Equine Veterinary Education December 2020

E Q UINE equine American Edition | December 2020 VETERINARY veterinary

EDUCATION/American education Edition

EQUINE FIELD

DIAGNOSTICS Volume

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in this issue: December

From the president: Flipping the script on an unconventional year The official journal of the American Association of Sarcocystis myositis and vitamin E deficiency in a Gypsy Vanner Equine Practitioners, produced

2020 stallion suspected of having equine motor neuron disease in partnership with BEVA. i-STAT and Alinity are trademarks of the Abbott Group of Companies in various jurisdictions. The use of magnetic resonance imaging for the assessment of All trademarks are the property of Zoetis Services LLC or a related company or a licensor unless otherwise noted. distal limb wounds in horses: A pilot study ©2020 Zoetis Services, LLC. All rights reserved. VTS-00125

PADX780EVE-coverspread-12-20.indd iSTAT Alinity Journal 1Ad EVE V1 FINAL 050420.indd 1 5/4/20 12:30 PM 11/30/20 12:59 PM equine veterinary education American Edition %&$&.#&3t70-6.& t /6.#&3

AAEP NEWS In this issue contents From the president: Flipping the script on an unconventional year...... III AAEP publishes serology guidelines ...... IV Ethical consideration of referral cases ...... VII

Highlights of Recent Clinically Relevant Papers S. WRIGHT ...... 618

Case Reports Sarcocystis myositis and vitamin E deficiency in a Gypsy Vanner stallion suspected of having equine motor neuron disease A. C. TRIMBLE, K. M. DELPH, E. R. PERRY and S. J. VALBERG ...... 620

Pleomorphic sarcoma with giant cells infiltrating the infraorbital canal in an aged Thoroughbred mare G. L. ELANE, E. M. CORBIN, L. REIG and J. A. BROWN ...... 621

Haemoperitoneum secondary to testicular rupture caused by blunt trauma in a stallion Y. DA SILVA BONACIN, S. DOS SANTOS SOUSA, P. A. CANOLA, D. DA GRAÇA MACORIS, G. M. BUENO, D. J. DE QUEIROZ and J. A. MARQUES ...... 622

Chronic lameness caused by vascular compression of the iliac artery and vein by a malignant melanoma in the pelvis of a grey Spanish gelding A. VAN ONGEVAL, N. VAN DE VELDE, E. RAES and M. OOSTERLINCK ...... 623

Successful treatment of a splenic abscess secondary to migrant metallic wires in a horse C. THOMSON, D. ARCHER, B. AHERN and C. E. MEDINA-TORRES ...... 633

Clinical Commentaries Melanocytic tumours in horses K. E. SULLINS ...... 624

The potential role of sensors in equine melanoma prevention V. G. KANELLIS ...... 631

Splenic abscessation: Is partial splenectomy a treatment option? A. J. DART and S. A. BIASUTTI ...... 634

Original Articles The use of magnetic resonance imaging for the assessment of distal limb wounds in horses: A pilot study C. SHERLOCK, A. FAIRBURN, A. LAWSON and T. MAIR ...... 637

Clinical and ultrasonographic evaluation of three suture techniques for closure of the equine linea alba M. E. VERKADE, F. UGAHARY, A. MARTENS and P. WIEMER ...... 646

Review Articles Monitoring of the mare during the perinatal period at the clinic and in the stable M. MASKO, M. DOMINO, K. SKIERBISZEWSKA, Ł. ZDROJKOWSKI, T. JASINSKI and Z. GAJEWSKI ...... 654

A review of normal radiographical variants commonly mistaken for pathological findings in horses F. E. HINKLE, S. A. JOHNSON, K. T. SELBERG and M. F. BARRETT ...... 664

$GYHUWLVHUV·,QGH[ ...... 645 Cover photo by Dr. Nat White.

c.c.001_I-II_EVE1220.indd001_I-II_EVE1220.indd 1 112/1/202/1/20 110:180:18 AM American Association of Equine veterinary education Equine Practitioners American Edition 4033 Iron Works Parkway Lexington, KY 40511 %&$&.#&3 t70-6.&t /6.#&3 5&- r FAX (859) 233-1968 EMAIL [email protected] Editor (UK) Assistant Editors S. Love aaep.org T. S. Mair, BVSc, PhD, DEIM, DESTS, F. Andrews M.L. Macpherson To access our website, go to aaep.org, select DipECEIM, MRCVS D. Archer M.J. Martinelli LOGIN, then enter your email and password. If you F.T. Bain I.G. Mayhew have difficulty logging in or have forgotten your Editors (USA) A.R.S. Barr M. Mazan password, please call or email the office. N. A. White II, DVM A. Blikslager C.W. McIlwraith W. D. Wilson, MRCVS M. Bowen B. McKenzie ""&10GGJDFST N. Cohen R. Moore David Frisbie, DVM, President Deputy Editors V. Coudry M. Oosterlinck Y. Elce A. Dart A. Parks Scott Hay, DVM, President-Elect P.R. Morresey J.-M. Denoix S. Puchalski Emma Read, DVM Vice President P.A. Wilkins T. Divers A.G. Raftery P. Dixon C. Riggs Lisa Metcalf, DVM, Treasurer Management Group W. Duckett H. Schott Jeff Berk, VMD, Immediate Past President D. Foley B. Dunkel J. Schumacher S. Dyson S. Semevelos AAEP Staff T. S. Mair N. A. White T. Fischer J. Slater D. Freeman B. Sponseller David Foley, CAE, Executive Director W. D. Wilson [email protected] T. Greet C. Sweeney J. L. N. Wood Lori Rawls, Director of Finance & Operations R. Hanson H. Tremaine [email protected] P. Harris K. Wareham Management Board Sally J. Baker, APR, Director of Marketing M. Hillyer S. Weese & Public RelationstTCBLFS!BBFQPSH A. R. S. Barr C. Scoggin M. Holmes R. Weller D. Foley N. A. White (US Editor) Keith Kleine, Director of Industry Relations N. Hudson C. Yao [email protected] D. Mountford S. White P. Johnson (Editor) (US Editor) Nick Altwies, Director of Membership T. S. Mair W. D. Wilson P.T. Khambatta Ex-officio [email protected] S. E. Palmer J. L. N. Wood (Chairman) J.-P. Lavoie J. Cooney Kevin Hinchman, Director of Information Technology [email protected] Equine Veterinary Education is a refereed educational journal designed to keep the practicing veterinarian up to Karen Pautz, Director of Education 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 Sadie Boschert, Student Programs Coordinator coverage of issues in equine practice. [email protected] Equine Veterinary Education (American Edition ISSN 1525-8769) is published monthly by the American John Cooney, Publications Coordinator Association of Equine Practitioners, an international membership organization of equine veterinarians. Office of [email protected] publication is 4033 Iron Works Parkway, Lexington, KY 40511. Periodicals Postage paid at Lexington, KY and Giulia Garcia, Communications Coordinator additional mailing office. POSTMASTER: Send address changes to: Equine Veterinary Education, 4033 Iron Works [email protected] Parkway, Lexington, KY 40511. Megan Gray, Member Concierge Communications regarding editorial matters should be addressed to: The Editor, Equine Veterinary Education, [email protected] Mulberry House, 31 Market Street, Fordham, Ely, Cambridgeshire CB7 5LQ, UK. Telephone: 44 (0) 1638 720250, Dana Kirkland, Sponsorship & Advertising Fax: 44 (0) 1638 721868, Email: [email protected]. CoordinatortELJSLMBOE!BBFQPSH All manuscript submissions for the journal should be submitted online at http://mc.manuscriptcentral.com/eve. Full Katie McDaniel, EDCC Communication Manager instructions and support are available on the site and a user ID and password can be obtained on the first visit. If you [email protected] require assistance, click the Get Help Now link that appears at the top right of every ScholarOne Manuscripts page. Deborah Miles, CMP, Trade Show Coordinator [email protected] All subscription inquiries should be addressed to: Subscriptions Department, AAEP, 4033 Iron Works Parkway, Lexington, KY 40511, Telephone: (859) 233-0147, Email: [email protected]. Subscription rates: AAEP annual Jayson Page, Office Manager membership dues include $40 for a subscription to Equine Veterinary Education. Other subscriptions at $151.80. [email protected] Single copies $37.50. Paul Ransdell, Senior Development Officer Canadian Subscriptions: Canada Post Corporation Number 40965005. Send change address information and [email protected] blocks of undeliverable copies to AAEP, 1415 Janette Avenue, Windsor, ON N8X 1Z1, Canada. Carey Ross, Scientific Publications Coordinator [email protected] © World copyright by Equine Veterinary Journal Ltd 2020.

Sue Stivers, Executive Assistant The authors, editors and publishers do not accept responsibility for any loss or damage arising from actions or [email protected] decisions based or relying on information contained in this publication. Responsibility for the treatment of horses Amity Wahl, Communications & under medical or surgical care and interpretation of published material lies with the veterinarian. This is an aca- Technology Coordinator demic publication and should not be used or interpreted as a source of practical advice or instruction. [email protected] The American Association of Equine Practitioners cannot accept responsibility for the quality of products or ser- Kristin Walker, Membership & Event vices advertised in this journal or any claim made in relation thereto. Every reasonable precaution is taken before Services Coordinator advertisements are accepted, but such acceptance does not imply any form of recommendation or approval. [email protected] Equine Veterinary Education Elaine Young, Development & Communications All companies wishing to advertise in , American edition, must be current AAEP exhibitors. Coordinator AAEP retains the right, in its sole discretion, to determine the circumstances under which an exhibitor may advertise in this [email protected] journal. While all advertisers must comply with applicable legal guidelines, Compounding Pharmacies are specifically 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 Published monthly. Deadlines are the seventh of the preceding month. mimicry of drugs and dosage forms of FDA approved formulations will not be accepted. Compounding Pharmacies, or any other exhibitors/advertisers who violate this rule in any fashion, will render their advertising contract null and void. Address advertising inquiries to Dana Kirkland (859) 233-0147 / [email protected] As a private organization, the AAEP reserves the right to exclude any company from advertising in Equine Veterinary Education, American edition, for any reason. The signing and delivery of the advertising contract shall AAEP Mission Statement: To improve the health and constitute an offer subject to acceptance by the AAEP. In its sole and absolute discretion, the AAEP may revoke its welfare of the horse, to further the professional acceptance of the advertising contract or may terminate any contract by delivery of written notice, in which event development of its members, and to provide resources the AAEP shall have no liability to the advertiser for damages for any other remedy. and leadership for the benefit of the equine industry. Printed by: Cenveo Publisher Services, Lancaster Division, Lancaster, PA.

cc.001_I-II_EVE1220.indd.001_I-II_EVE1220.indd 2 112/1/202/1/20 10:1810:18 AMAM Association AAEP News December 2020 III

From the president: Flipping the script on an unconventional year By David Frisbie, DVM, Ph.D., DACVS, DACVSMR

Despite immense, pandemic- commitment to these principles is strong, and a new induced challenges this year, Diversity, Equity and Inclusion Task Force was formed your association has remained this fall. We eagerly anticipate the outcome of their efforts laser-focused on the horse and in 2021. its members. The AAEP staff and volunteer members Horse health and welfare is core to our mission and deserve kudos for maintaining always a focus of our efforts. When racing came under all core services for members intense scrutiny for equine injuries sustained in training as well as a healthy financial and racing, particularly at Santa Anita, we saw the stake- balance. In addition, in every holders, including many of our members, take bold steps meeting in which I have par- to address safety issues. Not surprisingly, this effort ticipated this year, two central included veterinarians stepping up to personally certify Dr. David Frisbie questions have guided discus- each horse’s fitness to race. This initiative has moved the sions and decisions: What is best for the horse and what needle as Santa Anita reported zero fatalities during their have our members told us they need or want? autumn meet. I applaud the efforts of all involved for not only enduring the hard times but also rising up to It is this dedication and focus that enabled us to make implement novel measures for the wellbeing of those significant progress on strategic initiatives and turn the equine athletes. challenges of 2020 into opportunities for growth. The Racing Committee Societal events in the AAEP strives to provide the best and most respected also grappled with the continuing education. Although the pandemic prevented federal legislation United States and us from hosting in-person events, launch of the Virtual addressing uniform safety across the globe CE Summer Series under program chair Dr. Sherry and medication standards Johnson provided a new and needed outlet for members in U.S. horseracing, prompted the board to obtain premier education. With over 250 participants keeping horse welfare at to consider the role and overwhelmingly positive reviews, the virtual event the forefront of discus- this association should was a huge success. It also provided valuable insight into sions. While the members’ consumption of online content as well as a Horseracing Integrity and be playing in ensuring blueprint for this year’s virtual convention and future Safety Act was not viewed diversity and inclusion CE opportunities. As the Educational Programs as perfect, the veterinary in both equine Committee wraps up the year, the ball is rolling to ensure expertise added to its your continuing education needs will be met with the governance structure practice and the asso- same care to standards and personal safety in the helped it garner support ciation itself. upcoming year. from the committee and, ultimately, the board. Turning to the many unique circumstances facing our profession, the board of directors embarked on a The Performance Horse Committee also made significant multiyear effort to address the declining numbers of strides, beginning with an in-depth outline of issues facing veterinary students pursuing equine practice and new that sector, including medication-related concerns. The equine practitioners staying in the profession beyond five committee surveyed the membership to learn more about years. The board formed a task force and approved funds how various medications are used as well as to identify to retain a consultant in an effort to use the mission the most important areas to investigate further. Survey model canvas, developed in part by Stanford University results are expected to be published in early 2021. and utilized by numerous mission-focused organizations, to unpack the issues and validate the effectiveness of Meanwhile, the Infectious Disease Committee has worked solutions addressing retention and recruitment of equine diligently to protect horse health while providing veterinarians. Look for this group to reach out to the members and their clients with the information necessary membership as well as report out in 2021. to make thoughtful and educated decisions. This year alone, the committee issued revised guidelines for the Societal events in the United States and across the globe administration of selected core and risk-based vaccines, prompted the board to consider the role this association and published new guidelines for Glanders, African horse should be playing in ensuring diversity and inclusion in both equine practice and the association itself. Our continued on next page

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5 things to know about AAEP this month

1. Register for the AAEP’s 2. Enjoy free access until 3. The Annual Convention 4. View or download new 5. Acquire tips to maintain Virtual Convention by Jan. 29 to all of the EVE Proceedings books were AAEP Guidelines for or reignite your passion Dec. 31 at convention. and EVJ articles highlighted mailed to all members on Serology in Horses with for the profession by aaep.org and receive during the Kester News Hour Nov. 11. Proceedings Adverse Events from listening to the latest on-demand access to and cited in the Milne Lecture papers can also be found Vaccination at AAEP Practice Life all sessions and CE at wileyonlinelibrary.com/ on the Convention app. https://tinyurl.com/aaepsg. Podcast, “Equine Practice until June 30, 2021. journal/evj. is Pretty Good, Part 2,” at podcast.aaep.org.

AAEP publishes serology guidelines

AAEP Guidelines for Serology in equine influenza, equine herpesvirus Horses with Adverse Events from 1&4, and strangles. Vaccination is now available on the AAEP website. Interpretation and utilization of serologic data to guide vaccination The guidelines are intended as a decisions should be done with reference for veterinarians who wish caution and with consideration of all to utilize serological testing to other factors associated with determine levels of circulating occurrence of disease. These include antibodies to specific pathogens in a but are not limited to risk of disease, horse that previously experienced an consequences of disease, risk of adverse vaccination event. The systemic vaccine-associated adverse guidelines were developed by the events, prior vaccination history, and AAEP Serology Guidelines Task data to support titer correlates to Force composed of Drs. D. Craig protection against the disease. Barnett, Beth Davis, Amanda House, Nicola Pusterla and W. David It should be emphasized and Wilson, and approved by the recognized that circulating Infectious Disease Committee and antibodies are only one component vaccine-induced serologic response board of directors. of a very complex immune system. and protection has either not been Levels of circulating tetanus toxin established or is not plausible based Guidelines are presented for core binding antibody and rabies virus on the disease in question. diseases Eastern equine encephalo- neutralizing antibody appear to myelitis, Western equine encephalo- correlate with protection in the Access the guidelines or save them to myelitis, rabies, tetanus and West horse. For most other vaccine your mobile device for access in the Nile virus; and risk-based diseases antigens, the correlation between field at https://tinyurl.com/aaepsg.

From the president, continued

sickness, Borrelia burgdorferi infection and Lyme disease you to all the member and industry volunteers who and, most recently, serology in horses with adverse events stepped up, especially Keith Kleine, who coordinated from vaccination. The Foundation/AAEP’s response, and Dr. Bill Moyer, who has long championed the importance of disaster AAEP’s charitable arm, The Foundation for the Horse, preparedness. has continued to prioritize the welfare of the horse while taking giving to new levels under the leadership of Dr. It has been quite a year. As I reflected on the final letters Rick Mitchell. The response from The Foundation—and of my predecessors, a common theme arose: admiration from many AAEP members and others—to the devastat- and awe at the organization as a whole. Having now had ing wildfires in the west and flooding along the Gulf that experience firsthand, I, too, stand back in admiration Coast that impacted many horses and their caretakers in of our profession and the AAEP. I sincerely thank you for recent months has been uplifting and inspiring. Thank the opportunity to contribute.

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Nominate a distinguished researcher for the 2022 Milne Lecture Deadline to nominate is January 29

The Frank J. Milne State-of-the-Art Lecture is a traditional highlight of each year’s annual convention, and you can help determine the 2022 honoree by nominating an accomplished researcher.

The Milne Lecture was created in 1997 to recognize an individual with a distinguished career in research and discovery, and who has presented and published their findings in a specific area of equine health. The lecture is intended to honor the accomplishments of the presenter and provide a meaningful learning experience to the AAEP membership. The lecture is a perspective on the state-of-the-art in the presenter’s area of expertise. Dr. Dean W. Richardson delivers the 2019 Milne Lecture on The award recipient will be determined by a subcommit- the topic of equine fracture repair. tee of the Educational Programs Committee in February 2021 and will then be presented to the board of directors topic to the audience. A nomination form must be for approval. The selected individual will deliver their completed and include qualifications and accomplish- lecture and receive their award at the AAEP’s 2022 ments of the nominee. Annual Convention in San Antonio, Texas. Request a nomination form from Carey Ross, scientific Nominees should be an expert in their field with a track publications coordinator, at [email protected]. Completed record of accomplishment and the ability to relate the forms must be returned to her by Jan. 29, 2021.

Help equine rescue and retirement facilities apply for free vaccines 2021 UHVRC application deadline is February 1

AAEP members affiliated with 501(c)(3) equine rescue and rehabilitation facilities in the United States should work with those facilities now to complete the application for complimentary vaccines from the Unwanted Horse Veterinary Relief Campaign (UHVRC) by the Feb. 1 deadline.

The UHVRC is a non-profit partnership between Merck Animal Health and the AAEP to safeguard the health and facilitate the adoption of rescue horses. Since its inception in 2008, the UHVRC has provided nearly 40,000 doses of core vaccines to safeguard the health and facilitate the adoption of rescue horses.

The UHVRC provides qualifying equine facilities with Merck Animal Health vaccines to protect against Eastern and Western equine encephalomyelitis, equine herpesvirus (EHV-1 and EHV-4), West Nile virus, equine influenza and tetanus. Eligible facilities must coordinate an application with an AAEP-member veterinarian and adhere to the AAEP Care Guidelines for Equine Rescue and Retirement Facilities.

Visit uhvrc.org and click the “Get Involved” button to download the application and equine vaccine order form.

EVENewsINSERT_12-20.indd 5 11/30/20 1:11 PM Association AAEP News December 2020 V

Nominate a distinguished researcher for the 2022 Milne Lecture Deadline to nominate is January 29

The Frank J. Milne State-of-the-Art Lecture is a traditional highlight of each year’s annual convention, and you can help determine the 2022 honoree by nominating an accomplished researcher.

Help equine rescue and retirement facilities apply for free vaccines 2021 UHVRC application deadline is February 1

AAEP members affiliated with 501(c)(3) equine rescue and rehabilitation facilities in the United States should work with those facilities now to complete the application for complimentary vaccines from the Unwanted Horse Veterinary Relief Campaign (UHVRC) by the Feb. 1 deadline.

The UHVRC provides qualifying equine facilities with Merck Animal Health vaccines to protect against Eastern and Western equine encephalomyelitis, equine herpesvirus (EHV-1 and EHV-4), West Nile virus, equine influenza and tetanus. Eligible facilities must coordinate an application with an AAEP-member veterinarian and adhere to the AAEP Care Guidelines for Equine Rescue and Retirement Facilities.

Visit aaep.org/horse-owners/unwanted-horse-veterinary-relief-campaign to download the application.

Thor, a 2-year-old-Belgian, was among the rescues at A Place for Peanut in Cypress, Texas, to receive core vaccines through the UHVRC in 2020.

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Present your research at the 67th Annual Convention in Nashville Deadline to submit an educational paper is March 15, 2021

AAEP members and others are invited to submit papers Types of papers accepted for consideration for presentation during the AAEP’s 67th All paper presentations are limited to 15 minutes plus 5 Annual Convention in Nashville, Tenn., Dec. 4–8, 2021. minutes for Q&A. Eligible for consideration are scientific papers, “how-to” papers, review papers, 250-word abstracts and The Scientific papers should be a minimum of 600 words. Business of Practice papers. Special attention will be given to material with practical content or new information. Submitting your paper • All papers must be submitted by March 15, 2021, How-to papers should describe and explain a technique 3:00 p.m. ET at https://s3.goeshow.com/aaep/ or procedure used in veterinary medicine or the equine annual/2021/AAEP_paper_submission.cfm. The industry. The technique should be relatively new or not system will shut down after this time. widely understood or used in practice. There is no word limit for how-to papers. • Be sure to familiarize yourself with the submission process well in advance of the deadline. You can set Review papers should update the membership on a new up your profile with paper and author information in subject or gather information that may be conflicting. advance and then upload your paper when it is Although a review paper does not necessarily contain complete. original data, it is anticipated that the presenter will have • Since the review process is blinded, make sure your considerable experience in the field. paper does not include author or institution names. Abstracts ≤ 250 words may be submitted by authors who A few key points intend to publish in a refereed journal. An abstract • Products and equipment must be identified by conforming to the AAEP guidelines to authors must also chemical or generic names or descriptions and be submitted (for review purposes only) to allow the footnoted. reviewers to assess the experimental design, materials and • Due to the length and complexity of the process, all methods, statistical analyses, and results (with graphs, deadlines are strictly enforced. tables, charts, etc.) and to discuss the results as they • Submission of a paper represents a commitment to pertain to interpretation and conclusions. present this paper at the meeting if it is selected. The Business of Practice papers may cover any business • Selected papers will be printed in the 2021 AAEP management topic that can help the practitioner and their Proceedings and presented at the 2021 Annual practice achieve more success and improve profitability. Convention. The presenting author will receive The theme for 2021 is “Practice Transitions.” complimentary registration and a travel allowance. Contact Carey Ross, scientific publications coordinator, at Ethical Considerations [email protected] with questions concerning educational • Authors are expected to disclose the nature of any paper submission. financial interests they have with companies that manufacture or sell products that figure prominently Note: At this time, we are planning the 2021 AAEP Annual in the submitted paper or with companies that manu- Convention & Trade Show as an in-person meeting. However, due facture or sell competing products. to the COVID-19 pandemic and uncertainty of how the situation will look next year, the meeting could pivot to a virtual format, which • If your presentation references the use of a would require you to record your presentation for on-demand compounded pharmaceutical, ensure that you are viewing. The Annual Convention is an incredibly important event familiar with the FDA guidelines on the use of for the AAEP and a favorite way to not only educate but also compounded pharmaceuticals and that the product celebrate equine veterinarians from around the world. However, we you reference is in compliance. need to prioritize the health and safety of our members, partners, • All AAEP abstracts submitted for presentation should employees, and everyone who helps make this meeting happen. cite levels of evidence-based medicine. Thank you for understanding.

EVENewsINSERT_12-20.indd 6 11/30/20 1:11 PM ETHICS AAEP News December 2020 VII

Ethical consideration of referral cases By Stacy Anderson, DVM, MVSc, Ph.D., DACVS-LA

The cornerstone of a referral of an animal to another veterinarian. However, successful and ethical case you are ethically responsible for the care of the animal referral is communication— until the point of referral, at which point you are obligated with your client, with the to communicate with the referral practice any data referral practice, and with any acquired on the case and any treatments administered additional players that vary prior to referral (not a week later). The act of referring a with case, such as trainers, case and the data that is communicated to the practice haulers, etc. Based on most accepting the referral is encompassed in that practice’s veterinary practice acts, any medical record. Therefore, accuracy and timeliness of case licensed veterinarian may data are important for the referral practice to maintain receive a referred case or refer medical records for purposes of accreditation or licensure. a case to another licensed vet- Dr. Stacy Anderson erinarian. The question left Veterinarians who accept referrals are also held to ethical unanswered by a veterinary practice act is at what point standards—they must abide by the AVMA Principles of should a patient be referred? Veterinary Medical Ethics (accessible at https://tinyurl. com/pvmeavma). The veterinarian who accepts a referral This is the point of ethical consideration that a referring has an ethical obligation to keep the referring veterinarian veterinarian must navigate. Usually during the progression apprised of the progression of the case and return the case of a case, there is a tipping point that leads to case referral. to them when it is resolved. A veterinarian who has Sometimes the tipping point is obvious, such as a colic that accepted a referral should only provide services or does not respond to treatment in the field; but sometimes treatments relative to the condition for which the referral it is inapparent, causing a delay in referral and possibly was made and should consult with the referring veterinari- costing a client precious time and money without a an if additional services or treatments become necessary. diagnosis or definitive treatment. Communication between the referring veterinarian and the Referral of a horse may be one of the most terrifying referral veterinarian needs to take place, ideally in advance things a horse owner ever experiences, or it may be a of a referral situation, so that the expectations are clear regular occurrence. As such, the ethical obligation of the with both parties. Indeed, if a referring veterinarian is referring veterinarian should be to educate the client as capable of performing a procedure in-house, should the best they can by laying out the processes that will occur referral veterinarian even accept the case? Public referral upon referral. The referring veterinarian also may have to practices, such as teaching hospitals, are ethically bound to make the decision to refer based on the best interests of not only accept referral cases, but to also be prepared to the patient. Will the horse survive the 5-hour trailer ride to educate referring veterinarians where appropriate. a hospital? Is it humane to refer a horse with a clearly terminal disease, such as a ruptured viscus? These are In teaching hospitals where there is a significant rotation choices that often need to be made by the veterinarian, but of caregivers (i.e., veterinary students) for any given case, it they must be made in conjunction with the client who is critical that patient confidentiality is maintained. This is owns the animal. a learning outcome that should be addressed on every equine rotation in a teaching environment. Hospitals Referring veterinarians should develop collegial relation- should strive to maintain patient confidentiality so ships with referral practices so they can make well- thoroughly that even the horse’s name is not written on informed decisions on when to refer a case. Furthermore, the exterior of the stall where other clients might see. it is important that lack of funds, perceived or real, not be a reason for delay of recommendation of referral. Failure Lastly, veterinarians on both ends of the referral spectrum to offer timely referral could be considered malpractice. are ethically bound to provide the best treatment to their patients, whether it be by themselves or a veterinarian to Upon referral, it is critical to remember that the referring whom they refer the case. Veterinarians are ethically veterinarian has the primary relationship with the client bound to help clients make informed decisions about their and the patient. But what are you ethically obligated to patient’s care and quality of life. In the perfect referral provide a client and patient during a referral? Most situation, both the patient and the client come out as veterinary practice acts are not explicit on requirements of winners regardless of the case outcome.

Dr. Anderson is dean of the Lincoln Memorial University College of Veterinary Medicine in Harrogate, Tenn., and a member of the AAEP’s Professional Conduct & Ethics Committee.

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Ethics in action

CE event, AAEP member “Dr. C” required, but did call and leave an became upset with a small group of angry message with the AAEP office. veterinarians who were talking during an award presentation. Dr. C Following committee deliberation, it struck one of the veterinarians across was decided to give Dr. C another As an educational resource for the face and used extensive profanity chance to respond to the committee’s members, the AAEP’s Professional and slurs. Dr. C was escorted out of inquiry. A second letter was sent to Conduct & Ethics Committee has the event. The following day, the Dr. C, who did not respond within compiled synopses of real-life ethical leadership of the organization the prescribed 30-day period. At this situations and issues addressed by the suspended Dr. C’s membership. point, the committee recommended committee in recent years. The case to the AAEP board that Dr. C’s series began in the November 2020 Soon after, an AAEP member filed a membership be suspended until such issue, and a different matter is being member-on-member complaint time as Dr. C agrees to meet with the presented each month, with names against Dr. C with the Professional committee on this issue. omitted to protect the privacy of Conduct & Ethics Committee those involved. pertaining to this incident. Per Outcome: Dr. C’s AAEP membership committee procedures, a letter of was suspended indefinitely until such Case of the month – December inquiry was sent to Dr. C asking for time as they agree to meet with the While attending an evening social their account of what occurred. Dr. C Professional Conduct & Ethics function at a non-AAEP veterinary did not respond in writing, as is Committee.

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Whether you’re an associate seeking a new opportunity or a practice owner seeking qualified candidates for an open position, the AAEP Career Center will help you make a career connection.

The Career Center provides a targeted and cost-effective means for employers to reach qualified candidates, with rates significantly below the mass market job boards. For just a little more, employers can expand the reach of their job post through inclusion in the Veterinary Career Network, which will push their post out to nearly 60 veterinary-related sites like the AVMA, many state VMAs and other VCN participants.

After posting a job opening, employers can proactively search resumes on file in the Career Center using multiple criteria to identify potential candidates. They will also receive email notice when job seekers apply for the posted position. such as assistance with effective resume and cover letter writing, salary negotiation and more. Job seekers, meanwhile, can view all available openings or narrow their search by location, keyword or other Post your job opening or your resume in the AAEP’s criteria; sign up for job alerts to receive notice when new Career Center today at jobs.aaep.org. If you have positions of interest are posted; upload an anonymous questions about the Career Center or need assistance resume available for review by employers; and take crafting a job post, contact Megan Gray, AAEP’s member advantage of resources to assist with their job search concierge, at [email protected].

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Members in the News

Dr. Jean-Yin Tan named Committee and Reproduction Committee, and he also Top 40 Under 40 served on the Finance, Nominating and Political Liaison Avenue Calgary magazine has committees. He received his veterinary degree from recognized Dr. Jean-Yin Tan, senior Colorado State University. instructor with the University of Calgary Faculty of Veterinary Medicine, Dr. Kelly Knickelbein dually recognized for among its list of the Top 40 Under 40 research Calgarians who are moving the city Dr. Kelly Knickelbein, an ophthalmolo- Dr. Jean-Yin Tan forward. gy resident at the University of California, Davis, recently received a Dr. Tan chairs the AAEP’s Diversity, Equity and Inclusion pair of awards for her publication, “A Task Force and received the AAEP’s Good Works for missense mutation in damage-specific Horses Award in June 2019 for her veterinary outreach to DNA binding protein 2 is a genetic risk Calgary’s Indigenous communities. She received her factor for ocular squamous cell veterinary degree from Cornell University. carcinoma in Belgian horses,” which appeared in the January 2020 issue of Dr. Phil Matthews elected Dr. Kelly Equine Veterinary Journal. president of FTBOA Knickelbein Dr. Phil Matthews, partner in A 2015 veterinary graduate of the University of Peterson & Smith Equine Hospital Pennsylvania, Dr. Knickelbein received the American in Ocala, Fla., and director of the College of Veterinary Ophthalmology Resident Manuscript practice’s equine reproduction center, Award as well as the James M. Wilson Award as the has been elected president of the graduate student or UC Davis veterinary hospital resident Florida Thoroughbred Breeders and who published the year’s most outstanding research report. Owners Association. Dr. Phil Matthews An abstract of her publication is available at https:// pubmed.ncbi.nlm.nih.gov/30903710. Dr. Matthews served on the AAEP board of directors from 2000–2002. He is a former chair of the Insurance

EVENewsINSERT_12-20.indd 10 12/1/20 11:51 AM FOUNDation AAEP News Decmber 2020 XI

Your year-end gift makes a difference

2020 has been a challenging year for everyone. End it on a positive note and make 2021 a little brighter with a year-end, tax-deductible gift to The Foundation for the Horse.

You can give in three ways: • Online: foundationforthehorse.org • By phone: (859) 705-0430 • By mail: 4033 Iron Works Parkway, Lexington, KY 40511

The Foundation works to improve the welfare of the world’s horses and working equids. Your generous gift Kate Montgomery and other St. George’s University today, added to the gifts of others, will have lasting veterinary students participate in a Foundation-sponsored impact and help change the world for horses. podiatry lab and workshop in February 2020.

Foundation launches ‘Proud Supporter’ program

Help make a difference by becoming a Foundation Proud Supporter!

The Proud Supporter Program welcomes those who have given to The Foundation, are passionate about its’ mission and have a desire to help.

What does a Proud Supporter do? PROUD SUPPORTER • Supports financially • Educates others about The Foundation’s mission and its work • Advocates and encourages others to get involved and support The Foundation • Supports The Foundation campaigns, events and programs as an advocate and participant • Promotes the brand • Assists in other ways

Learn more or join The Foundation Proud Supporter Program at foundationforthehorse.org/support/proud-supporter.

Dr. Tom Riddle authors book on veterinary career The Foundation for the Horse among beneficiaries of proceeds

Rood and Riddle Equine Hospital co-founder and longtime chair of the AAEP’s Professional Conduct & Ethics Committee Dr. Tom Riddle has added “author” to his distinguished resume following release of his first book The Riddle Half (of Rood and Riddle).

Including stories from his childhood and career, Dr. Riddle recounts with humility and pride his role in establishing and building the venerable practice with Dr. Bill Rood. Rood & Riddle began as an ambulatory practice in Lexington, Ky., in 1982 and established a full- service equine hospital in 1986. The practice now includes satellite hospitals in Saratoga Springs, N.Y. and Wellington, Fla.

All profits from the sale of The Riddle Half (of Rood and Riddle) will benefit The Foundation for the Horse and the Theriogenology Foundation.

The book is available for purchase from Rood & Riddle Veterinary Pharmacy at (859) 246-0112 or rrvp.com.

EVENewsINSERT_12-20.indd 11 12/1/20 11:51 AM XII AAEP News December 2020 INDUSTRY

AAEP Educational Partner Profile: Boehringer Ingelheim

About the equine business of Boehringer Ingelheim As the global leader in equine health, Boehringer Ingelheim’s main goal is to improve equine patients’ health and quality of life. We are dedicated to providing the latest product technology for the treatment and prevention of disease in horses. Learn more about our product portfolio and what we can offer the veterinary community by visiting bivetmedica.com/species/equine.html.

About Boehringer Ingelheim Animal Health USA, Inc. Boehringer Ingelheim is the second largest animal health business in the world, with net sales of almost $4.7 billion (3.9 billion euros) worldwide in 2018, about 10,000 employees and a presence in more than 150 markets. We have pioneered advancements in vaccines, parasite-control products and therapeutics that limit pain and slow disease, and we aim to create the future of animal wellbeing for pets, horses and livestock by focusing on prevention. Learn more at boehringer-ingelheim.us, facebook.com/BoehringerAHUS or twitter.com/Boehringer_AH.

About Boehringer Ingelheim Improving the health of humans and animals is the goal of the research-driven pharmaceutical company Boehringer Ingelheim. The focus in doing so is on diseases for which no satisfactory treatment option exists to date. The company therefore concentrates on developing innovative therapies that can extend patients’ lives. In animal health, Boehringer Ingelheim stands for advanced prevention.

Family-owned since it was established in 1885, Boehringer Ingelheim is one of the pharmaceutical industry’s top 20 companies. Some 50,000 employees create value through innovation daily for the three business areas: human pharmaceuticals, animal health and biopharmaceuticals. In 2018, Boehringer Ingelheim achieved net sales of around $20.7 billion (17.5 billion euros). R&D expenditure of about $3.8 billion (3.2 billion euros), corresponded to 18.1% of net sales.

As a family-owned company, Boehringer Ingelheim plans in generations and focuses on long-term success. The company therefore aims at organic growth from its own resources with simultaneous openness to partnerships and strategic alliances in research. In everything it does, Boehringer Ingelheim naturally adopts responsibility towards mankind and the environment.

More information about Boehringer Ingelheim can be found onboehringer-ingelheim.com or in the company’s annual report at http://annualreport.boehringer-ingelheim.com.

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618 EQUINE VETERINARY EDUCATION Equine vet. Educ. (2020) 32 (12) 618-619 doi: 10.1111/eve.13401

Highlights of recent clinically relevant papers

Blood sampling in foals phenylbutazone and omeprazole in horses, especially with a concurrent change in management. This study by Chiara Del Prete and colleagues in Italy compared venous blood gas parameters from samples collected by a push-pull technique through a jugular Computer-assisted orthopaedic surgery catheter with those sampled by direct jugular venipuncture in In this retrospective study Mathieu de Preux and colleagues 17 hospitalised foals. in Switzerland described clinical applications of computer- Three different techniques for drawing a blood sample assisted orthopaedic surgery (CAOS) in horses with a from a catheter are described: the discard, the reinfusion, navigation system coupled with a cone beam computed and the push-pull methods. The push-pull technique avoids tomography unit. the loss of blood associated with the discard method and A search of medical records for horses that underwent reduces the risk of contamination associated with the CAOS between 2016 and 2019 identified 13 adult horses. reinfusion method. Data including signalment, diagnosis, lameness grade prior to A 10 mL syringe was used to aspirate a volume of blood surgery, surgical technique and complications, anaesthesia equal to three times the dead space volume of a 16 gauge and surgery time, and perioperative case management and catheter and extension set (total 2.4 mL). This was immediately outcome were retrieved. reinfused into the vein without disconnecting the syringe. This Surgical implants were placed in the proximal phalanx, procedure was repeated three times before connecting a third metatarsal bone, ulna, or medial femoral condyle in 10 1 mL heparinised syringe to collect venous blood. A 20 gauge cases. Navigated transarticular drilling was performed to 1-inch needle and 1 mL syringe were used to obtain a blood promote ankylosis of the distal tarsal joints in one case. An sample from the contralateral jugular vein. There was a high articular fragment of the middle phalanx was removed with level of agreement between the results obtained by the two CAOS guidance in one case. A focal osteolytic lesion of the sampling methods at both 0 and 24 h for almost all parameters calcaneal tuber was curetted with the aid of CAOS in the except haematocrit and PVO values. final case. A purpose-built frame was used for the surgical The push-pull technique is an acceptable method for procedure in seven cases. All surgeries were performed obtaining blood samples for venous blood gas analysis in successfully and according to the preoperative plan. foals and avoids repeated needle sticks. A manual PCV Computer-assisted orthopaedic surgery can be an should be performed in place of haematocrit measurement. integral part of the clinical case management in equine surgery. Once equine surgeons have become familiar with Phenylbutazone and gastric ulcers the operational principles, CAOS can be readily applied for a This experimental study by Megan Ricord and colleagues at broad spectrum of indications. Louisiana State University, USA, evaluated the effect of omeprazole on phenylbutazone-induced equine gastric ulcer Endotoxaemia in donkeys syndrome (EGUS) in adult horses. Twenty-two horses with equine glandular gastric disease This study by Francisco Javier Mendoza Garcia and (EGGD) and equine squamous gastric disease (ESGD) colleagues in Spain examined the pathophysiology and gene scores ≤2 were divided into three groups: PBZ group (8 expression associated with experimentally induced horses) received 4.4 mg/kg of oral phenylbutazone every endotoxaemia, and evaluated the effects of meloxicam on 12 h; PBZ/OME group received the same phenylbutazone endotoxaemia in donkeys and in equine monocyte cultures. dose plus 4 mg/kg of oral omeprazole every 24 h (8 horses); Endotoxaemia was induced in six healthy adult female and the control group (CON) consisted of six horses. Horses donkeys by an i.v. infusion of lipopolysaccharide (LPS) for were treated for up to 14 days and gastroscopy was 30 min. Animals received either 20 mL of saline or 0.6 mg/kg performed every 7 days. A CBC was performed at the of meloxicam i.v. after LPS infusion. Blood samples were beginning and end of the study period. Five horses did not collected serially for haematology, serum biochemistry, complete the trial due to intestinal complications (3 PBZ/OME interleukin measurement, and leukocyte gene expression and 2 PBZ). analysis. Monocyte cultures were used to test the effects of Median EGGD score increased in the PBZ group compared meloxicam on LPS-activated monocytes. to the PBZ/OME group over the study period. No difference Lipopolysaccharide induced fever, leukopenia, and was seen in ESGD scores between the two groups. Serum neutropenia of similar magnitude in both groups, but albumin concentration decreased in the PBZ group compared meloxicam attenuated increases in plasma lactate, tumour to the CON group over the course of the study. There was no necrosis factor-alpha (TNFa), and interleukin 1b concentrations significant difference in albumin concentration between the compared to controls. No differences were detected between PBZ/OME and the CON groups. In the PBZ/OME group, 6/8 groups for cytokine mRNA expression. Furthermore, meloxicam horses developed intestinal complications, compared to 2/8 in decreased TNFa release in LPS-activated monocyte cultures. the PBZ group and 0/6 in the CON group. These complications Meloxicam could be a feasible option for the treatment were fatal in two of the horses in the PBZ/OME group. of endotoxaemia and SIRS in donkeys. Additional studies are Although concurrent omeprazole reduced the severity of necessary to investigate possible meloxicam-related post- EGGD, caution should be exercised when co-prescribing transcriptional regulation and to compare this drug with other

nonsteroidal anti-inflammatory drugs (NSAIDs) in animals with A total of 29 horses in two groups were vaccinated. endotoxaemia. Group 1 consisted of 18 horses which were further divided into nine subgroups of two horses. These horses were NSAIDs after castration individually immunised with one of 1 to 9 AHS serotypes. Group 2 consisted of 11 horses that were immunised with all This study by Francielli Gobbi and colleagues in Brazil nine serotypes simultaneously with two different vaccinations, evaluated and compared the efficacy of flunixin meglumine one containing serotypes 1, 4, 7, 8 and 9, and the other (FM), firocoxib (FX), and meloxicam (MX) after castration of containing serotypes 2, 3, 5 and 6. The duration of this study horses. was 12 months. Blood samples were periodically withdrawn Thirty horses undergoing open castration were divided for serum antibody tests using ELISA and VNT and for 2 weeks into three groups (n = 10) depending on the anti- after each vaccination for PCR and virus isolation. inflammatory drug administered: Group I (FM, 1.1 mg/kg bwt, After the booster vaccination, 27 horses seroconverted; i.v., once a day for 5 days); Group II (FX, 0.1 mg/kg bwt, i.v., however, two horses responded poorly as measured by ELISA. once a day for 5 days), and Group III (MX, 0.6 mg/kg bwt, In Group 1 ELISA and VN antibodies declined between 5– i.v., once a day for 5 days). Clinical, behavioural, and 7 months post-vaccination. After 12 months the antibody levels haematological parameters and the peritoneal fluid (PF) in most of the horses decreased to the seronegative range until were evaluated before and 1, 2, 3, 5, and 7 days after the annual booster where all horses again seroconverted castration. strongly. In Group 2, ELISA antibodies were positive after the first Post-operatively, scores of limb rigidity and prepuce booster and VN antibodies started to appear for some oedema in Groups II and III were greater than those of Group serotypes after primary vaccination. After booster vaccination, I. Tachycardia was observed in Groups II and III and VN antibodies increased in a different pattern for each hyperthermia in Group III. An increase in the number of serotype. Antibodies remained high for 12 months and leukocytes, neutrophils, and monocytes, below the reference increased strongly after the annual booster in 78% of the horses. values, and hyperfibrinogenaemia was observed in Groups I PCR and virus isolation results remained negative. (Day 7), Group II (Days 1-7), and Group III (Day 7). Serum These results indicated that horses vaccinated with single protein was reduced after castration, together with an serotypes need a booster after 6 months and simultaneously increase of this in the PF of all three groups. The PF on Day 0 immunised horses after 12 months. No challenge infection was straw yellow and limpid, became reddish and cloudy on could be carried out as facilities were not available. Day 1, then gradually moved toward its normal colour without returning to normal on Day 7 in any of the groups. S. WRIGHT Castration triggers significant clinical and laboratory EVE Editorial Office changes and FM, FX, and MX are equally effective in controlling pain and inflammation in horses after castration; however, FM was more advantageous. References Knotless barbed sutures Adler, D.M.T., Østergaard, S., Jørgensen, E. and Jacobsen, S. (2020) Bidirectional knotless barbed versus conventional smooth suture for This study by Ditte Marie Top Adler and colleagues in closure of surgical wounds in inguinal castration in horses. BMC Denmark compared a bidirectional absorbable knotless Vet. Res. 16, 250. barbed suture (KBS) with a conventional smooth suture (SS) Del Prete, C., Lanci, A., Cocchia, N., Freccero, F., Di Maio, C., for closure of inguinal castration surgical wounds in the horse. Castagnetti, C., Mariella, J. and Micieli, F. (2020) Venous blood gas Bilateral inguinal castration was performed on 45 horses parameters, electrolytes, glucose and lactate concentration in sick neonatal foals: direct venipuncture versus push-pull technique. (21 KBS and 24 SS). Suturing time as well as the short-term and Equine Vet. J. Epub ahead of print; https:// post-discharge complications were evaluated. beva.onlinelibrary.wiley.com/doi/abs/10.1111/evj.13332 At 24 h minor swelling occurred in 29% of KBS horses and Gobbi, F.P., Di Filippo, P.A., de Macedo^ Mello, L., Lemos, G.B., Martins, 33% of SS horses. Cutaneous dehiscence during recovery C.B., Albernaz, A.P. and Quirino, C.R. (2020) Effects of flunixin occurred in two horses of each group. Post-discharge meglumine, firocoxib, and meloxicam in equines after castration. complications ocurred in three horses (scrotal swelling (KBS); J. Equine Vet. Sci. 94, 103229. wound exudation (SS) and wound dehiscence after return to Mendoza Garcia, F.J., Gonzalez-De Cara, C., Aguilera-Aguilera, R., pasture (SS)). Wound closure was achieved 6 min faster with Buzon-Cuevas, A. and Perez-Ecija, A. (2020) Meloxicam ameliorates the systemic inflammatory response syndrome KBS than with SS. associated with experimentally induced endotoxemia in adult Use of the KBS suture did not result in increased donkeys. J. Vet. Intern. Med. 34, 1631–1641. occurrence of post-operative complications. Wound closure de Preux, M., Klopfenstein Bregger, M.D., Brunisholz,€ H.P., Van der Vekens, was faster with KBS than with SS in equine bilateral inguinal E., Schweizer-Gorgas, D. and Koch, C. (2020) Clinical use of computer- castration. These results show that KBS can safely be used in assisted orthopedic surgery in horses. Vet Surg. 49,1075–1087. the horse following bilateral inguinal castrations without Ricord, M., Andrews, F.M., Yniguez,~ F.J.M., Keowen, M., Garza, F. Jr, adverse effects and with a reduction in suturing time. Paul, L., Chapman, A. and Banse, H.E. (2020) Impact of concurrent treatment with omeprazole on phenylbutazone- induced equine gastric ulcer syndrome (EGUS). Equine Vet. J. African horse sickness vaccination Epub ahead of print; https://beva.onlinelibrary.wiley.com/doi/abs/ 10.1111/evj.13323 ı In this study Marina Rodr guez and colleagues in Dubai Rodrıguez, M., Joseph, S., Pfeffer, M., Raghavan, R. and Wernery, U. evaulated the immune response of horses to inactivated (2020) Immune response of horses to inactivated African horse African horse sickness (AHS) vaccines. sickness vaccines. BMC Vet. Res. 16, 322.

Case Report Sarcocystis myositis and vitamin E deﬁciency in a Gypsy Vanner stallion suspected of having equine motor neuron disease A. C. Trimble†* , K. M. Delph†, E. R. Perry† and S. J. Valberg‡ †Kansas State University Veterinary Health Center, Manhattan, Kansas; and ‡Michigan State University Diagnostic Center for Population and Animal Health, Lansing, Michigan, USA

*Corresponding author email: [email protected]

Keywords: horse; sarcocystosis; Sarcocystis fayeri; musculoskeletal; EMND

Summary A 3-year-old Gypsy Vanner stallion was presented for evaluation of intermittent recumbency, muscle fasciculations, weakness, low head carriage, shifting of weight between the hindlimbs and an elevated tail head post breeding accident (Fig 1). Initial diagnostics revealed leukocytosis characterised by a mature neutrophilia, mild anaemia, mild hypoalbuminaemia, hyperglobulinaemia, hyperphosphataemia, hypochloraemia, elevated anion gap and elevated muscle enzymes. Serum a- tocopherol concentrations (results not available until Day 6 of hospitalisation) were critically low at 0.9 lg/mL (r.r. 2–4). History, physical examination and serum a-tocopherol concentrations were highly suggestive of vitamin E deficiency and equine motor neuron disease (EMND), and a-tocopherol therapy was initiated. Sacrocaudalis dorsalis medialis muscle biopsy (obtained on Day 4 of hospitalisation) results were not available Fig 2: High magnification of a thick-walled (vertical arrow) until Day 16 after presentation. Prominent mononuclear and sarcocyst containing merozoites typical of S. fayeri and rare polymorphonuclear cells surrounding and invading surrounded by mononuclear cells (horizontal arrow) PAS 403. myofibres were evident in the biopsy. Numerous sarcocysts that resembled Sarcocystis fayeri were present both within and separate from areas of inflammation (Fig 2). Muscle fibre sizes repeat muscle biopsy 6 months later. Four other horses on the were generally decreased but there were no angular atrophied property also had evidence of anaemia and low serum vitamin fibres that would be indicative of neurogenic atrophy and E levels and were serially monitored for the development of EMND. Thus, the confirmed diagnosis was severe myositis similar clinical signs of sarcocystosis. This case illustrates the secondary to sarcocystosis and vitamin E deficiency. Aggressive importance of muscle biopsy in horses with neuromuscular treatment with a-tocopherol, ponazuril (6 weeks duration) and disease, as concurrent diseases may be present that require sulfadiazine/pyrimethamine (4 months duration) resulted in specific treatment for a positive outcome. significant improvement in muscle weakness and body condition, with resolution of sarcocystosis and inflammation on Key points

• Symmetric muscle atrophy, weakness, and critically low serum a-tocopherol are highly suggestive of vitamin E deficiency-related disorders such as EMND, but muscle histopathology is necessary to make a definitive diagnosis. • The concomitant presence of both a large number of sarcocysts and mononuclear and polymorphonuclear cell infiltrates in the sacrocaudalis muscle of the horse is suggestive of sarcocystis myositis being a concurrent, if not primary, underlying cause of muscle pain, weakness and malaise. • Diagnosis and resolution of such clinical cases is best achieved by assessing a-tocopherol status, evaluation of sacrocaudalis muscle histopathology and aggressive, combined, long-term therapy.

Fig 1: Body condition in July at presentation.

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BRIEF SUMMARY: Prior to use please consult the product insert, a summary of which follows: CAUTION: Federal law restricts this drug to use by or on the order of a licensed veterinarian. INDICATIONS: Adequan® i.m. is recommended for the intramuscular treatment of non-infectious degenerative and/or traumatic joint dysfunction and associated lameness of the carpal and hock joints in horses. CONTRAINDICATIONS: There are no known contraindications to the use of intramuscular Polysulfated Glycosaminoglycan. WARNINGS: Do not use in horses intended for human consumption. Not for use in humans. Keep this and all medications out of the reach of children. PRECAUTIONS: The safe use of Adequan® i.m. in horses used for breeding purposes, during pregnancy, or in lactating mares has not been evaluated. For customer care, or to obtain product information, visit www.adequan.com. To report an adverse event please contact American Regent, Inc. at (800) 734-9236 or email [email protected]. Please see Full Prescribing Information at www.adequan.com.

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1 Data on file. 2 Adequan® i.m. Package Insert, Rev 1/19. 3 Burba DJ, Collier MA, DeBault LE, Hanson-Painton O, Thompson HC, Holder CL: In vivo kinetic study on uptake and distribution of intramuscular tritium-labeled polysulfated glycosaminoglycan in equine body fluid compartments and articular cartilage in an osteochondral defect model.J Equine Vet Sci 1993; 13: 696-703. 4 Kim DY, Taylor HW, Moore RM, Paulsen DB, Cho DY. Articular chondrocyte apoptosis in equine osteoarthritis. The Veterinary Journal 2003; 166: 52-57. 5 McIlwraith CW, Frisbie DD, Kawcak CE, van Weeren PR. Joint Disease in the Horse.St. Louis, MO: Elsevier, 2016; 33-48. All trademarks are the property of American Regent, Inc. © 2020, American Regent, Inc. PP-AI-US-0372 02/2020 EQUINE VETERINARY EDUCATION 621 Equine vet. Educ. (2020) 32 (12) 621 doi: 10.1111/eve.13148_1

Case Report Pleomorphic sarcoma with giant cells inﬁltrating the infraorbital canal in an aged Thoroughbred mare G. L. Elane*† , E. M. Corbin‡, L. Reig† and J. A. Brown† †Marion DuPont Scott Equine Medical Center, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic and State University, Leesburg, Virginia; and ‡The Joint Pathology Center, Silver Spring, Maryland, USA

*Corresponding author email: [email protected]

Keywords: horse; sarcoma; neoplasia; giant cells; infraorbital canal

Summary Deviation and lysis of the infraorbital canal was evident from the maxillary foramen to the infraorbital foramen, with A 27-year-old Thoroughbred mare presented for computed extensive lysis of the maxilla, alveolar bone and facial crest. tomography (CT) of the head following a 4-year history of Bony lysis was present in the ventral nasal concha, left nasal sensitivity, pruritis and rubbing the left side of the face. Three bone and left side of the hard palate. Soft tissue swelling was months prior to presentation, swelling at the infraorbital present lateral to the infraorbital foramen; no evidence of foramen developed, and the mare began to self-mutilate lysis or soft tissue expansion was evident surrounding the optic the area and head-shake. Referral radiographs showed chiasm, or the orbital fissure containing the oculomotor, extensive lysis of the left maxilla and both compartments of trochlear, abducens or ophthalmic nerves. These findings the left maxillary sinus; however, both infraorbital canals were suggestive of left maxillary neoplasia with extensive lysis, appeared normal. Temporary improvement was seen consistent with soft tissue sarcoma, fibrosarcoma or following oral doxycycline and topical steroid application. chondrosarcoma. On presentation, the mare was bright and alert, in fair The mare was euthanised, and a post-mortem body condition (BCS 4/9), with moderate hirsutism and poor examination revealed a proliferative tan soft tissue mass coat quality. Physical examination revealed left masseter and overlying the infraorbital nerve (Fig 1b). The mass was easily temporalis atrophy, submandibular lymph node enlargement, separated from the infraorbital nerve and did not appear to hypotonia of the left dorsal palpebrum, enophthalmos and infiltrate the nerve on gross examination. A histopathologic an absent menace response. Moderate left-sided facial diagnosis of pleomorphic sarcoma with giant cells was nerve paralysis and multiple superficial abrasions were made. Immunohistochemical analysis failed to fully elucidate present on the left facial crest and medial canthus. the mesenchymal cell of origin of the sarcoma. Pleomorphic CT imaging showed soft tissue attenuation within the left sarcoma with giant cells involving the infraorbital canal of maxillary sinuses, involving the infraorbital canal (Fig 1a). the horse has not been previously described. While inflammation of the infraorbital canal has been associated with head-shaking and self-mutilation, the unusual histomorphologic characteristics of this sarcoma with marked pleomorphism and giant cells make this case unique. This case highlights chronic subtle behavioural changes attributable to this neoplasm prior to development of overt clinical signs and the utility of advanced imaging in the diagnosis.

a) b) Key points Fig 1: a) Coronal CT image of the skull. Note the soft tissue- • Pleomorphic sarcoma with giant cells inﬁltrating the attenuating material within the left rostral and caudal maxillary infraorbital canal was diagnosed in an aged sinuses (red arrow) centered around the infraorbital canal with Thoroughbred mare. concurrent deviation and lysis of the maxilla, alveolar bone and • Standing CT was found to be superior to radiography facial crest. b) Post-mortem examination. The skull is sectioned in identifying the extent of the neoplasm. rostroventrally at the level of the infraorbital canal caudodorsally • through the turbinates and sinuses. Note the irregular and Subtle clinical signs (head-shaking, pruritis, facial thickened mucosa in the left caudal maxillary sinus with small, sensitivity) should be investigated early, and neoplasia tan-yellow, circular growths (black arrow). Left is to the right of should be considered as a differential diagnosis. the image, rostral is at the bottom.

Case Report Haemoperitoneum secondary to testicular rupture caused by blunt trauma in a stallion Y. da Silva Bonacin* , S. dos Santos Sousa, P. A. Canola, D. da Gracßa Macoris, G. M. Bueno, D. J. de Queiroz and J. A. Marques Department of Veterinary Clinic and Surgery, School of Agricultural and Veterinarian Sciences, Sao~ Paulo State University (UNESP), Jaboticabal, Brazil *Corresponding author email: [email protected]

Keywords: horse; pain; reproduction; scrotum; testis

Summary identified over the right internal inguinal ring. Peritoneal fluid, collected as part of the colic emergency protocol, was A 13-year-old American Quarter Horse stallion presented at the serosanguinous, and the laboratory analysis results were veterinary hospital with a 6-h clinical history of abdominal consistent with a haemoperitoneum. Testicular ultrasonography discomfort, after being kept with a mare for breeding failed to reveal any abnormalities of the testicular purposes. On physical examination, the stallion showed signs parenchyma. Based on clinical and laboratorial findings and of abdominal discomfort. Conjunctival and oral mucous suspicion of inguinoscrotal herniation, the patient was referred membranes were slightly hyperaemic with a capillary refill time for exploratory celiotomy. Further analysis of the images of 3 s. There was no spontaneous reflux on nasogastric obtained from the ultrasound showed a large intra-testicular intubation. On visual inspection, the right testicle was retracted haematoma over the right testicle. Exploration of the in relation to the contralateral but no external wound was abdominal cavity revealed haemoperitoneum with normal visible. During palpation, the right side of the scrotum was cold anatomical positioning of the viscera and no signs of intestinal to the touch and the anatomical structures could not be incarceration through the right internal inguinal ring. A second identified due to its firm consistency. The patient exhibited incision over the right testicle revealed an extensive severe discomfort on palpation. Intravenous sedation was haematocele within the vaginal tunic, which was incised, given, and 15 min after, the patient was painful again. showing a longitudinal rupture through the testicular Transrectal palpation was performed, and a structure that parenchyma (Fig 1). Unilateral orchiectomy was performed, could not be differentiated from an intestinal segment was and the midline incision was closed. Clinical signs of abdominal discomfort were not perceived during the post- operative period, and the horse was discharged on day 10. The owner did not express any interest in performing a reproductive examination, but at clinical follow-up after 3monthsprovidedfeedbackregardingthestatusofthe patient, with mention of him returning to breeding and sport activities. The rapid surgical intervention permitted unilateral orchiectomy, thus hopefully preserving functionality of the contralateral testicle.

Key points

• Extensive testicular trauma can cause acute haemoperitoneum that needs to be differentiated from intestinal infarction cases, which present with similar clinical signs. • The infarcted spermatic cord may be difﬁcult to differentiate from an incarcerated segment of bowel in the internal inguinal ring, during transrectal palpation; however, the ultrasonography can help with diagnosis. • Testicle rupture diagnosis and rapid surgical intervention permitted unilateral orchiectomy, preserving functionality of the contralateral testicle. Fig 1: Longitudinal rupture of the testicular parenchyma at surgery.

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Case Report Chronic lameness caused by vascular compression of the iliac artery and vein by a malignant melanoma in the pelvis of a grey Spanish gelding A. Van Ongeval†‡, N. van de Velde§, E. Raes¶ and M. Oosterlinck†* †Department of Surgery and Anaesthesiology of Domestic Animals, Faculty of Veterinary Medicine, Ghent University; ‡Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University; §Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University; and ¶Department of Veterinary Medical Imaging and Small Animal Orthopaedics, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium

*Corresponding author email: [email protected]

Keywords: horse; melanoma; lameness; neoplasia; orthopaedics

Summary An 11-year-old grey Spanish gelding was presented with chronic right hind lameness with abduction of the limb during the swing phase, and several small multifocal, black nodules at the base of the tail, the preputium and the penis. Diagnostic analgesia including perineural and intra-articular blocks up to the stifle was negative. Rectal palpation revealed a small mass (2 9 3 cm) at the level of the lumbosacral region. Ultrasonographically (Esaote MyLab Class C with a rectal probe of 5.5–7.5 MHz), the mass presented a heterogeneous, hyperechoic echogenicity and measured approximately 2– 3 cm in thickness. There was no clear delineation between the mass and the wall of the iliac vein. The bone surfaces appeared intact. The mass displaced the aorta and the external and internal iliac arteries. Moreover, the internal iliac artery seemed interrupted or at least deviated where it came in contact with the mass at the level of the mid-ventral aspect of the sixth lumbar vertebra. Doppler imaging (5.6 MHz) showed Fig 1: Macroscopic view of the multinodular, infiltrative, turbulences in the internal iliac artery just cranial to the mass. nonencapsulated, black-pigmented mass surrounding the iliac Post-mortem examination revealed a poorly demarcated vein and artery, with multinodular masses bulging into the lumen black mass (approximately 1 kg; 20 9 15 9 10 cm) at the of the vein (asterisk). cranial part of the right ilium, close to the iliac vein and artery. Additionally, there were multinodular infiltrative, and multifocal melanomas at various other locations, resulted nonencapsulated intramural black masses of approximately 4 x in a melanoma being considered most likely. Rectal palpation 3 cm, bulging into the lumen of the iliac vein (Fig 1). The severely underestimated the size of the mass (2 9 3cmvs. surrounding lymph nodes were swollen and contained black 20 9 15 9 10 cm on post-mortem examination). pigmentation. Histological examination of the mass close to the iliac vein confirmed the presumptive diagnosis of a melanoma. In contrast with the fact that melanomas are frequently Key points diagnosed in daily veterinary practice, lameness associated • Intra-pelvic malignant melanoma is a rare cause of with this neoplasm has been reported infrequently. The chronic, progressive lameness, and should be considered vascular compression and infiltrative growth of the melanoma especially in grey, middle-aged horses with melanomas in the iliac vessels may have resulted in decreased muscular at other locations, when other causes of lameness have perfusion of the hind limb, with secondary ischaemia, pain and been excluded using diagnostic analgesia. lameness. It cannot be excluded that the mass also resulted in • Vascular compression and infiltrative growth of the compression of nerves (e.g. femoral nerve), or periosteum, melanoma in the iliac vessels may result in ischaemia, which could also have caused lameness. The main differential pain and lameness. diagnoses were intra-vascular infiltrative growth of a melanoma • The size of the mass may be underestimated by rectal or another neoplastic mass, intra-vascular thrombosis, or less palpation. probably haematoma formation or abscessation. The chronic, progressive lameness in the absence of fever or weight loss,

Clinical Commentary Melanocytic tumours in horses K. E. Sullins* Midwestern University College of Veterinary Medicine, Glendale, Arizona, USA

*Corresponding author email: [email protected]

Keywords: horse; melanocytic tumour; excision; chemotherapy; malignant

Most grey horses will develop at least one melanocytic fortunately uncommon tumours usually affect ageing non- tumour if they live long enough (McFadyean 1933). grey horses. Pigmentation is variable and they are often not Histopathology and clinical features define three or four black at all. Reports and the author’s experience indicate the clinical types (depending upon source) of melanocytic tail and tail head to be sites predilection (Fig 1a; Valentine tumours (Valentine 1995; Knottenbelt et al. 2015b). Whiter or 1995; Knottenbelt et al. 2015b). Isolated skin lesions can lighter grey horses seem to be more susceptible, while darker respond to wide excision (Knottenbelt et al. 2015a) but grey, dappled or flea-bitten grey horses tend to be less typical lesions subjectively seem to have metastasised by the affected. time of diagnosis and are almost universally fatal (Fig 1b). Valentine reported a series of 29 melanocytic nevi Separating reports of these tumours in the literature from (Valentine 1995). Horses of all colours with a mean age of metastatic/malignant-behaving dermal melanoma/ 5 years were affected by solitary masses in a variety of sites. melanomatosis can be a challenge. Histologically, the pigmented masses are located at the Veterinarians worldwide daily face treating hundreds of dermoepidermal junction (Valentine 1995). Excision was horses with dermal melanoma/melanomatosis. For these generally curative. Foley et al. (1991) described 18 horses with tumours, this author has struggled with the terms ‘malignant’ occurrences before 2 years of age with similar outcomes. and ‘metastatic’. The term benign describes a histologically Dermal melanoma and dermal melanomatosis are well-differentiated cell type that is not prone to invasion of histologically identical in that the pigmented masses are surrounding tissue or distant metastasis. The term malignant located in the deep dermis (Valentine 1995). Isolated single or describes a less differentiated (more anaplastic) cell type multiple discrete lesions are termed dermal melanoma, that is prone to invasion of surrounding tissue, post-operative whereas multiple coalescing lesions are considered dermal recurrence and distant metastasis (Knottenbelt et al. 2015c). melanomatosis. Dermal melanoma is generally seen in Metastatic tumour typically has a primary source. So, with younger mature horses, while dermal melanomatosis was multifocal/disseminated melanoma, which (of the possibly found in horses over 15 years old in one series (Valentine 1995). many sites) was the primary location? Should it follow that all Some (including this author) consider the two presentations as distant/internal foci are evidence of malignancy? Size has stages of a single type (Moore et al. 2013; Knottenbelt et al. been related to malignancy. One report stated that benign 2015b). Isolated lesions may occur in more variable sites, but melanomas were generally <4 cm in diameter (Valentine both types are heavily pigmented masses with predilections for 1995). Another proposed that all dermal melanomas be tail, perineum, perianus, vulva, dorsal prepuce, commissures of labelled ‘equine malignant melanoma’ and staged (1–4) by the lips and parotid salivary gland. Subjectively, these factoring size, number, rate of growth and the presence of favoured sites seem to facilitate larger or multiple growth into distant lesions. Lesions >4 cm in diameter were defined as dermal melanomatosis. Older horses with dermal stage 4 equine malignant melanoma (Moore et al. 2013). melanomatosis are more likely to have distant or internal Many sources would consider nondermal internal metastases (Valentine 1995) which makes sense since time melanocytic masses metastatic and/or malignant by their would allow more opportunity for spread. However, location and behaviour (MacGillivray et al. 2002; Moore et al. melanocytic tumours have been reported in almost every 2013). Approximately 22 of 38 resected melanocytic tumours external and internal location in horses. In this issue, an internal 4–20 cm in diameter were nondermal deeper (parotid, pelvic melanoma dispersed itself around the iliac artery and cervical, thoracic inlet, perirectal) masses, but none recurred invaded the iliac vein resulting in hindlimb lameness (Van and no systemic growth acceleration followed (Groom and Ongeval et al. 2020). Anecdotally, the author has also Sullins 2018). So, is it possible to have ‘benign’ metastases? observed hindlimb lameness due to diffuse proximal perineural Because surgery or other treatments successfully address so impingement by melanocytic tumours. Smaller lesions typically many lesions, this author opposes labelling dermal cause no clinical signs. Larger tumours may obstruct the melanoma/melanomatosis as malignant unless histologically rectum or prepuce and parotid melanomas can limit neck proven (Groom and Sullins 2018). flexion or impinge upon the upper airway (Moore et al. 2013; Compelling evidence for a ‘primary’ source for distant Groom and Sullins 2018). Necrosis of the tumour and the metastases is an unpublished long-term prospective study overlying skin may result in substantial open wounds with a comparing surgical excision of dermal melanomas upon tarry black discharge and bleeding (Moore et al. 2013). discovery to leaving them alone. Of thirty-five 2- to 4-year-old Anaplastic malignant melanoma presents a completely light grey horses, 30 underwent surgical removal of every different clinical picture and possibly should not be included detectible dermal melanoma as it appeared until age 22. in discussion of the previous melanocytic tumours. These Eighteen horses reached age 22 with the others succumbing

a) et al. 2013). Further, this and other evidence (Groom and Sullins 2018) should dispel the notion that removal of dermal melanoma/melanomatosis activates the tumour process (Frank 1959). Excision has been reported to be curative for melanocytic nevi and small dermal melanomas but is a controversial option for larger tumours (Valentine 1995). Some have suggested that surgical excision of large tumours is not possible (Moore et al. 2013; Phillips and Lembcke 2013). For amenable cases, this author considers resection of individual tumours to be definitive and the process is over sooner than some other less invasive procedures. Thirty-eight horses underwent resection of superficial and deep melanocytic lesions 4–20 cm in diameter with no recurrence or new local growth for a mean of 39-month follow-up period (Groom and Sullins 2018). Some authors would have considered some of those lesions inoperable. Case selection for resection of tumours is important. Rate of tumour growth and horse’s age are important b) considerations in that (for example) a 10-cm tail base/ perianal tumour with additional internal perirectal masses may be left alone in a 20-year-old horse whereas surgery becomes more advisable for a 10-year-old horse due to potential growth and complications throughout the horse’s remaining lifetime. Proximity to critical anatomic structures and extensive necrosis or ulceration also factor into the decision-making process. External lesions would usually be dermal melanomatosis, whereas internal lesions would be considered metastatic melanomas from one of the external ‘primary’ locations. However, solitary deeper lesions do occur (Groom and Sullins 2018). Histology is not predictive of tumour dissemination (MacGillivray et al. 2002), and it is generally accepted that the diagnosis of melanocytic tumours in horses can be reliably made from gross appearance and signalment (Knottenbelt 2016). These tumours are usually located at the intradermal and/or (possibly deep) Fig 1: a) Anaplastic malignant melanoma (deep surface) subcutaneous level and have variably well-defined margins resected from the tail head of a chestnut horse. Tail amputation (Knottenbelt et al. 2015b). (perhaps a valid consideration) would have been required for General comment on surgical resection of a few specific deeper margins on this variably pigmented mass. Adjunctive types of melanomas may be useful. Perianal, perineal, local cisplatin and radiation therapy did not save this horse. b) perivaginal and ventral tail locations are the most common Necropsy specimen of caudal thoracic spine approximately 1.5 years after initial surgery and radiation. The horse returned to presentations in grey horses. Small dermal melanomas readily work but later presented with ataxia and was subjected to respond to complete removal by almost any means. Surgical euthanasia. Metastatic tumour is present in the vertebral body, excision of all the black tissue and simple wound spinal canal and surrounding soft tissue. management works. Black masses can be effectively and

completely ablated with a CO2 laser. Layer by layer ablation until the black tissue is removed is both precise and clean to unrelated conditions. None of the 18 had detectable (Fig 2a–d). evidence of melanocytic lesions, and none was destroyed for Deep perirectal spheroid tumours at approximately 10 reasons of melanoma. Four horses in the treatment group and 2 o’clock positions are common and are detected by that later died and underwent necropsy had no internal lifting the tail straight up thereby pulling them caudally melanocytic lesions. The untreated control group consisted of towards the skin, or rectal or ultrasound examination (Fig 3a). five horses whose owners had refused surgery on the belief Less common flatter lesions dorsal to the rectum more often that surgery would make the tumours worse. One died of an obstruct faecal passage. Particularly large perirectal masses unrelated cause while another developed dermal melanoma (such as those reaching the peritoneal reflection) may be and the owner insisted that it be removed. The three better left alone. These internal tumours are approached remaining unoperated horses were subjected to euthanasia directly or as extension of dissections of external lesions. between 15 and 20 years of age due to unacceptable Surgery in this area is always performed in the standing horse; melanoma growth (D. Knottenbelt, personal communication recumbency pushes viscera into the pelvic canal placing 2019). While larger numbers and more necropsies would have pressure on the dissection. Preoperative mineral oil or laxative improved the study, the consistent results bear consideration. diet is often helpful; with pain control, the tendency to retain Although the primary source lesion was still not strictly faeces usually passes within 1–3 days. Epidural analgesia may identified, the study supports reduction of tumour load and require local augmentation with local infiltration. Margins of illustrates significance of each dermal melanoma (Moore resection are planned and outlined during surgery. Dissection

a) c)

b) d)

Fig 2: a) A 1-cm dermal melanoma (arrow) on the ventral tail of a grey horse. b) Intraoperative image of the lesion in (a) undergoing

CO2 ablation. Margins have been established and the laser will work inward until all the black tissue is gone. c) Same horse shown in (b). The black pigment tissue is exposed and is in the process of being ablated. d) Same horse shown in (c). Post-operative image showing complete ablation of the melanoma. This one happens to have gone full thickness through the skin but not all penetrate that far. Be cognisant of the tail vein on the midline of the ventral tail. may need to be extensive. A carbon dioxide laser is useful in packed until they fill in. Phenylbutazone (2.2 mg/kg bwt per limiting haemorrhage as long as the target tissue is visible os b.i.d. 5–7 days) and turn out or exercise keep horses willing (Sullins 2012). Hand/finger or blunt or careful sharp scissor to defecate. Broad-spectrum oral antimicrobial is dissection should be used for the deeper less visible areas. administered until granulation tissue is established but, despite The rectum and larger pelvic vessels should be protected as the location, infection has not been problematic. Extensive dissection gets deeper; the rectum itself is very rarely preoperative client education is mandatory because diligent involved. Dorsal internal masses can be particularly tedious. nursing care is required. A tail wrap and meticulous fly control Resection of large masses leaves a sizeable wound often are advisable particularly where Habronema is a problem. with exposed rectum (Fig 3b and c). If the sphincter is absent, Petroleum jelly applied below the wounds protects the the rectal wall may require suturing to the surrounding normal skin from scalding by plasma exudate and faeces. subcutaneous fascia. Moderate to large wounds usually Even extensive wounds granulate, contract and epithelialise cannot be primarily sutured and often dehisce if they are. well (Fig 3d). These types of lesions are usually well Open wounds are lavaged daily. Deeper defects are demarcated and can be completely resected so adjunctive

a) c)

b) d)

Fig 3: a) Preoperative image of a horse with moderately large perianal dermal melanomatosis and deep perirectal tumours. b) Immediate post-operative image of horse in (a). The anal sphincter is gone so the rectum has been sutured to the exposed fascia. The deep defect at the 1 o'clock position has been packed. c) The melanomas removed from the perianal region of the horse in (a and b). The upper right and left masses were internal perirectal masses not connected to skin. d) Image of horse shown in (a–c) almost completely healed. chemotherapy is not usually applied. However, all visible glandular tissue making dissection challenging. However, black tissue should be removed. within reasonable size limits, good results usually follow. Quite large ventral tail lesions can be resected (Fig 4a Noticeable seroma/saliva accumulation may occur but this and b) but the author does not operate on cases where the resolves in a few weeks. The facial nerve exits adjacent to the tumour surrounds the entire tail where resection would leave more dorsal aspect of these masses and must be protected; no skin. Bandaging helps the post-operative care for these more ventral masses are simpler to operate. Most cases have lesions considerably. noticeable adjacent vascular wall black stains that are left Preputial lesions involve the dorsum almost universally. alone. No new growth has been observed in these sites after Size, growth potential and possible ulceration factor into the surgery (Groom and Sullins 2018). decision for surgery. A longitudinal fusiform dissection with Internal melanocytic tumours can appear almost horizontal closure usually preserves preputial patency (Fig 5a anywhere in the horse. An example is a horse with a series of and b). Uncommonly, a stricture may have to be revised so spheroid melanocytic tumours displacing the trachea (Fig 7a the penis can protrude; however, time usually resolves that and b). Margins were obvious to follow with combined blunt issue. and sharp dissection but the recurrent laryngeal nerve The commissures of the lips are a further preferred site for required protection. The wound was closed primarily with dermal melanoma/melanomatosis. Size and rate for growth Penrose drains. Cisplatin (cis-diamminedichloroplatinum) is a mainly determine the need for surgery. No matter how wide broad-spectrum alkylating antineoplastic drug used widely in the outer portion of the mass, the bases can usually be the local treatment of solid tumours in horses (Theon et al. 1 resected in a wedge shape. The CO2 laser noticeably 2007). Biodegradable cisplatin beads (1.6 mg cisplatin/ reduces haemorrhage and swelling. Buried absorbable bead) are preferred due to diffusion of the drug into sutures prevent the horse from worrying the area with its surrounding tissue, and they have a 1-month duration of tongue and they are eating hay the same day (Fig 6a–c). action. Melanocytic tumours are cisplatin sensitive but, Healing is invariably uneventful. Internal melanocytic tumours without debulking, visible response is usually slow. In one series present their own set of issues. Size and physical compression of horses, cisplatin beads were placed into tumour beds or distortion of adjacent structures are the most common when complete excision was not possible (assessed visually problems. Tumour invasion of adjacent tissues is relatively by presence of black tissue) or when other melanocytic uncommon. Parotid lesions are located within the salivary tumours were located close to the resection margins (Groom

a) a)

Fig 5: a) Preoperative example image of a moderately large dorsal preputial melanocytic tumour. b) One-month post- operative example of resection of a moderately large dorsal preputial melanocytic tumour. The transverse closure can still be seen.

surgically. Other chemotherapeutic agents including mitomycin C are worth investigation. Electrochemotherapy (EC) is becoming more widely available. This process couples the administration of a Fig 4: a) Preoperative image of a large, necrotic ventral tail dermal melanoma. Post-operative bandaging expedites wound chemotherapeutic agent (usually injectable cisplatin in oil) care in this location. b) Nine-month post-operative image of with the delivery of electric pulses having appropriate surgical site in (a). waveforms to increase the cellular uptake and the efficacy of the drug (electroporation) (Spugnini et al. 2011). Repeated general anaesthesia is required because the stimulation and Sullins 2018). Beads were placed at 1.5–2 cm intervals to causes seizure-like activity. Success has been observed provide adequate drug concentration across the lesion. (Spugnini et al. 2011). Reasonably, EC may be more efficient Intratumoural (injectable) cisplatin has been than cisplatin injections alone. However, comparison has not recommended as a series of four treatments at 2-week been made directly between cisplatin beads producing intervals, either with or without surgical debulking (Theon tissue levels for a month and requiring no general et al. 2007). Using this protocol, the reported cure rate for anaesthesia vs. biweekly EC treatments in anaesthetised equine melanomas was 81%. However, this author has not horses. observed consistent substantial reduction of large lesions Irreversible electroporation (IRE) is a yet experimental but implanted with cisplatin beads. Lesions amenable to monthly promising technique for the focal treatment of pathologic treatment with relatively few cisplatin beads may be tissues that involves placing minimally invasive electrodes effectively and economically addressed. However, within the targeted region. A series of short, intense electric amenable larger lesions are more efficiently addressed pulses are then applied to destabilise the cell membrane,

a) a)

b) b)

Fig 7: a) Intraoperative image showing resection of one of three spheroid internal melanocytic lesions that were compressing the trachea. The mass is held in a set of human obstetric head forceps. b) The series of three spheroid masses removed and arranged as they occurred along the trachea of the horse. The wound was sutured primarily with Penrose drains.

used. A recent case report of two grey horses with dermal melanomas describes tumour reduction of 52 and 99% following standing treatment (Byron 2019). Various topical or locally injectable substances have surfaced and have been submerged over the years. To date, no objective results have been published in refereed journals. This author’s opinion is that causing necrosis of a surface tumour producing an open c) wound is less efﬁcient and more trouble than surgically resecting amenable tumours. Tumours not amenable to surgery for a variety of reasons would typically be in a location where inducing necrosis would not be advisable in any case. Anecdotally, this author has used laser energy to raise the measurable temperature of surface melanocytic tumour to 50°C or slightly less where tissue is known to more or less quietly necrose (Hildebrandt et al. 2002). The tumour did necrose to the depth measured to have reached temperature. Much more work will be required to predictably cause tumours of various depths to reach that temperature. This technique may have tumour size limitations as well. Fig 6: a) Preoperative image of a moderately large Van Ongeval et al. (2020) and many others have pedunculated dermal melanoma at the commissure of the lips of described inaccessible multicentric/metastatic melanocytic a horse. b) Intraoperative image of a laser wedge resection of tumours and the insurmountable problem presented if they the tumour in (a). Haemorrhage is noticeably reduced. c) Post- operative image of the incision shown in (b). This horse was are causing clinical signs (Van Ongeval et al. 2020). Certainly, eating hay the same evening and the wound healed an effective systemic treatment would be miraculous. Various uneventfully. autologous vaccine preparations have been attempted for many years. This author’s observations of the results of these methods have been equivocal at best. inducing cell death in a nonthermal manner. A large Similar to dogs with malignant melanoma, equine coxofemoral/proximal femoral sarcoma in a dog was melanocytic tumours have been shown to overexpress successfully treated using IRE (Neal et al. 2011). More tyrosinase (Phillips et al. 2012). It followed that a canine recently, high-frequency IRE (HFIRE) has eliminated the melanoma vaccine that targets tyrosinase could potentially systemic muscular responses such that it can be applied to a be protective in horses with melanocytic tumours. standing horse (Arena et al. 2011), which this author has Vaccinated horses produced humoral and cell-mediated

immunoreactive responses to the tyrosinase stimulus Hildebrandt, B., Wust, P., Ahlers, O., Dieing, A., Sreenivasa, G., Kerner, (Lembcke et al. 2012). Moderately widespread vaccination T., Felix, R. and Riess, H. (2002) The cellular and molecular basis of hyperthermia. Crit. Rev. Oncol. Hematol. 43, 33-56. of horses with Oncept2 has ensued in the past few years. The product has been made available only to board-certified Knottenbelt, D.C. (2016) Integumentary disorders including cutaneous neoplasia in older horses. Vet. Clin. North Am. Equine Pract. 32, internists or institutions and requires a needleless injector. No 263-281. comprehensive review of results has been published. Knottenbelt, D.C., Patterson-Kane, J. and Snalune, K. (Eds) (2015a) Anecdotal information is that the vaccine may have largely Malignant melanoma/melanosarcoma. In: Clinical Equine limited growth and may even have resolved some early small Oncology, Elsevier Health Sciences, Philadelphia. pp 570-573. lesions. No adverse reactions have been reported but no Knottenbelt, D.C., Patterson-Kane, J. and Snalune, K. (Eds) (2015b) cure for the typical disseminated condition has occurred. A Melanocytic neoplasms. In: Clinical Equine Oncology, Elsevier recent report of a similar product describes noticeable Health Sciences, Philadelphia. pp 237-246. tumour shrinkage of melanocytic tumours in one trial Knottenbelt, D.C., Patterson-Kane, J. and Snalune, K. (Eds) (2015c) (Mahlmann€ et al. 2015). No further results have been Tumour nomenclature. In: Clinical Equine Oncology, Elsevier Health published. Any product that effectively limits growth would Sciences, Philadelphia. pp 11-22. be useful. Laus, F., Cerquetella, M., Paggi, E., Ippedico, G., Argentieri, M., Castellano, G., Spaterna, A. and Tesei, B. (2010) Evaluation of Cimetidine has been administered to countless grey cimetidine as a therapy for dermal melanomatosis in grey horse. horses with melanocytic tumours since a report of Israel J. Vet. Med. 65, 48-52. effectiveness in three horses was published (Goetz et al. Lembcke, L.M., Kania, S.A., Blackford, J.T., Trent, D.J., Odoi, A., 1990). Another cited improvement in four of 12 horses based Grosenbaugh, D.A., Fraser, D.G., Leard, T. and Phillips, J.C. (2012) upon client questionnaires (Hare and Staempfli 1994). Development of immunologic assays to measure response in Two more recent reports cite no significant clinical effect horses vaccinated with xenogeneic plasmid DNA encoding human tyrosinase. J. Equine Vet. Sci. 32, 607-615. of cimetidine (Warnick et al. 1995; Laus et al. 2010). This author has treated many horses that have been treated with MacGillivray, K.C., Sweeney, R.W. and Del Piero, F. (2002) Metastatic melanoma in horses. J. Vet. Int. Med. 16, 452-456. long-term cimetidine and observed no reduction in tumour € size(s). Mahlmann, K., Feige, K., Juhls, C., Endmann, A., Schuberth, H.-J., Oswald, D., Hellige, M., Doherr, M. and Cavalleri, J.-M.V. (2015) Local and systemic effect of transfection-reagent formulated DNA Author's declaration of interests vectors on equine melanoma. BMC Vet. Res. 11, 107. McFadyean, J. (1933) Equine melanomatosis. J. Comp. Pathol. Ther. No conflicts of interest have been declared. 46, 186-204. Moore, J.S., Shaw, C., Shaw, E., Buechner-Maxwell, V., Scarratt, W.K., Crisman, M., Furr, M. and Robertson, J. (2013) Melanoma in horses: Ethical animal research current perspectives. Equine Vet. Educ. 25, 144-151. No ethical review was required as this paper is a review of Neal, R.E., Rossmeisl Jr, J.H.L., Garcia, P.A., Lanz, O.I., Henao-Guerrero, the literature and personal clinical experience. N. and Davalos, R.V. (2011) Successful treatment of a large soft tissue sarcoma with irreversible electroporation. J. Clin. Oncol. 29, e372-e377. Manufacturers' addresses Phillips, J.C. and Lembcke, L.M. (2013) Equine melanocytic tumors. Vet. Clin. North Am. Equine Pract. 29, 673-683. 1Royer, Biomedical Inc., Frederick, Maryland, USA/Westwood Pharmacy, Richmond Virginia, USA. Phillips, J.C., Lembcke, L.M., Noltenius, C.E., Newman, S.J., Blackford, 2Merial Ltd., Duluth, Georgia, USA. J.T., Grosenbaugh, D.A. and Leard, A.T. (2012) Evaluation of tyrosinase expression in canine and equine melanocytic tumours. Am. J. Vet. Res. 73, 272-278. References Spugnini, E.P., D'Alterio, G.L., Dotsinsky, I., Mudrov, T., Dragonetti, E., Murace, R., Citro, G. and Baldi, A. (2011) Electrochemotherapy for Arena, C.B., Sano, M.B., Rossmeisl Jr, J.H., Caldwell, J.L., Garcia, P.A., the treatment of multiple melanomas in a horse. J. Equine Vet. Sci. Rylander, M.N. and Davalos, R.V. (2011) High-frequency irreversible 31, 430-433. electroporation (h-fire) for non-thermal ablation without muscle contraction. Biomed. Eng. Online 10, 102. Sullins, K.E. (2012) Lasers in equine surgery. In: Equine Surgery,4th edn., Eds: J.A. Auer and J.A. Stick, Elsevier, St Louis, MO. pp 165- Byron, C. (2019) Hfire electroporation of melanomas in two horses. 180. Front. vet. sci., in press. Theon, A.P., Wilson, W.D., Magdesian, K.G., Pusterla, N., Snyder, J.R. Foley, G.L., Valentine, B.A. and Kincaid, A.L. (1991) Congenital and and Galuppo, L.D. (2007) Long-term outcome associated with acquired melanocytomas (benign melanomas) in eighteen young intratumoral chemotherapy with cisplatin for cutaneous tumors in horses. Vet. Pathol. 28, 363-369. equidae: 573 cases (1995–2004). J. Am. Vet. Med. Assoc. 230, Frank, E.R. (1959) Neoplasma and cysts. In: Veterinary Surgery, 6th 1506-1513. edn., Burgess Publishing Company, Minneapolis. pp 90-92. Valentine, B.A. (1995) Equine melanocytic tumors: a retrospective Goetz, T.E., Ogilvie, G.K., Keegan, K.G. and Johnson, P.J. (1990) study of 53 horses (1988 to 1991). J. Vet. Intern. Med. 9, 291-297. Cimetidine for treatment of melanomas in three horses. J. Am. Vet. Van Ongeval, A., van de Velde, N., Raes, E. and Oosterlinck, M. Med. Assoc. 196, 449-452. (2020) Chronic lameness caused by vascular compression of the Groom, L.M. and Sullins, K.E. (2018) Surgical excision of large iliac artery and vein by a malignant melanoma in the pelvis of a melanocytic tumours in grey horses: 38 cases (2001–2013). Equine grey Spanish gelding. Equine Vet. Educ. 32, 623. Vet. Educ. 30, 438-443. Warnick, L.D., Graham, M.E. and Valentine, B.A. (1995) Evaluation of Hare, J.E. and Staempfli, H.R. (1994) Cimetidine for the treatment of cimetidine treatment for melanomas in seven horses. Equine Pract. melanomas in horses: efficacy determined by client questionnaire. 17, 16-22. Equine Pract. 16, 18-21.

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Clinical Commentary The potential role of sensors in equine melanoma prevention V. G. Kanellis* Department of Dermatology, The Canberra Hospital, Canberra, Australia *Corresponding author email: [email protected]

Keywords: horse; cancer; melanometer; skin; ultraviolet

Summary light intensity from 1 to 11+ that quantifies how damaging a It is common knowledge that avoiding excessive ultraviolet given UV intensity will be to skin is called the UV index (UVI) light exposure is key to good sun safety practices in humans (He et al. 2013). This scale allows the public to appropriately and horses. Photoprotection and avoiding excessive modify their sun protection behaviours by adjusting their sun ultraviolet light exposure can reduce the risk of actinic safety practices. The World Health Organization (WHO) damage, skin cancers and premature ageing. Accurate, recommends that people use sun protection when the UVI cheap and self-contained ultraviolet light sensor devices can exceeds safe levels, defined as an index score of ≥3. measure parameters such as light intensity that in turn can be Although the use of the UVI has not been studied in animals used to quantify the potential of light to cause harm. and despite the obvious differences in the skin anatomy Knowledge of local light intensity is important because it can between humans and animals, when extrapolated from actively guide good sun safety practices. Other devices, human use, the UVI has great potential to reduce the called melanometers, can measure an individual’s skin incidence of melanoma in horses and other animals by sensitivity to ultraviolet light, quantify their tendency to reducing excessive UV exposure. sunburn and determine the degree of photoprotection There are numerous sensor devices ranging from stickers, required by that individual whilst outdoors. This article handheld devices and satellite-based sensors that can be highlights the potential of the aforementioned devices and used to measure various parameters of UV such as the UVI good sun safety practices to reduce the incidence and and accumulated UV dose (Kanellis 2019b). For example, UVI burden of skin cancers caused by excessive sunlight values are taken every minute at every major capital city in exposure in horses and other companion animals. Australia and can be freely obtained from the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) Metastatic melanoma, especially when presenting with government website or by using the Australian Cancer ominous clinical signs, often leads to devastating and Council SunSmart App using any smartphone or web-linked distressing consequences in humans, horses and other computer. However, independently functioning devices are companion animals (Van Ongeval et al. 2020). I have read available that directly measure local UV measurements and with great interest about advances made by recent studies may be useful in regional and rural locations, far away from in understanding the molecular pathophysiology of grey ARPANSA’s ground-based research-grade instruments. Other horse melanoma and the potential for this knowledge for the sensors, called melanometers, have the potential to quantify treatment of melanoma in horses and other animals including UV sensitivity by measuring an individual horses’ epidermal humans (Seltenhammer et al. 2004; Metcalfe et al. 2013; melanin concentration (EMC) and individual maximum safe Daud 2015; Xu et al. 2017). Given the possibility of radiant exposure (IMSRE) (Kanellis 2019a). This kind of data extrapolating this knowledge into human melanoma can make possible customised sun safety practices for a treatment, I believe it is sensible to reciprocate our current single horse according to its own risk factors such as skin knowledge of sun safety practices in humans for the benefit pigmentation, geographical location and hair distribution. of our equine friends as well as other companion animals. These melanometers also have potential applications for Actinic damage will most frequently occur in horses and other companion animals. other animals in non-pigmented skin regions not protected by hair such as the eyes and nose. Such areas receive the Authors’ declaration of interests highest dose of ultraviolet radiation (UV) from sunlight and so fl are most likely to develop actinic keratosis and malignant No con icts of interest have been declared. neoplasms such as melanoma. Whilst studies have examined the similarities and differences between human and equine Ethical animal research melanoma (Seltenhammer et al. 2004), there are few publications exploring animal photoprotection and sun safety Not applicable. practices. As with humans, good sun safety practices are the best way to minimise the potential burden of actinic-induced Source of funding malignancy. In horses, such practises anecdotally include None. daytime use of water-resistant zinc oxide-based sunscreen lotion, UV-protective fly masks with dropped nose pieces and housing horses indoors when the UV intensity is most References damaging and therefore most likely to cause sunburn. In Daud, A. (2015) Current and emerging perspectives on humans, a universally accepted linear numerical scale of immunotherapy for melanoma. Semin. Oncol. 42, Suppl. 3,S3–S11. Continued on page 645

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ADMequine.com EQUINE VETERINARY EDUCATION 633 Equine vet. Educ. (2020) 32 (12) 633 doi: 10.1111/eve.13132_1

Case Report Successful treatment of a splenic abscess secondary to migrant metallic wires in a horse C. Thomson, D. Archer, B. Ahern and C. E. Medina-Torres* School of Veterinary Science, Equine Specialist Hospital, The University of Queensland, Gatton, Queensland, Australia *Corresponding author email: [email protected]

Keywords: horse; mass; spleen; splenectomy; weight loss

Summary values declined to 0.16 L/L and subsequently increased, with a decrease in TP after 72 h. The abscess and splenic tissue This case report describes the first successful treatment of a removed weighed 15 kg. Culture of a sample of its purulent large splenic abscess secondary to accidental ingestion and content (Fig 1b) yielded a mixed population of bacteria. The migration of multiple metallic wires from the small intestine into colt was discharged after 14 days in hospital. On follow-up 3 the spleen of a horse. A 2-year-old Thoroughbred colt was months after discharge the patient remained clinically normal hospitalised 5 weeks after an episode of severe colic followed and haematological parameters had normalised after by gradual weight loss and anorexia, pyrexia for 5 days and 60 days. This paper summarises the potential advantages of dehydration on the day of referral. A large splenic abscess was using a partial vs. a total splenectomy and highlights the identified ultrasonographically. Severe neutrophilic potential complications of these surgical procedures in equine (23.0 9 109/L) leucocytosis, hyperproteinaemia (91 g/L) with cases. severe hyperglobulinaemia (74 g/L) and hypoalbuminaemia (17 g/L), increased serum amyloid A (SAA; 409.3 mg/L), fi l hyper brinogenaemia (7 g/L) and hypoferraemia (5.9 mol/L) Key points were present. Following initial medical treatment for • rehydration and stabilisation, including isotonic crystalloid There are limited case reports of splenic abscesses fluids, broad spectrum antimicrobial and anti-inflammatory associated with migrant metallic wires in horses, and all therapy, an exploratory laparotomy was performed. The mass documented cases in which surgical treatment has been attempted have not survived to discharge. was exteriorised, and two metal linear foreign bodies (0.2 cm • thick and approx. 4 and 6 cm in length) were identified within Both medical and surgical treatment of splenic the splenic mass and penetrating through the wall of the abscessation carry a grave prognosis due to the high jejunum, causing it to adhere to the spleen. The adhesion was risk of splenic haemorrhage, abscess perforation and subsequent peritoneal contamination. broken down and the jejunal wall repaired. Following ligation • of arcuate splenic vessels, a partial splenectomy was This report describes the successful treatment of a performed using a linear stapler (ILA 100); approximately 70% large splenic abscess and intestinal adhesions, of the spleen was removed (Fig 1a). Blood loss occurred secondary to migration of multiple linear metallic following splenic transection; this was successfully controlled foreign objects in a 2-year-old colt. via manual ligation over the staples. Post-operatively, PCV

a) b)

Fig 1: Photograph of a) the splenectomised portion of the spleen containing the abscess, weighing 15 kg and showing the area of transection (arrows); and b) close up (white box in a) of the incised abscess exuding pus. Culture of the exuded material yielded a mixed population of bacteria including Streptococcus spp., E. Coli and an anaerobic Gram-negative bacillus.

Clinical Commentary Splenic abscessation: Is partial splenectomy a treatment option? A. J. Dart* and S. A. Biasutti Research and Clinical Training Unit, University Veterinary Teaching Hospital Camden, University of Sydney, Camden, New South Wales, Australia

*Corresponding author email: [email protected]

Keywords: horse; spleen; abscess; peritonitis; abdomen

The spleen in the horse is of variable size and weight, penetrating the wall of the gastrointestinal tract adjacent to suspended high in the left side of the cranial abdomen the spleen. However, infection secondary to trauma and adjacent to the diaphragm, between the rib cage and left haematoma formation and perforation of the stomach by part of the greater curvature of the stomach. The long axis Gasterophilus intestinalis larvae have also been reported as contours around the greater curvature of the stomach with potential causes (Spier et al. 1986; Dart et al. 1987; Saulez the base in contact with the diaphragm and sublumbar et al. 2009; Thomson et al. 2020). muscles and the apex at the level of the 10th or 11th rib, The most common clinical signs associated with splenic about a hand’s breadth or more above the costal arch. abscesses in the horse are nonspecific and include fever, Blood supply is delivered through the splenic artery and vein. anorexia, lethargy, weight loss, tachycardia, tachypnoea and The spleen acts as a filter for the blood, removing foreign intermittent abdominal pain (Coleman and Schmitz 2019). material and bacteria, as well as recognising and removing Clinical pathology reflects a severe chronic inflammatory old degenerating blood cells from the circulation. In the process including marked, often mature, leucocytosis, horse, the spleen also acts as a reservoir for up to 30% of the hyperfibrinogenaemia and hyperproteinaemia characterised body’s total red blood cells. When commencing exercise, by a hyperglobulinaemia and often hypoalbuminaemia. during periods of excitement or where there is blood loss, the Recently, elevations in hepatic enzymes, in the absence of spleen will contract and release these cells into the general liver pathology, have been reported in some cases of splenic circulation providing a substantial increase in the capacity to abscessation (Coleman and Schmitz 2019). Dehydration, transport oxygen. While removal of spleen is reported to elevations in blood urea nitrogen and creatinine and mild compromise optimal athletic function, it is thought that horses abnormalities in serum electrolytes have also been noted. can live without a spleen (Persson and Bergsten 1975; The prognosis for horses with splenic abscesses is poor, Mangseth and Hornof 1983; Wagneft et al. 1995; Sherlock whether treated medically or surgically, because the 2011). Nonetheless, the spleen, in most species, has an nonspecific clinical signs and chronic disease process delay a extremely important role in immune function including the diagnosis. By the time horses are diagnosed, the disease production of IgM, optimising the function of B cells, a process is usually associated with a generalised peritonitis reservoir for immunocompetent lymphocytes and antibody characterised by elevated total protein and white cell counts production, and filtration and elimination of bacteria (Peroni in an abdominal fluid sample and evidence of substantial 2008). In humans undergoing total splenectomy, intestinal and mesenteric adhesions. Transabdominal overwhelming post-splenectomy syndrome may develop ultrasound will, more often than not, be rewarding in years after surgery. Patients with this syndrome have as much detecting the presence of a splenic mass and may help as a 5-fold increase in susceptibility to sepsis from determine the size and extent of the mass and associated encapsulated polysaccharide-coated bacteria that would adhesions (Zicker et al. 1990; Coleman and Schmitz 2019). ordinarily be removed by the spleen. These bacteria are Generally speaking, the differentiation between peritoneal often highly resistant to antimicrobials, poorly immunogenic abscesses and neoplasms has been reported to be and resist antibody binding (Waldron et al. 1989; Okabayashi problematic based on clinical and laboratory data alone and Hanazaki 2008; Peroni 2008). While this complication of (Zicker et al. 1990). However, ultrasound-guided aspirates of splenectomy has not been reported in horses, a decreased the mass may provide samples that help make this resistance to protozoa and equine piroplasmosis has been differentiation on cytology and guide appropriate noted, raising overwhelming post-splenectomy syndrome as a antimicrobial therapy (Coleman and Schmitz 2019). Medical potential issue that should be considered after total therapy is reported to be more likely to be successful in splenectomy in this species (Mahoney et al. 1977; Rosner horses that are not severely, systemically compromised by the et al. 1984; Sherlock 2011). septic process, if the underlying cause can be identified (Dart Splenic rupture and haemorrhage, splenic haematoma, and Bischofberger 2011). In these horses, the abscess is more tumours and splenic abscesses have all been reported in the likely to be localised or contained and treatment can be horse, although splenic disorders are generally uncommon. targeted against the causative organisms based on culture Splenic abscessation is particularly rare, possibly because the and sensitivity. There have been no previous reports of role of the spleen as a blood filter and its contribution to the successful surgical treatment of splenic abscesses (Rosso immune system renders it less susceptible to bacterial et al. 2012; Coleman and Schmitz 2019). infection. Where splenic abscessation has been reported in The case presented by Thomson et al. (2020) in this horses, it has often been associated with foreign bodies edition of Equine Veterinary Education describes a 2-year-old

Thoroughbred colt presenting with a splenic abscess over the staples. The staples of the ILA 100 come in various secondary to migrating metal wires. This colt underwent a sizes, and the B-shaped configuration is noncrushing while partial splenectomy and is the first reported case of compressing tissues aimed to create some haemostasis successful surgical treatment of a splenic abscess (Rosso without necrosis (Dart and Dart 2016). While stapling devices et al. 2012; Coleman and Schmitz 2019). The clinical history are not infrequently used in equine surgery for organ and presenting signs in this colt were consistent with the resection, they are suited to intestinal transection or chronic process described in previous reports of horses with a anastomosis and not designed to be effective in thicker splenic abscess (Rosso et al. 2012; Coleman and Schmitz tissues such as the spleen. Despite combining multiple 2019). The systemic effects were well established prior to a discharges of the ILA 100 and ligation, there was still clinically definitive diagnosis being confirmed. The colt had clinical significant and concerning abdominal haemorrhage during and laboratory evidence of a chronic, severe, infectious and after surgery in this colt. It is not entirely clear in the case process and associated inflammation which was localised to report whether complete splenectomy was a treatment the spleen on ultrasound; however, the cause of the abscess option (Thomson et al. 2020) but, in the absence of reports of (metallic foreign bodies) could not be determined by overwhelming post-splenectomy syndrome being a concern ultrasound or radiographs. After the colt was rehydrated and in the horse, a complete splenectomy may have been broad-spectrum antimicrobials were commenced, a decision associated with less risk of haemorrhage and provided an was made to perform an exploratory laparotomy. alternative approach in this or future cases. Alternatively, Albeit in a small number of cases, culture and sensitivity other approaches to haemostasis such as large jaw thermal of transcutaneous ultrasound-guided aspirates of the vessel sealers and haemostatic scaffolds alone, or in abscess in previous reports have been successful and combination, along with other means of haemostasis could provided useful information to decide the best way to be considered in future cases. proceed, without significant complications or risk (Coleman The follow-up on the colt in this case (Thomson et al. and Schmitz 2019). Furthermore, cytology of either an 2020) was limited to 3 months. The long-term prognosis aspirate or abdominal fluid sample to detect any evidence remains unknown. There were surgically significant small of neoplasia may be a useful prognostic indicator before intestinal adhesions identified and broken down during initiating treatment. Despite the author’s concerns about risk surgery that must be considered to potentially predispose the of perforation and contamination of the peritoneal cavity or colt to further post-surgical adhesion formation with haemorrhage (Thomson et al. 2020), successful ultrasound- potentially fatal consequences. Further, as noted by the guided aspiration of the mass or even retrieval of an authors, horses undergoing total splenectomy can return to abdominal fluid sample in the case presented in this edition competitive levels of athletic competition (Ortved et al. 2008; may have provided a more complete picture to decide Dart and Bischofberger 2011); however, at the elite level and whether attempting medical management would have at maximal intensity exercise, effects on the efficiency of the been a more suitable approach to treatment, at least cardiovascular system have been reported (Persson and initially, particularly in light of the poor success reported with Bergsten 1975; Mangseth and Hornof 1983; Wagneft et al. surgical treatment. 1995; Sherlock 2011). These are most likely associated with the Laparoscopic and more traditional, invasive techniques loss of a splenic reserve of red blood cells. How and whether including a left paralumbar fossa approach or left-sided this would be ameliorated by performing a partial transthoracic approach with rib resection have been splenectomy are unknown. However, given the current body described as surgical approaches for experimental of knowledge on splenic abscessation, a favourable splenectomy (Rigg et al. 1987; Ortved et al. 2008). A study of prognosis for return to any level of athletic activity for a horse the angioarchitecture of the normal equine spleen as an undergoing surgery for this condition would be optimistic. anatomical basis for partial splenectomy has also been Despite the successful outcome in this case 3 months documented (Foz Filho et al. 2013). However, splenic following discharge, based on the current literature, the abscesses are usually associated with extensive adhesions to primary decisions made around diagnosis and treatment of the body wall and associated intra-abdominal organs, splenic abscesses should focus on whether it is possible to including the intestinal tract. The surgical approaches salvage the horse. Future athletic performance should be a described for elective experimental splenectomy in healthy secondary consideration. horses may, therefore, not be appropriate for horses with The case report in this edition of Equine Veterinary clinical disease. The authors of the case report in this edition Education provides valuable insight into surgical treatment (Thomson et al. 2020) elected to use a ventral midline and complications of splenic abscessation in the horse and approach which is better suited to wider abdominal provides some optimism for this approach to treatment for exploration (Dart and Bischofberger 2011) and is likely to select cases. More experience with surgical treatment of have contributed to the successful outcome in this case. splenic abscesses is needed before clinicians can be In the colt reported in this edition (Thomson et al. 2020), confident this is an appropriate treatment option. adhesions were limited to the body wall and adjacent intestine and were amenable to resection. The localisation of Authors’ declaration of interests the infection and the ability to surgically access, manipulate and free the adhered intestinal segments without excessive No conflicts of interest have been declared. contamination or haemorrhage were features of this case that facilitated the surgical process and outcome. Partial Ethical animal research splenectomy and removal of the mass were performed using a combination of the ILA 100 stapler and manual ligation Not applicable.

Source of funding Peroni, J. (2008) Equine splenectomy: do we understand the consequences?. Equine Vet. Educ. 20, 371-372. None. Persson, S.G. and Bergsten, G. (1975) Circulatory effects of splenectomy in the horse. IV. Effect on blood flow and blood lactate at rest and during exercise. Zentralbl. Veterinarmed. A 22, Authorship 801-807. Both authors sourced the information and references. A. Dart Rigg, D.L., Reinerston, E.L. and Buttrick, M.L. (1987) A technique for wrote the initial version and S. Biasutti reviewed and made elective splenectomy of equidae using a transthoracic approach. Vet. Surg. 16, 389-391. comments. A. Dart finalised the document. Both authors gave their final approval of the manuscript. Rosner, F., Zarrabi, M.H., Benach, J.L. and Habicht, G.S. (1984) Babesiosis in splenectomized adults: review of 22 reported cases. Am. J. Med. 76, 696-701. References Rosso, A., Bullone, M., Gillono, E., Greppi, M.C. and Bertuglia, A. (2012) Splenic abscesses due to migrant metallic wires from small Coleman, M.C. and Schmitz, D.G. (2019) Splenic abscessation in the intestine in a horse. Equine Vet. Educ. 24, 286-290. horse: a retrospective study of 12 cases. Equine Vet. Educ. 31, 67- Saulez, M.N., Burton, A., Steyl, J.C., Williams, J.H. and Clift, S.J. (2009) 70. Perforation of the gastrointestinal tracts of four horses by metallic Dart, A.J. and Bischofberger, A.S. (2011) Peritonitis in the horse: a wires. Vet. Rec. 164, 86-88. treatment dilemma. Equine Vet. Educ. 23, 294-295. Sherlock, C. (2011) The considerations and complications involved in Dart, A.J. and Dart, C.M. (2016) Suture material – Conventional and equine splenectomy. Equine Vet. Educ. 23, 612-615. stimuli responsive. In: Comprehensive Biomaterials, Volume 6, Spier, S., Carlson, G.P., Nyland, T.G., Snyder, J.R. and Fischer, P.E. Biomaterials and Clinical Use: Other Surgical Disciplines General, (1986) Splenic haematoma and abscess as a cause of chronic 2nd edn., Ed: P. Ducheyne, Elsevier, Philadelphia. pp 573-588. weight loss in a horse. J. Am. Vet. Med. Assoc. 198, 557-559. Dart, A.J., Hutchins, D.R. and Begg, A.P. (1987) Suppurative splenitis Thomson, C., Archer, D., Ahern, B. and Medina-Torres, C. (2020) and peritonitis in a horse after gastric ulceration caused by larvae Successful treatment of a splenic abscess secondary to migrant of Gasterophilus intestinalis. Aust. Vet. J. 64, 155-158. metallic wires in a horse. Equine Vet. Educ. 32, 633. Foz Filho, R.P., Martin, B.W., Lima, A.R. and Miglino, M.A. (2013) Horse Wagneft, P., Erickson, B.K., Kubo, K., Hiraga, A., Kai, M., Yamaya, Y., spleen segmentation technique as large animal model of Richardson, R. and Seaman, J. (1995) Maximum oxygen transport preclinical trials. An. Acad. Bras. Cienc. 85, 1411-2417. and utilisation before and after Splenectomy. Equine Vet. J. 27, 82- Mahoney, D.F., Wright, I.G., Frerichs, W.M., Groenendyk, S., O’Sullivan, 89. B.M., Roberts, M.C. and Waddell, A.H. (1977) The identification of Waldron, D.J., Harding, B. and Duignan, J. (1989) Overwhelming babesia equi in Australia. Aust. Vet. J. 53, 461-464. infection occurring in the immediate post-splenectomy period. Br. Mangseth, G.R. and Hornof, W.J. (1983) A review of knowledge J. Clin. Pract. 43, 421-422. regarding blood volume and splenic reserve in the horse. J. Zicker, S.C., Wilson, W.D. and Medearis, L. (1990) Differentiation Equine. Vet. Sci. 3, 94-98. between intra-abdominal neoplasms and abscesses in horses Okabayashi, T. and Hanazaki, K. (2008) Overwhelming using clinical and laboratory data: 40 Cases (1973-1988). J. Am. postsplenectomy infection syndrome in adults - a clinically Vet. Med. Assoc. 196, 1130-1134. preventable disease. World J. Gastroenterol. 14, 176-379. Ortved, K.F., Witte, S., Flemming, K., Nash, J., Woolums, A.R. and Peroni, J.F. (2008) Laparoscopic-assisted splenectomy in a horse with splenomegaly. Equine Vet. Educ. 20, 357-361.

® enclosed plastic dispensing cap. Remove cover from bottle dispensing tip and connect luer lock syringe period with active ovaries to prepare and schedule the mare for breeding. immediately with soap and water. REGU-MATE (without needle). Draw out appropriate volume of Regu-Mate® solution. (Note: Do not remove syringe while 3. Permit scheduled breeding of mares during the physiological breeding season. To permit scheduled INFORMATION FOR HANDLERS: (altrenogest) Solution 0.22% bottle is inverted as spillage may result.) Detach syringe and administer solution orally at the rate of 1 mL per breeding, mares which are regularly cycling or which have active ovarian function should be given Regu- WARNING: Regu-Mate® (altrenogest) Solution 0.22% is readily absorbed by the skin. Skin contact must be Intervet/Merck Animal Health 110 pounds body weight (0.044 mg/kg) once daily for 15 consecutive days. Administer solution directly on the Mate® (altrenogest) Solution 0.22% daily for 15 consecutive days beginning 20 days before the date of the avoided; protective gloves must be worn when handling this product. base of the mare’s tongue or on the mare’s usual grain ration. Replace cover on bottle dispensing tip to planned estrus. Ovulation will occur 5 to 7 days following the onset of estrus as expected for non-treated ORAL PROGESTIN Effects of Overexposure prevent leakage. Excessive use of a syringe may cause the syringe to stick; therefore, replace syringe as mares. Breeding should follow usual procedures for mares in estrus. Mares may be regulated and FOR USE IN ANIMALS ONLY There has been no human use of this specific product. The information contained in this section is necessary. scheduled either individually or in groups. SOLUTION 0.22% (2.2 mg/mL) extrapolated from data available on other products of the same pharmacological class that have been used DOSAGE CHART ADDITIONAL INFORMATION in humans. Effects anticipated are due to the progestational activity of altrenogest.Acute effects after a single For suppression of estrus in mares. A 3-year well controlled reproductive safety study was conducted in 27 pregnant mares, and compared with exposure are possible; however, continued daily exposure has the potential for more untoward effects such Suppression of estrus allows for a predictable occurrence of estrus following drug withdrawal in mares with Approximate Weight in Pounds Dose in mL 24 untreated control mares. Treated mares received 2 mL Regu-Mate® (altrenogest) Solution 0.22% /110 lb as disruption of the menstrual cycle, uterine or abdominal cramping, increased or decreased uterine ovarian follicles 20 mm or greater. 770 7 body weight (2 x dosage recommended for estrus suppression) from day 20 to day 325 of gestation. This bleeding, prolongation of pregnancy and headaches. The oil base may also cause complications if swallowed. Suppression of estrus will facilitate: study provided the following data: In addition, the list of people who should not handle this product (see below) is based upon the known • Attainment of regular cyclicity during the transition from winter anestrus to the physiological breeding 880 8 1. In filly offspring (all ages) of treated mares, clitoral size was increased. effects of progestins used in humans on a chronic basis. season. 990 9 2. Filly offspring from treated mares had shorter interval from Feb. 1 to first ovulation than fillies from their • Management of prolonged estrus conditions. untreated mare counterparts. PEOPLE WHO SHOULD NOT HANDLE THIS PRODUCT • Scheduled breeding during the physiological breeding season. 1100 10 3. There were no significant differences in reproductive performance between treated and untreated animals 1. Women who are or suspect they are pregnant. WARNING: DO NOT USE IN HORSES INTENDED FOR HUMAN CONSUMPTION. 1210 11 (mares & their respective offspring) measuring the following parameters: 2. Anyone with thrombophlebitis or thromboembolic disorders or with a history of these events. Keep this and all medication out of the reach of children. 1320 12 • interval from Feb. 1 to first ovulation, in mares only 3. Anyone with cerebral-vascular or coronary-artery disease. • mean interovulatory interval from first to second cycle and second to third cycle, mares only. 4. Women with known or suspected carcinoma of the breast. CAUTION • follicle size, mares only. 5. People with known or suspected estrogen-dependent neoplasia. Federal law restricts this drug to use by or on the order of a licensed veterinarian. WHICH MARES WILL RESPOND TO REGU-MATE® (altrenogest) SOLUTION 0.22%: Extensive clinical trials have • at 50 days gestation, pregnancy rate in treated mares was 81.8% (9/11) and untreated mares was 100% 6. Women with undiagnosed vaginal bleeding. DESCRIPTION demonstrated that estrus will be suppressed in approximately 95% of the mares within three days; however, (4/4). 7. People with benign or malignant tumors which developed during the use of oral contraceptives or other ® Regu-Mate (altrenogest) Solution 0.22% contains the active synthetic progestin, altrenogest. The chemical the post-treatment response depended on the level of ovarian activity when treatment was initiated. Estrus • after 3 cycles, 11/12 treated mares were pregnant (91.7%) and 4/4 untreated mares were pregnant (100%). estrogen-containing products. name is 17α-allyl-17β-hydroxyestra-4,9,11-trien-3-one. The CAS Registry Number is 850-52-2. The chemical in mares exhibiting regular estrus cycles during the breeding season will be suppressed during treatment; • colt offspring of treated and control mares reached puberty at approximately the same age (82 & 84 8. Anyone with liver dysfunction or disease. structure is: weeks respectively.) these mares return to estrus four to five days following treatment and continue to cycle normally. Mares in Accidental Exposure • stallion offspring from treated and control mares winter anestrus with small follicles continued in anestrus and failed to exhibit normal estrus following Altrenogest is readily absorbed from contact with the skin. In addition, this oil based product can penetrate showed no differences in seminal volume, spermatozoal concentration, spermatozoal motility, and total withdrawal. porous gloves. Altrenogest should not penetrate intact rubber or impervious gloves; however, if there is sperm per ejaculate. Response in mares in the transition phase between winter anestrus and the summer breeding season leakage (i.e., pinhole, spillage, etc.), the contaminated area covered by such occlusive materials may have • stallion offspring from treated and control mares showed no difference in sexual behavior. depended on the degree of follicular activity. Mares with inactive ovaries and small follicles failed to respond increased absorption. The following measures are recommended in case of accidental exposure. • testicular characteristics (scrotal width, testis weight, parenchymal weight, epididymal weight and with normal cycles post-treatment, whereas a higher proportion of mares with ovarian follicles 20 mm or Skin Exposure: Wash immediately with soap and water. ® height, testicular height, width & length) were the same between stallion offspring of treated and Each mL of Regu-Mate® (altrenogest) Solution 0.22% contains 2.2 mg of altrenogest in an oil solution. greater in diameter exhibited normal estrus cycles post-treatment. Regu-Mate (altrenogest) Solution 0.22% Eye Exposure: Immediately flush with plenty of water for 15 minutes. Get medical attention. control mares. was very effective for suppressing the prolonged estrus behavior frequently observed in mares during the If Swallowed: Do not induce vomiting. Regu-Mate® (altrenogest) Solution 0.22% contains an oil. Call a ACTIONS transition period (February, March and April). In addition, a high proportion of these mares responded with REFERENCES Shoemaker, C.F., E.L. Squires, and R.K. Shideler, 1989. physician. Vomiting should be supervised by a physician because of possible pulmonary damage via Regu-Mate® (altrenogest) Solution 0.22% produces a progestational effect in mares. regular estrus cycles post-treatment Safety of Altrenogest in Pregnant Mares and on Health and Development of Offspring. Eq. Vet. Sci. (9); No. 2: aspiration of the oil base. If possible, bring the container and labeling to the physician. ® INDICATIONS Regu-Mate (altrenogest) Solution 0.22% is indicated to suppress estrus in mares. Suppression ® 69-72. SPECIFIC USES FOR REGU-MATE (altrenogest) SOLUTION 0.22%: Store at or below 25°C (77°F). of estrus allows for a predictable occurrence of estrus following drug withdrawal. This facilitates the Squires, E.L., R.K. Shideler, and A.O. McKinnon. 1989. SUPPRESSION OF ESTRUS TO HOW SUPPLIED attainment of regular cyclicity during the transition from winter anestrus to the physiological breeding Reproductive Performance of Offspring from Mares Administered Altrenogest During Gestation. Eq. Vet. Sci. 1. Facilitate attainment of regular cycles during the transition period from winter anestrus to the Regu-Mate® (altrenogest) Solution 0.22% (2.2 mg/mL). season. Suppression of estrus will also facilitate management of prolonged estrus conditions. Suppression of (9); No. 2: 73-76. physiological breeding season. To facilitate attainment of regular cycles during the transition phase, mares Each mL contains 2.2 mg altrenogest in an oil solution. estrus may be used to facilitate scheduled breeding during the physiological breeding season. should be examined to determine the degree of ovarian activity. Estrus in mares with inactive ovaries (no WARNING For oral use in horses only. Keep this and all other medications out of the reach of children. Do Available in 1000mL plastic bottles. CONTRAINDICATIONS Regu-Mate® (altrenogest) Solution 0.22% is contraindicated for use in mares having a follicles greater than 20 mm in diameter) will be suppressed but these mares may not begin regular cycles not use in horses intended for human consumption. previous or current history of uterine inflammation (i.e., acute, subacute, or chronic endometritis). Natural or following treatment. However, mares with active ovaries (follicles greater than 20 mm in diameter) Manufactured for: Intervet Inc., d/b/a Merck Animal Health, HUMAN WARNINGS: synthetic gestagen therapy may exacerbate existing low-grade or “smoldering” uterine inflammation into a frequently respond with regular post-treatment estrus cycles. 2 Giralda Farms, Madison, NJ 07940 Skin contact must be avoided as Regu-Mate® (altrenogest) Solution 0.22% is readily absorbed through fulminating uterine infection in some instances. 2. Facilitate management of the mare exhibiting prolonged estrus during the transition period. Estrus will be Made in France suppressed in mares exhibiting prolonged behavioral estrus either early or late during the transition unbroken skin. Protective gloves must be worn by all persons handling this product. Pregnant women or PRECAUTIONS Various synthetic progestins, including altrenogest, when administered to rats during the women who suspect they are pregnant should not handle Regu-Mate® (altrenogest) Solution 0.22%. NADA # 131-310, Approved by FDA period. Again, the posttreatment response depends on the level of ovarian activity. The mares with greater 01/07 embryogenic stage of pregnancy at doses manyfold greater than the recommended equine dose caused ® Women of child bearing age should exercise extreme caution when handling this product. Accidental ovarian activity initiate regular cycles and conceive sooner than the inactive mares. Regu-Mate 141990 R1 fetal anomalies, specifically masculinization of the female genitalia. (altrenogest) Solution 0.22% may be administered early in the transition period to suppress estrus in absorption could lead to a disruption of the menstrual cycle or prolongation of pregnancy. Direct contact with the skin should therefore be avoided. Accidental spillage on the skin should be washed off DOSAGE AND ADMINISTRATION While wearing protective gloves, remove shipping cap and seal; replace with mares with inactive ovaries to aid in the management of these mares or to mares later in the transition NAC N0.: 1047378.2

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Original Article The use of magnetic resonance imaging for the assessment of distal limb wounds in horses: A pilot study C. Sherlock*† , A. Fairburn†, A. Lawson†‡ and T. Mair† †Bell Equine Veterinary Clinic, Mereworth, UK; and ‡Institute of Veterinary Science, University of Liverpool, Neston, UK

*Corresponding author email: [email protected]

Keywords: horse; MRI; trauma; foreign body; distal limb

Summary more effectively in horses with penetrating solar wounds The utility of magnetic resonance (MR) imaging in the (Meehan 2017). evaluation of equine solar foot penetrations is well Although MR imaging studies of horses with foot established. The objective of this pilot study was to evaluate penetrations have been acquired in both standing and the utility of MR imaging in assessment of equine distal limb anaesthetised horses, reports of horses imaged in low-field wounds excluding solar penetrations. Low-field MR images of magnets under standing sedation predominate (Boado et al. 23 horses that had previously sustained distal limb wounds 2005; Kinns and Mair 2005; Urraca del Junco et al. 2012; were reviewed in consensus by two ECVDI diplomats. Findley et al. 2014). This is likely to be due to the lower risks of Structures (bone; synovial structure; subcutaneous tissue and standing image acquisition compared with the risks of skin; and ligament/tendon) were identified as normal or morbidity and mortality in adult horses undergoing abnormal on MR images, radiographs and ultrasound images anaesthesia (Andersen et al. 2006; Franci et al. 2006). The and reports. All abnormalities were described. The presence safety and practicality of MR imaging of standing sedated of artefacts and their effect on image interpretation were also horses yields varying possibilities for its utility in horses that are noted for each modality. Comparisons were made between worthy of exploration. imaging modalities, and it was noted if MR imaging In addition to imaging the foot, MR imaging has been influenced case management. Abnormalities of the bone used for the evaluation of penetrating wounds elsewhere in were identified in 26% of horses on MR images and 17% of the body in both human patients (Ledermann et al. 2002; horses on radiographs; there were no osseous abnormalities Imokawa et al. 2003) and small animals (Dobromylskyj et al. identified on radiographs that were not identified on MR 2008; Ober et al. 2008) and its benefits and limitations have images, and additional features and better characterisation been described. These include the acquisition of high of lesions were noted on MR images. Tendon/ligament contrast resolution images and tomographic slices which can abnormalities were identified in 57% horses on MR and 47% of aid identification of a foreign body and its relationship to horses on ultrasound images. Magnetic susceptibility artefacts adjacent anatomy, thereby guiding surgical planning. This compromised MR image interpretation in 17% of horses. MR contrasts with the signal voids and magnetic susceptibility imaging of equine distal limb wounds allowed identification artefacts potentially compromising image interpretation as of both osseous and tendon/ligament abnormalities in more well as partial volume averaging artefacts preventing cases than either radiography or ultrasonography, and identification of small foreign bodies. altered case management in 20/23 horses. Although MR Therefore, the objectives of this study were to assess the imaging should not replace conventional imaging, this study utility of MR imaging of recent distal limb wounds, excluding highlights that MR imaging of equine distal limb wounds can solar penetrations, in horses. The hypothesis was that MR yield information not detected on conventional imaging imaging will yield more information about the involvement of which may direct treatment and affect prognostication. soft and osseous tissues in horses with distal limb wounds than conventional imaging modalities (radiography and/or ultrasonography). Introduction

Distal limb wounds are commonly encountered in equine Materials and methods practice. The utility of MR imaging for the investigation of foot penetrations in horses was reported in 2005 (Boado et al. A pilot study was conducted at Bell Equine Veterinary Clinic 2005; Kinns and Mair 2005). Since then, MR imaging has between July 2012 and July 2017. The study was approved and become well established as a diagnostic tool for evaluation conducted in accordance with the clinic’s Animal Care and of known and suspected solar foot penetrations and has also Use Committee. Owners of horses or ponies admitted for identiﬁed previously undiagnosed solar foot penetrations management of a distal limb wound that could be imaged (Urraca del Junco et al. 2012; Findley et al. 2014). Its value lies with MR within 5 days of conventional imaging were offered MR in its ability to assess the tract direction and depth, and also imaging, and the uncertainty of the diagnostic utility was assess involvement of individual structures within the hoof explained to ensure speciﬁc informed client consent was capsule (Meehan 2017). MR imaging therefore may provide obtained prior to undergoing MR imaging. The MR imaging was information useful for directing treatment and prognosticating offered free of charge but the remainder of the diagnostics

and treatments were performed at the discretion of the treating and the remainder were adult horses with a mean age of clinician with client consent and at cost to the client. All 10.5 years (range 2–22 years). There were three entire males, wounds were distal to the mid metacarpus/metatarsus, and nine geldings and 11 females. Forelimbs were imaged in 14 horses with solar penetrations were not included in the study. horses (five left fore and nine right fore), and hindlimbs were Sample size was dictated by owner consent over the 5-year imaged in nine horses (five left hind and four right hind). time course of the study. All horses and ponies included in the The mean length of time between the injury and study underwent low-field MR imaging1 for the evaluation of a presentation to the hospital was 6 days (range 0–35 days), recent wound (sustained within the previous 6 weeks) to the and the mean time between hospital presentation and MR distal limb. History, treatments and outcome were recorded for imaging was 2 days (range 0–7 days). MR and conventional each case. Horses were diagnosed as having affected imaging occurred within 48 h in 20 horses. The delay (breached or contaminated) synovial structures at presentation between conventional imaging and MR imaging in the if the nucleated cell counts of synovial fluid was >30 9 109 cells/ remaining horses was 4 days in two horses and 5 days in one Lor>90% neutrophils and/or degenerative changes within horse. neutrophils, and two or more of the following were present: The wounds involved the pastern region only (including affected limb lameness, increased heat in the affected region the coronary band) in 18 horses, the fetlock region only and/or effusion of the affected synovial structure, bacteria seen (metacarpophalangeal or metatarsophalangeal joint) in on cytological examination of Gram-stained synovial fluid and three horses, the pastern, fetlock (metatarsophalangeal joint) a total protein concentration >30 g/L (Taylor et al. 2010). and distal metatarsal regions in one horse and the distal Synovial cavities were also considered breached if there was metacarpal region only in one horse. Synovial structures were egress of fluid from the wound after instillation of sterile saline considered to be affected (contaminated or breached) at into the affected synovial cavity. the time of presentation in 11 horses. An additional two All adult horses underwent MR image acquisition under horses had evidence of intrathecal tendon damage in the standing sedation, and foals <3 months underwent MR location of the wound on MR images in the absence of imaging under general anaesthesia using varying sequences evidence of synovial cavity contamination or breach at depending on the area of interest using a dedicated presentation (Fig 2). extremity radiofrequency coil. All MR images were reviewed All horses received systemic antimicrobials and local in digital imaging and communications in medicine (DICOM) wound management. format using an image analysis workstation by consensus by Twelve horses underwent surgical treatment. Nine horses two ECVDI-LA diplomats (C.S. and A.F.), and anatomic underwent surgical intervention that was not directed by the structures (skin and subcutaneous tissues; tendon/ligament; MR imaging (Supplementary Item 1). The surgery performed bone; and synovial structures) were graded as normal or was lavage of the digital flexor tendon sheath (DFTS) in six abnormal. Imaging abnormalities of each structure were horses (Figs 3 and 4), lavage of the navicular bursa and distal recorded in detail. The presence of MR artefacts and interphalangeal (DIP) joint in one horse (Fig 5), lavage of the whether the artefact compromised image interpretation DIP joint only in one horse and lavage of the were recorded for each case. metacarpophalangeal joint in one horse. Subsequent MRI Horses also underwent conventional imaging (radiography2 examinations afforded no advantage in one horse, were and/or ultrasonography3) under standing sedation using routine misleading in one horse whose lameness persisted for protocols determined by the area of interest (Kidd et al. 2014; 2.5 months at which time it was subjected to euthanasia, Butler et al. 2017) directed by the treating clinician. ruled out soft tendon/ligament damage suspected at surgery To prevent observer bias, following a 2-week interval after in one horse and altered the post-operative treatment and/or examining the MR images, anatomic structures were similarly prognosis in six horses. graded as normal or abnormal on both radiographs and Four horses underwent surgery after the MR imaging that ultrasound images and imaging abnormalities were recorded was directed by the MR images (Supplementary Item 2), in detail. The presence of artefacts and whether the artefact including partial hoof wall resection to remove a sequestrum compromised image interpretation were also recorded for in one horse (Fig 6a,b), partial hoof wall resection over a tract each case. This was achieved by examining both the clinical in one horse and exploratory surgery to remove a wooden notes and the stored images/cineloops where possible on the foreign body in two horses (Fig 7a,b). One of these two horses same imaging workstation as for the MR images. with a wooden foreign body underwent surgery prior to the The utility of MR imaging was estimated by comparing the MR imaging for a DIP joint lavage and post-MR imaging for percentage of abnormalities identified on each imaging another DIP joint lavage and wound exploration to attempt modality for each anatomic structure. Additionally, cases removal of the foreign material; the horse also had evidence were grouped into those where MR imaging changed the of damage to the collateral ligament of the DIP joint and its treatment and/or prognosis beyond conventional imaging, entheses on MR imaging (Fig 8a,b). those where MR imaging afforded no additional benefit over Eleven horses were treated medically (Supplementary conventional imaging and those where MR imaging misled Item 3). Surgical intervention was recommended but the clinician. Any follow-up MR imaging examinations were declined in two of these horses with synovial cavity also evaluated, but comparisons between imaging modalities involvement, both of which were subjected to euthanasia. were limited to the initial studies. Against veterinary advice, one of these horses was not subjected to euthanasia until 20 days after the MR imaging Results study at which time more extensive soft tissue damage was notable grossly than on the MR images. There were six horses There were 23 horses and ponies that met the inclusion where MR imaging altered the treatment and/or prognosis, criteria for the study (Fig 1). Two cases were foals <3 months, four horses where MR imaging ruled out soft tissue lesions

n = 23

Surgery Surgery not Medical directed by directed by management MRI Case 7 in MRI n = 11 n = 4 both n = 9 groups

MRI altered MRI altered MRI altered case case case management management management n = 4 n = 7 n = 10

Case MRI 1 in MRI both misleading misleading groups n = 1 n = 1

MRI MRI afforded afforded no value no value n = 1 n = 1

Fig 1: Flow chart of cases included in the study.

Lat

Fig 3: Case 11: STIR fast spin echo image at the level of the proximal interphalangeal joint of the right fore after a pastern Fig 2: Case 16: Transverse T2 fast spin echo image at the level of wound. ‘Lat’ denotes lateral. Images were acquired after surgical the distal aspect of the proximal phalanx of the right fore after a lavage of the digital flexor tendon sheath. There is hyperintense pastern wound. ‘Lat’ denotes lateral. There is an oblique linear lesion affecting the lateral lobe of the deep digital flexor tendon hyperintensity across the medial lobe of the deep digital flexor extending from the dorsal to the palmar tendon surface (arrow). tendon extending from the dorsal to the palmar tendon surface (arrow). The medial lobe is also enlarged. There is effusion within when their persistent lameness was inconsistent with the the digital flexor tendon sheath. On presentation, synoviocentesis severity of the wound that was subsequently treated of the digital flexor tendon sheath was not consistent with sepsis. successfully for cellulitis, and there was one horse where the

Lat Lat

Fig 4: Case 9: Transverse T1 gradient echo motion insensitive image of the right fore distal metacarpal region after a wound. ‘Lat’ denotes lateral. There is loss of the normal contour and definition of the medial palmar aspect of the superficial digital flexor tendon with a small curvilinear hyperintensity within the tendon (arrow). There is subcutaneous tissues enlargement adjacent to the tendon lesion.

Lat a)

Fig 6: Case 2: a) Dorsopalmar radiograph of the distal phalanx of the left fore. ‘Lat’ denotes lateral. There is a well-deﬁned radiopacity within a poorly demarcated radiolucency (arrows) at b) the medial aspect of the distal phalanx. b) Transverse T2* 3D gradient echo image of the distal phalanx after a pastern wound. ‘Lat’ denotes lateral. There is low signal intensity lesion surrounded by a high signal intensity circular defect (arrows) in the medial aspect of the distal phalanx. The adjacent distal phalanx has low signal intensity.

MR imaging study afforded no further value to the horse’s management. There were two horses that had wooden foreign body penetrations in the coronary band region. A signal void was identified on all sequences and was interpreted as a wooden foreign body and correlated with surgical findings in one horse. In contrast, the wooden foreign body appeared as a signal void on T1-weighted images and a well-defined linear Fig 5: Case 6: a) T1 3D gradient echo sagittal images at day 7 and b) 2.5 months after presentation of a wound to the right hind hyperintensity within a signal void on T2*-weighted images in pastern. The navicular bone is normal on day 7 (a) although there the other horse (Fig 7a). After surgical foreign body removal, are hypointense tracts through the toric digital cushion likely there was a heterogeneous intermediate T1- and T2*- secondary to navicular bursocentesis (arrows). At repeat MRI weighted signal in the location of the previous tract and 2.5 months later (b), as well as the hypointense tracts, there are foreign body (Fig 7b) on follow-up MR imaging. marked abnormalities within the navicular bone characterised by Magnetic resonance imaging identified more osseous decreased signal intensity within the spongiosa and a abnormalities (26% horses) than radiography (17% horses) fl hyperintense defect in the plantar ( exor) and compact bone (Table 1). There were no osseous abnormalities identified on with an adjacent hyperintensity in the spongiosa. There is a radiographs that were not identified on MR imaging, and diffuse increased in signal intensity in the deep digital flexor tendon at the palmar aspect of the navicular bone. additional features and better characterisation of lesions

a) a)

Lat Lat

Lat

Fig 7: Case 10: a) Transverse T2* 3D gradient echo image at the level of the distal phalanx after a penetrating pastern wound. ‘Lat’ Fig 8: Case 7: a) Transverse STIR fast spin echo image at the denotes lateral. There is a linear hyperintensity surrounded by a level of the middle phalanx of the left hind after a penetrating ‘ ’ hypointense region (arrows) at the lateral aspect of the distal pastern wound. Lat denotes lateral. There is marked loss of fi phalanx extending towards the distal phalanx. The horse de nition, enlargement and increased STIR signal within the underwent standing surgery, and a piece of wood was removed. lateral collateral ligament of the distal interphalangeal joint. There b) Transverse T2* 3D gradient echo image at the level of the are increased signal intensity and disruption of the soft tissue distal phalanx of the right fore after a penetrating pastern wound. abaxial to the collateral ligament. There is increased STIR signal in ‘Lat’ denotes lateral. The previously noted linear hyperintensity the trabecular bone of the middle phalanx adjacent to the surrounded by a hypointense region at the lateral aspect of the collateral fossa (arrows). b) Gross post-mortem image of the left distal phalanx extending towards the distal phalanx is resolved. A hind foot of Case 7 with the keratinised hoof removed. There was diffuse hyperintense region remains. The lateral hoof wall is a large necrotic tract extending from the pastern distal and demarcated by a damp dressing. axially into the distal interphalangeal joint through the collateral ligament of the distal interphalangeal joint. were noted on MR images (Supplementary Items 1–3). fi Ultrasonography identi ed more synovial structure Discussion abnormalities (63% horses) than MR imaging (48%) (Table 1). Magnetic resonance imaging identified more tendon/ This pilot study describes the utility of low-field MR imaging in ligament abnormalities (57% horses) than ultrasonography a heterogeneous group of horses with distal limb wounds. (47% horses) (Table 1). There were four horses in which Magnetic resonance imaging altered the treatment and/or abnormalities were identified on MR imaging but not on prognosis of most (20) horses with distal limb wounds, ultrasonography, and there was one horse that had suspicion including four horses where surgery was directed by the MR of damage to the lateral collateral ligament of the DIP joint imaging and five horses in which tendon/ligament lesions on ultrasonography but magnetic susceptibility artefacts were ruled out as a cause of unexpected/persistent prevented complete evaluation of the ligament on MR lameness. Magnetic resonance imaging afforded no imaging initially; the ligament was normal on repeat MR advantage over conventional imaging techniques in two imaging. There were an additional three horses that had horses and underestimated the ultimate severity of the lesion magnetic susceptibility artefacts that compromised in two horses which were subsequently subjected to interpretation of the area of interest on the first MR euthanasia 20 days and 2.5 months after MR imaging one of examination; this was improved in one horse on follow-up MR whom was treated against medical advice after MR imaging examination and did not resolve in one horse, and there was had identified severe tendon and osseous lesions. no indication for follow-up examination in one horse. Fast spin The potential for magnetic susceptibility artefacts to echo sequences were used to minimise the detrimental create nondiagnostic studies was a concern relating to the effects of magnetic susceptibility artefacts. use of MR imaging in the evaluation of recent distal limb

TABLE 1: Table documenting the numbers and percentages of cases identiﬁed with abnormalities affecting anatomic structures on MR imaging, radiography and ultrasonography and the presence of imaging artefacts

Subcutaneous Bone Synovial structure tissue/skin Ligament/tendon Artefacts Modality No. of cases (% abnormal) (% abnormal) (% abnormal) (% abnormal) (% identiﬁed)

MR imaging 23 26 48 100 57 43 Radiography 18 17 39 100 N/A 67 Ultrasonography 19 0 63 89 47 42

wounds. Magnetic susceptibility artefacts have been noted in Smith 2014). The presence of a wound and associated horses with solar penetrations (Boado et al. 2005; Urraca del subcutaneous gas impedes identification of soft tissue injuries Junco et al. 2012; Findley et al. 2014), horses that have as well as subtle periosteal changes and may take several undergone previous arthroscopic procedures (Thomas et al. days to resolve, thereby delaying thorough evaluation. 2016) and secondary to needle tracts after bursocentesis Additionally, tendon and/or ligament lesions may not be (Black et al. 2013). These artefacts are likely to be caused by immediately apparent on ultrasound examination (Cauvin hemosiderin deposits (Gomori and Grossman 1988; Bradley and Smith 2014), with MR imaging having better soft tissue 1993) and/or small metallic or rust particles (Freer and Scrivani contrast and reported as having a higher sensitivity for soft 2008). Magnetic susceptibility artefacts cause focal areas of tissues lesions in several studies (Brokken et al. 2007; Sampson signal void and adjacent regions of signal hyperintensity et al. 2007). These could be potential reasons for the lower resulting from ‘piling up’ of signal assigned to the wrong rates of detection and assessment of severity of tendon and/ anatomic location and are more prominent on gradient or ligament lesions on ultrasonography compared with MR echo compared with fast spin echo sequences (Arena et al. imaging, and suggests that further MR imaging of horses with 1995; Hecht et al. 2011; Bushberg et al. 2012). In this study, distal limb wounds may be warranted, especially in those there were magnetic susceptibility artefacts noted in 43% of horses whose lameness severity does not correlate with the cases imaged, although they were only considered to clinical and conventional imaging findings; however, compromise image interpretation in 17% of cases. The effects conventional imaging should remain the initial approach to were minimised by using fast spin echo sequences with short such horses. echo times in two horses and by performing a repeat study In an additional four out of 20 horses, the MR study 5 days after the initial study (4 days after surgery) in one directed surgical intervention. Magnetic resonance imaging horse and 5 days after the initial study (1 day after surgery) in has previously been reported to help direct surgical another horse. This highlights the necessity to explain to approaches for the treatment of keratomas, and its use has owners that MR imaging may be nondiagnostic in the early been associated with lower complication rates and shorter stages after wounds have occurred; however, the effects of convalescent times compared with conventionally treated these artefacts can be minimised by sequence selection and horses without advanced imaging-directed surgical repeat imaging, potentially after lavage and debridement of approaches (Getman et al. 2011). Two of the distal limb the affected wound. It is noteworthy that after experimental wounds in this study that benefitted from MR imaging to aid arthroscopic procedures, magnetic susceptibility artefacts surgical planning used similar principles to those used to have been reported to persist for 12 weeks in 40% of cases, direct partial hoof wall resection for removal of keratomas. although these artefacts did not affect evaluation of the The other two horses that underwent surgery directed by the operated metacarpophalangeal joint (Thomas et al. 2016), MR imaging had wooden penetrating foreign bodies. There and magnetic susceptibility artefacts have been reported to are contradictory reports regarding the sensitivity of MR persist for years in human patients after intracranial imaging to accurately diagnose wooden foreign bodies; haemorrhage (Imaizumi et al. 2003; Schommer et al. 2013). some reports suggest MR imaging findings correlate well with In 11 of the 20 horses where MR imaging altered the the presence of wooden foreign bodies, whereas others treatment or prognosis, the main contribution of the MR report that computed tomography is more sensitive. This may imaging was the recognition of tendon and/or ligament be associated with a number of factors including the size of damage that was previously undiagnosed or underestimated. the foreign body and the duration of its presence, with MR The tendon and/or ligament damage identified affected the imaging having worse sensitivity for acute small wooden rehabilitation type and duration after injury, and recognising foreign bodies (Dobromylskyj et al. 2008; Ober et al. 2008). involvement of the soft tissues allowed provision of a more Wooden foreign bodies have been reported as areas of accurate prognosis. Although it is arguable that a more signal void that correlate well with the size and shape of the thorough ultrasound examination could have yielded similar retrieved foreign body in human patients (Bodne et al. 1998). information without the necessity for MR imaging, the majority Failure of MR imaging to identify foreign bodies in two of 55 of horses had undergone detailed ultrasound examination by horses with solar penetrations that were subsequently found the senior clinician during the work-up, and the lesions were during surgical intervention has been reported (Urraca del not observed or were underestimated, with the MR imaging Junco et al. 2012). The sensitivity and specificity of low-field providing additional or new information. There are inherent MR imaging for detection of wooden foreign bodies is difficulties in ultrasound evaluation of some areas of the distal currently unknown, and it is very likely that small wooden limb, including the collateral ligaments of the DIP joint within foreign bodies may be overlooked, although in two horses in the hoof capsule and areas of the deep digital flexor tendon this study wooden foreign bodies were correctly identified that are off incidence to the primary beam (Carstens and and surgical removal validated the imaging findings.

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There were two horses in this study that were diagnosed More horses (63%) were noted as having ultrasonographic with severe intrathecal tendon injuries in the palmar pastern abnormalities of synovial structures compared with MR in the same region as the previously sustained wound, in the imaging (48%). This is likely to be due to the superior spatial absence of evidence of breach of the DFTS. Although it is resolution of ultrasound for diagnosis of small areas of fibrin possible that the tendon injuries were caused indirectly by and synovial membrane abnormalities compared with low- blunt trauma at the time the wound was sustained, it is more field MR imaging. Magnetic resonance imaging is susceptible likely that the original wounds did cause breach of the DFTS to partial volume averaging artefacts, and the motion and the tendon injuries directly and that the synovial insensitive sequences with thicker slices in particular lend structures were contaminated (although not necessarily themselves to this type of artefact. Partial volume artefacts infected) at the time of the injury (Cauvin and Smith 2014). can cause a signal intensity within a single pixel on MR The absence of evidence of synovial infection at images to represent both fibrin and synovial fluid within its presentation (7 and 18 days after injury) may be attributed to corresponding voxel which would be difficult to clearly misleading synovial fluid results, such as with sequestration of differentiate from an adjacent pixel only representing infection within the DFTS or, more likely, because the synovial fluid. Previously, MR imaging has been reported to contamination of the synovial structure resolved. identify capsular thickening, joint effusion and synovial Unfortunately, a definitive explanation for the intrathecal proliferation in 93% of 14 adult horses with septic arthritis tendon injuries detected on MR imaging in the absence of (Easley et al. 2011). However, intrasynovial fibrin was only synovial breach is not possible retrospectively. identified after administration of intravenous gadolinium There were an additional five horses in which MR imaging (Easley et al. 2011). Additionally, 4/6 foals with septic arthritis was performed due to suspected severe tendon and/or were noted to have a heterogeneous appearance to ligament injury and an unexplained severe and/or persistent synovial fluid in contrast to a homogeneous appearance in lameness in the absence of synovial sepsis. Magnetic foals with nonseptic arthritis (Gaschen et al. 2011). Possible resonance imaging was useful in these cases at ruling out explanations for the discrepancy are that images were severe tendon and ligament injury as a cause for the lameness. acquired in a 1.5 Tesla high-field magnet under general In one horse, there was a soft tissue defect palpated at surgery anaesthesia with better spatial resolution in both studies although there was no soft tissue abnormality identified on the (Easley et al. 2011; Gaschen et al. 2011). The study in foals MR images. The horse was rehabilitated based on the absence (Gaschen et al. 2011) compared findings in septic and of soft tissue damage and the lameness resolved. It was nonseptic arthritis, but the aim of the study in adults (Easley therefore presumed that the defect palpated was of the et al. 2011) was to describe the characteristics of equine subcutaneous tissue or a fascial plane. septic arthritis in 14 affected horses and therefore was Regarding the two horses with misleading MR imaging potentially biased. Two additional important features to studies, pathology of the navicular bone and bursa was not consider are the duration of sepsis, which may have a large noted on MR imaging on days 1 and 7 of hospitalisation, but impact on the synovial cavity pathology, and the size of the was present on a third MR study obtained 2.5 months after synovial cavity affected. In human patients, only 22% of the pastern wound in one horse with unexplained severe cases with synovial sepsis were noted to have synovial lameness during hospitalisation that had recurred proliferation in one study, and the low prevalence was intermittently after discharge. The horse had also undergone attributed to the small size of most of the human joints navicular bursal lavage on days 0 and 5 of hospitalisation. included in the study (Karchevsky et al. 2004). This highlights The horse was subjected to euthanasia after the third MR the importance of considering each imaging modality’s examination. Post-mortem examination was declined by the characteristics when choosing and interpreting imaging owner but the imaging findings were consistent with an investigations. aggressive osseous lesion with flexor compact bone There are several limitations to this study that are destruction and marked STIR signal within the navicular associated with the clinical study design. The study includes a spongiosa. In light of the history, these changes are most heterogeneous population of horses as the case inclusion likely to represent a low-grade osteomyelitis, likely to be was based on client consent for an imaging study with related to the initial pastern region wound and treatment. In unproven value. This prohibited standardisation of imaging view of the failure of the first two MR examinations to detect and investigative protocols, and not all horses had available pathology, the sensitivity of MR imaging for osteomyelitis radiographs, ultrasound images and/or reports, and the detection is uncertain and questionable; however, in human design also limited the numbers of cases. Although there was patients, it has been reported that it may take 3–5 days a delay between reading the diagnostic images, due to the before detection of osteomyelitis on MR imaging (Kocher clinical nature of the study, the clinicians involved were not et al. 2006). An additional horse with severe imaging changes blinded to the cases, which could have introduced bias into of the superficial digital flexor tendon, metatarsus, proximal the study. However, the study does not aim to make sesamoid bones and proximal phalanx identified on MR definitive recommendations regarding indications for MR images was noted to have changes in the DDFT grossly at imaging of distal limb wounds, but to describe its potential post-mortem examination 20 days later. It is uncertain in this use and provide a basis for future study and describe the horse if MR imaging underestimated the DDFT damage ability to safely achieve diagnostic MR images in standing initially or if the untreated sepsis within the DFTS caused the adult horses. DDFT pathology subsequent to the MR imaging, as has been In conclusion, this pilot study has demonstrated that low- noted previously (Kidd et al. 2004). Although uncommon, field MR imaging may have a utility in horses with distal limb both horses demonstrate that repeat MR imaging wounds. As with all imaging modalities, its value in case examinations are warranted if lameness persists beyond what management is dependent on appropriate case selection. is expected for the diagnosed severity of injury. Magnetic resonance imaging may be useful to rule in or out

soft tissue and osseous abnormalities, and the presence of Bushberg, J.T., Seibert, J.A., Leidholt, E.M. and Boone, J.M. (2012) The foreign bodies in horses with distal limb wounds with persistent Essential Physics of Diagnostic Imaging, Lippincott Williams and Wilkins, Philadelphia. or severe lameness was not explained by conventional imaging modalities. It may also be useful to guide surgical Butler, J.A., Colles, C.M., Dyson, S.J., Kold, S.E. and Poulos, P.W. (2017) Clinical Radiology of the Horse, 4th edn., John Wiley & Sons Ltd, interventions in horses with distal limb wounds. Further studies Chichester, West Sussex, UK. into the utility of MR imaging in distal limb wounds, wounds Carstens, A. and Smith, R.K.W. (2014) Ultrasonography of the foot and involving the carpus and tarsus and the use of gadolinium pastern. In: Atlas of Equine Ultrasonography. Eds: J.A. Kidd, K.G. Lu contrast enhancement are warranted. and M.L. Frazer, Wiley Blackwell, West Sussex, UK. pp 25-44. Cauvin, E.R. and Smith, R.K.W. (2014) Ultrasonography of the fetlock. In: Atlas of Equine Ultrasonography. Eds: J.A. Kidd, K.G. Lu and M.L. Author's declaration of interests Frazer, Wiley Blackwell, West Sussex, UK. pp 45-72. No conflicts of interest have been declared. Dobromylskyj, M.J., Dennis, R., Ladlow, J.F. and Adams, V.J. (2008) The use of magnetic resonance imaging in the management of pharyngeal penetration injuries in dogs. J. Small Anim. Pract. 49, Ethical animal research 74-79. Easley, J.T., Brokken, M.T., Zubrod, C.J., Morton, A.J., Garrett, K.S. and The study was approved and conducted in accordance with Holmes, S.P. (2011) Magnetic resonance imaging findings in horses the clinic’s Animal Care and Use Committee. with septic arthritis. Vet. Radiol. Ultrasound. 52, 402-408. Findley, J.A., Pinchbeck, G.L., Milner, P.I., Bladon, B.M., Boswell, J., Mair, Acknowledgements T.S., Suthers, J.M. and Singer, E.R. (2014) Outcome of horses with synovial structure involvement following solar foot penetrations in The authors would like to thank Hallmarq Veterinary Imaging for four UK veterninary hospitals: 95 cases. Equine Vet. J. 46, 352-357. their generous support of this clinical study. We would also like Franci, P., Leece, E.A. and Brearley, J.C. (2006) Post anaesthetic to thank owners of the horses and their referring veterinarians myopathy/neuropathy in horses undergoing magnetic resonance imaging compared to horses undergoing surgery. Equine Vet. J. as well as colleagues at Bell Equine Veterinary Clinic. 38, 497-501. Freer, S.R. and Scrivani, P.V. (2008) Postoperative susceptibility artifact Authorship during magnetic resonance imaging of the vertebral column in two dogs and a cat. Vet. Radiol. Ultrasound. 49, 30-34. All authors have made an active contribution to the study Gaschen, L., LeRoux, A., Trichel, J., Riggs, L., Bragulla, H.H., and manuscript, and all have critically reviewed its content Rademacher, N. and Rodriguez, D. (2011) Magnetic resonance and have approved the final version submitted for imaging in foals with infectious arthritis. Vet. Radiol. Ultrasound. 52, publication. 627-633. Getman, L.M., Davidson, E.J., Ross, M.W., Leitch, M. and Richardson, D.W. (2011) Computed tomography or magnetic resonance Manufacturers' addresses imaging-assisted partial hoof wall resection for keratoma removal. Vet. Surg. 40, 708-714. 1Hallmarq Veterinary Imaging, Guildford, Surrey, UK. 2Sound digital radiography unit, Carlsbad, California, USA with a Gomori, J.M. and Grossman, R.I. (1988) Mechanisms responsible for Canon CXDI-801C wireless cassette, Canon Europe Ltd, Middlesex, UK. the MR appearance and evolution of intracranial hemorrhage. 3GE Logiq E9 or GE Logiq P5 with varying linear probes, GE Radiographics 8, 427-440. Healthcare, Buckinghamshire, UK. Hecht, S., Adams, W.H., Narak, J. and Thomas, W.B. (2011) Magnetic resonance imaging susceptibility artifacts due to metallic foreign bodies. Vet. Radiol. Ultrasound. 52, 409-414. References Imaizumi, T., Chiba, M., Honma, T. and Niwa, J. (2003) Detection of Andersen, M.S., Clark, L., Dyson, S.J. and Newton, J.R. (2006) Risk hemosiderin deposition by T2*-weighted MRI after subarachnoid factors for colic in horses after general anaesthesia for MRI or hemorrhage. Stroke 34, 1693-1698. nonabdominal surgery: absence of evidence of effect from Imokawa, H., Tazawa, T., Suqiura, N., Oyake, D. and Yosino, K. (2003) perianaesthetic morphine. Equine Vet. J. 38, 368-374. Penetrating neck injuries involving wooden foreign bodies: the role Arena, L., Morehouse, H.T. and Safir, J. (1995) MR imaging artifacts of MRI and the misinterpretation of CT images. Auris Nasus Larynx that simulate disease: how to recognize and eliminate them. 30, S145-S147. Radiographics 15, 1373-1394. Karchevsky, M., Schweitzer, M.E., Morrison, W.B. and Parellada, J.A. fi Black, B., Cribb, N.C., Nykamp, S.G., Thomason, J.J. and Trout, D.R. (2004) MRI ndings of septic arthritis and associated osteomyelitis in (2013) The effects of perineural and intrasynovial anaesthesia of adults. Am. J. Roentgenol. 182, 119-122. the equine foot on subsequent magnetic resonance images. Kidd, J.A., Voute, L.C. and Hewetson, M. (2004) Rupture of the flexor Equine Vet. J. 45, 320-325. tendons of a horse secondary to a non-responsive digital sheath Boado, A., Kristoffersen, M., Dyson, S. and Murray, R. (2005) The use of sepsis. Vet. Rec. 155, 201-204. nuclear scintigraphy and magnetic resonance imaging to Kidd, J.A., Lu, K.G. and Frazer, M.L. (2014) Atlas of Equine diagnose chronic penetrating wounds in the equine foot. Equine Ultrasonography, John Wiley & Sons Ltd, Chichester, West Sussex, Vet. Educ. 17, 62-68. UK. Bodne, D., Quinn, S.F. and Cochran, C.F. (1998) Imaging foreign glass Kinns, J. and Mair, T. (2005) The use of magnetic resonance imaging and wooden bodies of the extremities with CT and MR. J. Comput. to assess soft tissue damage in the foot following penetrating injury Assist. Tomogr. 12, 608-611. in 3 horses. Equine Vet. Educ. 17, 69-73. Bradley Jr, W.G. (1993) MR appearance of hemorrhage in the brain. Kocher, M.S., Lee, B., Dolan, M., Weinberg, J. and Shulman, S.T. (2006) Radiology 189, 15-26. Pediatric orthopedic infections: early detection and treatment. Brokken, M.T., Schneider, R.K., Sampson, S.N., Tucker, R.L., Gavin, P.R. Pediatr. Ann. 35, 112-122. and Ho, C.P. (2007) Magnetic resonance imaging features of Ledermann, H., Schweitzer, M.E. and Morrison, W.B. (2002) proximal metacarpal and metatarsal injuries in the horse. Vet. Nonenhancing tissue on MR imaging of pedal infection: Radiol. Ultrasound. 48, 507-517. characterisation of necrotic tissue and associated limitations for

diagnosis of osteomyelitis and abscess. Am. J. Roentgenol. 78, 215- postarthroscopic magnetic susceptibility artifacts in horses. Vet. 222. Radiol. Ultrasound. 57, 587-593. Meehan, L. (2017) Should I use MRI to evaluate horses with foot Urraca del Junco, C.I., Mair, T.S., Powell, S.E., Milner, P.I., Font, A.F., penetrations?. Equine Vet. Educ. 29, 521-522. Schwarz, T. and Weaver, M.P. (2012) Magnetic resonance imaging findings of equine solar penetration wounds. Vet. Radiol. Ober, C.P., Jones, J.C., Larson, M.M., Lanz, O.I. and Werre, S.R. (2008) Ultrasound. 53, 71-75. Comparison of ultrasound, computed tomography, and magnetic resonance imaging in detection of acute wooden foreign bodies in the canine manus. Vet. Radiol. Ultrasound. 49, 411-418. Supporting information Sampson, S.N., Schneider, R.K., Tucker, R.L., Gavin, P.R., Zubrod, C.J. and Ho, C.P. (2007) Magnetic resonance imaging features of Additional Supporting Information may be found in the online oblique and straight distal sesamoidean desmitis in 27 horses. Vet. version of this article at the publisher’s website: Radiol. Ultrasound. 48, 303-311. Schommer, K., Kallenberg, K., Lutz, K., Bartsch, P. and Knauth, M. Supplementary Item 1: Cases that underwent surgery not (2013) Hemosiderin deposition in the brain as footprint of high- directed by the MR imaging. altitude cerebral edema. Neurology 81, 1776-1779. Taylor, A.H., Mair, T.S., Smith, L.J. and Perkins, J.D. (2010) Bacterial Supplementary Item 2: Cases that underwent surgery after culture of septic synovial structures of horses: does a positive MR imaging that was guided by the MRI. bacterial culture influence prognosis?. Equine Vet. J. 42, 213-218. Thomas, A.L., Schramme, M.C., Lepage, O.M. and Segard, E.M. (2016) Supplementary Item 3: Cases where no surgical intervention Low-field magnetic resonance imaging appearance of occurred.

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He, H., Fioletov, V.E., Tarasick, D.W., Mathews, T.W. and Long, C. (2013) Seltenhammer, M.H., Heere-Ress, E., Brandt, S., Druml, T., Jansen, B., Validation of environment Canada and NOAA UV index forecasts Pehamberger, H. and Niebauer, G.W. (2004) Comparative with brewer measurements from Canada. J. Appl. Meteorol. histopathology of grey-horse-melanoma and human malignant Climatol. 52, 1477–1489. melanoma. Pigment Cell Res. 17, 674–681. Kanellis, V.G. (2019a) A review of melanin sensor devices. Biophys. Van Ongeval, A., van de Velde, N., Raes, E. and Oosterlinck, M. Rev.,1–7. https://doi.org/10.1007/s12551-019-00581-8 (2020) Chronic lameness caused by vascular compression of the Kanellis, V.G. (2019b) Ultraviolet radiation sensors: a review. Biophys. iliac artery and vein by a malignant melanoma in the pelvis of a grey Spanish gelding. Equine Vet. Educ. 32, 623. Rev.,1–5. https://doi.org/10.1007/s12551-019-00556-9 Xu, D.H., Zhu, Z., Xiao, H., Wakeﬁeld, M.R., Bai, Q., Nicholl, M.B., Ding, Metcalfe, L.V., O'Brien, P.J., Papakonstantinou, S., Cahalan, S.D., V.A. and Fang, Y. (2017) Unveil the mysterious mask of cytokine- McAllister, H. and Duggan, V.E. (2013) Malignant melanoma in a – grey horse: case presentation and review of equine melanoma based immunotherapy for melanoma. Cancer Lett. 394,43 51. treatment options. Irish Vet. J. 66, 22.

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Original Article Clinical and ultrasonographic evaluation of three suture techniques for closure of the equine linea alba M. E. Verkade†* , F. Ugahary‡, A. Martens§ and P. Wiemer†§ †De Lingehoeve Diergeneeskunde, Lienden, The Netherlands; ‡MD Surgeon n.p., Consultant in General Surgery, Tiel, The Netherlands; and §Department of Surgery and Anaesthesiology of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium *Corresponding author email: [email protected]

Keywords: horse; closure; linea alba; incisional; suture technique

Summary still up to 10% (Gibson et al. 1989; French et al. 2002; Mair and Surgical technique plays an important role in preventing Smith 2005a,b,c; Kelmer 2009). Most incisional hernias are ventral midline incisional complications. The aim of this study associated with the development of oedema, drainage or was to compare the clinical and ultrasonographic outcome of infection in the first week after surgery (Kelmer 2009). three suture techniques for closure of the linea alba. In this Several risk factors contribute to the development of post- prospective case series (n = 43), horses operated for acute surgical incisional complications. These include on the one abdominal intestinal disease through a midline incision were hand intrinsic factors, such as age, metabolic disorders, randomised in three groups: closure with a conventional immune status (and disorders), level of pain, body condition continuous technique (Group 1), a small stitches continuous score, and on the other hand extrinsic factors, such as technique (Group 2) and the UX-technique (shoe-lace surgical technique, suture material characteristics and configuration, Group 3). Age, sex, body weight, type and experience of the surgical team (Humphreys 2009). Whereas duration of surgery were recorded and the suture to wound intrinsic factors can only be improved to a certain extent as length ratio was calculated. Clinical evaluation of the wound they are related to the horse, extrinsic factors can be (wound discharge) was performed daily during hospitalisation. optimised by the surgeon. Several studies describe the At 7 weeks post-operatively the linea alba was evaluated importance of suture technique in the prevention of incisional clinically and ultrasonographically. The linea alba width was complications both in humans and horses. The choice of measured halfway along the length of the incision. One horse suture material and suture technique plays an important role in Group 1 had acute incisional dehiscence, but there were no in wound healing by contributing to incisional strength, further significant differences between the groups in the short preservation of the vascularisation and tension on the wound term. Seven weeks post-operatively two horses had complete edges (Gibson et al. 1989; Israelsson and Jonsson 1993; herniation in Group 1 and one horse had partial herniation in French et al. 2002; Kelmer 2009; Auer 2012; Darnaud et al. Group 2. In the UX group no herniation occurred. The incidence 2016). Therefore, an optimal closure technique of the linea of herniation was not significantly different between the groups. alba is important to prevent complications. The On ultrasound at 7 weeks the linea alba width was significantly recommended conventional technique after a midline smaller in Group 2 (P = 0.00029) and Group 3 (P = 0.0018) laparotomy in horses is a continuous pattern with a bite size compared with Group 1, even with exclusion of the acute and interval size of 1.5 cm (Trostle et al. 1994; Hassan et al. incisional dehiscence and two herniated horses. Limitations 2006; Kummerle€ 2012). In human surgery there is evidence were the small group size and relatively low incidence of that a continuous closure with smaller stitches reduces the incisional complications for statistical analysis. It was complication rate and increases the strength of the suture concluded that the use of small stitches and the UX-technique line (Israelsson and Jonsson 1993; Harlaar et al. 2009; Millbourn resulted in a smaller linea alba width compared with the et al. 2011). The described small stitch pattern uses a stitch conventional continuous suture technique and might therefore interval of 5 mm and incorporates only the linea alba without be preferred for closure of the linea alba in equine colic passing through the rectus muscle sheath. surgery. Another technique described in human surgery for abdominal incision closure is the UX-technique (Ugahary 2006). ‘ ’ Introduction In this technique, a double continuous suture pattern (the X )is supported by a longitudinally placed tape in the medial corner Colic surgery is frequently performed in horses and the ventral of the rectus sheath (the ‘U’) to re-inforce the linea alba. midline incision is the most commonly used surgical The aim of the present study was to compare the clinical approach. Incisional complications are frequently observed and ultrasonographic outcome for closure of the equine and include incisional infection, hernia formation and acute linea alba using three different suture techniques: the dehiscence (Gibson et al. 1989; French et al. 2002; Mair and conventional continuous technique, the small stitches Smith 2005a,c; Isgren et al. 2017). These complications can continuous technique and the UX-technique. The hypothesis be serious and herniation may need surgical re-intervention in is that the small stitches continuous technique and the UX- the long term, while acute dehiscence always needs surgical technique would reduce the risk of incisional herniation and repair. The incidence of hernia formation after abdominal would result in a smaller linea alba width, compared with the surgery in horses has decreased over the last decades, but is conventional continuous technique.

Materials and methods and stitch interval were measured with a sterile stainless steel ruler, to make sure these were uniform throughout the The study was performed between April 2009 and February pattern. The suture was placed in the medial corner of 2012. Horses that had a midline laparotomy for acute the external rectus sheath, passing through the external abdominal intestinal disease were included if owners gave fascia of the rectus sheath, the rectus abdominis muscle informed consent for participation to the study. Exclusion and the internal fascia of the rectus sheath (Fig 1a). The criteria were horses younger than 3 years, a bodyweight end of the suture line was knotted with surgical knots with under 500 kg, pregnant mares, horses with a previous 5–6 throws. laparotomy and diseases interfering with wound healing (e.g. pituitary pars intermedia dysfunction, recurrent airway Group 2: Small stitches continuous technique obstruction, neoplasia, renal disease or liver disease). To A bite size of 6 mm and a bite interval of 6 mm were used in eliminate variations based on individual surgeons, only horses the small stitches continuous technique group using a 150-cm admitted on days when the same surgeon was on duty were long polydioxanone USP 2 (PDS7). The bite size and stitch included. Horses were randomised into three groups just prior interval were measured with a sterile stainless steel ruler, to to surgery by picking an envelope. All horses were sedated make sure these were uniform throughout the pattern. The â1 – with detomidine (Detosedan ) (0.01 0.02 mg/kg bwt) and stitches were placed in or closer to the linea alba compared â2 – butorphanol (Dolorex ) (0.05 0.1 mg/kg bwt), and received with the conventional technique (Fig 1b). If the suture fl â2 unixin meglumine (Finadyne ) (1.1 mg/kg bwt) and material was too short, a second suture strand was used, gentamicin (Genta-ject 10%â3) (6.6 mg/kg bwt) â1 starting on the opposite site of the incision. In these cases, intravenously (i.v.) and procaine penicillin (Procapen ) sutures lines were overlapped 2–3 cm in the centre of the (22.000 IU/kg bwt) intra-muscular (i.m.) prior to surgery. â4 incision and the suture ends were knotted separately with Anaesthesia was induced with midazolam (Midazolam ) surgical knots with 5–6 throws. (0.1 mg/kg bwt) and ketamine (Narketan 10â5) (2 mg/kg bwt) i.v. and the horses were maintained under general Group 3: UX-technique fl â6 anaesthesia with Iso urane (IsoFlo 100 ) into a mixture of Using the UX-technique, a PDS tape of 5 mm width and oxygen and air. The horses were placed in dorsal 200 cm length (PDS7), was positioned in a U-shaped recumbency and the abdomen was clipped, prepared configuration in the medial corner of each rectus sheath, aseptically and draped in a routine matter. A ventral midline and oversewn using an X-shaped pattern (Fig 1c). To incision was made through the linea alba starting at the achieve this UX suture configuration, two tunnelling devices umbilicus and directing cranially. The length of the incision (custom made9) are required. These tunnelling devices are was measured with a sterile stainless steel ruler and recorded. slightly curved metal tubes of 40 cm length and a 5 mm The length of any incisional deviation from the linea alba, external diameter with a blunt trocar (Fig 2). A small incision fi evident by exposed muscle bres from the rectus abdominis was made in the external fascia of the rectus sheath, 1 cm muscle, was measured in the longitudinal axis with a ruler and lateral to the cranial end of the midline incision. The recorded. The surgical procedure was dictated by the acute tunnelling device was introduced through this small incision abdominal intestinal disease the horse was suffering from and and guided through the medial corner of the rectus sheath was performed by the same surgeon for all groups. Closure of to the caudal end of the midline incision. At the caudal the linea alba was performed using one of the three end of the midline incision the tunnelling device was techniques described below, depending on the group to exteriorised by making a small incision in the external fascia which the horse was assigned. The subcutaneous layer was over the tip of the tunnelling device. The same was done closed with a continuous suture pattern using polyglactin 910 at the opposite side of the midline incision. The tape was USP 0 (Vicryl7) and the skin was closed with polyamide USP 2 8 divided into two equal parts (but not cut) and suturing was (Supramid ) in a continuous interlocking suture pattern. A started at the cranial side of the midline incision. The tape sterile cotton stent was sutured on the abdominal wound and was placed from left to right in a simple continuous pattern all horses had a head and tail rope-assisted recovery. Most with a curved Buhner needle with a diameter of 2.5 mm fi horses got up at the rst or second attempt and were kept in (custom made9, Fig 2), perpendicular to and just around a standing position with the assistance of the ropes. No the tunnelling device, moving from the cranial edge to the abdominal bandage was applied during recovery or in the caudal edge of the incision. The bite size was 1.5 cm from days after. The horses were allowed to lie down in the stable the wound edge and had a stitch interval of 3 cm. The bite after surgery. Post-operative care was performed according size and stitch interval were measured with a sterile stainless to the needs of the horses. The cotton stent remained in steel ruler, to make sure these were uniform throughout the place for 5 days after surgery. It was removed sooner if it pattern. After having placed one half of the tape from the became soaked with wound discharge. All horses received left to the right, the other half of the tape was encircled 5 days of i.v. gentamicin (6.6 mg/kg bwt, s.i.d.) and i.m. around the tunnelling devices from the right to the left in procaine penicillin (22.000 IU/kg bwt, b.i.d.) post-operatively. the same pattern. This created a X-shaped ‘shoe-lace’ The horses were box rested with 10 min in hand walking daily configuration, with both ends of the tape at the caudal until re-evaluation at 7 weeks post-operatively. end of the incision. At this stage the ends of the tape on both sides were attached to the trocar in the tunnelling Linea alba suture techniques device and retrieved through the tunnelling device to the Group 1: Conventional continuous technique cranial side of the incision. Thereafter, the tunnelling device In the conventional group, the linea alba was closed was withdrawn from the rectus sheath, leaving the tape in with a bite size of 1.5 cm and an interval of 1.5 cm using a place. In this way, the longitudinal part of the tape was 150-cm long polydioxanone USP 2 (PDS7). The bite size positioned in the medial corner of the rectus sheath (U-

a) c) Running tape

ERS

RAM RAM Longitudinal tape LA cranial IRS

caudal 1 23

4 5 6

Fig 1: Schematic presentation and picture of the three suture techniques. The diagrams represent a transverse section of the abdominal wall with the two rectus sheaths fusing to the linea alba. ERS, external rectus sheath; IRS, internal rectus sheath; LA, linea alba; RAM, rectus abdominis muscle. a) Conventional continuous technique. b) Small stitch continuous technique. c) UX-technique (the six steps to obtain the shoe-lace conﬁguration). 1. Introduction of the tunnelling device through a small incision in the fascia external rectus sheath. 2. Both the tunnelling devices are placed in the medial corner rectus sheath. 3. One side of the shoe-lace pattern is completed. 4. Both sides of the shoe-lace pattern are completed. 5. Removal of the tunnelling devices from the medial corner of the rectus sheath, leaving the longitudinal tape in place. 6. Tightening of the shoe-lace pattern. The circle represents the surgical knot to secure the tape.

shaped), and was encircled by the running part of the (SL) was measured by reducing the total suture length with suture (X-shaped). The loose ends of the tape were looped the cut ends which were measured with a ruler. The SL:WL several times under the running part (2nd or 3rd X) and ratio was calculated for Groups 1 and 2. Acute dehiscence attached to it with a polyglactin 910 USP 0 (Vicryl7) surgical was defined as the failure of the abdominal wall closure with knot with 5–6 throws. protrusion of the abdominal contents and was acted upon immediately, by re-operating if possible. Clinical evaluation of Data recording and measurements the wound for signs of infection was performed daily during Age, sex, bodyweight, type of surgery (with or without hospitalisation. Infection was defined as any purulent enterotomy/resection) and duration of surgery were discharge from the incision 48 h post-operatively and of more recorded. The longitudinal length of the linea alba incisional than 36 h of duration. Seven weeks after surgery, the wound deviation was recorded in centimetres with a ruler and, if this was evaluated clinically for herniation, which was defined as occurred at multiple locations, these numbers were added a palpable or visible defect in the abdominal wall with up to one length. Wound length (WL) was measured with a overlying intact skin. Ultrasonography of the linea alba was ruler for all horses and for Groups 1 and 2 the suture length performed 7 weeks after surgery (Aloka 3500, linear probe 5–

surgery and duration of hospitalisation between the three different groups. The mean length of the linea alba incisional deviation was greater in Group 3 than in Groups 1 and 2, although not 1. significantly (3.0 cm Æ 0.76 cm in Group 3, 1.64 cm Æ 0.47 cm (P = 0.414) and 1.5 cm Æ 0.62 cm (P = 0.306) in Groups 1 and 2 respectively). Any deviation from the linea 2. alba always occurred in the cranial part of the incision. The mean incision length (in cm) did not differ significantly between groups (19.5 cm Æ 1.2 cm in Group 1, 19.9 cm Æ 3. 1.4 cm in Group 2 and 22.3 cm Æ 1.1 cm in Group 3). The conventional technique had a SL:WL ratio of 4.5:1, while the ratio in the small stitch group was 5.6:1. Fig 2: Custom-made tunnelling device and Buhner needle. One horse in Group 3 developed a surgical site infection 1. Slightly curved tunnelling device with trocar inserted, tip is 48 h after surgery and still present 96 h post-operatively. There displayed to the left. 2. Slightly curved tunnelling device and were no horses in the other groups with signs of surgical site trocar separate, tip is displayed to the left. 3. Curved Buhner fi needle, needle tip is displayed to the left. infection as previously de ned. This difference between the groups was not significant. There was no prolonged antimicrobial treatment or additional wound drainage 10 MHz10). The incisional area was cleaned, clipped and necessary during this period of time. The skin sutures were alcohol was applied to retrieve the best image. The area of removed 14 days post-operatively, at which time no wound interest was halfway along the length of the incision, and this drainage was encountered in either groups. In Group 1, there was determined with a tape measure. Transverse images of was one horse with an acute dehiscence during recovery the linea alba were obtained and the width of the linea alba from anaesthesia, because of a rupture of the suture at 2/3 was measured by measuring the distance between the of the incision length. This horse was re-operated and medial corners of the rectus abdominis muscle. All excluded from the ultrasonographic evaluation at 7 weeks. measurements were done using an automatic ruler. Standard Clinical evaluation 7 weeks post-operatively showed two machine settings for tendons were used and the frequency, horses in Group 1 with a complete herniation. In Group 2 one focus and depth were adjusted to individual horse and area horse showed a herniation of the cranial third of the incision. of interest. In Group 3 no herniation occurred. This difference was not significant between the groups (Group 2; P = 0.321, Group 3; Statistical analysis P = 0.079 compared with Group 1). On ultrasonographic Relationships between suture techniques and the recorded evaluation 7 weeks post-operatively (Fig 3) the width of the variables (age, sex, bodyweight, type of surgery, length of linea alba was significantly smaller in Groups 2 and 3 incisional deviation, length of incision, surgical site infection, compared with Group 1 (6.0 Æ 1.0 cm in Group 1, with width of the linea alba 7 weeks post-surgery, occurrence of exclusion of the acute burst and two herniated horse; herniation and duration of hospitalisation) were explored. For 2.5 Æ 0.3 cm (P = 0.012) in Group 2 and 3.0 Æ 0.1 cm continuous variables, differences between suture techniques (P = 0.03) in Group 3) (Fig 4). were analysed using ANOVA. Normality of residuals was evaluated on QQ plots and by Shapiro-Wilk tests. Discussion Homogeneity of variances was evaluated on residuals VS fitted plots and by a Levene’s test. When residuals were not Despite extensive research into intrinsic risk factors, different normally distributed, a Kruskal-Wallis test was performed suture materials and methods to protect the incision after instead. When heteroscedasticity was detected, the data surgery, the incidence of incisional complications after were analysed using a Welch test with Games-Howell post- ventral midline celiotomy is still high (Fogle 2019). Human hoc test. For discrete variables, differences between suture literature states that up to 70% of incisional complications can techniques were analysed using chi square tests, except actually be linked to extrinsic risk factors like the experience when occurrences of an event were low, in which case a of the surgical team and the surgical technique used Firth regression was used. Significance was set at P<0.05 (Israelsson 1998; Humphreys 2009). This finding urges the (SPSS 25 for Windows11). necessity to investigate the outcome of different surgical techniques to prevent incisional complications in equine ’ fi Results horses. To the authors knowledge, this is the rst prospective study comparing different suture techniques for closure of the Seventy-three horses were initially included in the study: 11 linea alba in clinical equine horses. were subjected to euthanasia during surgery, 10 were The incidence of herniation in this study (9.3%) is in subjected to euthanasia within a week after surgery for other agreement to previous studies (Trostle et al. 1994; French reasons than wound complications and 9 were lost during the et al. 2002). Although the numbers are small and there was follow-up period. Data were retrieved from the remaining 43 no significant difference, the occurrence of one acute horses and are presented in Table 1. Results were obtained dehiscence and two herniations in Group 1 suggests that the for 14 horses in both Groups 1 and 2 and for 15 horses in conventional technique might be the weakest of the three Group 3. The results are reported as mean Æ s.d. suture techniques in this study. In these three horses no There was no significant difference in age, sex, surgical site infection was present. The USP 2 suture material bodyweight, type of surgery, length of incision, duration of that was used is relatively small for the over 500 kg horses that

TABLE 1: Horse and surgical data for the 43 horses where follow-up after surgery was available

Group 1 Group 2 Group 3 Conventional Small stitch UX-technique N = 14 N = 14 N = 15

Pre-operative Mean age (years + range) 11.6 (4–30) 10.6 (3–22) 8.7 (3–20) Mean bodyweight (kg + range) 569 (510–628) 576 (506–620) 580 (504–698) Sex (N) Stallion 1 3 1 Gelding 6 5 7 Mare 7 6 7 Breed (N) Warmblood 11 11 12 Friesian 1 1 2 Other 2 2 1 Peri-operative Mean incision length (cm Æ s.d.) 19.5 Æ 1.2 19.9 Æ 1.4 22.3 Æ 1.1 Mean length deviation LA (cm Æ s.d.) 1.64 Æ 0.47 1.5 Æ 0.62 3.0 Æ 0.76 Type of surgery (N) Enterotomy/resection 6 8 7 No enterotomy/resection 8 6 8 Duration of surgery (min Æ s.d.) 80 Æ 5.5 94 Æ 5.5 91 Æ 6.2 SL:WL ratio 4.5:1 5.6:1 - Hospitalisation Clinical signs (N) Surgical site infection 0 0 1 Acute dehiscence 1 0 0 Days of hospitalisation (mean + range) 7.8 (5–18) 7.7 (5–14) 7.3 (5–14) 7 weeks post-operative Incidence herniation (N) 2 1 0 Width of LA (cm + s.d.) 6.0 Æ 1.0* 2.5 Æ 0.3 3.0 Æ 0.1

* Signiﬁcant (P < 0.05).

RAM RAM RAM RAM LA LA

a) c)

RAM RAM RAM RAM

LA LA b) d)

Fig 3: Ultrasonographic evaluation of the linea alba 7 weeks post-operatively. Transverse image of the linea alba obtained with a linear ultrasound probe. LA, linea alba; RAM, rectus abdominis muscle. a) Normal LA (non operated = reference image). b) LA after conventional closure (Group 1). c) LA after small stitch closure (Group 2). d) LA after UX-closure (Group 3). The longitudinal PDS tape (arrows) in the rectus sheath as well as the running PDS tape (asterisk) are still visible. were included in the study. A larger suture material size could case in the present study (Trostle et al. 1994). Deviation from potentially improve the results, especially for the conventional the linea alba and opening of the rectus sheath impairs the technique. The small stitches technique in Group 2 could suture strength, because the holding power of the external apparently compensate for the smaller sized suture material, fascia of the rectus sheath is less than the holding power of since complete incisional herniations did not occur. A larger the linea alba (Boone et al. 2014). Not only the fibrous mass size suture material, in combination with the small stitch contributes to this holding power, but also the alignment of technique could be even more resistant to hernia formation. the fibres (Axer et al. 2001; Levillain et al. 2016). In the As the linea alba becomes smaller in width when it external fascia of the rectus sheath the collagen fibre pattern advances cranially, incisional deviation is more likely to is orientated predominantly in a craniolateral-caudomedial happen in the cranial part of the incision, which was also the oblique pattern. The internal fascia of the rectus sheath

10 The choice for including the UX-technique in the comparison was based on the promising results obtained in human medicine (Ugahary 2006) and on the results of an 8 ex vivo study showing that equine linea alba closed with the UX-technique had a significantly higher tensile strength compared with the conventional suture pattern (Wiemer and 6 Ugahary 2008). From a technical point of view, the UX- technique is superior in terms of tension distribution, because the longitudinal part of the tape reinforces the linea alba by 4 distributing the tension on the linea alba equally (Hollinsky * et al. 2007; Wiemer and Ugahary 2008). The technique Width of LA (cm) * however has some potential downsides in equine horses. 2 There is a higher amount of suture material needed to complete the UX-technique, but no knots are made with the tape to prevent bulking of the suture material. Although no surgical site infections occurred in this study, there could be a 0 risk of the tape forming a nidus and becoming infected. To Conventional Small stitch UX reduce the risk of infection, it is preferable to place the tape Suture technique in a flat configuration to avoid pocket formation by twisting Fig 4: Width of the linea alba 7 weeks post-operatively in the three of the tape. Compared with a standard continuous pattern, groups. Bar graph representing the mean values for the width of the the UX-technique is more challenging to perform. Therefore, linea alba at 7 weeks post-operatively. The error bars represent the the authors do not use this technique routinely, but it is standard deviation. The asterisk represents a significant difference considered in horses with an increased risk for herniation. < compared with the conventional technique. (P 0.05). Further research should be done to investigate the possibility of using a combination of different suture materials with this mainly has fibre patterns in a transverse direction. In the linea technique (e.g. tape for longitudinal part, normal suture alba, where the fascia of both external and internal rectus material for running part). sheaths join, the fibre directions from both sides are The incidence of surgical site infections in this study (2%) is continued, resulting in a complex crossing pattern of fibres. As lower than the 10–37% previously described (Fogle 2019). This a result, the suture cannot cut through the linea alba as could partially be related to the fact that the cotton stent easily as compared with the fascia of the rectus sheath (Axer stayed in place for 5 days post-operatively. The outcome of et al. 2001; Boone et al. 2014; Levillain et al. 2016). In the using a stent as preventative for incisional complications conventional suture technique, the stitches are placed lateral varies widely in the literature (Gibson et al. 1989; Mair and to the linea alba through the rectus sheath. Because of the Smith 2005a,c; Torfs et al. 2010; Tnibar et al. 2013). Although tensile forces the suture is pulled through the external fascia the incision was checked daily for drainage and the stent of the rectus sheath until it reaches the lateral border of the was removed when it became soaked with discharge, the linea alba (Wiemer and Ugahary 2008). This could have stent could have contributed to missing horses with mild contributed to the pronounced widening of the scar of the incisional discharge. At the time of suture removal 14 days linea alba which was observed ultrasonographically 7 weeks post-operatively, none of the horses showed signs of either post-operatively. With this tearing, additional tissue trauma surgical site infection or incisional drainage. occurs, leading to disturbances in vascularisation and Ultrasonography is a useful diagnostic tool to evaluate the possible inflammation which may result in delayed healing linea alba (Mendes et al. 2007; Beer et al. 2009; Verkade and an increase in complications (Kelmer 2009). Several et al. 2018). At ultrasonographic evaluation 7 weeks post- surgical aspects, like surgical time, type of surgery and operatively, both the small stitch and the UX-technique had incision length have previously been described as risk factors significantly less widening of the linea alba. This is probably for incisional complications (Wilson et al. 1995; Honnas and due to a stronger suture-wound interface, with less tearing of Cohen 1997; Colbath et al. 2014; Darnaud et al. 2016). In our the suture, resulting in reduction of vascular compromise and study, these risk factors did not appear to be significantly inflammation. The UX-technique showed a slightly wider linea different between the groups. alba scar compared with the small stitch technique, which There is limited data available on suture bite intervals in a could be explained by the fact that the Buhner needle is not simple continuous suture pattern for the equine linea alba. so curved that it could follow the radius of the tunnelling Trostle et al. (1994) suggested an ideal suture interval and bite device. Because of that, the running tape is not entirely size of 1.5 cm. Hassan et al. (2006) then investigated a smaller tightly apposing the longitudinal part of the tape. In the small suture interval with the same bite size and did not find any stitch technique, the stitches are placed in or just beside the significant differences in bursting strength, compared with the linea alba with a narrow stitch interval. The tensile forces are 1.5 cm interval and bite size. Both these studies only distributed onto more stitches (Æ5 stitches/3 cm vs. Æ 1.8 investigated the strength of the linea alba in cadaver tissue by stitches/3 cm for a conventional suture pattern), resulting in tensile forces in a transverse direction, with one single failure less tearing at the wound edges. The small stitches technique load. This does not represent a clinical situation where the achieved a good outcome even with the small suture linea alba shows an anisotropic behaviour and is exposed to material size (USP 2) used in this study. This finding suggests multi-directional tension and repetitive loading (Cooney et al. that with the smaller stitch interval technique the suture 2015, 2016). Further research on clinical horses is needed to material size could potentially be down-sized from the find the ideal suture interval and bite size. conventional used material (USP5-7), thereby contributing to

the reduction of the infection rate at the suture material Beer, G.M., Schuster, A., Seifert, B., Manestar, M., Mihic-Probst, D. and (Marshall and Blikslager 2019). Weber, S.A. (2009) The normal width of the linea alba in nulliparous women. Clin. Anat. 22, 706-711. Objective data concerning the quality of the fibrous scar tissue could not be obtained due to the design of the study Boone, L.H., Epstein, K., Cremer, J., Rogers, A., Foutz, T., Quandt, J. and Mueller, P.O.E. (2014) Comparison of tensile strength and early and the small group sizes and the relatively low incidence of healing of acute repeat celiotomy through a ventral median or a incisional infection were other important study limitations. right ventral paramedian approach. Vet. Surg. 43, 741-749. Colbath, A.C., Patipa, L., Berghaus, R.D. and Parks, A.H. (2014) The Conclusion influence of suture pattern on the incidence of incisional drainage following exploratory laparotomy. Equine Vet. J. 46, 156-160. Although the numbers are relatively small, the present study Cooney, G.M., Moerman, K.M., Takaza, M., Winter, D.C. and Simms, indicates that both the small stitch technique and the UX- C.K. (2015) Uniaxial and biaxial mechanical properties of porcine technique resulted in a significantly smaller linea alba scar linea alba. J. Mech. Behav. Biomed. Mater. 41, 68-82. compared with the conventional continuous suture technique Cooney, G.M., Lake, S.P., Thompson, D.M., Castile, R.M., Winter, D.C. and might be preferred for closure of the linea alba in equine and Simms, C.K. (2016) Uniaxial and biaxial tensile stress-stretch colic surgery. response of human linea alba. J. Mech. Behav. Biomed. Mater. 63, 134-140. ’ Darnaud, S.J.M., Southwood, L.L., Aceto, H.W., Stefanovski, D., Authors declaration of interests Tomassone, L. and Zarucco, L. (2016) Are horse age and incision length associated with surgical site infection following equine colic No conflicts of interest have been declared. surgery? Vet. J. 217, 3-7. Fogle, C.. (2019) Chapter 41 - postoperative care, complications, and Ethical animal research reoperation of the colic patient. In: Equine Surgery, 5th edn., Eds: Auer, J.A., Stick, J.A., Kummerle,€ J.M. and Prange, T., W.B. The authors confirm that Dutch law allows randomised Saunders, Philadelphia. pp 660-677. prospective research studies on clinical horses with existing French, N.P., Smith, J., Edwards, G.B. and Proudman, C.J. (2002) techniques to proceed without oversight from an Ethical Review Equine surgical colic: risk factors for postoperative complications. Committee. Equine Vet. J. 34, 444-449. Gibson, K.T., Curtis, C.R., Turner, A.S., McIlwraith, C.W., Aanes, W.A. and Stashak, T.S. (1989) Incisional hernias in the horse incidence Sources of funding and predisposing factors. Vet. Surg. 18, 360-366. No funding received. Harlaar, J.J., van Ramshorst, G.H., Nieuwenhuizen, J., ten Brinke, J.G., Hop, W.C.J., Kleinrensink, G. and Lange, J.F. (2009) Small stitches with small suture distances increase laparotomy closure strength. Acknowledgements Am. J. Surg. 198, 392-395. Hassan, K.A., Galuppo, L.D. and van Hoogmoed, L.M. (2006) An in vitro We thank Dr M. Haspeslagh for his assistance with statistical comparison of two suture intervals using braided absorbable loop consulting and H. Tremaine for proof-reading the manuscript. suture in the equine linea alba. Vet. Surg. 35, 310-314. Hollinsky, C., Sandberg, S. and Kocijan, R. (2007) Preliminary results with the reinforced tension line: a new technique for patients with Authorship ventral abdominal wall hernias. Am. J. Surg. 194, 234-239. M. Verkade and P. Wiemer contributed to study design, study Honnas, C.M. and Cohen, N.D. (1997) Risk factors for wound infection following celiotomy in horses. J. Am. Vet. Med. Assoc. 210, 78-81. execution, data analysis and interpretation, and preparation of the manuscript. F. Ugahary contributed to study design Humphreys, H. (2009) Preventing surgical site infection. where now? J. Hosp. Infect. 7, 316-322. and study execution. A. Martens contributed to preparation of the manuscript. All authors gave their final approval of the Isgren, C.M., Salem, S.E., Archer, D.C., Worsman, F.C.F. and Townsend, N.B. (2017) Risk factors for surgical site infection following manuscript. laparotomy: effect of season and perioperative variables and reporting of bacterial isolates in 287 horses. Equine Vet. J. 49, 39-44. Manufacturers' addresses Israelsson, L.A. (1998) The surgeon as a risk factor for complications of midline incisions. Eur. J. Surg. 164, 353-359. 1 AST Farma, Oudewater, the Netherlands. Israelsson, L.A. and Jonsson, T. (1993) Suture length to wound length 2MSD Animal Health Nederland, Boxmeer, the Netherlands. 3 ratio and healing of midline laparotomy incisions. Br. J. Surg. 80, Dopharma, Raamsdonksveer, the Netherlands. 1284-1286. 4Actavis, Baarn, the Netherlands. 5Vetoquinol, ’s Hertogenbosch, the Netherlands. Kelmer, G. (2009) Update on recent advances in equine abdominal 6Zoetis, Capelle a/d IJssel, the Netherlands. surgery. Vet. Clin. N. Am: Equine Pract. 25, 271-282. 7 Ethicon, Norderstedt, Germany. Kummerle,€ J.M.. (2012) Chapter 16 - suture materials and patterns. In: 8 B Braun Medical, Melsungen, Germany. Equine Surgery, 4th edn., Eds: Auer, J.A. and Stick, J.A., W.B. 9 Knijpers instruments, Groesbeek, The Netherlands. Saunders, St. Louis. pp. 181-202. 10Aloka Co. Ltd., Tokyo, Japan. Levillain, A., Orhant, M., Turquier, F. and Hoc, T. (2016) Contribution of 11IBM Corp. Released 2017. IBM SPSS Statistics for Windows, Version collagen and elastin fibers to the mechanical behavior of an 25.0., Armonk, NY. abdominal connective tissue. J. Mech. Behav. Biomed. Mater. 61, 308-317. References Mair, T.S. and Smith, L.J. (2005a) Survival and complication rates in 300 horses undergoing surgical treatment of colic. part 2: short-term Auer, J.A. (2012) Chapter 12 - surgical techniques. Equine Surgery, 4th complications. Equine Vet. J. 37, 303-309. edn., W.B. Saunders, St Louis. pp 138-149. Mair, T.S. and Smith, L.J. (2005b) Survival and complication rates in 300 fi Axer, H., Keyserlingk, D.G. and Prescher, A. (2001) Collagen bers in horses undergoing surgical treatment of colic. part 1: short-term linea alba and rectus sheaths. J. Surg. Res. 96, 127-134. survival following a single laparotomy. Equine Vet. J. 37, 296-302. Continued on page 672 © 2019 EVJ Ltd EQUIPMENT THAT WORKS AS HARD AS YOU DO.

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c.page653.indd 1 11/17/20 3:05 PM 654 EQUINE VETERINARY EDUCATION Equine vet. Educ. (2020) 32 (12) 654-663 doi: 10.1111/eve.13018

Review Article Monitoring of the mare during the perinatal period at the clinic and in the stable M. Masko†* , M. Domino‡, K. Skierbiszewska‡, Ł. Zdrojkowski‡, T. Jasinski‡ and Z. Gajewski‡ †Department of Animal Breeding, Faculty of Animal Science, WULS – SGGW; and ‡Department of Large Animal Diseases with Clinic, Veterinary Research Centre and Center for Biomedical Research, Faculty of Veterinary Medicine, Warsaw University of Life Sciences (WULS – SGGW), Warsaw, Poland *Corresponding author email: [email protected]

Keywords: horse; perinatal period; monitoring; clinic; stable; mare

Summary physiological and pathological. The duration of gestation is Complications in late gestation are challenging problems for sometimes exceedingly long, 360 days or more, with no the equine clinician and are causes of considerable distress adverse effects on the fetus or mare (Bos and van der Mey to owners. Health problems in a pregnant mare in each stage 1980; Lester 2005; Clothier et al. 2017). The pregnancy length of gestation can adversely affect the pregnancy. It is may vary not only because of pathologies but also due to important to obtain a thorough history and perform a detailed some individual factors that may be important in the and systematic examination of the pregnant mare so that the assessment of pregnancy length: fetal gender (a male fetus mare may be classified as normal or high-risk. However, even may lengthen pregnancy), breed, number of previous after a thorough examination, practitioners may face pregnancies proceeding, the mare’s rank in the herd and problems with the interpretation and assessment of risk. environmental agents (e.g. maternal nutrition). Infectious Normal mares should foal in the stable or pasture. Mares agents (Leptospirosis, rhinopneumonitis/herpesvirus type I/, classified as having a high-risk pregnancy need to be infections and inflammations of the uterus and placenta) as monitored precisely for signs of oncoming foaling with well as exposure of mares to ergot alkaloids may lengthen the attendance of trained personnel when labour begins. A duration of gestation (Marteniuk et al. 1998; Davies Morel et al. valuable method for monitoring of the high-risk mare is 2002; Dwyer et al. 2003). assessing fetoplacental well-being. Fetoplacental well-being Foals born before 320 days of gestation are typically is most accurately assessed with ultrasonography as well as premature and nonviable (Leadon et al. 1986; Lester 2005). several available hormone profiles. We are proposing our Some authors define abortion as the expulsion of the fetus scoring system of the mare’s health, which may be useful in before day 300 of gestation and use the term prematurity to the assessment of risk during pregnancy and help clinicians designate birth of an underdeveloped foal between days to decide whether sending the mare to the clinic is 300 and 320 of gestation (Dwyer et al. 2003; Clothier et al. reasonable or unnecessary. 2017). Overall survival rate of foals born prematurely is estimated to be around 5% (Leadon et al. 1986; Lester 2005). Mares which previously experienced complications during Introduction pregnancy or gave birth to a premature foal or a stillborn foal should be designated as high-risk. The perinatal period includes the last month of pregnancy, There are some rarely occurring abnormalities, which parturition and puerperal period, 7–9 days after foaling prove troublesome when it comes to risk management. Their (Deskur 1964). Perinatal period monitoring requires many symptoms are often equivocal and difficult to interpret for years of practical experience in observing pregnant mares, inexperienced veterinarians. With the growth of horse assisting parturition and looking after neonates. Early population, many practicing veterinarians are treating horses detection of signs of disease or pregnancy disorders is as an addition to their usual routine, rather than as their field essential, considering that some illnesses or injuries of the of specialisation. Transportation of a pregnant mare is both pregnant mare can predispose to fetal stress and abortion. costly and can prove risky for the health of both mare and Owners may observe more frequent genital discharge or the foal, therefore the decision to drive the mare to clinic precocious udder development with premature lactation; this should be made carefully and responsibly. We created a may be a sign of abortion or premature delivery. Rarely, scoring system based on our own experience and thorough enlargement of the abdomen suggesting twin pregnancy or analysis of available literature that may be used in evaluation hydrops of the fetal membranes may be observed. Those of a pregnant mare’s condition and outline a contingency conditions indicate the need for performing a general plan for equine practitioners. examination to determine the viability of the fetus or to identify a high-risk pregnancy. Although improved diagnostic techniques are available in equine reproduction, the ’ incidence of pregnancy loss is still high, varying between 10 The mare s requirements during normal and 15% during gestation (Bucca 2006; McCue and Ferris pregnancy 2012; Baska-Vincze et al. 2014). Pregnant mares that are not designated as having high-risk A mare’s pregnancy lasts for about 11 months (330– pregnancies do not require special management or more 345 days) and its length depends on many factors both attention than other horses. Mares should have permanent

access to a safe pasture in an established, stable herd, due selenium ad libitum should be offered to mares (Hintz 1993; to three important, inseparable issues: social relations in the Peugnet et al. 2016). herd, exercise and nutrition. Permanent access to the pasture ensures the ability to move freely and covers all social and Routine management of the pregnant mare in nutritional needs. It is important to remember that pregnant the stable mares need to be removed from endophyte-infected tall fescue 90 days before foaling (Brendemuehl et al. 1994). In the perinatal period, the breeder’s goal is to decrease the Rank among other horses and relations in the herd are incidence of complications during parturition and their important factors influencing a mare’s welfare, thus affecting consequences as well as reduce the influence of foaling risk of pregnancy and parturition complications associated trauma. This can be achieved with proper preparation of the with stress. Excluding young and aggressive horses from the mare for parturition, providing sanitary conditions and group improves herd epizootic status (by eliminating exposure collecting equipment and medicine necessary in case of to herpes virus infections which are common in young horses) dystocia. Routine management of the pregnant mare in the and decreases the risk of accidents and trauma (Watson stable includes: preparation of a place for delivery (if the 2016). delivery is planned in the stable), implementation of a Pasture hosting is more suitable for pregnant mares rather preventative health programme (vaccination and than box rest, even in cases of chronic orthopaedic problems deworming) and pregnant mare observation (to detect signs as demonstrated by Norton et al. (2007), who showed that of approaching labour). box hosted mares develop more pregnancy and parturition Under normal circumstances, parturition can take place pathologies compared to pasture hosted mares. either in the stable or at pasture. If the stable has a labour Proper nutritional support of the broodmare improves ward the mare should be placed there 4–6 weeks before the fertility and promotes normal growth and vigour of the estimated time of foaling. During this time the mare can developing fetus, and constant monitoring of body condition adapt to the new environment and produce antibodies, provides information about fulfilling dietary energy which pass to colostrum and will provide immunological requirements. It is very important to pay attention to the resistance against local pathogens for the foal. The labour condition of the mare, as healthy and strong animals will ward should be spacious and clean, typically measuring to endure parturition more easily and will be able to produce be a 4 m 9 4 m box and with large amounts of good quality better quality colostrum and milk. Pregnant mares should be bedding – preferably straw. Shavings have the capability to kept in good body condition (body score of 6–7, based on a harbour potential pathogens and as a result the use of scoring system 1–9; Cavinder et al. 2012). Mares should be in shavings for bedding in the labour ward is not recommended a positive energy balance at the time of parturition due to due to a greater risk of potential contamination to the mare’s enormous metabolic demands in late gestation and early reproductive tract; additionally shavings have the frustrating lactation. The balanced metabolism in this period will allow tendency to cover the wet neonate and get in the mouth of proper ovarian function, which is crucial for successful the mare while the mare grooms the foal. If shavings or breeding within 1 month after foaling (Peugnet et al. 2016). A sawdust has to be used, they should be nonetheless covered pregnant mare’s nutrition depends on the season of the year with straw (Dascanio 2014). and quality of the feed. Access to fresh water and high A preventative health programme recommended for quality hay or pasture is crucial, whereas oat supply should pregnant mares includes regular immunisation for common be established individually depending on the mare’s needs infectious diseases and serves two purposes: protection of the dictated by lactation status and stage of gestation (added dam (and gestating fetus) and eventual protection of the especially during the last quarter of gestation due to 60–65% newborn foal. Vaccinations, as the routine procedure in the of total fetal growth occurring in this period; Peugnet et al. perinatal period, are performed 1 month before parturition to 2016). In the last 3 months of gestation, feeding with at least increase the concentration of antibodies in colostrum to 0.5–1.0 kg of grain and 1–1.5 kg of good-quality hay per provide the highest possible passive immunity for the foal. It is 100 kg of body weight is recommended. Three different important to recognise that immunoglobulins produced in feeding programmes including energy, protein and minerals response to vaccine antigens are too large to diffuse through are necessary for pregnant mares. Digestible energy the placental barrier and should be concentrated in requirements for mares increase during late gestation over colostrum and ingested by the newborn foal in the first 24 h 8 months and remain at the level of 110% for 9 months, 115% after parturition. Vaccinations against equine herpes virus 1 for 10 months and 130% for 11 months in comparison to the (EHV-1) and equine arteritis virus (EVA) are very important for maintenance requirement (100%). Mares also need 44 g of pregnant mares due to risk of causing an abortion or giving crude protein per megacalorie of digestible energy in late birth to compromised foals (Fukunaga et al. 1997; Hullinger gestation because of the linear increase in needs during the et al. 1998; Brinsko et al. 2013; Damiani et al. 2014; Dascanio last 3 months. The intake of quality protein (for example 2014). alfalfa hay) should increase from 7 to 8% in the first 8 months Frequent deworming on a schedule and faecal egg to 9 to 10% of the total ration in 9–11 months of pregnancy testing mares allows one to discount additional treatments (Hintz 1993; Cavinder et al. 2012). The primary minerals before foaling. However, deworming on the day of foaling or considered essential in pregnant mare rations are calcium shortly after parturition is common practice as it prevents and phosphorus in addition to selenium in regions where Strongyloides westeri invasion within the foal. During lactation selenium deficiencies exist. Calcium should be added to the the infective larvae are ingested by the foal with milk starting grain mixture to avoid osteochondrosis of the fetus, though from the fourth day after birth. Nevertheless, due to phosphorus content should not exceed calcium content in increasing parasite resistance to medicines, it is important to the ration, especially in late gestation. Salt enriched in choose the deworming schedule based on faecal egg

testing results. Deworming medications are considered safe New signs or findings increasing the risk of abortion for use during pregnancy and a variety of anthelmintic drugs • Uterine torsion are approved, including ivermectin, pyrantel and pyrantel • Placental hydrops: hydroallantois, hydramnios tartrate. Thiabendazole, fenbendazole and piperazine are • Endotoxaemia not known to cause any adverse effects at the therapeutic • Colic dose; however, cambendazole should not be used during • Colitis the first 3 months of pregnancy (Lyons et al. 2008; Rose Vineer • Laminitis et al. 2017). • Abdominal hernia A month before the estimated date of parturition, a • Rupture of the rectus abdominis muscle insertion breeder should start observing the pregnant mare, paying • Pelvic fractures during pregnancy attention to somatic changes that precede approaching • Twin pregnancy labour. The changes include enlargement and development • Vaginal discharge indicating placentitis of the udder, vulvar region – relaxation and tissue oedema, same as in the pelvic region – and relaxation of the sacrosciatic ligaments (Stewart et al. 1982). The udder should This classification can cause difficulties in clinical practice gradually enlarge during the last month of pregnancy and because of ambiguous signs that may present in a patient. become significantly larger 2 weeks before delivery. In the Therefore, to summarise all aspects of the pregnant mare last 1–4 days of pregnancy, small amounts of colostrum may examination we are offering our clinical examination scoring ooze and create wax-like droplets on the end of the teats. system for veterinarians and horse breeders shown in Table 1. Somatic changes may be used as indicators of progression, In this marking system, all parts of the standard examination however tests based on calcium concentration (Ousey et al. were shown in three separate sections of the clinical 1984) and pH mammary gland secretions (Canisso et al. examination table. Each sign has a point value added when 2013) are more precise. The most precise test allows one to a sign is identified. This scoring system allows performance of estimate approaching labour with accuracy of up to 12 h. the clinical examination step by step, even if the signs are Major changes were also documented for sodium not specific. It is a consistent protocol that would prevent concentration, which starts decreasing a few days before the tendency to immediately focus on the most obvious parturition, while potassium increases slightly. However, clinical finding and foregoing a complete examination. Such calcium is still considered to be the best predictor for date of an approach will allow the detection of minor abnormalities parturition evaluation, but sodium and potassium may be before they become serious problems as well as used for evaluation of fetal maturity (Ousey et al. 1984). identification of immediate major dysfunctions determining Within the last hours before parturition it is recommended to the viability of the fetus, preterm labour or abortion. At the clean the perineum and udder in order to decrease the end of the examination the veterinarian would summarise foal’s exposure to pathogens before the colostrum intake the point total from all three sections: general examination, and decrease the incidence of diarrhoea in the first weeks obstetrical examination and any additional tests, which must (Magdesian 2005). In mares which underwent a Caslick’s be totalised. We suggest six points as a threshold indicating procedure, incision of the scar should be performed 1– a need of referral to a specialist or specialty hospital. Six 2 weeks before delivery (Dascanio 2014). Normally, parturition points or more should be designated as high-risk and without any complication does not require human assistance undergo pregnancy monitoring; furthermore, it is urgent that (McCue and Ferris 2012; Bazzano et al. 2016). all mares having more than 10 points should be monitored within the clinic. Our proposed system and the corresponding point values can be a helpful guideline in Designating a pregnancy as high-risk assessing the importance of particular signs found during the Designating a high-risk pregnancy is based on medical examination. While not all practitioners may agree with the history, clinical examination, obstetrical examination and designated scoring allocations, this system of classification is additional tests, including ultrasonographic examination and used in the authors’ practice and is being proposed as a blood testing (Daels et al. 1991; Bucca 2006). Factors which clinically useful tool, not as an official diagnostic classify a mare as high-risk are classically divided into two standardised system. categories, as shown below, based on the signs present during a previous pregnancy or the signs present during the The protocol of the clinical examination scoring current pregnancy (Lofstedt 1994; Frazer et al. 1997; Bucca system 2006; Christiansen et al. 2010). The clinical examination is initiated with the general physical Recurrent signs or findings from the previous examination and should include obtaining parameters such gestations: as the mare’s heart rate, respiratory rate and rectal • Vaginal discharge indicating placentitis temperature along with assessment of the mucous • Periparturient bleeding membranes, capillary refill time and lymph nodes. All findings • Placental abruption should be noted and compared to the scoring table in order • Previous pregnancy disorders: abortion, stillbirth, premature to sum the points from the first section of protocol. foals During the obstetrical examination, the origin of genital • Previous parturition disorders: dystocia discharge can usually be determined via the vulvar and • Disorders of the previous postnatal period: retained vaginal examination. A scar after the Caslick’s procedure placenta, neonatal isoerythrolysis in foals indicates the inadequate vulvar labia angulation and may • Pelvic fractures before current parturition be connected with minor mucopurulent discharge which

TABLE 1: New clinical examination scoring system

General examination Result Scoring Maximum score

1 Heart rate <48 beats/min 0 2 >48 beats/min 1 >60 beats/min 2 2 Respiratory rate <16 breaths/min 0 2 >16 breaths/min 1 >30 breaths/min 2 3 Rectal temperature 37.5°C–38.5°C02 <37°C1 >39°C2 >41°C3 4 Mucous membranes Pink, moist 0 2 Cyanosis/pale/dry 1 Hyperaemic 2 5 Capillary reﬁll time <2s 0 2 >2s 1 >4s 2 6 Lymph nodes Physiological 0 1 Swollen, slightly painful, warm 1 Highly swollen, painful, hot 2

Obstetrical examination Result Scoring Maximum score

1 Examination of vulva Physiological 0 4 Oedema 1 Discharge 2 Rupture or scar after Caslick’s procedure 2 2 Examination of vagina Physiological 0 2 Changes is mucous membrane 1 Discharge 2 3 Examination of udder Physiological 0 2 Premature development 2 4 Transrectal palpation No pathologies 0 6 Uterine torsion 6 Pelvic fractures 6 Placental hydrops 6 5 Speculum examination (not recommended) No pathologies 0 3 Cervix disorders 1 Changes in mucous cervical plug 2

Additional test Result Scoring Maximum score

1 Transrectal USG No pathologies 0 6 Lowered placenta thickness 2 Placental hydrops 6 Fetal abnormalities 6 2 Transabdominal USG Correct uteroplacental connection 0 6 Placental hydrops 6 Fetal abnormalities 6 3 Progesterone hormone tests Proper levels during gestation 0 6 Low level 1 Rapid increase 3 Sudden decrease 6 4 Oestrogen hormone test Proper levels during gestation 0 4 Lowered level 2 Slightly lowered level 4 5 Agglutination test No serological conflict 0 2 Serological conflict 2 6 Uterine bloodflow Medium 0 2 Lowered 1 Higher than usual 2

results from inflammation of the vulva or vestibulum. The an inflamed cervix, therefore when possible these problems presence of urine in the vagina, occurring occasionally in should be identified and surgically corrected via a urethral older mares, may cause an ascending infection and result in extension before mating/insemination. If not, such procedure

should be implemented after parturition. A urovagina is a et al. 1997; Bucca et al. 2005) and is heavily dependent on result of conformational changes associated with progressing measurement of areas in relation to the mare’s abdomen pregnancy. Bloody discharge with clots of blood suggests (Bucca et al. 2005). Renaudin et al. (1997) recorded CTUP that vaginal varicosities may be haemorrhaging from from the ventral aspect of the uterine body, both in subepithelial veins in the vulva or vagina; this condition transrectal and transabdominal imaging. They suggested typically occurs with decreased frequency in older mares. normal mean of CTUP summarised in Table 2. (CTUP: ventral Mucopurulent discharge may indicate a bacterial infection aspect of UB). Bucca et al. (2005) extended previous studies and placentitis, thus a speculum examination should be on measurements and performed transabdominal ultrasound performed with caution in order to determine the origin of examination in nine aspects of the uterine body. They discharge, evaluate the status of cervical relaxation and to suggested that focal areas of placental abnormality may be obtain a culture swab sample for microbiological testing. missed when only the parts of the uterus and placenta are Purulent or brownish bloody discharge through a relaxed examined. The comparison of these and previous (Renaudin cervix indicates the possibility of an impending abortion. In et al. 1997) results is quite difficult and the highest similarities this case, assessment of fetal viability, combined thickness are summarised in Table 2 (CTUP: selected aspects of UB). of the uterus and placenta (CTUP) and volume and The excessive thickening is indicative of placental failure appearance of amniotic fluid should be performed, and caused by ascending placentitis, progressive placental the discharge should once again be swabbed for separation (Reef et al. 1996) and impending delivery (Bucca microbiological tests. Speculum examination is also useful in et al. 2005). The daily monitoring of fetal heart rate and CTUP assessment of the cervical mucus plug state, which provides are useful tools post-operatively to determine the health of not only a structural barrier, but also numerous antimicrobial the fetoplacental unit. components to prevent placental infection and preterm The main indication for surgery in pregnant mares is colic, birth. Changes in its composition can be detrimental to which happens with some frequency. Most colic responds to pregnancy outcomes. While the vaginal speculum medical management but when surgical intervention is examination may be useful, it is extremely hazardous and required or endotoxaemia occurs the pregnancy is put at must not be performed if it is not indicated. In all indicated risk. In both cases, the mare should be closely monitored and cases, speculum examination should be performed carefully the therapies with anti-endotoxin and progestin components in an aseptic manner to avoid contaminating the vagina should be implemented to avoid abortion or fetal death and cervix (Macpherson and Bailey 2008; LeBlanc 2010; (Drumm et al. 2013). McCue and Ferris 2012). Transabdominal ultrasonography may be conducted in The second step of obstetrical examination is palpation advanced gestation due to the examiner’s inability to image per rectum, recommended for the assessment of fetal the fetus with transrectal ultrasonography. It can be applied viability, fetal position and development, cervical dimension in pregnancies with abnormalities such as omphalocele, fetal and uterine position (in a case of uterine torsion), CTUP and ascites, placental separation (excessive echogenic risk of pathological fluid accumulation (Lofstedt 1994; retroplacental fluid accumulations), placentitis (thickening of Christiansen et al. 2010; Loux et al. 2017). The transrectal the placenta), hydrallantois, hydramnios, compromised twin palpation is routinely combined with transrectal ultrasonography, pregnancies and fetal death (Reimer 1997; McCue and Ferris which is classified as an additional test and limited by month 2012). Transabdominal ultrasonography is considered useful in of gestation. assessing the fetal heart beat and its rate. A foal’s normal Transrectal ultrasonography is recommended to detect fetal heart rate in late gestation is 60–92 beats/min. The fetal movement, umbilical blood flow and fetal heartbeat in normal mean of HRR (fetal heart rate at rest) (beats/min/ early gestation. Combined thickness of the uterus and month [Mo.]) suggested by Bucca et al. (2005) is summarised placenta can be measured with transrectal ultrasonography in Table 2. Reduction of fetal heart rate combined with between the caudal uterine wall and the caudal boundary changes in fetal movements are indicators of fetal hypoxic of the allantoic fluid for detecting placental thickening or stress. Persistent brady- or tachycardia is correlated with separation and fluid accumulation between the deterioration of fetal well-being. The transient tachycardia to endometrium and allantochorion. The norm for CTUP the level of 100–130 beats/min may occur shortly after significantly differs between pregnancy months (Renaudin vigorous fetal movement, therefore the monitoring of fetal

TABLE 2: Information on fetal heart rate at rest (HRR) (Bucca et al. 2005) and CTUP recorded from the ventral aspect of the uterine body (UB) (Renaudin et al. 1997) in comparison to selected aspects of uterine body (UB) (Bucca et al. 2005)

Month of pregnancy CTUP ventral aspect of UB CTUP selected aspects of UB HRR/fetal heart rate at rest

References Renaudin et al. (1997) Bucca et al. (2005) Bucca et al. (2005) Month 6 3.84 mm 3.50 Æ 1.02 mm Mind cranial 113 Æ 9 beats/min Month 7 3.91 mm 5.02 Æ 1.11 mm Left caudal 112 Æ 11 beats/min Month 8 4.33 mm 5.20 Æ 0.80 mm Cervical pole 106 Æ 6 beats/min Month 9 4.38 mm 5.85 Æ 1.69 mm Left cranial 91 Æ 6 beats/min Month 10 5.84 mm 6.70 Æ 2.40 mm Mid crania 87 Æ 8 beats/min Month 11 7.35 mm 7.06 Æ 2.73 mm/7.53 Æ 2.30 mm Left cranial/right cranial 87 Æ 8 beats/min Month 12 9.52 mm 9.50 Æ 4.80 mm Right caudal 66 Æ 6 beats/min

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heart beats should be performed over a period of 10 min entering the normal window of parturition (i.e. prior to (Bucca et al. 2005; Baska-Vincze et al. 2015). It is important 320 days gestation), indicates the possibility of placental to remember that both in transrectal palpation and pathology occurrence (placentitis) and often results in transabdominal ultrasonography, the lack of fetal movement preterm labour of an immature foal. A lack of P4 prior to is not proof of fetal death (Reef et al. 1996; Macpherson and delivery occurs with poisoning with fescue grass or tall fescue Bailey 2008; Baska-Vincze et al. 2014). (Deskur 1964; Daels et al. 1991). When the fetus is in anterior presentation transrectal and Various progestogen and oestrogen (oestrone, 17-beta transabdominal ultrasonography may be used in fetal size oestradiol, equilin and equilenin) levels may reflect placental assessment, which include fetal aortic and orbital diameters. and fetal health. In the last months of pregnancy, oestrogens Fetal aortic diameter is significantly correlated with neonatal decrease gradually to baseline levels. In late gestation, total foal weight, girth and hip height in normal pregnancies (Reef oestrogen levels, including not only oestrone sulphate, but et al. 1995) whereas fetal orbital diameter was significantly also 17-beta oestradiol and its metabolites as well, may be correlated with foal birth weight (Bucca et al. 2005). The fetal used for fetal monitoring. Between 150 and 280 days of size determination is especially important in mares after pelvic pregnancy, total oestrogens concentration in the mare fractures. When pelvic fractures healed with exuberant callus should exceed 1000 ng/mL. During this period, oestrogen formation space occupying lesions in the pelvic canal occur. levels lower than 1000 ng/mL indicate stress or fetal weakness, In these cases, obstruction size should be compared with whereas a level lower than 500 ng/mL may indicate fetal estimated fetal size in order to determine whether elective death (Rossdale 1993; LeBlanc 2010; Shikichi et al. 2017). caesarean section will be necessary to obtain a living foal Progestogen levels usually are at low levels from 100 to (Watkins et al. 1990). All pregnant mares with pelvic fractures 300 days of gestation, while oestrogens in total may reach should be classified as high-risk and undergo special care levels above 1000 pg/mL in days 150–310. Elevated progestin management in the clinic, especially in late gestation. levels (>20 ng/mL) and low levels of oestrogens (<600 pg/mL) A new technology used in monitoring mares is were shown in both healthy and placentitis suspected mares. measurement of uterine blood flow. The higher total uterine Profiles change in different manners in regard to developing flow (especially in last 60 days of gestation) is correlated with pregnancy and progressing placentitis, respectively, therefore foal well-being – the foal is bigger and healthier. It may lower total oestrogen and progesterone concentrations should be in older mares, because of endometrosis. However, aborting monitored together in mid- and late gestation as helpful mares tend to have higher uterine blood flow in later diagnostic tools in the management of placentitis. In cases gestation, until the day of abortion via secretion of where placentitis appears to be progressing, fetal viability vasodilators by the foal. This technique, combined with should be monitored with heightened frequency in the event ultrasound monitoring of fetoplacental well-being may be that clinicians are forced to consider whether or not very helpful in early detection of pregnancy problems and induction of parturition is in the best interest of the foal. In a enables earlier initiation of treatment, which increases the situation such as this, the fetal examinations should occur chances of delivering a healthy foal (Bucca et al. 2005; within the clinic in the event that parturition needs to be Klewitz et al. 2015). abruptly induced. Being within the clinic allows clinicians to The blood hormone concentration tests are informative efficiently prepare staff, equipment, and treatments essential and are becoming an increasingly common procedure in the in providing intensive care for the compromised foal (Lester clinical examination used to evaluate placental condition. 2005; Macpherson and Bailey 2008; Conley 2016).

Mares’ progesterone levels (P4) gradually increase in the The third hormone, which can be monitored in high-risk second and third trimesters up to the level of 2–12 ng/mL. In mares is relaxin, produced by the placenta and is detectable the last week before parturition, P4 levels increase rapidly in blood after the 80th day of pregnancy pre-partum levels forming a progesterone peak. After 305 days of gestation, an range from 4 to 7 ng/mL without any changes until the increase in progesterone concentration should be interpreted second stage of labour when it increases rapidly up to 11 ng/ cautiously, as it can be a part of the physiological sequence mL (Stewart et al. 1982). Relaxin concentrations decrease of hormonal changes preceding the delivery. On the other below 4 ng/mL in mares with impaired placental function, in hand, a premature rapid increase of P4 level at <310 days of cases of placentitis, placental abruption, hydroallantois and gestation may reﬂect fetal stress, due to progesterone hydramnios. In the case of placental hydrops, the risk of synthesis from the fetal adrenal gland (Daels et al. 1991). spontaneous rupture of the fetal membranes increases

Serial assessment of P4 levels is a useful tool for pregnancy signiﬁcantly. After rupture, large amounts of allantoic or monitoring at the clinic, with limited application in the stable. amniotic ﬂuid evacuate, changing the mare’s blood pressure

Because of variations in P4 levels among mares, it is necessary which should be recognised as a life-threatening condition to determine the individual baseline for each mare. The (Christensen et al. 2006). Low circulating levels of relaxin have recommended frequency of blood sampling varies from as been reported both in pony mares affected by fescue frequently as three times a day to as little as once every 2– toxicosis associated with placental disease and agalactia 3 days, because only regular testing provides reliable and in Thoroughbred mares, with other forms of placental information on placental and fetal condition (Daels et al. disease or insufﬁciency (Ryan et al. 2009). Relaxin has been

1991; Conley 2016). While P4 levels are being monitored, explored as a potential marker of treatment success in three pathological proﬁles may be described in late placentitis due to its level decrease in cases of spontaneously gestation: a sudden decrease, a rapid increase, or lack of a occurring and experimentally induced pregnancy loss (Klein

P4 peak. The sudden P4 level decrease is connected with an 2016). However, using circulating relaxin levels is limited due acute condition, such as colic, uterine torsion, mare stress to signiﬁcant breed differences and lack of commercial tests and indicates high probability of fetal death. On the other for determining relaxin levels in blood samples (Rossdale 1993; hand, a rapid P4 level increase occurring prior to the mare Klein 2016).

It is also possible to measure androgen levels in a useful tools when providing constant supervision for foaling pregnant mare’s circulation; levels increase from the mares. Foaling occurs more often at night, so 24-h mare’s beginning of pregnancy (20–40 pg/mL), rises at the seventh monitoring, which is possible in clinic, is very important month (200–300 pg/mL) and returns to basal values after (McCue and Ferris 2012). parturition (Silberzahn et al. 1984). Androgen levels rise The most valuable tool available for continued around 210 days of gestation due to increasing production assessment of a high-risk pregnancy is transrectal or by the fetal gonads after which some of these androgens are transabdominal ultrasonographic examination. Transrectal converted into oestrogens by the placenta (Daels et al. and transabdominal ultrasonography should be performed 1996). Androgens and oestrogens levels drop rapidly after during the first clinical examination and repeated every fetal death and will decrease due to stress or fetal weakness. week, or even more often if monitoring of the fetus and Because of this metabolism, it is recommended to monitor placenta is necessary. This examination provides information levels of androgens simultaneously with oestrogens, for better about fetal well-being, probability of perinatal morbidity and determination of the state of fetus (Conley 2016). perinatal mortality in the mare. This profile became the ‘gold These changes are detectable in blood samples and standard’ for transabdominal ultrasonography for many years require several repeated blood testings. Regardless of the in the examination and treatment of pregnant mares in chosen schedule, to determine the tendency in hormone clinical practice (Baska-Vincze et al. 2014). Transabdominal profile at least three samples are required (Daels et al. 1991; ultrasonography is truly a useful diagnostic tool, whereas Conley 2016). transrectal palpation is not sensitive enough because only a Additional diagnostic markers used during assessment of small part of the fetus can be reached by hand (Reef et al. a high-risk pregnancy include electrolytes, platelet count, 1996; Renaudin et al. 1997; Troedsson and Zent 2004; Baska- fibrinogen, triglycerides and albumin concentrations in the Vincze et al. 2014). Reef et al. (1995, 1996) extended the mare’s plasma. In sodium, calcium, phosphorus and chloride ‘gold standard’ by providing a larger database of numerical ions concentrations, the most significant changes are values which can be referred to during ultrasonographic observed 2 weeks before and after parturition. In the last assessment of fetal and maternal measurements during late month of gestation, plasma concentration of sodium ions gestation. They suggested presentation, position, posture, increases due to the renin–angiotensin–aldosterone system activity, aortic diameter and heart rate should be activation, whereas plasma concentration of phosphorus ions determined to define the biophysical profile (scoring system) decreases in correlation with fetal skeletal mineralisation. for the equine fetus as a predictor of outcome. They also When deviations of plasma electrolyte levels are significant, stated that the transabdominal fetal monitoring and the the mare may be classified as high-risk after parturition application of the biophysical profile are promising to (Bucca 2006). The number of platelets increases significantly improve the ability to diagnose fetal distress and intervene prior to foaling and returns to the basal level 3 weeks after. In appropriately to decrease perinatal mortality and morbidity. females in general, not only in mares, fibrinogen levels On the other hand, the authors indicated that obtaining a increase during pregnancy in a progressive fashion, and drop maximal score on the equine biophysical profile still did not after foaling. Those changes are induced by a stress factor in guarantee a positive outcome therefore we suggest even pregnancy in order to develop a hypercoagulable state to further enhancement of this ‘gold standard’ by monitoring prevent excessive bleeding, thus those changes should not the reproductive hormones and the additional chemistry tests alarm clinicians (Bazzano et al. 2014). Similarly, triglycerides mentioned above. This extended profile may be considered and albumin concentrations increase during gestation, due as a ‘platinum standard’ and conducted if precise to higher needs of the organism (Vincze et al. 2015). The management of a pregnant mare is needed. The application sudden drop of one, several or all additional indicators of of the ‘platinum standard’ allows proper identification of high-risk mares being monitored may suggest impending problems with pregnancies and cautious monitoring of labour. Thus if basic blood tests are already provided, those fetoplacental well-being, including fetal movement and parameters may be also noticed (Vincze et al. 2015; Bazzano hypoxic stress, as well as effective initiation and evaluation of et al. 2016). the effects of treatment, which decreases the dystocia rate and increases the chance of a healthy foal delivery. Benefits of monitoring of the pregnant mare in Dystocia may occur even in the most precisely monitored the clinic mare. The percentage of parturition complications varies from 4% in warmblooded mares, to 10% in draught mares. Proper evaluation of a high-risk pregnancy is very important Dystocia is more frequent in multiparous, than in primiparous for estimating prognosis and formulating a treatment plan. mares (Lu et al. 2006). Causes of dystocia are: abnormalities Mares classified as high-risk should be monitored to detect in the presentation, position and posture and fetal congenital approaching parturition in an equine veterinary clinic, where defects. Dystocia occurs more frequently when the fetal well- an experienced team will be able to implement treatment being has deteriorated. About 75% of labours are in anterior procedures immediately. In the case of complications, a set presentation, 18% in posterior presentation and 7% in protocol prepared individually for high-risk mares will help in transverse presentation (Frazer et al. 2002; Carluccio et al. making proper decisions (Bucca 2006). Supervision of 2007; McCue and Ferris 2012). parturition at an equine veterinary clinic requires providing Parturition monitoring at the clinic allows the evaluation of 24 h cautious care in the last days of gestation. Equipment the progression of labour and in case of disorders to such as a locally placed alarm sensor in the vulvar region of implement necessary operations immediately, whereas the the mare that is able to detect an increase in humidity and assistance is not required at normal parturition. Physiological subsequently send notification once the mare has increased labour, divided into three phases, should progress in in sweating, or a simple mountable labour box camera, are particular timeframes: the first phase in 1–4 h, the second

phase in 30 min and the third phase in 3 h. It is estimated Acknowledgements that every 10 min of delay in the second phase of parturition increases the risk of foal’s death by 10% during the delivery This work was conducted in the Veterinary Research Centre and by 16% after birth (Vandeplassche 1993; McCue and WULS (WCB) and the Center for Biomedical Research (CBB) – Ferris 2012). Providing professional assistance at parturition up supported by EFRR RPO WM 2007 2013. to 90 min after the beginning of the second phase raises the foal survival rate from 83 to 95% (Norton et al. 2007). Survival Authorship rate decreases severely, even to 11%, when the second stage is prolonged for more than 60 min (Freeman et al. M. Masko, M. Domino, K. Skierbiszewska and Ł. Zdrojkowski 1999) due to progressive hypoxia and deterioration in the were responsible for manuscript design, references collection mare’s general condition. These changes are associated with and manuscript preparation. T. Jasinski and Z. Gajewski uterine contractions, mare’s anxiety, reduced connection reviewed and edited the manuscript. All authors approved between epitheliochorial placenta and the uterine wall and the final version of the manuscript. equine high susceptibility to infections and endotoxaemia. Disorders of labour progression are an indication for veterinary assistance at parturition, where the proper choice References of treatment method is essential. In 71% of cases, dystocia Baska-Vincze, B., Baska, F. and Szenci, O. (2014) Transabdominal can be managed without surgery and solved with correction ultrasonographic evaluation of fetal well- being in the late-term of fetal orientation and its controlled extraction. In more mare and cow. Acta Vet. Hung. 62, 439-451. complicated situations, fetotomy or a caesarean section is Baska-Vincze, B., Baska, F. and Szenci, O. (2015) Fetal heart rate and required. Mares classified as high-risk could be presumed to fetal heart rate variability in Lippizaner broodmares. Acta Vet. have an increased rate of dystocia due to fetal compromise Hung. 63, 89-99. preventing the foal from actively participating in the Bazzano, M., Giannetto, C., Fazio, F., Marafiotti, S., Giudice, E. and Piccione, G. (2014) Hemostatic profile during late pregnancy and parturition process as occurs in normal mares and early postpartum period in mares. Theriogenology 81, 639-643. consequently should be foaled out in a clinic setting (Lu et al. Bazzano, M., Giudice, E., Giannetto, C., Fazio, F., Scollo, C. and 2006; Norton et al. 2007; McCue and Ferris 2012). This Piccione, G. (2016) The peripartum period influenced the serum increased risk of dystocia should persuade owners in allowing macromineral profile in mares. Arch. Anim. Breed. 59, 65-70. their veterinarian to hospitalise their high-risk mare for Bos, H. and van der Mey, G.J.W. (1980) Length of gestation periods of constant monitoring so that the foaling can also be horses and ponies belonging to different breeds. Livest. Prod. Sci. attended. With increased expense resulting from that 7, 181-187. required level of care, veterinarians will want to be confident Brendemuehl, J.P., Boosinger, T.R., Pugh, D.G. and Shelby, R.A. (1994) in their recommendations and by utilising the provided Influence of endophyte-infected tall fescue on cyclicity, assessment tool above, a mare’s pregnancy status can be pregnancy rate and early embryonic loss in the mare. Theriogenology 42, 489-500. more accurately determined and the appropriate care provided. (Freeman et al. 1999; Carluccio et al. 2007). Brinsko, S.P., Blanchard, T.L., Varner, D.D., Schumacher, J., Love, C.C., Hinrichs, K. and Hartman, D.L. (2013) Management of the pregnant mare. In: Manual of Equine Reproduction, 3rd edn. Eds: S. Brinsko, T. Blanchard, D. Varner, J. Schumacher and C. Love. Mosby, Conclusion Maryland Heights. pp 114-130. The last weeks of gestation, as well as the time immediately Bucca, S. (2006) Diagnosis of the compromised equine pregnancy. after parturition, are crucial for foal survivability but are also Vet. Clin. North Am. Equine Pract. 22, 749-761. important time frames to be attentive to the mare’s health Bucca, S., Fogarty, U., Collins, A. and Small, V. (2005) Assessment of status. Diagnostic techniques and associated technologies feto-placental well-being in the mare from mid-gestation to term: transrectal and transabdominal ultrasonographic features. that were previously considered advanced have now Theriogenology 64, 542-557. become more common practice and affordable to clients, Canisso, I.F., Ball, B.A., Troedsson, M.H., Silva, E.S. and Davolli, G.M. making it easier for veterinarians to provide optimal veterinary (2013) Decreasing pH of mammary gland secretions is associated care to pregnant mares and their foals. However, qualifying with parturition and is correlated with electrolyte concentrations in animals as high-risk may still cause some difficulties. In this prefoaling mares. Vet. Rec. 173, 218. article, we present an innovative method of classification, Carluccio, A., Contri, A., Tosi, U., De Amicis, I. and De Fanti, C. (2007) which may solve this problem. We hope that the new clinical Survival rate and short-term fertility rate associated with the use of examination scoring system may become a very valuable fetotomy for resolution of dystocia in mares: 72 cases (1991-2005). J. Am. Vet. Med. Assoc. 230, 1502-1505. diagnostic tool and will make designating a high-risk pregnancy much easier. A clear system of scoring dissipates Cavinder, C.A., Burns, S.A., Coverdale, J.A., Hammer, C.J. and Hinrichs, K. (2012) Late gestational nutrition of the mare and doubts if more considerate care is required. We want to note potential effects on endocrine profiles and adrenal function of the that both mother and newborn wellness depends on offspring. Prof. Anim. Sci. 28, 344-350. conditions and treatment of them, even before parturition. Christensen, B.W., Troedsson, M.H., Murchie, T.A., Pozor, M.A., Macpherson, M.L., Estrada, A.H., Carrillo, N.A., Mackay, R.J., Roberts, G.D. and Langlois, J. (2006) Management of hydrops Authors’ declaration of interests amnion in a mare resulting in birth of a live foal. J. Am. Vet. Med. Assoc. 228, 1228-1233. No competing interests have been declared. Christiansen, D.L., Moulton, K., Hopper, R.M., Walters, F.K., Cooley, A.J., Leblanc, M.M. and Ryan, P.L. (2010) Evidence-based medicine Source of funding approach to develop efficacious therapies for late-gestation mares presenting with uterine infections using an experimentally None. induced placentitis model. Anil. Reprod. Sci. 121, 345-346.

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Review Article A review of normal radiographical variants commonly mistaken for pathological ﬁndings in horses F. E. Hinkle† , S. A. Johnson‡, K. T. Selberg† and M. F. Barrett†* †Department of Environmental and Radiological Health Sciences, Colorado State University; and ‡Department of Clinical Sciences, Colorado State University, Fort Collins, Colorado, USA *Corresponding author email: [email protected]

Keywords: horse; radiography; normal variants

Summary variants can be easily overinterpreted as degenerative A normal variant is an atypical finding present in a changes. The pointed, sharp contour variant of the percentage of the population that generally has no clinical distodorsal middle phalanx will generally be bilaterally significance and is considered within the spectrum of normal symmetrical without other evidence of joint disease, such as findings. Normal variants are recognised upon gross additional sites of osteophytosis, joint capsule enthesopathy, anatomical dissection and also observed radiographically. subchondral bone sclerosis or evidence of distal Understanding the range of normal variants is essential for interphalangeal joint effusion. Concurrent osteophytes on the proper radiographical interpretation. This ensures that these distopalmar/plantar aspect of the middle phalanx and variants are not mistaken for pathological lesions and helps articular surface of the navicular bone help indicate true joint avoid radiographical misdiagnosis. Common sites of normal pathology. Additional radiographical views can be used for anatomical variation in the foot, pastern, carpus, tarsus, the evaluation of distal and middle phalangeal osteophytes, elbow, shoulder and axial skeleton are reviewed. such as the dorso-60°proximo45°-lateral-palmarodistomedial and opposite dorso-60°proximo45°-medial-palmarodistolateral oblique views (Fig 1b). This radiograph will highlight the Introduction dorsomedial and dorsolateral articular margins of the distal Accurate radiographical interpretation requires more than interphalangeal joint with minimal superimposition. No recognition of abnormalities. A solid understanding of normal evidence of osteophytosis on these aspects of the articular anatomical and incidental variants is crucial to avoid margin helps confirm the pointed contour of the dorsodistal misinterpretation of radiographical findings. A normal aspect of the middle phalanx as a normal variant. variation commonly occurs in a typical location without other Anatomic variations of the navicular bone have also been evidence of concurrent pathological bone change, such as described, including variable thickness of the flexor cortex, sclerosis or lysis. The misdiagnosis of a normal variant as a parallel or convergent joint space between the navicular significant lesion can result in deleterious consequences, bone and distal phalanx, the shape of the central eminence, including inappropriate case management, unnecessary andawell-defined, crescent-shaped lucent region in the surgery or incorrect client counsel in the prepurchase sagittal ridge (also known as central eminence) of the flexor examination scenario. In addition, identifying a normal surface observed on the palmaroproximal-palmarodistal variant as pathological precludes accurate diagnosis of the (navicular skyline) view (Poulos et al. 1989; Kaser-Hotz and true source of lameness. The following is a review of normal Ueltschi 1992; Becht et al. 2001). This focal lucent area has radiographical variants that are commonly mistaken for previously been described as a normal indentation or synovial pathological abnormalities. fossa. A study of 48 forelimbs of Thoroughbred horses with radiography, computed tomography, histology and epifluorescence microscopy showed that the crescent-shaped Distal phalanx, navicular bone and distal lucent region is noncompact bone between a reinforcement interphalangeal joint line of compacted cancellous bone and the flexor cortex, Numerous anatomical variants of the foot have been resulting in a normal site of decreased mineralisation within the described. These include normal variation in the extensor cortex (Berry et al. 1992) (Fig 2). The size and prominence of process shape, separate centres of ossification of the palmar this lucent region will vary from horse to horse. Typically, the processes, ossification of the ungual cartilages, separate appearance is symmetrical between limbs on the same horse; centres of ossification of the ungual cartilages and the crena however, that does require that radiographical projections are marginalis solaris (Becht et al. 2001). The dorsal margin of the identical, as slight variation in the obliquity of the skyline view distal interphalangeal joint is a common area of can affect how conspicuous the crescent lucency appears. misinterpretation within the foot. The dorsodistal aspect of the The lateral radiographical view can also be of aid. Horses with middle phalanx and extensor process of the distal phalanx a more prominent central lucency on the skyline view tend to can have variable conformation. In some horses, these have a more prominent concave curvature of the flexor surfaces are smooth and rounded, whereas in others the cortex on the lateral view (Dyson 2011). margins are pointed with sharp contours (Fig 1). In some In contrast to the normal area of decreased bone density cases, it can be challenging to differentiate the sharply described above, erosions of the flexor cortex are classically pointed normal variant from an osteophyte and normal rounded or ill-defined areas of osteolysis with variable

a) a)

Fig 2: Palmaro55°proximal-palmarodistal (navicular skyline) ° ° Fig 1: Lateromedial a) and dorso60 proximo45 lateral- radiographical view a) and transverse CT b) of the navicular palmarodistomedial oblique radiographical views b) of the distal bone. There is a normal focal area of decreased mineral in the interphalangeal joint of the same horse. On the lateral image, the sagittal ridge of the ﬂexor surface. Gas packing artefact is extensor process of the distal phalanx and the dorsal distal incidentally present on the radiograph. c) For comparison: aspect of the middle phalanx have sharp, pointed margins. There Pathological lysis of the ﬂexor cortex at the sagittal ridge (black are no other signs of degenerative change associated with the arrow), accompanied by other degenerative changes of the ° distal interphalangeal joint, including the joint margins on the 60 navicular bone including trabecular sclerosis. oblique image. This dorsal contour is a normal variant for this horse.

comparison to a flat foot. A recent study investigating the use of varying angles of the palmaroproximal-palmarodistal amounts of endosteal sclerosis, which may result in a distinct oblique (navicular skyline) radiograph found that a 35° view concave radiolucent defect on the flexor surface. These in conjunction with the standard 55° view improved radiographical features help differentiate the normal radiographical detection of flexor cortical lysis (Johnson et al. architecture of the navicular bone from a flexor erosion. 2018). Including additional navicular skyline projections of Flexor cortex erosions are clinically relevant findings; therefore varying degrees can aid interpretation and result in a more it is important that these normal lucent regions within the accurate radiographical diagnosis. cortex are not overinterpreted and misdiagnosed as flexor cortical lysis. To achieve a diagnostic navicular skyline Proximal and middle phalanges, proximal radiograph, multiple factors need to be considered including interphalangeal joint and fetlock the position of the horse’s limb, conformation, exposure and x-ray beam angle. A horse’s limb should be placed caudally, The distal aspects of the middle and proximal phalanges behind the shoulder with the foot fully contacting the ground have a smooth, concave curvature between and proximal to achieve correct position of navicular bone relative to the to the palmar aspect of the condyles, creating a central, middle and distal phalanges with a distinct separation rounded relative lucency on the dorsopalmar view (Fig 3). between the middle phalanx and navicular bone. An upright This region can sometimes be confused for a cyst-like foot conformation will require an increased beam angle in lesion (Becht and Park 2000). In contrast to a true cyst-like

a) Carpus The distal most aspect of the ulna (styloid process) has a separate centre of ossification from the distal radius. In juvenile horses, a well-defined lucent, linear to ovoid region extends obliquely between the distal radius and the separate centre of ossification of the styloid process of the ulna. In most horses, this will fuse completely. However, in some skeletally mature horses, there is incomplete closure of the ossification centre (Fig 4). This persistent lucent ovoid junction between the remnant ulna and radius can be mistaken for a fracture of the distal radius. Another common area of confusion in the distal radius is the radial fossa (Becht and Park 2000). On the caudal aspect of the distal radius, there is a prominent, smooth indentation. This indentation appears as a round lucent area on the dorsopalmar view of the carpus and can be mistaken for a cyst-like lesion (Fig 5). Similar to the relative lucent region found in the proximal phalanx, this lucency can be distinguished from a cyst-like lesion due to the lack of surrounding sclerosis and lack of other evidence of joint disease. In advanced radiocarpal joint disease, this fossa can enlarge due to pressure resorption from chronic synovitis, creating even more of a cyst-like appearance. In a group of 222 horses, investigators found several variations in the equine carpus, including the inconsistent presence of the first and fifth carpal bones. The first carpal bone and fifth carpal bone were found in 29% and 1.4% of b) limbs respectively (Simon and Dyson 2010). In some horses, the first carpal bone does not separate from the second carpal bone completely, resulting in an oblong and irregular palmar surface of the second carpal bone (Fig 6). The inconsistent appearance and presence of these carpal bones can result in misdiagnosis of pathological osseous fragmentation. Additionally, the fossa of the first carpal bone within the second carpal bone can be quite prominent. This can occur whether or not the first carpal bone is present and should not

Fig 3: Dorsopalmar radiographical view of the pastern a) and transverse T2-weighted MRI of the distal aspect of the proximal phalanx b). The round ill-deﬁned lucent region in the distal aspect of the proximal phalanx on the radiograph (long white arrow) corresponds with the normal palmar concavity of the proximal phalanx seen on the MRI (short white arrow). The linear lucent region in the mid aspect of the middle phalanx represents a nutrient foramen.

lesion, these relative lucent regions are not surrounded by Fig 4: Dorsolateral-palmaromedial oblique radiographical view sclerosis and do not have a concurrent subchondral bone of the carpus. There is a persistent, well-defined lucent ovoid defect. The prominence of this lucency will vary region and line between the distal radius and the incompletely depending on patient conformation and the angle of the ossified separate centre of ossification for the styloid process of x-ray beam. the ulna (black arrow).

Fig 5: Dorsopalmar radiographical view of the carpus. The radial fossa has a prominent lucent zone in the central aspect of the distal radius. The prominence of this appearance will vary with x- ray beam angle and from horse to horse. be mistaken for a cystic lesion within the second carpal bone. Fig 6: Dorsomedial-palmaromedial oblique radiographical view Importantly, while the presence of a first carpal bone is of the carpus. There is incomplete separation of the first and typically bilateral, the degree of irregularity or concave second carpal bone, creating an irregular margin to the fossa on the second carpal bone (white arrow). defect of the second carpal bone is variable and often asymmetric or unilateral; therefore, comparison to the opposite limb should not be relied upon to distinguish whether this is a normal or abnormal finding (Simon and Dyson 2010).

Elbow The equine elbow is a region of few anatomic variations. Altered appearance of radiographical anatomy is more likely due to variation in radiographical position rather than true differences in gross anatomy (Dyson 1986). A common site of misinterpretation is the radioulnar articulation and the interosseous space between the ulna and radius (Fig 7). The superimposed undulating and irregular surfaces of the radial notch and the ulna at the level of the coronoid processes can be mistaken for a fracture or bone lysis in the mediolateral image. As with many of these variations, comparison with the contralateral limb can be performed to help clarify the normal heterogeneity of the bone at this site. The radial head has prominent medial and lateral eminences at the attachment of the collateral ligaments. This is often mistaken as enthesopathy of the medial collateral ligament when observed on the craniocaudal view (Dyson 1986). The normal eminence is well-deﬁned and smoothly marginated. In contrast, enthesopathy of the medial collateral ligament is relatively uncommon and typically results in bone roughening and bone spur formation (Fig 8).

Shoulder Fig 7: Mediolateral radiographical view of the elbow. There is an The glenoid notch of the scapula has a concave margin that undulating lucent line at the radioulnar articulation and creates an ovoid lucent region on the cranial aspect of the superimposition of the ulna (black arrow).

Fig 8: Craniocaudal radiographical views of the elbow in two a) different horses for comparison of normal anatomy vs. pathological change. a) A normal adult horse elbow with a medial eminence (white arrow). b) Smooth, triangular osseous proliferation on the proximal medial aspect of the radius consistent with medial collateral ligament enthesopathy of the elbow joint (white arrow). In addition, sclerosis of the medial humeral condyle and medial proximal radius is present with an ill-deﬁned ovoid lucent region at the articular margin, consistent with a subchondral cyst-like lesion of the proximomedial radius (black arrow).

b) b)

Fig 9: a) Mediolateral radiographical view of the shoulder. There is a lucent area within the cranial glenoid of the scapula due to the normal depression of the glenoid notch (white arrow), which corresponds to the labelled anatomic specimen. A second lucent line at the junction between the glenoid and the humeral head (black arrow). b) Anatomic specimen. The glenoid notch (white arrow) on the medial aspect of the glenoid of the scapula.

distal scapula that can be mistaken for a subchondral bone defect or cyst-like lesion (Fig 9). A second site of overinterpretation is a lucent zone at the junction of the glenoid cavity of the scapula and the humeral head that is often mistaken as subchondral cyst or fracture. This lucent zone is due to the medial rim of the glenoid being projected

more proximally than the lateral rim (Dyson 1986; Redding without evidence of bony lysis within the trabecular and Pease 2010). In contrast, osteochondrosis lesions of the subchondral bone (Fig 11). When joint sepsis is suspected, the shoulder joint more typically occur on the caudal aspect of irregularity of the trochlear ridges and varying degree of the shoulder with accompanying sclerosis and articular ossification of the patella can be challenging to interpret. surface irregularity. Radiographs of the contralateral limb can be helpful in differentiating normal juvenile bone irregularity from bone lysis Tarsus associated with sepsis. The medial femoral condyle has a normal variation in Previous studies have shown that the distal aspect of the shape from rounded to flattened on the caudocranial view medial trochlear ridge of the talus is a common site of (Jeffcott 1984) and the appearance can be affected by x- misinterpretation, in large part due to the variability in shape ray beam angle. A flat medial femoral condyle articular (Shelly and Dyson 1984; McIlwraith et al. 1991). The distal surface in the absence of subchondral bone defects or aspect can be rounded, pointed, or even a separate sclerosis is an incidental variant. A slight concavity on the osseous body. The separate osseous bodies are often referred caudocranial view is of variable significance, is not to as ‘dew drop’ lesions and are an incidental normal necessarily an incidental finding and deserves further variation (McIlwraith et al. 1991). The mid dorsal aspect of the exploration. A flexed lateral oblique view of the stifle can be medial trochlear ridges of the talus can be variably flattened incorporated into the stifle study to provide improved to focally concave. Apart from rare cases with concurrent visualisation of the weight-bearing aspect of the medial subchondral bone sclerosis or fragmentation, this is an femoral condyle and more completely assess for incidental variant and should not be confused with pathological changes at this site. This radiographical osteochondrosis (Fig 10). projection can help detect more subtle lesions that might otherwise be missed on the caudocranial or caudolateral Stifle oblique view or demonstrate that what looks like a small defect on the caudocranial view is actually a more In juvenile horses, the trochlear ridges of the femur have substantial articular surface defect (Barrett and Selberg 2012). irregular articular margins, which can persist until approximately 5 months of age (Adams and Thiisted 1985). Cervical spine The irregularity should be confined to the articular surface The C6-7 articular process joints are unlike the cranial and mid-cervical spine articular process joints. The sixth cervical

Fig 10: Lateromedial radiographical view of the tarsus with a ﬂat Fig 11: Lateromedial view of the stiﬂe in a normal 3-week-old contour to the dorsal aspect of the medial trochlear ridge (white foal. The trochlear ridges are irregular and undulating (white arrow). There is no subchondral bone sclerosis or fragmentation, arrows), consistent with the described appearance of a normal thus this is considered a normal anatomic variant. foal <5 months of age.

vertebra has shorter, thicker caudal articular processes that These separate centres of ossification are commonly are situated further laterally. Correspondingly, the cranial heterogeneously mineral with irregular margins and remain articular processes of the seventh cervical vertebrae are separate from the parent bone for the horse’s lifetime. wider and longer (Getty 1975). Consequently, these C6-7 These normal separate centres can be distinguished from articular process joints are normally more rounded and larger traumatic fractures by their alignment with the adjacent than the articular process joints in the cranial cervical spine. spinous processes and lack of other osseous abnormalities In addition to the anatomically normally larger articular of the withers. process joints at C6-7, these articular process joints frequently The thoracolumbar spinous processes and interspinous undergo modelling and enlargement, which can be clinically spaces are common areas of evaluation in prepurchase insignificant. Although challenging to obtain, right 55° dorsal- examinations and insurance claims (Penell et al. 2005). The left ventral and left 55° dorsal-right ventral oblique standard grading scales are based on interspinous distances radiographs of the cervical articular process joints can aid in of <4 mm indicating pathological abnormalities. This is differentiation between bilateral and unilateral changes with dependent on the age of the horse as the interspinous improved evaluation of the articular process joints with distances decrease with age (Jeffcott 1979). In Thoroughbred decreased osseous superimposition. horses, the summits of the spinous processes tend to be beak- Recent work has investigated the morphological shaped with narrower interspinous spaces, which can radiographical variation in the sixth and seventh cervical predispose Thoroughbreds to spinous process impingement. vertebrae and the first thoracic vertebra in 270 horses. This (Jeffcott 1979). Patient positioning, x-ray beam angle and group found the spinous process of the seventh cervical geometric distortion have also been proven to have vertebra was identifiable in 76.1% of horses with described significant effect in interspinous distances (Berner et al. 2012; shape variations, including sharp triangle, rounded triangle, or Djernaes et al. 2017). spur-like shape (Santinelli et al. 2016). The spinous process of Horses are commonly sedated for spinal radiographs and the seventh cervical vertebrae is partially superimposed with head position becomes low, resulting in flexion of the cranial the dorsal aspect of the C6-7 articular process joints and can thoracic spine and extension of the caudal thoracic spine be mistaken for osteophyte formation and osteoarthritis (Alvarez et al. 2006). The interspinous distances between (Fig 12). eighth and 14th spinous processes were significantly wider in A separate centre of ossification of the caudal aspect of a low head position compared with intermediate (neutral) the transverse process of the sixth cervical vertebra can be and high head positions. The 15th–17th interspinous distances present in juvenile horses. In one review of a large equine were significantly wider in the low head position compared population, this separate centre of ossification was only found with the high head position, but not significantly different in 4.8% of horses, the majority of which was <3 years of age than the intermediate head position. In the high head (Santinelli et al. 2016). This physis remains open until 4–5 years position, variable interspinous distances were significantly of age and should not be confused for a fracture (Whitwell narrowed compared with the intermediate head position and Dyson 1987). (Berner et al. 2012). A recent study also found x-ray beam angle to make a fi Thoracic spine signi cant difference in interspinous space measurements. If The cartilaginous summits of the thoracic spinous processes of T2 through T8 are not ossified in the newborn foal and begin to ossify around 12 months of age (Jeffcott 1979).

Fig 12: Lateral radiographical view of the caudal cervical spine. There is a prominent, triangular spinous process of C7 (white Fig 13: Lateromedial radiographical view of the proximal arrow). phalanx with a dorsally located vascular channel (white arrow).

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the interspinous space being evaluated was three spaces Ethical animal research caudal to the centre of the x-ray beam, the measurement of the interspinous space of interest was significantly Literature review with appropriate citations. All images were fi different compared with measurements of this space when obtained from previous, unidenti ed case archives or client centred in the radiographs or in closer positions (one or two owned animals who gave consent for diagnostics to be used spaces away from centre) (Djernaes et al. 2017). in research studies. This article neither directly impacted these Interestingly, this difference in width did not have a animals in diagnoses nor in outcome. consistent pattern and could not be predicted. Attempting to evaluate an interspinous space at a distant site (edge of Authorship film) will lead to geometric distortion, thus the reason for significantly different measurements. Concurrent osseous M. Barrett contributed to the study design, study execution, abnormalities, such as cortical lysis and sclerosis of the data analysis and interpretation, and preparation of the spinous processes, can help confirm true spinous process manuscript. F. Hinkle, S. Johnson and K. Selberg contributed impingement when present. For these reasons, veterinarians to the study execution, data analysis and interpretation, and acquiring spinal radiographs should be cognisant of head preparation of the manuscript. All the authors gave their fi position and x-ray beam angle creating limitations when approval of the nal manuscript. interpreting this region. A neutral head position with the spinous processes of concern centred in the x-ray beam is References advised for the best quality diagnostic radiographs and ease of interpretation. Adams, W.M. and Thiisted, J.P. (1985) Radiographic appearance of the equine stifle from birth to 6 months. Vet. Rad. 26, 126-132. Alvarez, C.B.G., Rhodin, M., Bobbert, M.F., Meyer, H., Weishaupt, M.A., Nutrient foramina Johnston, C. and Weeren, P.R. (2006) The effect of head and neck position on the thoracolumbar kinematics in the unridden horse. While most practitioners are familiar with the common Equine Vet. J. 38, Suppl. 36, 445-451. locations of the nutrient foramina within the long bones and Barrett, M.F. and Selberg, K.T. (2012) How to obtain flexed lateral phalanges, there are some nutrient foramina that are not oblique radiographs of the equine stifle, Proc. Am. Assoc. Equine consistently present in all horses and are often not bilaterally Practnrs, 58, 383-387. symmetric. These less commonly visualised nutrient foramina Becht, J.L. and Park, R.D. (2000) A review of selected normal can be easily mistaken for a fracture, particularly in patients radiographic variation of the equine fetlock, carpus, tarus, and with acute onset of severe lameness in which a fracture is stifle, Proc. Am. Assoc. Equine Practnrs, 46, 362-364. suspected. Common areas of misinterpretation include a Becht, J.L., Park, R.D., Kraft, S.L., Steyn, P.F. and Wrigley, R.H. (2001) variable present dorsal foramina in the proximal phalanx Radiographic interpretation of normal skeletal variations and pseudolesions in the equine foot. Vet. Clin. North Am. Equine (Kneller and Losonsky 1990; Smith 1996) (Fig 13). Smaller Pract. 17, 1-18. foramina are also seen extending from the more prominent Berner, D., Winter, K., Brehm, W. and Gerlach, K. (2012) Influence of nutrient foramen in the metacarpus. Nutrient foramina are head and neck position on radiographic measurement of cylindrical lucent regions with well-defined thin opaque linear intervertebral distances between thoracic dorsal spinous processes borders on either side of the foramen. In contrast, fracture in clinically sound horses. Equine Vet. J. 44, Suppl. 43, 21-26. margins can be sharp, but not cylindrical and do not have a Berry, C.R., Pool, R.R., Stover, S., O’Brien, T.R. and Koblik, P.D. (1992) thin, symmetric line of surrounding opacity. The typical Radiographic/morphologic investigation of a radiolucent crescent fl radiographical appearance of a nutrient foramen may aid in within the exor central eminence of the navicular bone in thoroughbreds. Am. J. Vet. Res. 53, 1604-1611. differentiating a nutrient foramen from a fracture. In cases where it is unclear if a linear lucent area in the bone is a Djernaes, J.D., Nielsen, J.V. and Berg, L.C. (2017) Effects of X-ray beam fi angle and geometric distortion on width of equine thoracolumbar normal foramen or a fracture, the patient should be con ned interspinous spaces using radiography and computed tomography- with repeat radiographs obtained in 7–10 days. A nutrient a cadaveric study. Vet. Radiol. Ultrasound. 58, 169-175. foramen will not alter in appearance, whereas a fracture will Dyson, S. (1986) Interpreting radiographs 7: radiology of the equine have widening of the fracture margins and progressive shoulder and elbow. Equine Vet. J. 18, 352-361. surrounding sclerosis. Dyson, S. (2011) Radiological interpretation of the navicular bone. Equine Vet. Educ. 23, 73-87. Conclusions Getty, R. (1975) In: Sisson and Grossman’s: the Anatomy of the Domestic Animals, W B Saunders Co, St. Louis. p 258. In summary, there are multiple radiographical variants Jeffcott, L.B. (1979) Radiographic features of the normal equine associated with normal conformational or anatomic variations. thoracolumbar spine. Vet. Rad. 20, 140-147. Recognising these normal variants is essential to avoid Jeffcott, L.B. (1984) Interpreting radiographs 3: radiology of the stifle inappropriate radiographical interpretation and subsequent joint of the horse. Equine Vet. J. 16, 81-88. improper case management. Understanding normal anatomy, Johnson, S.A., Barrett, M.F. and Frisbie, D.D. (2018) Additional radiographical signs of disease and engaging in collaboration palmaroproximal-palmarodistal oblique radiographic projections improve accuracy of detection and characterization of equine with veterinary colleagues will maximise accurate flexor cortical lysis. Vet. Radiol. Ultrasound. 59, 387-395. radiographical interpretation and minimise the risk of Kaser-Hotz, B. and Ueltschi, G. (1992) Radiographic appearance of misdiagnosis. the navicular bone in sound horses. Vet. Radiol. Ultrasound. 33,9- 17. Authors’ declaration of interests Kneller, S.K. and Losonsky, J.M. (1990) Variable locations of nutrient foramina of the proximal phalanx in forelimbs of Thoroughbreds. J. No conflict of interest has been declared. Am. Vet. Med. Assoc. 197, 736-738.

McIlwraith, C.W., Foerner, J.J. and Davis, D.M. (1991) Osteochondritis cervical vertebrae and the ﬁrst thoracic vertebra in horses. Equine dissecans of the tarsocrural joint: results of treatment with Vet. J. 48, 45-49. arthroscopic surgery. Equine Vet. J. 23, 155-162. Shelly, J. and Dyson, S. (1984) Interpreting radiographs 5: radiology of Penell, J.C., Egenvall, A., Bonnett, B.N., Olson, P. and Pringle, J. (2005) the equine hock. Equine Vet. J. 16, 488-495. ﬁ Speci c causes of morbidity among Swedish horses insured for Simon, V. and Dyson, S.J. (2010) Radiologic anatomic variation of the veterinary care between 1997 and 2000. Vet. Rec. 157, 470-477. carpus in horses with carpal lameness and control horses. Vet. Poulos, P.W., Brown, A., Brown, E. and Gamboa, L. (1989) On navicular Radiol. Ultrasound. 51, 601-606. disease in the horse. Vet. Rad. 30, 54-58. Smith, R.K.W. (1996) Radiography of the equine metacarpo-/ Redding, W.R. and Pease, A.P. (2010) Imaging of the shoulder. Equine metatarsophalangeal joint. Equine Vet. Educ. 8, 221-229. Vet. Educ. 22, 199-209. Whitwell, K.E. and Dyson, S. (1987) Interpreting radiographs 8: equine Santinelli, I., Beccati, F., Arcelli, R. and Pepe, M. (2016) Anatomical cervical vertebrae. Equine Vet. J. 19, 8-14. variation of the spinous and transverse processes in the caudal

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