29, 139-152. The rapid resolution of lameness following surgery would McIlwraith, C.W. (2002) Diseases of joints, tendons, ligaments, and indicate that a component of the pain was induced either by related structures. In: Adams’ Lameness in Horses, 5th edn., Ed: T.S. direct pressure of the organised haemarthrosis on MtIII or due Stashak, Lippincott Williams and Wilkins, Philadelphia. pp 459-644. to increased hydrostatic pressure within the MTPJ. By 6 months Murphy, D.J. and Nixon, A.J. (2001) Arthroscopic laser extirpation of post operatively, a significant amount of modelling of MtIII had metacarpophalangeal synovial pad proliferation in eleven horses. occurred; however, the bone had not returned to its normal Equine Vet. J. 33, 296-301. appearance. Removal of the haemarthrosis, the likely source Murray, R.C., Schramme, M.C., Dyson, S.J., Branch, M.V. and Blunden, T.S. (2006) Magnetic resonance imaging characteristics of the foot of increased osteoclastic activity in the plantar aspect of MtIII, in horses with palmar foot pain and control horses. Vet. Radiol. allowed the bone to model towards a normal shape. Whether Ultrasound 47, 1-16. the bone will regain its original appearance remains to be Myers, B.W., Masi, A.T. and Feigenbaum, S.L. (1980) Pigmented seen, although the limb is no longer causing a clinical problem villonodular synovitis and tenosynovitis: a clinical epidemiologic for the horse. Surgical removal of synovial pad proliferation in study of 166 cases and literature review. Medicine 59, 223-237. the dorsal MCPJ has a good prognosis for return to racing, Newell, S.M., Roberts, R.E. and Baskett, A. (1996) Presumptive although no follow-up data are available on whether the lytic tenosynovial osteochondromatosis in a horse. Vet. Radiol. Ultrasound 37, 112-115. radiographic lesions resolve following surgical removal (Dabareiner et al. 1996). Human PVNS is usually treated Nickels, F.A., Grant, B.D. and Lincoln, S.D. (1976) Villonodular synovitis of equine metacarpophalangeal joint. J. Am. Vet. Med. Ass. 168, with surgical excision, which appears to be curative, and 1043-1046. recurrence is infrequent (Mankin et al. 2011). Pool, R.R. and Meagher, D.M. (1990) Pathological findings and This case highlights a previously unreported clinical pathogenesis of racetrack injuries. Vet. Clin. N. Am.: Equine Pract. 6, scenario of a large organised haemarthrosis forming within the 1-30. Continued on page 258 © 2013 EVJ Ltd Every Case. Every Time. Support for Wellness, Performance & Conditions.

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Original Article A modified surgical technique for penile amputation and preputial ablation in the horse C. E. Wylie and R. J. Payne* Rossdales Equine Hospital and Diagnostic Centre, Exning, Newmarket, Suffolk, UK. *Corresponding author email: [email protected]

Keywords: horse; penis; genital; amputation; ablation; urethrostomy

[Correction added on 17 August 2015, after first online publication: There were errors in the summary, results section and Table 2 and have now been corrected. Please refer to the changes in italics and correction statement in bold.]

Summary Surgical complications associated with the previously The aim of this study was to describe a modified surgical described techniques have been observed in up to 100% of technique for treatment of severe penile pathology, and the cases (Markel et al. 1988; Howarth et al. 1991; Mair et al. long-term outcome. The surgery consisted of subischial 2000; Doles et al. 2001; Archer and Edwards 2004), and post urethrostomy and penile amputation with preputial ablation, discharge complications in 0–50% (Doles et al. 2001; Archer with the horse in dorsal recumbency. A redundant section of and Edwards 2004; van den Top et al. 2008). Results of the penis root and body was left in situ, rather than being long-term follow-up have varied, with variable definitions of retroflexed as described elsewhere. Follow-up was obtained success post surgery, different follow-up times reported and using a structured owner telephone questionnaire. The 15 cases different initial pathologies (Markel et al. 1988; Howarth et al. included: 11 squamous cell carcinomas (73.3%); 2 melanomas; 1991; Mair et al. 2000; Doles et al. 2001; Archer and Edwards one chronic preputial discharge with no associated neoplasia; 2004; van den Top et al. 2008). and one paraphimosis following routine sedation. Length of It was considered that penile retroversion may be an survival ranged from 0.9 to 74.6 months (median 25.1 months). unnecessary step in the previously described procedures. The From the 14 horses with follow-up, 9 survived >18 months objective of this paper was, therefore, to describe a modified (64.3%) [Correction added on 17 August 2015, after first online surgical technique for the treatment of severe penile publication: The percentage in the preceding sentence was pathology that does not require penile retroversion, and wrong and has been corrected to ’64.3%’ from ’69.2%’]. Four describe the features and long-term outcome of cases within euthanasias were due to presenting or post operative our hospital undergoing the procedure. complications, while 2 were unrelated to the procedure. This procedure presents a simplified, viable option for treatment of Materials and methods extensive mixed penile lesions; reducing surgical complexity Description of surgical technique and time in comparison to previously described techniques Preoperative planning requiring retroversion. Selection criteria included: 1) that the animal was in good general health, with no clinical signs of systemic disease, Introduction particularly weight loss; 2) physical examination did not reveal enlarged inguinal lymph nodes; and 3) no abnormalities were Surgical resection is indicated for the treatment of extensive detected on rectal examination. Preoperative assessment was penile and preputial pathology, both to remove the affected conducted in the standing patient to determine the most tissues and to ensure adequate margins are removed to suitable location of the urethrostomy site. By external digital reduce the risk of recurrence of neoplastic lesions. Indications palpation the surgeon identified the caudal limit of the bony for urethrostomy and penile amputation with preputial ablation pelvic floor (pubis), siting the urethrostomy at a level at least have most commonly been squamous cell carcinoma (SCC) 10 cm ventral to this. A permanent marker pen was used to (Markel et al. 1988; Howarth et al. 1991; Mair et al. 2000; Doles draw an impression of the surgical site on the horse’sskin(Fig 1). et al. 2001; Archer and Edwards 2004; van den Top et al. 2008), Routine premedication included sedation with 0.03 mg/kg but also squamous papilloma (Archer and Edwards 2004), bwt i.v. acetylpromazine (Vetranquil)1 and 0.08 mg/kg bwt lymphosarcoma (Markel et al. 1988), melanoma, habronemiasis i.v. romifidine (Sedivet)2, comprehensive broad-spectrum and traumatic paraphimosis (Doles et al. 2001). antibiotics 18 mg/kg bwt i.m. s.i.d. penicillin (Depocillin)3 and En bloc penile resection and retroversion was described by 6.6 mg/kg bwt s.i.d. i.v. gentamicin (Gento Equine)4, and Markel et al. (1988) for treatment of genital neoplasms that 1.1 mg/kg bwt i.v. flunixin (Cronyxin)5 analgesia. extensively involve the penis, prepuce and/or superficial Once the horse was anaesthetised, staple markers were inguinal lymph nodes. In 2004, Archer and Edwards published a inserted into the skin at the upper and lower limits of the slightly modified version of this technique in which a triangular urethrostomy site. After the horse was moved to theatre, a urethrostomy was created and the penis transected and large surgical field was scrubbed and aseptically prepared retroflexed towards a vertical subischial incision. A technique from the subischial region to the entire penis and prepuce, on for less severe cases, retaining the normal ventral position of the ventral abdomen. A 150 cm silicone balloon catheter6 was the penis, has been described by Doles et al. (2001). placed in situ, and the penis was kept in an elevated position

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Fig 1: An impression of the surgical site is drawn on the horse’s skin whilst standing to determine the most suitable location of the urethrostomy site, which should be located at a level at least 10 cm ventral to the pelvic floor in order to prevent retrograde movement of air into the bladder, and also to ensure that urine is voided at a level that does not ‘scald’ the hind legs. using a pair of sponge forceps. Once aseptic preparation was Fig 3: The urethra is carefully opened at a single point, dividing complete, the penis was handed to an assistant who took the the muscle tissue of the retractor penis muscle longitudinally for a sponge forceps during the draping procedure. total length of 10 cm, having oversewn the bulbospongiosus and corpus spongiosum muscles in a continuous crushing layer.

Subischial urethrostomy procedure (Fig 3). The distal urethra was completely transected, forming The midline subischial region was palpated carefully, with the an opened spatulated flat structure with approximation to the urinary catheter clearly palpable within the urethra. The skin edges using a single simple continuous 2 metric polyglactin urethra was identified via a vertical skin incision midline 9107 suture proximally, distally, and laterally at its left and right overlying a urethral catheter with reference to the preplaced midpoints. Multiple simple interrupted 2 metric polyglactin 9107 marker staples, and opened at a single point with a scalpel sutures were placed at 3 mm intervals around the blade (Fig 2). The incision was continued dividing the muscular urethrostomy to join it to the cutaneous margins. Prior to this tissues of the retractor penis muscle longitudinally for a part of the surgery the urinary catheter was withdrawn from the distance of 10 cm with Mayo scissors having over-sewn the penis, and re-inserted into the bladder via the newly created bulbospongiosus and corpus spongiosum muscles in a urethrostomy site. continuous, crushing layer with 2 metric polyglactin 9107 Penile amputation and preputial ablation The penis was elevated vertically from the horse in dorsal recumbency and placed under moderate traction. A

Fig 4: The penis is elevated vertically from the horse in dorsal Fig 2: The urethra can be identified by palpation of the urinary recumbency and placed under moderate traction. A relatively catheter within the urethra in the midline subischial region and an narrow fusiform skin incision is made from a point on the midline overlying vertical skin incision midline. abdomen, just cranial to the prepuce encompassing the penis.

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fusiform skin incision was made from a point on the midline abdomen, from just cranial to the prepuce encompassing the penis (Fig 4), ensuring an adequate amount of skin was preserved so that closure was not under any significant degree of tension. Using a combination of mostly blunt dissection using fingers and Mayo scissors a plane of dissection was established between the body wall and the prepuce at the cranial end of this incision. Dissection was then carried out along each side of the prepuce to identify and ligate arteries and veins (branches of the caudal superficial epigastric artery from the external pudendal artery). Once identified within the para-penile fat, these were ligated with a vessel sealing device (LigaSure)8. Once dissection was complete beneath the prepuce (along the body wall) and lateral to the prepuce, the body of the penis was clamped with large right-angled forceps, and transected using a scalpel blade. Transection occurred at the penis root with no attempt to minimise the length of the redundant penis. The penis and prepuce were then discarded and the corpus cavernosum and corpus spongiosum crushed and over-sewn using a simple continuous 4 metric polyglactin 9107 suture, relying on the strength of the tunica albuginea for holding this crushing suture. The dorsal arteries and veins of the penis were also identified and ligated. Once secure ‘crushing’ and over-sewing of the penile stump were achieved, the clamps Fig 5: Completed penile amputation and preputial ablation; a were released to check for haemorrhage. So long as no multilumen drain exits from the most cranial 6 cm of the penile haemorrhage was identified, the surgical site was flushed ablation surgical site, whilst a Foley catheter is placed in the prior to placement of a PVC/silicone multilumen drain9 bladder post operatively to prevent urinary obstruction. (Portex Yeates Tissue Drain) anchored at the caudal end of the incision by a retaining suture placed percutaneously. The subcutaneous fatty tissues were closed in 2 layers with 4 contacted. All cases were included (first case 16 March 2000 metric polyglactin 9107 along the entire length of the incision, to most recent 18 April 2013). All data analyses were with the exception of the most cranial 6 cm. This was left open performed in Microsoft Excel 200311. to drain and heal by secondary intention, with the preplaced multilumen drain exiting through this point. A subcutaneous Results simple continuous layer of 3 metric polyglactin 9107 was also placed before the skin was closed with staples. With this Case population technique, a redundant section of the penis root and body The details of the surgical cases (n = 15) are presented in was left in situ, rather than being retroflexed as described Table 1. All but one animal were geldings (93.3%, 95% CI elsewhere (Markel et al. 1988; Archer and Edwards 2004). 80.7, 100%). The range of ages was 8–19 years (median 16 years). Weight ranged from 275 to 750 kg (median Post operative care 492 kg). Most cases had extensive neoplasia (86.7%, 95% CI A Foley catheter6 was placed in the bladder post operatively 69.5, 100%), all of which were confirmed histologically; 11 to ensure no urinary obstruction (Fig 5), and removed 12–24 h cases had SCC changes (73.3%, 95% CI 50.6, 95.7%), two post operatively. Nursing care was required both to clean had melanoma, one had chronic preputial discharge with and monitor the ventral abdominal wound, and also to clean no associated neoplasia, and one had priapism following around the urethrostomy site and apply barrier cream to routine sedation by the referring vet with 5 mg detomidine prevent skin scalding to the medial thigh. The drain was and 8 mg butorphanol. The duration of the presenting removed from the ventral abdominal incision by cutting the complaint where known ranged from 0.25 to 96 months retained suture at approximately 7 days post operatively. Skin (median 10 months). Two cases had previous partial staples were removed at 14 days post operatively. The amputation of the penis due to SCC, undertaken elsewhere, cranial 6 cm of this incision was allowed to heal by second which was unsuccessful. Case 2 had undergone a previous intention, and usually did so uneventfully within the first reefing operation and partial resection in June 2010, followed 4 weeks. Post operative medication included 2.2 mg/kg bwt by laser surgery in November 2010, although extensive lesions b.i.d. oral or 4.4 mg/kg bwt s.i.d. oral phenylbutazone continued to recur and there remained a purulent sheath (Equipalazone)4 and 7.5 mg/kg bwt s.i.d. oral enrofloxacin discharge. Case 8 had undergone a previous reefing (Baytril)10 for 10 days. operation in May 2000, followed by partial resection using the Williams’ variation of the Boltz technique in July 2001 Follow-up (Williams 1943), but developed urethral stenosis and Long-term follow-up was obtained by contacting the owner extensive adhesions, which, despite manual breakdown via telephone using a structured questionnaire, or from review under general anaesthesia, resulted in severe dysuria and of the electronic case records if the owner could not be bladder distension.

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TABLE 1: Overview of 15 cases of penile amputation and preputial ablation undertaken at Rossdales Equine Hospital

Case Age (years)/Sex/Breed/Weight Duration of no. (kg)/Colour lesion (months) Lesion Site of lesion

1 19/G/Connemara/493/Grey 96 Melanoma Free penis, outer/inner laminae of preputial fold and preputial ring 2 10/G/New Forest/377/Grey 12 In situ squamous cell carcinoma with Free penis and outer/inner secondary infection *Previous resection laminae of preputial fold 3 17/G/Cob X/500/Piebald 3 Invasive squamous cell carcinoma Distal urethra, glans, free penis and outer/inner laminae of preputial fold 4 16/G/Hackney X Welsh 10 Papilloma with mucosal dysplasia, early Glans, fossa, free penis, D/543/Black precursor to squamous cell carcinoma outer/inner laminae of preputial fold and midline 5 15/G/Welsh/275/Coloured Missing Ulcerating squamous cell carcinoma Free penis and urethra 6 16/G/Cob/441/Skewbald 10 Chronic preputial discharge with Outer/inner laminae of ulceration and excoriation preputial fold 7 10/G/Irish X Thoroughbred/ Missing Ulcerated melanomas Outer/inner laminae of (missing)/Grey preputial fold 8 13/G/Arab X Cob/340/Bay 18 Recurrent squamous cell carcinoma Free penis, urethra and with complete urethral inguinal lymph nodes obstruction* 9 18/S/Cob/575/Piebald Missing Squamous cell carcinoma with ulceration Glans to preputial ring and infection 10 8/G/Hanoverian/750/Chestnut 0.25 Paraphimosis following sedation, with NA thrombosed corpus cavernosum and no response to treatment 11 17/G/Welsh X/(missing)/Dun Missing Invasive squamous cell carcinoma Glans, free penis, preputial ring 12 18/G/Crossbred/490/Bay Missing Invasive squamous cell carcinoma with Outer/inner laminae of metastasis within lymphatic and vascular preputial fold, spermatic structures and extensively within the cord, lymph and vascular spermatic cord metastasis 13 13/G/Irish Cob/491/Bay 8 Chronic unresolved infection of preputial Glans and free penis sheath associated with early squamous cell carcinoma changes 14 14/G/Crossbred/Missing/Missing Missing Squamous cell carcinoma Missing 15 17/G/AngloArab/493/Palomino 2 Invasive squamous cell carcinoma Free penis and outer/inner laminae of preputial fold

* Previous resection

Surgery time ranged from 120 to 210 min (median thrombosis of the left jugular vein, and Case 14 developed a 165 min), with recovery time ranging from 20 to 90 min haematoma at the surgical site which delayed wound (median 40 min). The length of total hospitalisation ranged healing. from 11 to 26 days (median 19.5 days). The length of Long-term follow-up was obtained via telephone convalescence until return to exercise ranged from 1.5 to questionnaire for 9/15 (60%) of the horses. Three owners (20%) 12 months (median 3 months). were not contacted as the follow-up was available through the electronic case records and as the animals had been Follow-up subjected to euthanasia it was not considered justifiable to The features associated with follow-up are described in potentially distress the owners by contacting them. Three Table 2. Seven animals developed short-term post operative animals (20%) were lost to long-term follow-up, although 2 complications (during hospitalisation), one of which was had been seen at Rossdales Equine Hospital at 10 months considered life-threatening. Case 1, a 19-year-old Connemara and 24.5 months post surgery. Using the available data for the in good body condition score, with no previous history of 14 horses, length of survival ranged from 0.9 to 74.6 months laminitis, and a normal ACTH level, developed acute bilateral (median 25.1 months). From the 14 horses with adequate forelimb laminitis after 10 days. Case 15 developed right-fore follow-up, 9 survived >18 months (64.3%, 95% CI 39.2, 89.4%). palmar carpal fragmentation upon recovery from general Overall satisfaction from the 9 owners contacted was excellent anaesthesia. More minor complications were observed in 5 in each case (excluding Cases 1, 9–12 inclusive and 15). cases. Case 4 developed low-grade haemorrhage from the Post discharge complications were described by 8 midline with oedema, Case 6 developed ventral oedema and owners. Three of these were considered to be continuations wound discharge, Case 8 developed perineal and hindleg of the predischarge complications with Case 1 continuing to scalding prior to posturing changes, Case 12 developed suffer from laminitis, Case 4 was reported by the owner to recumbency and weakness following anaesthesia with continue to ‘drip’ from the drainage site for a long time with a subsequent purulent discharge from the midline, and an ‘itchy scar’, and Case 6 continuing to discharge

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TABLE 2: Outcome of 15 cases of penile amputation and preputial ablation undertaken at Rossdales Equine Hospital

Case Previous level Recurrence of Survival time post no. of exercise Level of exercise post surgery the problem Outcome operatively (months)

1 General purpose Did not return to exercise No Euthanasia 3.8 2 Showing Showing at a lower level due to No Alive 28.9 bilateral suspensory ligament disease, inflammatory bowel disease and laminitis 3 Hacking Hacking at a lower level due to arthritis No Alive 58.8 in the coffin joint 4 General purpose General purpose at a lower level as still No Alive 7.1 convalescing 5 Driving Driving at a lower level Yes Euthanasia 24.3 6 General purpose Same level No Alive 74.6 7 General purpose Same level Yes – dock Alive 25.1 and tail 8 General purpose/ General purpose/Showjumping at a No Euthanasia 45.6 Showjumping higher level 9 Companion Missing Missing Missing Missing 10 Dressage Same level Missing Alive 24.5 11 General purpose Did not return to exercise No Euthanasia 3.2 12 General purpose Did not return to exercise Yes Euthanasia 0.9 13 General purpose General purpose at a higher level No Alive 38.1 14 General purpose Same level No Euthanasia 48.0 15 General purpose Missing Missing Alive 10.0

[Correction added on 17 August 2015, after first online publication: In Case no. 14, the data for Outcome has been changed to ’Eutha- nasia’ from ’Alive’.]

b-haemolytic Streptococcus spp. for approximately one year. be treated by amputation of the free penis, yet did not [Correction added on 17 August 2015, after first online extensively involve the fibrous tunic, sheath or regional lymph publication: The case number has been changed to Case 6 nodes regions, resulting in amputation of 11–19 cm of penis. from Case 5 in the preceding sentence.] New complications For more extensive pathology, two surgical techniques were reported in 5 animals. Two animals developed a requiring complete penile ablation and urethrostomy have midline infection: Case 13 developed a mild infection previously been described (Markel et al. 1988; Archer and treated with management and antibiotics, followed by Edwards 2004), both of which require blunt dissection of the occurrence of a discharging fistula below the perineal distal tip of the penis from the surrounding fascia prior to 180° urethrostomy treated with 3 sodium iodide infusions; and retroversion and retraction through a new incision. Clinical Case 15 had a thick serous discharge for 5 days, duration. judgement for the 15 horses/ponies described in this case Case 3 was reported to have a little staining of the hindlegs, series resulted in preference to amputate the penis as while haematuria was described in Case 10. Seven months proximally as possible, as stated by Archer and Edwards post operatively, Case 2 was reported to have developed a (2004); indeed the average length of penis removed was deviation of the urinary stream due to a submucosal considered to be closer to 25 cm due to the extensive varicosity at one side of the urethrostomy incision that was pathology, or clinical concern over metastasis of neoplastic excised under standing surgery along with a suspected lesions thereby resulting in clear margins based on clinical sarcoid from the wound. visual and palpation of the lesions to ensure the best Of the 6 animals that were subjected to euthanasia, 3 were prognosis. Although both techniques for extensive penile due to the complications of the presenting problem (Case 5, pathology are described as being easy to perform, it was owner-reported internal SCC metastasis; Case 11, severe considered that the penile retroversion may be an chronic urethritis/cellulitis with some bacterial involvement; unnecessary step. Adoption of a modification of the Case 12 became recumbent with histological examination of previously described techniques for surgical treatment of the sheath tumour and spermatic cord confirming invasive extensive penile lesions would result in a simpler surgical SCC with very likely spread to the lymphatic chain) and one procedure, with decreased tissue handling and suturing, and due to post operative complications (Case 1, laminitis). Two a resultant decrease in surgical time. were considered unrelated to the penile ablation surgery The key modification in this procedure was the creation of (Case 8, gastrointestinal tract infection and Case 14, proximal the urethrostomy site without retroversion of the penis; the interphalangeal joint infection). location of which is important. To aid identification, a permanent marker pen was used to draw an impression of the ’ Discussion surgical site on the horse s skin, and this must be done in the standing patient as the skin moves in relation to the underlying This paper describes a modified surgical technique for penile penile structures when the horse is in dorsal recumbency under amputation, preputial ablation and perineal urethrostomy for general anaesthetic. Staple markers were then inserted into extensive mixed penile lesions in 15 horses and ponies. Doles the skin at the upper and lower limits of the urethrostomy site, et al. (2001) described a technique for lesions that could not as permanent reference markers as pen may be erased during

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the process of surgical preparation or obscured by blood remaining 15 animals (60%). Seven cases (28%) were also during the surgical procedure. The urethrostomy was located observed to have signs of colic including reduced appetite at least 10 cm ventral to the caudal limit of the ischiatic arch and intermittent pawing for up to 48 h post operatively, with to prevent any possibility of retrograde movement of air into one requiring epidural analgesia, although it is not clear if the bladder, and to prevent urine being voided at a level these were horses concurrently haemorrhaging (Doles et al. which may scald the hind legs. Despite these precautions, we 2001). On balance, it was considered that the complications recognised urinary scalding of the perineum and inner aspect encountered within this case series were of no greater of the hindlegs in one horse in the immediate post operative detriment to the horse than the complications reported by the period, which resolved prior to discharge. Although horses are authors as described above. often startled when they first urinate post operatively, within a It is difficult to compare the rate of post discharge few days most animals learn to posture like a mare when they complications with other publications as data collection is are about to urinate, which may account for the resolution of not standardised, and occurs over variable time frames. the scalding in this horse. In addition, one owner reported a However, other studies identified that, based on a shorter little hindleg staining after discharge from the hospital, but this follow-up time (average 12 months compared to 29.5 months was of no clinical consequence. in the present study), 50% of animals developed Mild oedema at both the ventral and urethrostomy sites, complications – including laminitis requiring euthanasia and and minor haemorrhage within 24 h from the urethrostomy lateral deviation of urinary flow necessitating limb cleaning incision were very common post operative findings. This was every other day (Archer and Edwards 2004). Development of also reported in 100% of previous cases (Archer and Edwards post discharge complications within this case series was 2004). Within our case series partial mucocutaneous reported in 50% of animals and included urine staining, dehiscence of at least one side of the urethrostomy was haematuria and urinary stream deviation each in one horse, commonly identified (13/15 cases, 86.7%); but this was and wound discharge in 4 horses. All of these were managed invariably followed by second intention healing, by 2–3 weeks and eventually resolved, apart from one horse where post operatively. Any degree of wound dehiscence is a intermittent wound discharge associated with b–haemolytic disappointment; however, it is recognised that this appears to Streptococcus was still present after 12 months. In the case of occur predictably in these cases, and continued to resolve deviation of the urinary stream, this was caused by without problems. However, forewarning of the owners was unexpected formation of a submucosal varicosity at one side an important part of the post surgical discussion. Markel et al. of the urethrostomy incision. The authors have no satisfactory (1988) also reported dehiscence of the urethrostomy wound, explanation for this, although rupture of scar tissue within occurring in 40% of cases, and proposed that it was adjacent cavernous tissue must be a possibility. Given that associated with increased urethral handling. Other possible this was an isolated incident, and that the authors can only reasons include difficulty in eliminating all the dead space, speculate as to its cause, the authors remain unconvinced movement between the skin and urethra, inevitable tension that any alteration in surgical technique is justified. Thankfully around the site and the need for multiple sutures around the the varicosity was excised under standing surgery and spatulated area. Whilst it is acknowledged that mucus could resolved with no further occurrence. accumulate in the redundant urethral lumen within the In this case series, penile ablation and urethrostomy was section of nonexcised penis, to the authors’ knowledge this considered a salvage procedure for these animals which, has not resulted in any clinical consequence. to the authors knowledge, would otherwise have been The ventral midline approach required for the penile subjected to euthanasia due to the adverse welfare impact ablation inevitably resulted in the formation of dead space. of their presenting complaint. The median survival time of In the first case within this case series the midline incision was 25.1 months is therefore considered to be a favourable closed fully, but subsequently there was excessive swelling outcome, and all the contacted owners rated their and partial wound dehiscence. Therefore, in subsequent satisfaction with the procedure as excellent. Whilst there may cases rather than closing the surgical site fully by primary be a temptation to carry out less radical surgery, in many intention it was considered preferable to leave an cases the owners’ finances would only allow one attempt at abdominal drain in place for 5–7 days. Other previously treatment, for which reason after careful consideration the reported post operative complications include continuing current technique was considered to be justified, and in the intermittent minor haemorrhage in 2/5 (40%) and excessive best long-term interest of the animal. granulation tissue around the urethrostomy site in 1/5 cases It is difficult to compare accurately the long-term follow- (20%) (Archer and Edwards 2004), and one report each of up of different techniques of penile ablation surgery, with dehiscence of the ventral incision, urine scalding, cystitis and differing initial pathologies and variable definitions of post- severe diarrhoea necessitating euthanasia from 10 horses surgery success. There is also considerable variation in follow- (Markel et al. 1988). Mair et al. (2000) reported one case of up times reported. Long-term follow-up studies identified that marked oedema of the wound, one case of septic 50% of the SCC cases (n = 2) survived until the end of their tenosynovitis of the digital tendon sheath and one case of maximum 20 month follow-up (Archer and Edwards 2004). post anaesthetic haemorrhagic myelomalacia following en Markel et al. (1988) found that in 9 horses with mixed genital bloc resection in 4 cases. The surgical technique indicated neoplasms, one required euthanasia after one year, and 8 for less severe pathologies by Doles et al. (2001) was were recurrence free in a range of follow-up times between proposed to be beneficial due to fewer potential 6 and 96 months. Howarth et al. (1991) considered 2/3 complications; however, moderate haemorrhage occurred in (66.6%) of SCC cases a success owing to survival after 9/25 (36%) and was considered prolonged enough to require 18 months, with one case still alive at 2-years follow-up, one blood transfusion in 1/25 (4%) of cases, with minor subjected to euthanasia 5 years later and one subjected to haemorrhage (not further defined) reported from each of the euthanasia at 9 months post surgery due to recurrence.

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Follow-up of unknown duration identified that in 8 SCC The hospital currently uses an admission/consent form that cases with en bloc resection there was recurrence at the includes an option for owners to opt out of research studies. inguinal region in one case (12.5%), of which this horse and a further 3 had shown evidence of inguinal lymph node Source of funding metastasis (van den Top et al. 2008). The follow-up times for 3 SCC cases treated by en bloc resection by Mair et al. C.E. Wylie is supported by The Margaret Giffen Trust. (2000) are undeterminable from the larger case series published; however, each case was still alive after at least one year. Acknowledgements As with the previously described surgical techniques, the With thanks to all the horse owners who completed the most frequent pathology was genital neoplasia, including telephone questionnaire. SCC and melanoma. While the detection of metastatic spread by rectal palpation has been reported to be unreliable (Markel et al. 1988), Mair et al. (2000) suggested Authorship the use of laparoscopy to evaluate metastatic spread prior R.J. Payne performed the surgical procedure in each case, to conducting surgery. Whilst all of the cases were in good C.E. Wylie collected follow-up data and produced the results. bodily condition at the time of presentation and metastatic Both authors contributed to the writing of the manuscript and spread was considered unlikely at the time of surgery, checked the final version. implementation of such presurgical diagnostics may have affected the decision to carry out surgery in Case 12, which ’ had the shortest survival, and was subjected to euthanasia Manufacturers addresses due to recumbency attributed to metastatic disease after 1CEVA Animal Health Ltd, Amersham, Buckinghamshire, UK. only 0.9 months. The technique was also used for treatment 2Boehringer Ingelheim Ltd, Bracknell, Berkshire, UK. 3MSD Animal Health, Milton Keynes, Buckinghamshire, UK. of chronic (non-neoplastic) preputial discharge, and is the 4 first description of total penile ablation for treatment of Dechra Veterinary Products Ltd, Shrewsbury, Shropshire, UK. 5Bimeda UK Ltd, Llangefni, Angelsey, UK. paraphimosis with a thrombosed corpus cavernosum, which 6Mila International Inc, Erlanger, Kentucky, USA. was unresolvable by medical management. 7Johnson and Johnson Medical Ltd, Livingston, West Lothian, UK. In conclusion, this modified penile amputation, preputial 8Covidien (UK) Commercial Ltd, Bicester, Oxfordshire, UK. 9 ablation and perineal urethrostomy technique has been Smiths Medical International Ltd, Hythe, Hampshire, UK. 10Bayer Animal Health, Newbury, Berkshire, UK. used in 15 cases. Approximately 65% of animals were still 11 Microsoft, Redmond, Washington, USA. alive more than 18 months post-surgery. Of the 6 animals subjected to euthanasia, 4 were due to the complications of the presenting problem or to post operative complications, References while 2 were considered unrelated to the surgical Archer, D.C. and Edwards, G.B. (2004) En bloc resection of the penis procedure. This procedure therefore presents a simplified, in five geldings. Equine Vet. Educ. 16,12-19. viable option for treatment of extensive mixed penile lesions Doles, J., Williams, J.W. and Yarbrough, T.B. (2001) Penile amputation that can not be dealt with by a more simple procedure; and sheath ablation in the horse. Vet. Surg. 30,327-331. reducing surgical complexity in comparison to previously Howarth, S., Lucke, V.M. and Pearson, H. (1991) Squamous cell described techniques. carcinoma of the equine external genitalia: a review and assessment of penile amputation and urethrostomy as a surgical treatment. Equine Vet. J. 23,53-58. Authors’ declaration of interests Mair, T.S., Walmsley, J.P. and Phillips, T.J. (2000) Surgical treatment of 45 horses affected by squamous cell carcinoma of the penis and No conflicts of interest have been declared. prepuce. Equine Vet. J. 32, 406-410. Markel, M.D., Wheat, J.D. and Jones, K. (1988) Genital neoplasms Ethical animal research treated by en bloc resection and penile retroversion in horses: 10 cases (1977-1986). J. Am. Vet. Med. Assoc. 192, 396-400. Ethical approval obtained from the AHT Clinical Research van den Top, J.G., de Heer, N., Klein, W.R. and Ensink, J.M. (2008) Ethics Committee: AHT45-2013. Explicit informed consent Penile and preputial squamous cell carcinoma in the horse: a obtained for all telephone questionnaires. All owners signed retrospective study of treatment of 77 affected horses. Equine Vet. J. 40, 533-537. an informed consent form for the surgical procedure whilst not required for retrospective review of case records. Williams, W.L. (1943) The Diseases of the Genital Organs of Domestic Animals, Ethel Williams Plimpton, Worcester, MA.

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Review Article Equine laryngeal dysplasia S. Z. Barakzai Chine House Veterinary Hospital, Sileby, UK. Corresponding author email: [email protected]

Keywords: horse; laryngeal dysplasia; larynx; upper respiratory; endoscopy

Summary arches (Table 1). The cranial laryngeal nerve supplies the parts Equine 4th and 6th branchial arch defects are not uncommon of the larynx that develop from the 4th branchial arches and in the equine population at large but can be challenging to the recurrent laryngeal nerve supplies the parts of larynx that diagnose and treat. An understanding of the anatomical are derived from the 6th branchial arches. structures that can be involved and how structural Until recently, accurate description of the abnormal or abnormalities may affect laryngeal function is important for absent laryngeal structures in horses with equine laryngeal clinicians faced with such cases. Diagnosis is often made using dysplasia has relied upon post mortem examination and resting endoscopic examination alone but, in many cases, intraoperative findings of a small number of affected horses. laryngeal ultrasound, radiography and 3-dimensional (3D) In the last few years, alternative noninvasive imaging imaging techniques can be useful in confirming a diagnosis techniques such as ultrasonographic examination, computed and for detecting which structures are abnormal. Exercising tomography (CT) and magnetic resonance imaging (MRI) endoscopy is an important tool when ascertaining whether have dramatically improved our diagnostic capability and treatment is an option, for guiding treatment choice and should also increase the numbers of horses for which making a prognosis for athletic function. accurate anatomical recording of abnormalities can be performed. To provide a reference to the normal anatomical Introduction features of the equine larynx, a laryngeal specimen is shown in Figure 1. Surgical exploration certainly offers the The syndrome of equine laryngeal dysplasia, commonly opportunity to examine some aspects of the larynx. However, referred to as 4th branchial arch defect (4-BAD) syndrome, is a full evaluation of absent or abnormal structures is not now clinically well recognised (Goulden et al. 1976; Lane 1993; realistically possible in a live, anaesthetised patient. From post 2001, 2007; Smith and Mair 2009; Menendez et al. 2013; mortem dissections, affected horses were reported to have Townsend 2013). Recent advances in diagnostic imaging abnormal development (unilaterally or bilaterally) of the techniques have allowed us to learn significantly more about wing of the thyroid cartilage, including aplasia of the anatomical anomalies present (Garrett et al. 2009). What the caudal cornu of the thyroid cartilage and absence of has become apparent is that not only are laryngeal structures the articular process of the cricoid cartilage with a resultant formed from the 4th branchial arch affected but, in many absent crico-arytenoid articulation and hypoplasia or aplasia cases, the 6th branchial arch appears to have also undergone of the cricothryoideus and cricopharyngeus muscles abnormal development. Therefore, now may be the time for a (Goulden et al. 1976; Kannegieter et al. 1986; Wilson et al. re-branding of this syndrome and the term ‘equine laryngeal 1986; Klein et al. 1989; Dixon et al. 1993; Lane 1993, dysplasia’ has been aptly suggested (Garrett et al. 2009). 2001, 2007). Most published reports have been of single cases (Cook An excellent study by Garrett et al. (2009) reported the 1974; Goulden et al. 1976; Klein et al. 1989) or small case series results of magnetic resonance imaging (MRI) in only 5 cases (n = 3–7) (Wilson et al. 1986; Deegen and Klein 1987; Tulleners but demonstrated that there are a range of other anatomical et al. 1996; Blikslager et al. 1999). The exception is a population abnormalities likely to be present in the majority of equine of horses with laryngeal dysplasia reported on by Lane laryngeal dysplasia cases. Dorsal extension of the thyroid between 1993 (n = 19) and 2007 (n = 60). In 1993, it was laminae, past the dorsal aspect of the muscular processes of suggested that ‘the term 4-BAD gives an accurate indication the arytenoid cartilages, was reported in all 5 cases (Garrett of the prognosis’ (Lane 1993). More recent case reports have et al. 2009). This has also has been demonstrated using suggested that there may be effective treatment options computed tomographic (CT) images from affected cases available, particularly for nonracehorses (Garrett et al. 2009; (Fig 2). Cricoid abnormalities were also found to be common Menendez et al. 2013; Townsend 2013). In this author’s opinion, including malformation of the cricoid spine (5/5) and rotation exercising endoscopy is an essential tool for developing a of the dorsoventral axis of the cricoid cartilage (3/5, Fig 3) with treatment strategy for horses with laryngeal dysplasia because associated abnormal attachments of the cricoarytenoideus they can experience a variety of dynamic airway dorsalis (CAD) muscles and rotation of the axis of the arytenoid abnormalities. cartilages (Garrett et al. 2009). The cricoarytenoideus lateralis muscle was positioned consistently in an abnormal caudal Anatomical features of equine location, with the majority of the muscle lying in the abnormal laryngeal dysplasia space between the thyroid and cricoid cartilages (Garrett The cartilaginous and muscular components of the larynx are et al. 2009). Hyoid bone abnormalities were also reported in derived from the mesoderm of the 4th and 6th branchial one horse (Garrett et al. 2009).

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TABLE 1: Derivatives of the 4th and 6th branchial arches, anomalies reported in horses* and proposed functional effects

Branchial arch Anomalies reported with Structure derived from laryngeal dysplasia syndrome Proposed functional effects

Thyroid cartilage 4th Absent caudal cornu No crico-thyroid articulation → CAD Hypoplasia of caudal wing muscle action ineffective Rostral wing extends dorsally above Abnormal cricothyroid muscle level of muscular process of attachment arytenoid Arytenoid abduction is physically inhibited by wing of thyroid Cricoid cartilage 4th Abnormal shape of cricoid body Abnormal attachments of Articular process absent and/or Abnormal cricoid spine effect of CAD muscle Rotation of dorsoventral axis of the cricoid cartilage towards abnormal side Thyropharyngeus muscle 4th Absent or vestigial Aerophagia Dysphagia RDPA Cricopharyngeus muscle 4th Absent or vestigial Aerophagia Dysphagia RDPA Cricothyroid muscles 4th Absent or vestigial Reduced ability to increase dorsoventral height of rima glottis and tense vocal fold → vocal fold collapse Arytenoid cartilages 6th Arytenoid axis may be rotated if Arytenoid abduction hindered by cricoid cartilage is rotated contact with thyroid wing CAD muscles 6th Abnormally located attachments on Reduced arytenoid abduction cricoid cartilage Lateral attachments to thyroid laminae CAD muscle oedema CAD muscle hypertrophy Cricoarytenoid lateralis muscles 6th Abnormally caudal location, muscle Reduced arytenoid and vocal fold lies in abnormal space between the adduction thyroid and cricoid Transverse arytenoideus muscles 6th Not reported Vocalis and ventricularis muscles 6th Not reported

CAD = cricoarytenoid dorsalis, RDPA = rostral displacement of the palatopharyngeal arch. * Garrett et al. 2009; Lane 2001; Goulden et al. 1976; Dixon et al. 1993).

Clinical presentation and diagnosis MP Despite the disorder being a congenital defect, the age at CC presentation of reported cases ranges widely, from 3 months CP to 7 years (Kannegieter et al. 1986; Dixon et al. 1993; Lane 2001; 2007; Garrett et al. 2009; Smith and Mair 2009; Menendez et al. 2013). Presumably in older horses, the clinical Cr manifestation of the abnormality has been present but has RC gone unrecognised in the years prior to presentation. There is Tr currently no evidence to support degenerative changes in the larynx (Garrett et al. 2009) that could explain the sudden onset E of clinical signs described in some cases. Th CT Depending on the extent and severity of the structures affected and use of the horse, horses with laryngeal dysplasia can be asymptomatic with abnormalities only detected during endoscopic examination for sale or during investigation of unrelated disease. Such ‘incidental’ diagnoses account for 22% of cases reported in the largest series published to date (Lane 2001). The most common presenting sign is abnormal respiratory Fig 1: Normal larynx. E = epiglottic cartilage, Th = thyroid cartilage, noise during exercise reported in 85% of cases by Lane (2007). Cr = cricoid cartilage (overlapped by thyroid cartilage dorsally), Tr Exercise intolerance may accompany the respiratory noise, = first tracheal ring, CT = cricothyroid muscle, RC = rostral cornu of the thyroid, CC = caudal cornu of the thyroid, CP = corniculate depending on the use of the horse and degree of dynamic process of the arytenoid cartilage, MP = muscular process of the laryngeal obstruction present during exercise. Although the arytenoid cartilage. Original image c/o J. Perkins. causal relationship between specific anatomical

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a) b)

TC TC MP MP MP MP

TC TC

Fig 2: Computed tomographic images of a bilaterally affected horse (a) and a normal larynx (b) showing abnormal dorsal extension of the laminae of the thyroid Affected larynx Normal larynx cartilages (TC) so that they are positioned above the level of the muscular processes (MP) of the arytenoid. Images c/o L. Smith.

muscle action. Vocal fold collapse is also a common cause of respiratory noise in laryngeal dysplasia cases. This may be due to reduced tension on the vocal fold(s) caused both by incomplete abduction of the ipsilateral arytenoid and/or an absent or hypoplastic cricothyroideus muscle (Holcombe et al. 2006; Reesink et al. 2013). Alternatively, without a crico-thyroid articulation, the cricothryoid muscle may be ineffective resulting in vocal fold collapse. Aerophagia with associated symptoms of eructation and CAD tympanic colic is the other clinical manifestation of this syndrome, presumably related to aplasia or hypoplasia of the upper oesophageal sphincter muscles (thyropharyngeus and cricopharyngeus). True dysphagia has been previously reported (Dixon et al. 1993) but appears to be rare. Absence CP of these upper oesophageal sphincter muscles is hypothesised to manifest endoscopically as rostral displacement of the palatopharyngeal arch (RDPA) and this fold of tissue can also be observed on radiographs. Rostral displacement of the palatopharyngeal arch can occasionally only occur during exercise (Lane 2001; Barakzai 2007) or, conversely, horses can have RDPA at rest which resolves with exercise (Garrett et al. 2009). There has been no direct correlation between the presence of RDPA at rest and the state of the cricopharyngeus or thyropharyngeus muscles or between RDPA detected Fig 3: Magnetic resonance image showing rotation of cricoid and endoscopically at rest and the presence of air in the subsequent abnormal positioning of the left and right CAD muscles. The left cricopharyngeus muscle (CP) is present but the right oesophagus detected radiographically. cricopharyngeus muscle and cricoid articular process are absent. Diagnosis can be made in most cases using a combination Image reproduced with permission from Garrett et al. (2009), of laryngeal palpation and endoscopic examination at rest. It Diagnosis of laryngeal dysplasia in five horses using magnetic should be noted that although cases are most commonly resonance imaging and ultrasonography, Equine Veterinary right-sided (62%), bilateral (24%) and left-sided (14%) cases Journal, Wiley. have been reported (Lane 2001). There is no obvious explanation for the right-sided predilection of this disorder and malformations and clinical signs has not been determined with it is quite possible that the prevalence of right- and left-sided certainty, some hypotheses can be formulated and these are cases is actually more even than these statistics suggest. This is outlined in Table 1. Certainly, in many cases, there may be a because some cases of left-sided laryngeal dysplasia, which physical impediment to arytenoid abduction caused by dorsal show only reduced arytenoid abduction endoscopically, may extension of the thyroid cartilage and/or rotation of the axis of easily be misdiagnosed as recurrent laryngeal neuropathy. the arytenoid cartilage or the cricoid cartilage. Abnormal Radiography and laryngeal ultrasound can also assist with attachments of the CAD muscle, plus the lack of a cricothyroid confirming a diagnosis and are readily accessible to most articulation would certainly reduce the effectiveness of CAD equine veterinary practitioners. Three-dimensional imaging

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a) b)

CC CC

TC TC

Left Right

Fig 4: Dissected laryngeal cartilage skeleton of the bilaterally affected horse shown in Figure 2 showing abnormal shape of the cricoid and thyroid cartilages with no overlap present and an abnormal palpable gap illustrated by blue arrows. Photo c/o L. Smith.

Fig 5: Endoscopic photo taken at rest showing right-sided laryngeal dysfunction. techniques have been shown to be the most accurate and comprehensive way of diagnosing laryngeal dysplasia but Fig 6: Rostral displacement of the palatopharyngeal arch evident their availability is limited to referral centres. during endoscopic examination at rest. There is also right-sided dysfunction and a misshapen right corniculate process.

Laryngeal palpation abnormality observed is reduced right-sided arytenoid Laryngeal palpation reveals an abnormal gap between the abduction (65% of cases) (Lane 2001) which can be of varying dorsal two-thirds of the cricoid and thyroid cartilages (Fig 4). A severity (Fig 5). Reduction in left-sided or bilateral arytenoid small gap usually exists between these cartilages at their abductory function can also be observed. The former must be ventral aspects. In cases with dorsal extension of the thyroid differentiated from recurrent laryngeal neuropathy, which is lamina(e), the muscular process(es) of the affected side(s) will much more prevalent in the equine population at large. To not be palpable. In cases without dorsal extension of the complicate matters, horses may have both laryngeal thyroid lamina(e), a full CAD muscle (or nonprominent dysplasia and recurrent laryngeal neuropathy (Kannegieter muscular process) should be palpable despite there being et al. 1986; Dixon et al. 1993). Rostral displacement of the endoscopic evidence of reduced arytenoid abduction on the palato-pharyngeal arch (Fig 6) is also frequently seen in horses ipsilateral side. This should aid in differentiating cases of at rest (51% of cases, Lane 2007). Other endoscopic laryngeal dysplasia from cases of recurrent laryngeal abnormalities have also been reported including dorsal neuropathy. displacement of the soft palate (Menendez et al. 2013).

Endoscopic examination at rest Radiography Endoscopic examination at rest is a very sensitive technique for Radiography can be very useful for confirming cases of diagnosis of laryngeal dysplasia and the most common laryngeal dysplasia; those with absent upper oesophageal

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a) b)

Oe T

T

Fig 7: Lateral radiograph of the larynx and proximal trachea (T) of a normal horse (a) and a horse with laryngeal dysplasia (b). In the horse with laryngeal dysplasia, an abnormal column of air can be seen in the proximal oesophagus (Oe). The red arrow points to the fold of soft tissue which is the palatopharyngeal arch seen endoscopically. In this case it is caudal to the corniculate processes.

a) b)

Cr Th Th

Cr

Ar Ar

Fig 8: Ultrasound image: normal (a) and abnormal (b) crico-thyroid articulation. Arrow shows the cricoarytenoid lateralis bulging out through the abnormal space. Images c/o J-M. O’Leary. sphincter muscles may show an abnormal column of air within instead of being located deep to the thyroid cartilage on its the upper oesophagus (Fig 7) into which the rostrally displaced caudal aspect (Garrett et al. 2009). palatopharyngeal arch may be seen impinging dorsally as a ‘dew drop’ of soft tissue opacity (Lane 2001; Barakzai 2007). It Three-dimensional imaging should be noted that radiography is definitely not 100% Magnetic resonance imaging and CT are ideal for providing sensitive for detection of laryngeal dysplasia. definitive evidence of laryngeal dysplasia. Magnetic resonance imaging technique and findings have been Ultrasonography reported by Garrett et al. (2009) and has the advantage of Ultrasonography of the larynx is a relatively new technique, first showing intricate detail of soft tissues so that all intrinsic and described by Chalmers et al. (2006), with ultrasonographic extrinsic laryngeal muscles can be individually identified. features of laryngeal dysplasia then reported by Garrett et al. Computed tomography may have an advantage in that the (2009). Not all aspects of the larynx can be imaged technique does not require horses to be anaesthetised in ultrasonographically but using a 10 MHz linear transducer it is many centres. However, there is undoubtedly inferior definition possible to identify that the cricothryoid articulation is absent of soft tissue structures compared to MRI. (Fig 8) and visualise dorsal extension of the thyroid cartilage on the affected side(s) (Fig 9). The cricoarytenoideus lateralis Exercising endoscopy muscle can be seen on ultrasound images in the abnormal Exercising endoscopy is an essential diagnostic tool to space created between the thyroid and cricoid cartilage, ascertain if laryngeal dysfunction is present during exercise

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a) b)

Th Th

Ar Ar

Fig 9: Ultrasound image: normal left side of the larynx (a) and dysplasia right side of the larynx (b) showing abnormal dorsal extension of the wing of the thyroid (Th) above the muscular process of the arytenoid (Ar). Images c/o. J-M. O’Leary.

Fig 10: Exercising endoscopy of horse with laryngeal dysplasia showing grade B laryngeal function on the right side and right-sided axial deviation of the aryepiglottic fold.

Fig 11: Exercising endoscopy photo of horse with laryngeal and, if so, which structures are functioning abnormally and dysplasia showing complete (grade C) right arytenoid collapse obstructing airflow (Figs 10 and 11, Supporting Information during inspiration and bilateral (right>left) vocal fold collapse. Video S1). This is of great importance when selecting a suitable Photo c/o Neil Townsend. treatment option and may also provide a more accurate prognosis. A reasonable number of horses with laryngeal Treatment and prognosis dysplasia show no dynamic collapse of the upper respiratory tract when exercising. Grade B (partial) or grade C (total) Ventriculocordectomy arytenoid abduction during exercise is often seen in Many horses with laryngeal dysplasia can maintain full or conjunction with collapse of the vocal fold(s). Obstruction partial arytenoid abduction during exercise but do experience associated with the palatopharyngeal arch, including significant airway obstruction due to uni- or bilateral vocal aryepiglottic fold collapse and/or ventral displacement of the fold collapse. For these cases, unilateral or bilateral rostrally displaced dorsal aspect of the palatopharyngeal arch ventriculocordectomy is indicated (Fig 12). can also be observed. Dorsal displacement of the soft palate has also been recorded in a proportion of equine laryngeal Arytenoidectomy dysplasia cases. Table 2 shows the prevalence of dynamic Arytenoidectomy was first reported by Blikslager et al. disorders observed during treadmill endoscopy in horses from (1999) in one horse which was reported to have ‘limited a number of reports. success’ as a racehorse post operatively. More recently,

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TABLE 2: Results of exercising endoscopy in 26 horses with laryngeal cricoid and arytenoid towards the affected side and these dysplasia factors can make it impossible to physically abduct the arytenoid cartilage. Exercising endoscopic No. of horses with this finding finding (% affected) Laser thermoplasty for RDPA Arytenoid abduction 6 grade A (23%) Transendoscopic lasers can be used to ablate or divide the grade (Robinson 2003) 17 grade B (65%) rostrally displaced palatopharyngeal tissue in horses with 3 grade C (12%) Vocal fold collapse: 13 ipsilateral (50%) RDPA, but results are likely dependent on co-existing 5 contralateral VFC as abnormalities of the larynx (Blikslager et al. 1999; Garrett et al. well (19%) 2009). In this author’s opinion, RDPA less commonly has a DDSP 3 (12%) significant obstructive effect on respiration during exercise but Palatal instability 1 (4%) it certainly can cause turbulent airflow and noise. Aryepiglottic fold collapse 9 right (35%) 3 bilateral (12%) RDPA 3 (12%) Directions for future research Nasopharyngeal collapse 2 (8%) Three-dimensional imaging of a larger number of affected horses is important in order to define the prevalence and Cases from: Lane 2001 (n = 5), Townsend 2013 (n = 6), S Barakzai range of anatomical anomalies and ideally, to make links and P Dixon, unpublished data (n = 12), Garrett et al. 2009 (n = 2), Smith and Mair 2009 (n = 1). between specific abnormalities, clinical signs exhibited and the variety of dynamic upper airway disorders observed in laryngeal dysplasia cases. Similarly, publication of the results of exercising endoscopy in a large number of cases would be of great interest and given the sporadic nature of the disorder, multicentre studies are likely to be required. Long-term objective evaluation of various treatments for laryngeal dysplasia using pre- and post operative exercising endoscopic examination and/or sound analysis rather than subjective methods of assessment would provide the gold standard in defining whether a particular treatment method is truly ‘successful’ for horses with laryngeal dysplasia. The rates of ‘success’ that can be expected for various breeds and uses of horse is likely to vary and should be investigated.

Author’s declaration of interests No conflicts of interest have been declared.

Acknowledgements Thanks to Simon Turner for his assistance with proofreading this manuscript.

References Barakzai, S. (Ed) (2007) Larynx. In: Handbook of Equine Respiratory Fig 12: Right-sided ventriculocordectomy being performed in the Endoscopy, 1st edn., W.B. Saunders, Philadelphia. pp 77-79. standing sedated horse using a transendoscopic diode laser. Blikslager, A.T., Tate, L.P. and Tudor, R. (1999) Transendoscopic laser treatment of rostral displacement of the palatopharyngeal arch in four horses. J. Clin. Laser Med. Surg. 17, 49-52. Chalmers, H.J., Cheetham, J., Yeager, A.E. and Ducharme, N.G. (2006) 2 siblings that underwent partial arytenoidectomy and Ultrasonography of the equine larynx. Vet. Radiol. Ultrasound 47, ventriculocordectomy by Menendez et al. (2013) were able to 476-481. perform dressage and unspecified ‘ridden work’ after surgery. Cook, W.R. (1974) Some observations on diseases of the ear, nose and It appears that unilateral partial arytenoidectomy is a throat in the horse, and endoscopy using a flexible fibreoptic reasonable treatment option for horses with very little endoscope. Vet. Rec. 94, 533-541. abductory function (grade C function at exercise), particularly Deegen, E. and Klein, H.J. (1987) Rostrale verlagerung des arcus if they are racehorses or if arytenoid dysfunction is bilateral. palatopharygicus beim pferd. Pferdeheilkunde 3, 303-308. Dixon, P.M., McGorum, B.C. and Else, R.W. (1993) Cricopharyngeal-laryngeal dysplasia in a horse with sudden clinical Laryngoplasty onset idiopathic laryngeal hemiparesis. N. Z. Vet. J. 41, 134-138. Prosthetic laryngoplasty can be an option in horses with Garrett, K.S., Woodie, J.B., Embertson, R.M. and Pease, A.P. (2009) Diagnosis of laryngeal dysplasia in five horses using magnetic laryngeal dysplasia, depending on the structural abnormalities resonance imaging and ultrasonography. Equine Vet. J. 41, 766-771. that are present (N. Ducharme, personal communication). Goulden, B.E., Anderson, L.J., Davies, A.S. and Barnes, G.R. (1976) Access to the muscular processes is often poor due to dorsal Rostral displacement of the palatopharyngeal arch: a case report. extension of the thyroid cartilages and/or rotation of the Equine Vet. J. 8, 95-98.

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Holcombe, S.J., Rodrigeuz, K., Lane, J. and Caron, J.P. (2006) neuromuscular characterisation of the equine cricothyroid muscle. Cricothyroid muscle function and vocal fold stability in exercising Equine Vet. J. 45, 630-636. horses. Vet. Surg. 35, 495-500. Robinson, N.E. (2003) Workshop summary. In: Havemeyer Foundation Kannegieter, N.J., Goulden, B.E. and Anderson, L.J. (1986) Right-sided Monograph Series No.11. Proceedings of a workshop on equine laryngeal dysfunction in a horse. N. Z. Vet. J. 34, 66-68. recurrent laryngeal neuropathy, September 2003, Eds: P. Dixon, N.E. Robinson and J.F. Wade,R&WPublications Ltd., Newmarket. 96-97. Klein, H.J., Deegen, E., Stockhofe, N. and Wissdorf, H. (1989) Rostral Smith, L.J. and Mair, T.S. (2009) Fourth branchial arch defect in a Welsh displacement of the palatopharyngeal arch in a seven-month-old section A pony mare. Equine Vet. Educ. 21, 364-366. Hanoverian colt. Equine Vet. J. 21, 382-383. Townsend, N.B. (2013) DIagnosis and treatment of fourth branchial arch Lane, J.G. (1993) Fourth branchial arch defects in the horse. defects. Equine Vet. Educ. 25, 278-281. Proceedings of the 15th Bain-Fallon Memorial Lectures, Australian Equine Veterinary Association, pp 209-212. Tulleners, E.P., Ross, M.W. and Hawkins, J. (1996) Management of right laryngeal hemiplegia in horses: 28 cases (1987-1996). In: Lane, J.G. (2001) Fourth branchial arch defects in Thoroughbred horses: Proceedings of the American College of Veterinary Surgeons a review of 60 cases. In: Second World Equine Airways Symposium, Symposium, San Francisco. p 21. Edinburgh. CD-ROM. Wilson, R.G., Sutton, R.H. and Groenendyk, S. (1986) Rostral Lane, J.G. (2007) Fourth branchial arch defects. In: Equine Respiratory displacement of the palate pharyngeal arch in a Thoroughbred Medicine and Surgery, Eds: B.C. McGorum, P.M. Dixon, E. Robinson yearling. Aust. Vet. J. 63, 99-100. and J. Schumacher, Elsevier Health Sciences, Philadelphia. pp 467-472. Supporting information Menendez, I.M., Mancha, D.A.I. and Fitch, G. (2013) Fourth branchial Additional Supporting Information may be found in the online arch defects in full-siblings treated with a partial arytenoidectomy. Equine Vet. Educ. 25, 274-277. version of this article at the publisher’s website:

Reesink, H.L., Hermanson, J.W., Cheetham, J., Mu, L., Mitchell, L.M., Video S1 Exercising endoscopic video of horse with right-sided Soderholm, L.V. and Ducharme, N.G. (2013) Anatomic and laryngeal dysplasia.

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Review Article Evaluation of poor performance in competition horses: A musculoskeletal perspective. Part 1: Clinical assessment S. Dyson Centre for Equine Studies, Animal Health Trust, Newmarket, Suffolk, UK. Corresponding author email: [email protected]

Keywords: horse; pain; lameness; stiffness; behaviour

Summary How should a horse work correctly? Lack of willingness to go forward freely, lack of power, Based on the principles of training, an event horse or a shortened steps, stiffness of the cervical or dressage horse should ideally work ‘on the bit’ (see Glossary). fi thoracolumbosacral regions are common nonspeci c signs of The cranial aspect of the head should be in a vertical musculoskeletal causes of poor performance in sports horses. position, with the neck flexed at the poll, i.e. flexion of the Understanding musculoskeletal causes of poor performance cranial cervical vertebrae. The horse should accept the bit, requires knowledge of how normal horses move, the taking an even contact via the reins on the rider’s hands, fi requirements of speci c work disciplines, the nomenclature keeping the mouth shut and producing saliva. The horse used by riders to describe how a horse is performing and the should be pushing energetically with the hindlimbs, tracking interactions between horses and riders. Determining the up (see Glossary), with the hindlimbs following the tracks of underlying causes needs an in-depth history and clinical the forelimbs (i.e. on 2 tracks). There should be flexion at the assessment, including in hand, on the lunge and ridden. lumbosacral joint, and fluid movement through the horse’s Ridden exercise should include all aspects with which the thoracolumbar region. The horse’s trunk should be more or rider is experiencing problems. Change of the rider can less vertical in both straight lines and circles, with the trunk sometimes help to differentiate between horse and rider curved to follow the radius of curvature of a circle. The horse problems, but most normal horses are compliant and just should be in balance with proportionate weight distribution because a horse goes better for a more skilled rider does not between the forelimbs and hindlimbs. The horse should move preclude an underlying pain-related condition. Lungeing and willingly forward, being responsive to the rider’s aids (cues ridden exercise should include not only trot but also given by the rider). The best showjumping riders work their transitions and canter which may highlight gait abnormalities horses similarly; however, at lower levels there is much less not seen at trot. An accurate history combined with thorough attention paid to correct balance and bend. A horse that clinical examination of the whole horse should permit the has undergone correct basic training should be able to work establishment of a list of problems requiring further correctly. investigation. Horses’ responses to musculoskeletal pain Introduction Resentment of being tacked up, manifest as the horse To investigate the reason(s) for poor or reduced performance moving to the back of the stable as a rider enters with the in sports horses requires knowledge of both how normal tack, or laying the ears back, swishing the tail and horses move and the sports discipline in which the horse attempting to bite or kick as the girth is tightened, may ’ competes and an understanding of what the rider s problem reflect discomfort induced by the tack, anticipation of pain is. The latter requires acquisition of an accurate history by associated with being ridden or gastric ulcer syndrome. Many both listening to the rider and extracting relevant information musculoskeletal problems causing poor performance are fi using speci c questions. It must be recognised that some slow and insidious in onset. How pain is manifest when ridden performance problems may have been attributed to training depends on the temperament of the horse and its tolerance fi dif culties, behavioural problems or lack of ability of the rider. of pain (Dyson 2013). Unwillingness to go forward freely (not ’ ’ A trainer s or coach s inability to detect lameness does not because of lack of fitness, or cardiovascular or respiratory preclude lameness as the underlying cause of poor problems, or other systemic illness), so-called laziness and lack performance or alteration in behaviour. Riders and trainers of power are typical findings. However, there is a group of are generally poor at lameness recognition (Greve and horses in which pain is manifest as tension, ‘buzziness’, Dyson 2014). This 2 part review aims to describe features of a hurrying or wanting to run away, sometimes with ’ horse s gait or behaviour that may be a manifestation of disproportionate sweating relative to the work done and the musculoskeletal pain, to explain some of the terminology horse’s fitness. The horse may become less compliant and used by riders and to provide guidelines for investigation. responsive to the aids, become spooky (shying repeatedly) While the focus is on dressage, showjumping and event and evade the aids by putting the tongue over the bit or horses, the principles apply equally to horses from other sports putting the head up (going above the bit – see Glossary; disciplines. Part 1 focuses on recognition of the problem and Fig 1), or twisting the head and neck. A horse may start to Part 2 considers methods of investigation. buck or rear.

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a) b)

Fig 1: Above the bit. a) A 7-year-old crossbred used for Riding Club level competitions. The cranial aspect of the horse’sheadis cranial to vertical. The right hindlimb is crossing under the trunk toward the left forelimb. b) An 8-year-old Thoroughbred cross event horse. The cranial aspect of the horse’s head is almost horizontal. The cervical and thoracolumbar regions are extended. There is delayed lift off from the right hindlimb. There was no overt lameness but the horse lacked hindlimb impulsion and engagement and all these clinical signs were abolished by bilateral perineural analgesia of the deep branch of the lateral plantar nerve.

Pain often causes a generalised restriction of movement, direction. If bilateral, the horse may take symmetrically short with stiffness in the cervical and/or thoracolumbosacral steps with both forelimbs in all paces. A horse with hindlimb regions and shortened steps (Dyson 2009, 2011) (Fig 2; lameness may fail to push properly with the hindlimbs in (Supplementary Items 1 and 2). The horse may fail to track up upward transitions from walk to trot or from trot to canter and (see Glossary). The horse may become more difficult to turn may therefore appear to ‘jump’ in the transition. The horse in one direction, especially in small (10 m diameter) circles may be reluctant to flex the lumbosacral joint (Fig 2b) and (Figs 2b and 3b). A horse that had been similar to ride on engage (see Glossary) the hindlimbs in downward transitions both the left and right reins may have a deterioration in so the horse may become more on the forehand, be croup performance on one rein. A horse that formerly took a good high and fall abruptly from canter to trot or from trot to walk, quality, even contact with the bit may change by leaning on taking short steps with the hindlimbs. With hindlimb lameness, one side of the bit so giving a stronger pull (hanging) on the it is typical that there are difficulties in movements requiring rein in the rider’s hand, and avoiding taking a proper contact more collection (see Glossary) e.g. lateral movements via the other rein (Figs 2 and 3). Alternatively, a horse that is (shoulder-in, travers, half pass, walk or canter pirouettes). With on the forehand (see Glossary) because of inadequate either forelimb or hindlimb lameness, irregularities in the hindlimb impulsion may lean on both reins and be very heavy rhythm or asymmetries in limb flight may become apparent in in the rider’s hands. Many horses evade by becoming medium and/or extended trot (see Glossary). For example, overbent or behind the bit (see Glossary), often reducing the one forelimb may be elevated less than the other during weight of the contact in the rider’s hands (Fig 3). The tongue protraction. may loll out of the horse’s mouth, or the horse may constantly Although lameness cannot be detected in canter a hold its mouth open (Figs 2 and 3b). The mouth may be dry, change in the quality of the canter may be a reflection of lacking salivation. Pinning the ears back, flaring the nostrils pain, e.g. 4-time canter; stiff and stilted canter (see Glossary); and constant swishing of the tail (Fig 2) are often signs of cantering crookedly, with the hindlimbs not following the pain. same tracks as the forelimbs (usually with the hindquarters A low-grade forelimb lameness may result in the horse displaced to the inside of the track if working in an arena; taking slightly lame steps on turns, sometimes only in one Fig 4). The canter may become disunited or the horse may

a) b)

Fig 2: An 8-year-old event horse being ridden in a 10 m diameter circle to the right. The horse has its mouth open and is constantly swishing the tail. a) The inside hindlimb crosses under the trunk toward the contralateral forelimb. The horse is on the forehand. b) The horse is reluctant to turn to the right, has reduced flexion of the lumbosacral joint and limited hindlimb impulsion and engagement. There is mild hindlimb toe drag, with scuffing of the arena surface. The cranial aspect of the head is slightly caudal to vertical.

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a) b)

Fig 3: Behind or over the bit. a) An 8-year-old Warmblood dressage horse that had been competing at Advanced Medium level in right lead canter. The cranial aspect of the head is caudal to vertical despite the inside rein being loose. The highest point of the neck is at the level of the third to fourth cervical vertebrae. The horse had reduced flexion of the lumbosacral joint. Note hyperextension of the right metatarsophalangeal joint. b) An 8-year-old intermediate level event horse in trot, which had become difficult to turn to the left and lacked hindlimb power. The cranial aspect of the head is caudal to vertical, but in contrast to a) the horse is leaning on the bit especially on the left side. The bit has slid slightly to the left. The horse’s mouth is open. The horse is on the forehand.

repeatedly change limbs behind (see Glossary, also referred the leading limb should be on the same side as the direction to as changing leads behind). The horse may be reluctant to to which the horse is turning. On landing, there is greater canter with one forelimb leading. This usually reflects hindlimb ground reaction force in the trailing forelimb compared with pain: with right hindlimb pain the horse may be reluctant to the leading forelimb. So with right forelimb pain the horse canter with the left forelimb leading, because left lead may repeatedly land with the right forelimb leading even canter is initiated by the horse weightbearing on the right when turning to the left if the biggest component of pain hindlimb alone. Less commonly, unwillingness to lead with relates to impact. However, if pain is associated with one forelimb is a manifestation of forelimb pain. The horse extension of the right fetlock and increased load on the may show difficulties with flying changes (see Glossary) from suspensory apparatus, the horse may prefer to always land left to right or right to left or both, seen as reluctance to with the left forelimb leading. Uncharacteristic stopping at change, being croup high in the changes, leaping into the fences or running out may relate to either forelimb or changes, or being crooked with the horse swinging hindlimb pain. Horses with forelimb pain may be reluctant to excessively from side to side. These abnormalities usually jump going downhill. They may also show reluctance to reflect hindlimb pain. With forelimb pain, the horse may have gallop downhill. Lack of power and difficulties in making reduced height of the arc of the foot flight of the forelimbs in distances in combination fences usually reflect hindlimb pain. canter and paradoxically appear to land more heavily on If a horse jumps crookedly across a fence, for example the forelimbs than a normal horse. jumping from left to right, this usually reflects pain in the Specific problems may be seen when a horse is jumping. hindlimb on the same side to which the horse is jumping, The horse may fail to land with the correct limb leading, i.e. because the horse creates less propulsion from the lame(r) limb. Having rails down uncharacteristically may reflect forelimb or hindlimb pain.

How to recognise that the horse might have a pain-related gait problem although it does not look overtly lame in hand – other aspects of the history A number of horses develop problems relatively soon after purchase. These often reflect pre-existing problems that were masked by a previous rider, or were exacerbated by a change in rider and training programme, or were not apparent at the time of sale because the horse had not been in regular work at the time of sale. The horse world is unscrupulous. So it is important to determine how long the horse has been in the current ownership. Was it sold privately or via a dealer? Was the horse in regular work at the time of purchase and if not, why not? Does the horse have a previous competition record? Are there any unexplained gaps in the competition record? Was a prepurchase examination performed? fl Fig 4: A 6-year-old Warmblood event horse in right lead canter. The development of muscle tension or pain may re ect The horse is on the forehand and croup high. The horse is underlying lameness. Physiotherapists are good at detecting crooked, with ‘quarters in’ so that the right hindlimb is placed to subtle changes. It is therefore helpful to determine if the horse the right of the right forelimb. has regular physiotherapy assessments and whether any

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changes have been noted. The thoracolumbosacral apparent on firm terrain or going downhill. Is the horse willing musculature is a good indicator of how the horse has been to go up and down hills? Horses with hindlimb pain may find it moving its body as a whole (Fig 5). Change in shape difficult to walk or trot straight going downhill. Does the horse reflecting muscle atrophy usually signifies an underlying trip or stumble and under what circumstances? Tripping or musculoskeletal problem. Saddle slip persistently to one side stumbling with forelimbs or hindlimbs may reflect altered limb may reflect hindlimb lameness (Greve and Dyson 2013, 2014), flight and/or foot placement due to pain. so it is useful to determine if the rider has been aware of Does the horse wear its shoes evenly? When was it last saddle slip. Poor saddle fit can cause pain and compromise shod? Uneven shoe wear usually reflects altered limb flight or performance, so determine when and by whom saddle fit foot placement due to lameness. Are there any problems was last checked, bearing in mind that the skill of fitters varies holding up the limbs for trimming and shoeing? Has the horse and that thoracolumbar dimensions can change quickly become fidgety or awkward? Horses with sacroiliac joint depending on a variety of factors including season, lameness region pain or hindlimb lameness may be unwilling to load and saddle fit (Greve and Dyson 2014). A different saddle one hindlimb in certain positions or to hold a limb in flexion. may distribute weight differently and temporarily allow a If the horse bucks, under what circumstances does this horse to feel more comfortable, so it is helpful to know if there occur? Bucking going into canter often reflects sacroiliac has been a change in tack and whether this made any joint region pain (Barstow and Dyson 2015). Does the horse difference to the horse’s performance. Determine whether buck and kick out? This is also usually a reflection of sacroiliac the rider has had any injuries that may have influenced their joint region pain (Barstow and Dyson 2015). Does the horse ability to ride effectively, symmetrically and in balance. buck to try to throw the rider off? Bucking associated with Change in work intensity or level can exacerbate a pre- sacroiliac joint region pain is rarely manifest as trying to get a existing subclinical problem, so determine whether there has rider off. Bucking can also be associated with primary there been a change in work intensity and/or difficulty or a thoracolumbar pain but affected horses rarely kick out. change in rider skill level. A better rider may be more If the horse competes in dressage what scores does it demanding and make a pre-existing problem more generally achieve and has this changed? If the horse was apparent. A less-skilled rider, by not concealing a problem by regularly scoring >68% and is now only scoring 62% this usually continually adjusting the balance of the horse, may allow a reflects an underlying problem. If an event horse never pre-existing problem to become evident. Does the problem scored well in dressage, but jumped well at novice level and vary with work intensity? If the horse is better after a day off, is now struggling at intermediate level this may reflect a or after a day hacking, this usually reflects underlying pain. longer-term problem that has surfaced because more Establish whether the problems are manifest under all athletic demands are being placed on the horse. circumstances, or only when working on the flat or jumping. fi fl Willingness to jump, but dif culties with at work does not Clinical assessment preclude underlying pain; the horse may really enjoy jumping and this may over-ride underlying discomfort. Unwillingness to Clinical assessment at rest go forward freely or ‘running out of steam’ usually reflect It is not within the scope of this article to discuss all aspects of pain, but it is necessary to know if the horse is fit enough for a clinical examination, which are described more the work demands and if it is being fed appropriately. comprehensively elsewhere (Ross 2010a,b,c,d). Such an It is useful to learn about the horse’s normal work and examination should systematically cover not only the management regime. Is the horse getting sufficient variety in musculoskeletal system, but also the mouth and teeth. work pattern to avoid both repetitive strain injuries and However, it is relevant to discuss some aspects of mental ‘staleness’? Is the horse’s performance influenced by conformation that have potentially important implications for the surface on which it is working, e.g. grass vs. waxed sand performance and long-term soundness. It is also important to and fibre vs. deep going? Foot-related pain may be more consider assessment of the thoracolumbosacral region,

a) b)

Fig 5: Poor development or atrophy of the epaxial muscles. a) An 8-year-old Warmblood dressage horse working at medium level with bilateral hindlimb proximal suspensory desmopathy. If this horse had been working correctly ‘through the back’ the epaxial muscles would be better developed. b) A 7-year-old showjumper with sacroiliac joint region pain; there is marked atrophy of the thoracolumbosacral muscles and the gluteal muscles, resulting in prominence of the summits of the lumbar spinous processes and the tubera sacrale and a concavity in the dorsal contour cranial to the tubera sacrale.

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because this area often reflects the horse’s musculoskeletal Passive stimulation of the horse to flex and extend and rotate health as a whole (Fig 5). the thoracolumbosacral region, and assessment of the The horse’s conformation should be in proportion and presence of focal or diffuse muscle hypertonicity or pain are balance. A tendency for hyperextension of the key parts of the clinical assessment. Left-right symmetry or metacarpophalangeal and metatarsophalangeal joints at asymmetry of muscle hypertonicity and pain are important to rest or in motion (Fig 3a) potentially places excessive load on appreciate. Left hindlimb lameness usually results in greater the suspensory apparatus. An association between straight hypertonicity and pain in the left caudal thoracic and lumbar hindlimb conformation (Figs 6 and 7b) and proximal regions. However, left hindlimb lameness may result in saddle suspensory desmopathy has been noted (Dyson 1994), slip to the left, which means that the saddle ‘jams’ against although to date a causal relationship has not been the right side of the thoracolumbar spine, which may make established. A horse in which the tubera sacrale are higher right sided pain predominant. Saddle slip may also be than the wither (Fig 7) has a natural tendency to be on the associated with an asymmetric pattern of hair wear. Poor forehand and will find it physically more difficult to perform development of the pelvic musculature relative to the neck collected movements than a better conformed horse. may reflect hindlimb lameness; pelvic muscle asymmetry Asymmetrical front feet are associated with leaving the sports usually indicates chronic lameness. horse population earlier than horses with symmetrical front feet (Ducro et al. 2009). Small feet relative to body size (Balch Examination in hand and on the lunge et al. 1991; Turner 1992) and large bodyweight (Parkes et al. When assessing the horse in hand, pay particular attention to 2013) are risk factors for foot-related lameness. There are the type of horse and the quality of trot that you would many factors which influence foot shape and size and it is expect to see. Bilateral forelimb lameness may be manifest therefore not surprising that it has been difficult to show as a short stepping forelimb gait, or mild discomfort when associations between specific causes of foot-related turning. Bilateral hindlimb lameness may be apparent as a lameness and different foot conformations (Dyson et al. failure to track up, a short stepping gait, lacking hindlimb 2011). However, there is little doubt that horses with poor foot impulsion Æ a mild unilateral or bilateral toe drag. The conformation are at high risk of foot-related problems. hindlimb gait may appear stiff, with reduced flexion of the A horse that is moving correctly when worked under limbs. The horse may move unusually closely behind or have saddle should ‘move through the back’, i.e. flex and extend a base wide hindlimb gait. The limb flight of the hindlimbs in the sagittal and frontal planes and have some rotation of may be asymmetrical. One or both hindlimbs may cross the thoracolumbar spine. The epaxial muscles should be well under the body during protraction and then move outwards developed. With any lameness, the horse may adapt by before landing. The position and stability of the hindlimbs stiffening the thoracolumbosacral region. Failure to ‘move during the stance phase of the stride should be noted; through the back’, ill-fitting saddles and thoracolumbosacral excessive side to side wobble of the hindlimbs usually reflects pain and sacroiliac joint region pain can result in epaxial muscle weakness (Fig 8). Placing a hind foot axially, with the muscle atrophy and poor abdominal muscle tone. The toe of the foot intermittently rotating outwards, with the pattern of muscle atrophy may reflect the underlying cause. metatarsophalangeal joint moving through an abnormal range of motion from side to side places undue torque on the limb. Occasionally the tail may be held crookedly as direct consequence of pain, but this can also be a normal a) b) feature for a particular horse. An overly exuberant horse may mask clinical signs. A horse not used to being trotted in hand may need to be encouraged to go forward freely with a lunge whip in order to get a fair assessment of the gait. The absence of overt lameness certainly does not preclude a musculoskeletal problem. On the lunge in a circle of approximately 15 m diameter, a normal mature competition horse should be sufficiently well balanced and coordinated so that the body is held more or less upright with each hindlimb following the track of the ipsilateral forelimb. Mild inward lean measured using inertial measurement units is symmetrical on left and right reins in horses free from lameness (L. Greve, S. Dyson, unpublished data). The horse should swing through its back and carry its tail, which should also oscillate from side to side. The horse should trot rhythmically and energetically, looking in the direction in which it is going. The canter should be a clear 3- time gait, with the hindlimbs well spaced both temporally and spatially when viewed from the side. Lame horses may adapt their posture to minimise pain Fig 6: Straight hock conformation in 2 horses with poor hindlimb and make lameness less apparent. The horse may lean in action in association with proximal suspensory desmopathy. a) and look out (Fig 9). The lunger may feel that the horse pulls An 8-year-old Warmblood. b) A 4-year-old Warmblood. This out of the circle much more on one rein than the other. The horse has greater extension of the metatarsophalangeal joints inside hindlimb may cross in under the trunk toward the than a), a feature that was accentuated when the horse moved. contralateral forelimb during protraction. The horse may hold

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a) b)

Fig 7: The tubera sacrale are higher than the wither. a) A 6-year-old Warmblood cross Thoroughbred with bilateral hindlimb proximal suspensory desmopathy. b) A 9-year-old Irish Sports Horse with bilateral hindlimb proximal suspensory desmopathy and sacroiliac joint region pain. This horse also has straight hock conformation.

a) b)

Fig 8: Hock and fetlock instability. A 6-year-old Warmblood cross with poor hindlimb action associated with proximal suspensory desmopathy and suspensory branch injury. The horse is on a left circle in trot. In both (a) and (b) the left hindlimb is placed slightly inwards under the trunk and the hock and fetlock lean outwards and ‘wobbled’ during the stance phase. Both hindlimbs were affected, the left more than the right. its back stiffly, sometimes exhibiting exaggerated contractions overtly lame steps, but on a firm surface may appear to be of the epaxial muscles. The swing of the tail may be reduced less well balanced, look out of the circle and take shorter and the tail may sometimes be clamped. A tail that is steps. Beware of over interpretation of an intermittent low- crooked related to pain may become more crooked on one grade forelimb lameness seen only on a firm surface. This rein. There may be a toe drag of one or both hindlimbs, with may be an incidental finding completely unrelated to the reduced hindlimb impulsion and engagement, with reduced cause of the horse’s poor performance when ridden. flexion and stiff gait. The rhythm may become irregular, with a Likewise, be aware that a long-stepping, exuberantly reduced cranial phase of the step of one hindlimb. The moving horse may protect itself by shortening the step absence of overt lameness does not preclude lameness length on a firm surface. when ridden. Transitions from walk to trot and trot to walk should be observed, paying particular attention to both The role of ridden exercise regularity and length of the hindlimb steps and whether or Ridden exercise is crucial, because there are some not the horse appears to flex the lumbosacral joint. A horse lamenesses, both forelimb and hindlimb, that are only with front foot pain may move more fluently on the lunge on apparent ridden (Supplementary Items 1 and 2). It is vital to a soft surface compared with in hand on a hard surface. recognise the problems that the rider is experiencing when The quality of the canter should be assessed, focusing on they ride the horse. Ideally, the horse should be assessed the horse’s balance, movement of the thoracolumbosacral ridden by its normal rider in its usual tack. The fit of the tack region, the degree of flexion of the hindlimbs and the energy should be assessed. The skill and balance of the rider and generated, and the forelimb step length. Placing the their size relative to the horse should be noted. It is important hindlimbs closer together than normal, both spatially and to recognise that a rider can potentially induce lameness by temporally, being croup high or becoming disunited may overly restricting the horse via the reins and failing to ask the reflect discomfort. horse to go forwards with sufficiently strong seat and leg aids. Ideally the horse should be first assessed on the lunge A rider who is poorly balanced, has poor core strength or on a soft surface and then on a firm surface with good moves out of synchrony with the horse’s gait can create grip. A horse with bilateral foot pain may still not take irregularities of the horse’s gait. A rider who is both large for a

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a) b)

Fig 9: Leaning in and looking out of a right rein circle on the lunge. a) The right hindlimb crosses under the trunk towards the contralateral forelimb during protraction. The horse’s neck is flexed slightly to the left. b) The flexion of the neck to the left is accentuated; the horse looks to the outside of the circle. horse and out of balance can inhibit the movement of the mind that saddle slip secondary to hindlimb lameness may horse’s thoracolumbar region with secondary changes in limb induce rider crookedness. flight. A rider who is constantly moving their hands may Pay attention to the diagonal on which the rider sits induce movement of the horse’s head and neck, which during rising trot. It is convention that the rider should sit sometimes may mimic lameness. A good rider can mask when the inside hindlimb and outside forelimb are bearing problems by making subtle readjustments to the horse’s weight. With hindlimb lameness, a horse usually appears balance and by riding the horse forward strongly. A horse lamer when the rider sits on the diagonal of the lame limb. that only experiences problems when doing advanced Some horses may alter their gait and hop to try to displace collected work, especially lateral work, may not show its the rider to sit on the diagonal of the nonlame or less lame problems unless ridden by a rider capable of producing that hindlimb. level of collection. Compare the horse’s posture and rhythm in rising trot The horse should work through the movements that it and sitting trot. A horse with thoracolumbosacral pain may would normally do in training and competition. This should stiffen its back in sitting trot, and become slightly above the include walk, trot and canter, upward and downward bit. Ask the rider if they feel any differences in the gait transitions and lateral movements depending on the horse’s between rising and sitting trot. Consider the relative quality level of training. Working, collected, medium and extended of the trot and the canter. The quality of canter in horses trot and canter should be assessed. If the horse has with sacroiliac joint region pain is usually worse than trot. The experienced problems when jumping it should be assessed clinical features of sacroiliac joint region pain are usually jumping. dramatically worse in a ridden horse than under other With any horse, it can be helpful to see the horse ridden circumstances (Dyson and Murray 2003; Dyson 2008; Barstow in 10 m diameter circles at the trot, and circular figures of 8, and Dyson 2015). i.e. linking 10 m circles to the left and to the right alternately. In some horses, the quality of canter may be consistently The circle diameter is crucial because larger circles are too worse on one rein (e.g. left rein) compared with the other easy. It is quite remarkable how a horse may maintain a (e.g. right rein) which may reflect asymmetrical pain. The normal posture and rhythm in a circle of 12 m diameter, but rider may feel jarred by the horse (i.e. there is a high impact look very different on a circle of 10 m diameter. Loss of transmitted through the rider’s seat and back). The horse may rhythm, becoming overbent or more overbent, leaning in, hold the thoracolumbosacral region stiffly, so that the rider crossing the inside hindlimb under the trunk during will comment that the horse feels ‘solid behind the saddle’. protraction, being more difficult to turn in one direction Flying changes are physically more demanding for the compared with the other may also reflect an adaptation to hindlimbs than maintaining canter on the same lead, and pain. difficulties in performing changes correctly may highlight the The horse and rider should be viewed coming toward and presence of pain. going away from the examiner, and from the side. This means With collected paces, the horse has to engage the that the horse is best assessed from 2 corners of the arena. If hindlimbs more than in working trot, with the centre of gravity the saddle continually slips to one side on one rein this is moved caudally and more weight being carried by the usually a reflection of hindlimb lameness (Greve and Dyson hindlimbs. Obviously this is more demanding than working trot 2013). However, it could be the result of an ill-fitting or and may be the only occasion when resistances are asymmetrically flocked saddle, asymmetry of the recognised. Lateral work requires collection and increases the thoracolumbar musculature or rider crookedness. Bear in rotational forces on the trunk and limbs.

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Detailed assessment of tack fit is out of the scope of this Changes limbs behind – see disunited canter. review. Nonetheless it is important to recognise the Collection: The horse’s centre of gravity moves backwards importance of correct saddle fit for both the horse and rider because of increased hindlimb engagement. The horse takes and the implications of poor fit (Dyson et al. 2015). If the shorter, higher steps, with a relative increase in the duration saddle is too far forward it can severely restrict forelimb gait. of the stance phase compared with a working pace. There is Merely repositioning the saddle can have a remarkable greater extension of the metacarpophalangeal and effect on the horse’s action. A saddle that is too narrow can metatarsophalangeal joints compared with working trot, and impair function of the thoracic sling and thus influence greater hock flexion. forelimb gait. Any ill-fitting saddle can cause thoracolumbar pain and influence the horse’s forelimb and/or hindlimb gait. Disunited canter (‘cross-cantering’): The horse changes the Throughout the clinical assessment, it should be borne in leading and trailing hindlimbs but not the forelimbs. Thus in mind that ataxia, either alone or in conjunction with left lead canter the left hindlimb is placed to the ground first lameness, can be an underlying cause of poor performance. (instead of the right hindlimb) followed by the right hindlimb Although some ataxic young horses excel in young horse and right forelimb more or less together, followed by the classes because of their extravagance of movement, few leading left forelimb. become advanced level performers because of their lack of fl musculoskeletal strength and coordination. Engagement of the hindlimbs: The hindlimbs are exed and fl Distinguishing between sacroiliac joint region pain and protracted under the body, with exion of the lumbosacral primary thoracolumbar pain can be challenging because joint, so that the hindlimbs can carry more load than the many horses with sacroiliac joint region pain have atrophy of forelimbs. the epaxial muscles (usually symmetrical), especially in the Extended trot: There is greater hindlimb impulsion and lumbar region (longissimus dorsi and middle gluteal muscles), engagement than in working trot, with a longer step length of Æ pain on palpation of the epaxial back muscles fascia the forelimbs and hindlimbs than in medium trot. This results in (symmetrical or asymmetrical, depending on the presence of greater extension of the metacarpophalangeal and factors such as left-right symmetry of sacroiliac joint region metatarsophalangeal joints compared with working and fi pain, lameness, saddle t and rider crookedness/straightness) collected trot, and greater hock flexion. and thoracolumbar-sacral stiffness. The latter is manifest particularly as limited induced extension and lateral bending Flying change: The horse changes from canter with one at rest, especially in the caudal thoracic and lumbar regions, forelimb leading (e.g. right forelimb) to canter with the other and reduced lumbosacral flexion during dynamic forelimb leading (e.g. left forelimb) during the suspension examination, especially when ridden. phase of the stride. Four-time canter: Normal canter is a 3-beat gait. The gait Conclusions from the clinical assessment becomes 4-time because of disassociation of landing of the diagonal placement of the trailing forelimb and leading Having undertaken this in depth clinical assessment it should, hindlimb. For example in left lead canter, which is initiated by with experience, be possible to draw up a problem list. The list the right hindlimb, then the left hind and right forelimbs bear should comprise the potential existence of hindlimb lameness, weight simultaneously and finally the leading left forelimb forelimb lameness, cervical and/or thoracolumbosacral region strikes the ground, landing of the left hindlimb and right pain, sacroiliac joint region pain, ataxia, a tack-related forelimb is disassociated, thus the beat becomes 4-time not problem and a rider problem. The problem list should help to 3-time. The hindlimbs are often placed closer together both determine how the horse should be investigated further, which temporally and spatially, when viewed from the side, is discussed in Part 2 of this review. compared with normal.

Author’s declaration of interests Hindlimb impulsion: The hindlimbs generate forward and upward thrust, propelling the horse forward in an energetic No conflicts of interest have been declared. powerful manner.

Lateral work: In all lateral movements (shoulder in, renvers, Source of funding travers and half pass) the horse is bent through its body and moves the forelimbs and hindlimbs on >2 different tracks, None. usually increasing torque on both the limbs and the thoracolumbosacral region. Glossary Medium trot: There is greater hindlimb impulsion and Above the bit: The cranial aspect of the head is in front of engagement than in working trot, with a longer step length of the vertical, with reduced flexion of the cranial cervical the forelimbs and hindlimbs. vertebrae, and when extreme the cranial aspect of the head is almost horizontal with extension of both cranial and caudal On the bit: A horse is said to be on the bit when the hocks cervical vertebrae. As a consequence there will be reduced are correctly placed (i.e. the hindlimbs are engaged), and flexion of the thoracolumbar-sacral regions. the neck is more or less raised and arched according to the stage of training and the collection or extension of the pace, Behind the bit: The cranial aspect of the head is behind the and the horse accepts the bridle with a light and soft vertical, with increased flexion of the cranial and mid cervical contact and submissiveness throughout. The head should vertebrae. remain in a steady position, with the cranial aspect vertical or

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slightly in front of the vertical, with a supple poll at the highest Greve, L. and Dyson, S. (2013) An investigation of the relationship point of the neck, and no resistance should be offered to the between hindlimb lameness and saddle slip. Equine Vet. J. 45, 570- 577. rider. Thus the cranial cervical vertebrae are in flexion. Greve, L. and Dyson, S. (2014) The interrelationship of lameness, On the forehand: The horse’s centre of gravity is too far saddle slip and back shape in the general sports horse population. forward and the horse is disproportionately loading the Equine Vet. J. 46, 687-694. forelimbs compared with the hindlimbs. Parkes, B., Newton, R. and Dyson, S. (2013) An investigation of risk factors for foot-related lameness in a UK referral population of Over the bit – see behind the bit. horses. Vet. J. 196, 218-225. Ross, M. (2010a) Observation: symmetry and posture. In: Diagnosis and Poor quality contact with the bit: The horse takes an uneven Management of Lameness in the Horse, 2nd edn., Eds: M. Ross contact via the bit and reins to the rider’s hands, and/or and S. Dyson Elsevier, St Louis. pp 32-43. leans on the bit, and/or opens the mouth. The mouth is Ross, M. (2010b) Palpation. In: Diagnosis and Management of usually dry without obvious salivation. The horse has reduced Lameness in the Horse, 2nd edn., Eds: M. Ross and S. Dyson, responsiveness to rein aids. Elsevier, St Louis. pp 43-63. Ross, M. (2010c) Movement. In: Diagnosis and Management of Renvers: The hindlimbs remain on the track, with the forelimbs Lameness in the Horse, 2nd edn., Eds: M. Ross and S. Dyson, on an inner track, with the horse bent through the trunk Elsevier, St Louis. pp 64-80. toward the outside of the arena. Ross, M. (2010d) Manipulation. In: Diagnosis and Management of Lameness in the Horse, 2nd edn., Eds: M. Ross and S. Dyson, Stiff, stilted canter: Canter lacking hindlimb impulsion, with Elsevier, St Louis. pp 80-88. reduced flexion of both the hindlimbs and the lumbosacral Turner, T. (1992) The use of hoof measurements for the objective joint. The hindlimbs are often placed closer together when assessment of hoof balance. Proc. Am. Assoc. Equine Practnrs. 38, viewed from the side than normal. 389-395.

Tracking up and over tracking: At both walk and trot the horse should place each hind foot in the imprint made by Supporting information the ipsilateral front foot (tracking up) or cranial to the imprint Additional Supporting Information may be found in the online of the ipsilateral front foot (over tracking). version of this article at the publisher’s website: Travers: Otherwise known as haunches in; the forelimbs Supplementary Item 1: An 8-year-old Warmblood with a remain on the track but the hindlimbs follow an inside track history of reduced performance is seen ridden. No lameness ’ with bend through the horse s trunk toward the inside of the had been detectable in hand or ridden. The horse tends to arena. be overbent with the mouth open and holds its back stiffly. There is a bilateral hindlimb toe drag, right > left. On the right rein the horse shows moderate (Grade 4/8) right hindlimb References lameness when viewed from behind. The horse moves closely Balch, O., White, K. and Butler, D. (1991) Factors involved in the behind. On the left rein, the horse shows moderate left balancing of equine hooves. J. Am. Vet. Med. Assoc. 198, 1980- hindlimb lameness (Grade 4/8) when viewed from behind. 1989. The horse moves closely behind; there is instability (wobble) of Barstow, A. and Dyson, S. (2015) Clinical features and diagnosis of the left hock during the stance phase of the left hindlimb. In sacroiliac joint region pain in 296 horses: 2004-2014. Equine Vet. 10 m diameter circles the horse slows the rhythm slightly; Educ. 27, 637-647. there is bilateral hindlimb toe drag and the horse is shorter Ducro, B., Gorisson, B., van Eldik, P. and Back, W. (2009) Influence of stepping in front. As the horse changes from the left rein to foot conformation on duration of competitive life in a Dutch Warmblood horse population. Equine Vet. J. 41, 144-148. the right rein, it shows overtly lame steps on the right forelimb fi Dyson, S. (1994) Proximal suspensory desmitis in the hindlimb: 42 cases. (Grade 3/8). The horse is more dif cult to turn to the right but Br. Vet. J. 150, 279-291. was stiffer to the left and began to show left forelimb Dyson, S. (2008) Clinical features of pain associated with the sacroiliac lameness (Grade 2/8) on the left rein. In leg yield to the left, joint region. Prat. Vet. Equine 40, 123-128. the hindquarters trail and the horse lays its ears back. The Dyson, S. (2009) The clinician’s eye view of hindlimb lameness in the horse is initially reluctant to canter to the right and comes horse: technology and cognitive evaluation. Equine Vet. J. 41, 99- above the bit in the transition. In canter, the horse has an 100. unsteady head carriage and is on the forehand. The horse Dyson, S. (2011) Can lameness be reliably graded?. Equine Vet. J. 43, has poor hindlimb engagement and impulsion and is over 379-382. bent and stiff and tends to swing the hindquarters outward Dyson, S. (2013) Equine lameness: clinical judgement meets on a turn. The horse lacks hindlimb engagement in the advanced diagnostic imaging. Proc. Am. Assoc. Equine Practnrs. downward transition from canter right to trot, stepping short 59, 92-122. behind. The horse comes above the bit in the transition from Dyson, S. and Murray, R. (2003) Pain associated with the sacroiliac trot to canter left, becoming croup high and shoots forward. joint region: a clinical study of 74 horses. Equine Vet. J. 35, 240-245. In canter left, the horse is short stepping in front and the Dyson, S., Tranquille, C., Collins, S., Parkin, T. and Murray, R. (2011) forelimbs have little lift from the ground. There is instability of External characteristics of the lateral aspect of the hoof capsule differ between non-lame and lame horses. Vet. J. 190, the left hock during the stance phase of the step. 364-371. fi Supplementary Item 2: After bilateral perineural analgesia of Dyson, S., Carson, S. and Fisher, M. (2015) Saddle tting, recognising fi an ill-fitting saddle and the consequences of an ill-fitting saddle to the deep branch of the lateral plantar nerve, in ltration of horse and rider. Equine Vet. Educ. 27, 533-543. local anaesthetic solution around the left and right sacroiliac

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joints and bilateral perineural analgesia of the palmar nerves are more fluent and the canter has increased elasticity and at the level of the base of the proximal sesamoid bones. The lift of the stride. The tail is still held to the left in trot and canter horse is more forward going and works with increased on the left rein. There is persistent instability of the hocks hindlimb engagement and impulsion, taking longer steps. The during the stance phase. The horse’s mouth is still open but horse is no longer overbent and has increased swing of the the horse is now mouthing the bit and there is a better quality trunk and increased flexion at the lumbosacral joint. The contact with the bit and a more even feel in the rider’s horse moves more symmetrically behind, but a mild bilateral hands. The horse is now much more comfortable for the rider hindlimb toe drag persists. The transitions from trot to canter and is more responsive to the aids.

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and histopathological examination. The horse showed a firm 2011). In our case, the horse showed a good recovery after plate-like mass underneath the skin in the right thigh region. treatment with surgical removal of the mass with routine After surgical removal, the histopathology revealed a thin antibiotic, analgesic and anti-inflammatory agents. plate of well-differentiated bone. The absence of inflammation and dystrophic mineralisation of collagen fibres Authors’ declaration of interests and the presence of mature cortical bone surrounded by No conflicts of interest have been declared. fibrous connective tissue in our case were consistent with primary plate-like osteoma cutis. To our knowledge, this is the Acknowledgement first report describing naturally occurring osteoma cutis in a horse. This work was supported by the Basic Science Research In our case, differentiation from calcinosis cutis was made Program through the National Research Foundation of Korea by a combination of laboratory data and histopathology (KRF) funded by the Ministry of Education, Science and results. In particular, calcinosis cutis exhibits calcium salt Technology (2010-0024447). deposition along the collagen and elastin fibres in the basement membrane zones and dermis enclosed by a foreign References body granuloma reaction histopathologically (Scott et al. Al-Ajmi, H.S., Abdulkader, A.M. and Mustafa, A.M.M. (2004) Adult onset 2000). In contrast, osteoma cutis exhibits osseous tissue with plate-like osteoma cutis. Gulf. J. Dermatol. Venereol. 11, 48-50. trabeculae surrounding the fat, with the occasional presence Brower, A. (2013) Bone tumour classification: still a work in progress. Equine Vet. Educ. 25, 235-236. of bone marrow cells in the dermis and subcutaneous tissue (Al-Ajmi et al. 2004). In our case, the following findings met the Burgdorf, W. and Nasemann, T. (1977) Cutaneous osteomas: a clinical and histopathologic review. Arch. Dermatol. Res. 260, 121-135. diagnostic criteria of osteoma cutis, especially the plate-like Cilliers, I., Williams, J., Carstens, A. and Duncan, N.M. (2008) Three cases form: no abnormal calcium or phosphorus metabolism, no of osteoma and an osseous fibroma of the paranasal sinuses of calcium deposition accompanied by a granulomatous horses in South Africa. J. S. Afr. Vet. Ass. 79, 185-193. response, no history of trauma, infection or other preceding Douri, T. and Shawaf, A.Z. (2006) Plate-like cutaneous osteoma on the conditions, and the presence of a bony plate (Douri and scalp. Dermatol. Online J. 12, 17. Shawaf 2006; Vashi et al. 2011). Kold, S.E., Ostblom, L.C. and Philipsen, H.P. (1982) Headshaking caused Surgical intervention is generally indicated in the case of by a maxillary osteoma in a horse. Equine Vet. J. 14, 167-169. osteoma cutis with the absence of underlying disease. Martin, D.M., Hall, J., Keirstead, N. and Lowe, A. (2006) Multifocal Treatment consists of closure of the surgical wound combined osteoma cutis in a golden retriever. Can. Vet. J. 47, 360-362. with medical treatment with antibiotics, analgesics, and Scott, D.W., Miller, W.H. Jr and Griffin, C.E. (2000) Neoplastic and anti-inflammatory agents (Scott et al. 2000; Al-Ajmi et al. 2004; non-neoplastic tumours. In: Muller and Kirk’s Small Animal Dermatology, 6th edn., Eds: D.W. Scott, W.H. Miller Jr and C.E. Griffin, Vashi et al. 2011). Other described therapies include W.B. Saunders, Philadelphia. pp 1314-1315, 1388-1399. administration of bisphosphonates, which inhibit bone Steinman, A., Sutton, G.A., Lichawski, D. and Johnston, D.E. (2002) resorption (Martin et al. 2006) and thereby reduce progression Osteoma of paranasal sinuses in a horse with inspiratory dyspnoea. of the lesion via remodelling. However, because the Aust. Vet. J. 80, 140-142. effectiveness of this treatment is limited, it is not recommended Vashi, N., Chu, J. and Patel, R. (2011) Acquired plate-like osteoma cutis. once complete ossification is already established (Vashi et al. Dermatol. Online J. 17,1.

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