AAEP Convention 44 Digestive Health 47 Medicine/Surgery 51 Horse Management a Supplement to the Horse 55 Infectious Diseases 58 Nutrition 63 Ophthalmology

A Layman’s Guide to the 2007 American Association of Equine Practitioners Convention

2 Contents 4 Highlights and Awards 7 Lessons from Barbaro 11 Kester News Hour 15 Reproduction 24 Diagnostics 30 Foot/Lameness 42 Arthritis AAEP Convention 44 Digestive Health 47 Medicine/Surgery 51 Horse Management A supplement to The Horse 55 Infectious Diseases 58 Nutrition 63 Ophthalmology

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2629_Steadfast_TheHorse_ad_fnl.indd 1 1/22/08 4:49:13 PM AAEP WRAP-UP 2007 Sponsored by

AAEP 2007 Convention FEATURES

6 Awards & Officers 32 Foot/Lameness 55 Dentistry The first woman took the helm of the Topics included therapeutic shoeing, Discussions on the horse’s mouth AAEP while others were honored. stem cells, and tendonitis. included bitting and sinus problems. By Kimberly S. Brown By Christy West and Nancy Loving, DVM By Les Sellnow 10 Lessons from Barbaro 38 Arthritis 56 Nutrition Dean Richardson, DVM, Dipl. ACVS, of the New studies on treatments for arthritis Research on feeding horses with University of Pennsylvania, told Barbaro’s in horses, including doxycycline, Sur- equine metabolic syndrome, equine medical story. pass, and Myristol. Cushing’s disease, and colic. By Kimberly S. Brown By Christy West By Nancy Loving, DVM 40 Digestive Health 61 Ophthalmology Research clues for vets and owners on Information on a normal eye exam and management practices for problems moon blindness. with sand, ulcers, and acidosis. By Nancy Loving, DVM By Christy West 62 And More ... 44 Medicine/Surgery Other information included corneal Topics included traumatic brain injury, ulcers, uveitis, and a list of topics that IV lidocaine for pain management, couldn’t fit in the print version, but will cisplatin beads for cancer treatment, be available online. 14 The Latest News and hernia surgery. By Nancy Loving, DVM, et al. Research and accomplishments in By Christy West veterinary medicine that either were too 62 Advertising Index new to make the regular AAEP presenta- 48 Horse Management tions, or warranted additional commen- Topics included airlifting a horse, back tary, were presented in the revamped the 2007 Convention Proceedings with sensitivity and treatment, poisoning, synopses from each speaker can be pur- Kester News Hour. chased from the AAEP by calling chelsea at and Healthy Horses Workshop talks. 800/443-0177; 859/233-0147; or writing to AAEP, By Christy West By Les Sellnow and Christy West 4075 Iron Works Parkway, Lexington, KY 40511.

20 Reproduction 54 Infectious Disease Partners in AAEP Media Partners Among the many presentations was Researchers discussed strangles, R. Equine Health are an esteemed group an in-depth discussion of sperm in the equi, West Nile virus, Leptospira spp of industry-leading cor- porations dedicated to Milne State-of-the-Art Lecture. that causes moon blindness, and more. providing resources and By Les Sellnow By Les Sellnow education, through the AAEP, to veterinarians and horse owners to 26 Diagnostics improve the health and Discussions ranged from MRI to pre- Many more articles from the 2007 welfare of the horse. purchase exams and airway evaluations. AAEP convention will be available in a PDF on TheHorse.com. Photo credits: Cover and above—Cookie serletic By Christy West barbaro—Courtesy Dr. Dean Richardson

March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 3 AAEP WRAP-UP 2007 Convention Highlights Research, Learning The 53rd American Association of Equine Practitioners Convention offered the latest in research findings and by Kimberly S. Brown honored leaders in the veterinary field

eterinarians, veterinary technicians, and horse owners gathered in Or- Vlando, Fla., Dec. 1-5 for the 2007 convention of the American Association of Equine Practitioners (AAEP), which is the largest educational event for horse veterinarians in the world. This convention was the second consecutive meeting that broke attendance records, with 7,238 veterinary professionals, guests, and exhibitors at the gathering. The previous attendance record of 6,842 was set at the 2006 convention in San Antonio, Texas. Another first was the swearing in of the association’s first woman president, El- Cha d M e nd ll eanor Green, DVM, Dipl. ACVIM, ACVP. The 2008 Executive Committee includes (left to right): Immediate Past President Doug Corey, DVM; Green was the program chair for the 2007 Vice President Nat White II, DVM, MS, Dipl. ACVS; President Eleanor Green, DVM, Dipl. ACVIM, convention. Green is professor and chair of ACVP; Treasurer R. Reynolds Cowles Jr., DVM; and President-elect Harry W. Werner, VMD. the Department of Large Animal Clinical Sciences at the University of Florida’s Col- II, DVM, MS, Dipl. ACVS, Jean Ellen She- the Dec. 4 President’s Luncheon. The Dis- lege of Veterinary Medicine. She also is the han Professor and director of the Marion tinguished Educator Award is given to college’s chief of staff at the Large Animal duPont Scott Equine Medical Center in those who “have significantly impacted Veterinary Medical Center. Leesburg, Va., vice president; Doug Corey, the development and training of equine “Dr. Eleanor Green and the Educational DVM, a private practitioner in Adams, practitioners.” The 2008 recipients were Programs Committee put together another Ore., immediate past president; and R. Howard “Gene” Gill, DVM, a retired great meeting program for our members,” Reynolds Cowles Jr., DVM, a private prac- practitioner and former faculty member said David L. Foley, AAEP executive direc- titioner from Free Union, Va., treasurer. at Michigan State University, and James tor. “I continue to be overwhelmed each New members of the board of directors Moore, DVM, PhD, Dipl. ACVS, of the and every year with the increasing atten- are: Dickson D. Varner, DVM, MS, Dipl. University of Georgia. dance and the quality of the material.” ACT, Texas A&M University; W. David Wil- Gill served on the faculty of Michigan son, BVMS, MS, University of California, State University beginning in 1966, and New Officers and Board Members Davis; Roxy J. Bell, DVM, MSc, Dipl. ACT, he led a four-veterinarian practice in Pine The 2008 Executive Committee and new a private practitioner from Alberta, Cana- Bush, N.Y. Gill is now retired, although he members of the Board of Directors took of- da; and Brian S. Carroll, DVM, a private occasionally assists with surgery at his old fice on Dec. 4. Executive Committee mem- practitioner from Edmond, Okla. practice. He has been an AAEP member bers are: Green, president; Harry W. Wer- since 1957, has served on the Resident Vet- ner, VMD, a private practitioner in North Distinguished Educators erinarian and Constitution/Bylaws Com- Granby, Conn., president-elect; Nat White Several awards were presented during mittees, and he now holds the distinction

4 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

of Honor Roll member within the associa- is given to an individual “who has provided in orthopedics for the development of tion. exemplary service to the AAEP or a simi- the self-compressing bone plate. In 1975, Convention Highlights Moore is known for his research in lar organization to the benefit of the horse, Bagby created a visitation program be- endotoxemia, and he has worked within horse industry, or the profession of equine tween the Washington State University a group of investigators to develop inno- veterinary medicine.” The 2007 recipient College of Veterinary Medicine and Sacred vative computer-aided teaching modules was Gary Norwood, DVM, a private prac- Heart Hospital in Spokane, Wash. This depicting some of the more complex as- titioner formerly from Louisiana and now unique program introduced veterinary pects of endotoxemia, gastrointestinal residing in Texas. Norwood, a former AAEP surgery residents at Washington State to Research, Learning abnormalities in horses, and intracellular president, assumed the leadership role in surgical procedures in human medicine. signal transduction pathways (known as the World Equine Veterinary Association The collaboration resulted in the devel- The Glass Horse; watch for clips from this for 2008. Norwood served in the U.S. Army opment of the Cloward technique, which animated educational video coming to Veterinary Corps during the Vietnam War, treats cervical (neck vertebrae) malfor- TheHorse.com soon). Moore received the and he has lead and served on numerous mations in horses. This procedure has University of Georgia’s Creative Research AAEP and other industry committees. He been utilized in more than 1,000 horses Medal in 1988 for his research on intesti- also is a spokesperson in the AAEP On Call to date. nal diseases and endotoxemia; the David Program, offering veterinary insight dur- The spotlight was shone on the Jacksons Tyler Award for Innovation in Teaching ing various televised elite equine competi- and those associated with the Thorough- at the University of Georgia in 1998; the tions. bred racehorse Barbaro during his fight World Equine Veterinary Association Re- against catastrophic injury and laminitis. search Award in 1999; and the Alumni George Stubbs Award “The Barbaro team has made significant Achievement Award from the School of The AAEP’s George Stubbs Award rec- contributions to equine veterinary medi- Veterinary Medicine at the University of ognizes contributions made to equine cine through the creation of multiple re- California, Davis in 2006. Moore was the veterinary medicine by individuals other search funds, an endowed chair in equine 2001 Frank J. Milne Memorial Lecturer than veterinarians. The 2007 recipients disease research at the University of Penn- at AAEP, and he has been a Distinguished were George Bagby, MD, and Barbaro’s sylvania School of Veterinary Medicine, Research Professor at the University of owners Roy and Gretchen Jackson, along and positive public outreach efforts that Georgia since 2002. with the horse’s trainer, Michael Matz. helped showcase the advances in equine Bagby is an orthopedic surgeon still medicine and surgery,” noted the AAEP. Distinguished Service Award practicing medicine even now at 84 years “This all stemmed from their unwavering The AAEP Distinguished Service Award of age. Bagby received a master’s degree support and love for Barbaro.”

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Veterinary Hospital, which is a private Convention Highlights hospital and referral practice owned and The Lavin Cup for Welfare operated by five veterinarians, with an ad- Named for AAEP Past President Gary ditional seven associate veterinarians. Lavin, VMD, the Lavin Award is presented An AAEP member since 1976, Lewis to a nonveterinary individual or organiza- has been very active within the association that has demonstrated exceptional tion. In addition to serving as president compassion or developed and enforced in 1999, he served on the board of direc- rules and guidelines for the welfare of tors from 1987 to 1993. He is an On Call the horse. The 2007 recipient was Finger team member and he also has served on Lakes Thoroughbred Adoption Program. the AAEP Long-Range and Strategic Plan- The Finger Lakes Thoroughbred Adop- ning, Constitution and Bylaws, Problems tion Program is dedicated to finding Analysis, Research, Convention Planning, homes for former racehorses. Racetrack Cha d M e nd ll President’s Advisory, Nominating, Public George Bagby, MD, (left) received the George veterinarian Margaret Ohlinger, DVM, Stubbs Award for his contributions to equine Policy, and Foundation Advisory Commit- trainer Phyllis Shetron, and horse owner veterinary medicine. tees. Lewis also is the AAEP representa- Valerie Morrison, together with manage- tive for the Racing Medication and Testing ment from Finger Lakes Gaming and Distinguished Life Member Consortium and the AAEP representative Racetrack, founded the program in 2005. AAEP Past President Robert D. Lewis, for the Legislative Advisory Council of the It is the first Thoroughbred adoption facil- DVM, of Elgin, Texas, was recognized for American Veterinary Medical Association. ity in the country to be run as a collabora- his contributions to veterinary medicine tive effort between racetrack management with a Distinguished Life Member Award. About AAEP and horsemen. They have found new Lewis received his veterinary degree The AAEP, headquartered in Lexington, homes for more than 100 former race- from the Louisiana State University Ky., was founded in 1954 as a nonprofit horses and are currently fundraising for School of Veterinary Medicine in 1977. He organization dedicated to the health and the construction of a new barn to house entered private practice upon graduation welfare of the horse. Currently, the AAEP retirees before adoption. and began working at Cardwell and Gra- reaches more than 5 million horse owners Previous recipients of the Lavin Cup ham Veterinary Hospital. He became a full through its nearly 9,000 members world- include the Thoroughbred Retirement partner in 1979, at which time the busi- wide, and it is actively involved in ethics is- Foundation, American Quarter Horse As- ness entity was renamed Elgin Veterinary sues, practice management, research, and sociation, California Horse Racing Board, Hospital. He was also a partner in Elgin continuing education in the equine veteri- Professional Rodeo Cowboys Association, Breeding Service until 1985, and a partner nary profession and horse industry. Thoroughbred Charities of America, and in Southwest Stallion Station until 1993. The AAEP’s 54th Annual Convention will Days End Farm Horse Rescue. Currently Lewis is president of Elgin be held in San Diego, Calif., Dec. 6-10. h

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STEADFASTTM EQUINE is a product of Arenus, a division of Novus Nutrition Brands, LLC. | www.arenusperformance.com The One and Only One.TM 6 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by Lessons from Barbaro by Kimberly S. Brown

arbaro first captured America’s imagination, then its heart. “People Bthought a superstar was on the ho- rizon” after Barbaro’s easy win in the Ken- tucky Derby, said Dean Richardson, DVM, Dipl. ACVS, the veterinary surgeon who headed the team that attempted to save Barbaro’s life after a catastrophic injury in the 2006 Preakness Stakes. Richardson’s presentation, sponsored by Merial, was designed to walk the audience of several thousand equine practitioners through the ups and downs of medically attending a horse of this caliber with an injury one veterinarian had described to this editor as “a bag of ice” because of the multiple bone fragments involved. He said his unique presentation was designed “for veterinarians and adults” as he dealt in-depth with the injuries and techniques used to try to save Barbaro. Richardson is known for his ability to handle complicated surgery cases and became quite adept at fielding complicated press relations during Barbaro’s stay at the University of Pennsylvania’s New Bol- ton Center. He was just as adept and calm in handling a difficult speaking scenario while contending with a sound system

problem during about a quarter of his pre- Barbara Livingston sentation. The fire alarm went off in a sec- Kentucky Derby winner and champion Thoroughbred Barbaro captured America’s imagination and tion of the hotel attached to the conference heart with a thrilling victory and his brave struggle to overcome catastrophic injury. center, which turned on the house sound system speakers, which caused feedback after saving three children during a plane At that juncture he showed a video of deafening squeals. Richardson only paused crash. “He’s a legitimately great human the Preakness, Richardson said, “It’s re- when the feedback became unbearable. being,” said Richardson. ally hard still for me to watch that tape.” “There’s no such thing as a good horse He accentuated the athleticism of Bar- The Story of Barbaro without good owners,” continued Rich- baro to keep galloping on three legs, and He said the story of Barbaro became ardson, “and you can’t do better than the the skill of jockey Edgar Prado in pulling a phenomenon for several reasons, in- Jacksons (Roy and Gretchen, Barbaro’s up Barbaro and keeping him from run- cluding trainer Michael Matz, the former owners). They are private people who had ning off. Olympian who was a hero in his own right to become public.” Richardson and moderator Eleanor

March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 7 AAEP WRAP-UP 2007

Barbaro Green, DVM, Dipl. ACVIM, ACVP, head of the large animal hospital at the Univer- sity of Florida veterinary school, both paid tribute to long lists of people who were involved in the Barbaro story. The group included those at the track who stabilized Barbaro and those who drove him to New Bolton, to the nurses and technicians at the hospital who cared for the horse on a daily basis. Richardson singled out Larry Bram- lage, DVM, Dipl. ACVS, an orthopedic surgeon at Rood & Riddle Equine Hospi- tal in Lexington, Ky., who was the AAEP On Call veterinarian at the Preakness who spoke to media to try and explain what had happened to Barbaro. One rough recovery left the entire team sitting along the wall around the recovery pool exhausted while Barbaro stayed in the recovery raft with some hay in front of him. The Surgery Barbaro was transported and stabilized the night of the Preakness, and Richardson flew back from Florida, where he had been performing surgery. He had seen X rays taken at the racetrack prior to leaving Florida, “so I knew what I was dealing with,” he said. The extent and type of injuries “pre- cluded certain options, such as external fixation,” explained Richardson. “He was placed under general anesthesia in a sling and the leg was unwrapped. There were no gross breaches in the skin, but there was serum coming through the skin.” He said there was no option but to do C o u r te sy D r. Dea n R ic ha rdson a fetlock arthrodesis (fusion). Richard- Richardson credited the water recovery raft system of waking horses up from anesthesia for help- son said there was no history of lame- ing keep Barbaro alive through his numerous surgeries and cast changes. ness for Barbaro, and no evidence of pre- existing injuries evident at surgery. A grafts, etc., that were used, and why. his stall in the intensive care unit, which question from the audience at the end of “Infection is the No. 1 concern with this was about 100 yards away. the presentation asked whether Barbaro type of surgery,” he said. In his “Lessons “He got used to it,” said Richardson of breaking from the gate prior to the start Learned” section at the presentation’s end, the use of the pool, sling, and being hoist- of the race had any predisposing effect he said he wished there could have been ed. But he did cite one “difficult” recovery on Barbaro’s injury. Richardson said, “I better fixation of the pastern joint. “We got that in hindsight, he said, was probably didn’t address his early breaking from the into trouble when the pastern joint didn’t when the horse was developing laminitis. gate because I don’t think it was part of remain stable and we had to go back in “Things were working really well the the injury. The horse was examined by and the horse developed an infection and first six weeks,” said Richardson. “He was a veterinarian when he broke out of the foundered,” reflected Richardson. comfortable with Bute. But I knew all the gate. It doesn’t take much effort to break problems were not going to be addressed through a starting gate. The Long Road in the first two, six, or eight weeks. But “My gut feeling is I don’t think it was Richardson credited the water recov- I’m still human, and I got my hopes up.” related, but we’ll never know,” he said. ery raft system of waking horses up from When Barbaro’s right hind pastern be- Richardson walked his veterinary au- anesthesia for helping keep Barbaro alive gan to be unstable, he became sore. Rich- dience through the entire surgical proce- through his numerous surgeries and cast ardson found on X rays that one of the dure, showing images of the various stag- changes. He showed several videos of Bar- screws was bent and coming out of the es of the operation with comments on the baro being lifted in the sling while anes- plate. That screw was replaced and more type of equipment, plates, screws, bone thetized and while awake and heading to screws were added.

8 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

“If you put one moment that was the turning point of this case … he ended up If you put one moment that was the turning point getting a local infection at the distal end of the plate” after that surgery, said Rich- of this case … he ended up getting a local infection ardson. at the distal end of the plate. That required going back into the pastern, removing the plate, cleaning it up, dr. Dean Richardson putting two plates back in, and two cast changes. It was at this point he had a and suggested it might be time to quit,” to just wearing a bandage and cast. At “rough recovery” from anesthesia, said said Richardson. “None of us could do it that point Richardson could lead him out Richardson. “That was one of the low because all of us were in front of his stall a few feet to a grassy patch outside the points in this eight-plus-month saga.” and Barbaro looked like he had barely a hospital for the horse to graze. It took 16 hours to try and get him on his care in the world. Barbaro had the final “Just having him munch grass made feet. “Every time we got him out he strug- vote, and we pressed on.” me happy,” said Richardson. “He was gled,” said Richardson. “It took three of At that point the foot was completely walking on both hind limbs very well.” four tries.” One image Richardson showed unstable since most of the hoof capsule That progress continued through the was Barbaro in the recovery raft with some had been removed. “There was nothing fall of 2006, with the horse going out to hay in front of him, and the team sitting but a blood clot (under the hoof wall),” hand graze every day. He was out of his along the wall around the pool, visibly ex- said Richardson. The only stable part of cast for several months before things took hausted (see top photo on page 8). the foot that was connected was the lat- a final downturn. His fracture healed, but “I was sure we were in big trouble at eral quarter. “The medial side never re- the excess weight bearing resulted in less- that point,” recalled Richardson. The pas- covered,” said Richardson. A hoof cast than-perfect alignment of the right hind tern healed (fused), but that was about the was applied, and “a dozen different ap- pastern. Barbaro was still not growing time that Barbaro foundered badly in his pliances” were used. “He still had to bear enough hoof. left hind. weight on the right hind, and that result- “The real thing that led to his demise There was distal displacement of the ed in some collapse,” he noted. is when he developed a horrific sole ab- coffin bone (it sank) within two days. “We For two weeks Barbaro was in and out scess in his right hind,” said Richardson. had him on intense analgesia, including of his sling. “He was a smart horse, and as “Because his left hind foot was still not an epidural,” noted Richardson. “He was long as you gave him plenty of attention, growing adequately and not comfortable remarkably comfortable.” he was good in the sling,” said Richardson. for him, it was impossible to manage the A meeting was held in front of Barba- Most of the leg cast and foot cast changes abscess in the right hind foot.” Then Bar- ro’s stall with Richardson, the Jacksons, were done under general anesthesia. baro foundered in his front feet, and, as and the Matzes to discuss his future. Then Barbaro began having some Richardson termed it, “the story faded to “I told them this was catastrophic healthy coronary tissue, and he improved black.” H

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variety of topics, including methicillin-resistant Staphylococcus au- Areus, influenza outbreaks, stem cell therapy, and reproductive research were highlighted during the reinvented Kester News Hour. The popular two-hour scientific program kickoff featured three new presenters discussing the latest advances in equine surgery, internal medicine, and reproduction. Replacing outgoing presenters John Ma- digan, DVM, MS, Dipl. ACVIM, and Larry Bramlage, DVM, MS, Dipl. ACVS, were Scott Palmer, VMD, Dipl. ABVP; Bonnie Rush, DVM, MS, Dipl. ACVIM; and Margo Macpherson, DVM, MS, Dipl. ACT. The new panel presented the fast-paced news broadcast format under the call letters WKNH (W Kester News Hour), complete with equine-themed “commercials” for comic relief. The work of Bramlage and Madigan as Kester News Hour hosts was not forgot- ten. As starting time approached, a video accompanied by the song “The Way We Were,” was presented, highlighting both poignant and humorous moments during Cha d M e nd ll the Kester News Hour through the years. The Kester News Hour featured three new presenters discussing advances in equine surgery, The program is designed to give a quick internal medicine, and reproduction. (Left to right) Margo Macpherson, DVM, MS, Dipl. ACT; Scott overview of some of the research and ac- Palmer, VMD, Dipl. ABVP; and Bonnie Rush, DVM, MS, Dipl. ACVIM, presented the fast-paced complishments in veterinary medicine news broadcast format under the call letters WKNH. during the previous year that either were too new to make the regular presentations A second study published in the Jour- Equine Veterinary Journal (EVJ) study or warranted additional commentary. nal of Orthopedic Research found that ar- found that polysulfated glycosaminoglycan throscopic scores for MSC-implanted car- (PSGAG, i.e., Adequan) injected into the Lameness/Surgery tilage defects were significantly better than coffin joint for treatment of arthritis had a Stem Cells A study published in Vet- controls at 30 days post-treatment, but no 76% success rate one year after treatment erinary Surgery (VS) in 2007 evaluated fat better in the long-term (at eight months). based on owner surveys, compared to a tissue (adipose)-derived stem cells (ASC) “This field is relatively young, but holds 46% success rate for methylprednisolone in an attempt to discover whether these promise,” Palmer summarized. “It’s im- acetate (MPA, i.e., Depo-Medrol). stem cells are as effective as those har- portant to balance our expectations with “But in this study it’s not possible to vested from bone marrow (MSC). “(ASC) the scientific knowledge we have available. make a direct comparison between these are capable of adipogenic (fat-producing) Our clinical expectations have outpaced two medications because if horses didn’t and osteogenic (bone-producing) differen- our scientific knowledge at this point.” resolve with MPA treatment, they were tiation, and their expansion characteris- He also noted that stem cells derived later treated with the Adequan,” cautioned tics are similar to those of other species,” from skin tissue might hold promise for Palmer. The exercise recommendations Palmer reported. “But osteogenic induc- equine use. for the two treatments were also different, tion of ASC is slower than that of MSC.” Coffin joint medication success An introducing still another variable. Addi-

March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 11 AAEP WRAP-UP 2007

tional findings were that dressage horses for ways to minimize catastrophic injuries equine slaughter plant. enjoyed better results than jumpers, and (severe injuries necessitating humane eu- “Prior to that, about 80 horses per week in general horses did better if they were thanasia) on racetracks. Palmer discussed were shipped from the United States to older than 10 years, had lameness of less a study published in Clinical Techniques Mexico for slaughter, but during the week than three months duration, or had uni- in Equine Practice regarding track factors after the Illinois plant closure, that num- lateral lameness (in one front or hind foot that might influence injuries. Turf tracks ber jumped to 1,345,” she reported. “It’s es- only). had one-third the risk of breakdowns timated that 40,000 horses will be shipped Interleukin-1 receptor antagonist pro- than dirt tracks with fast conditions had, to Mexico for slaughter by the end of this tein (IRAP) This relatively new treatment and muddy dirt tracks had a significantly year; 31,086 horses have been transported did well in a study of arthritis published lower rate of breakdowns compared to as of Dec. 6, whereas only a total of 6,392 in the American Journal of Veterinary Re- fast tracks. The injury rate per 1,000 start- horses were transported last year. search (AJVR). Treated horses showed a ers was found to be 3.5-7.3, and the rate “Doug Corey (DVM, then the chair of significant improvement in clinical lame- of catastrophic injuries was found to be AAEP’s Welfare Committee) and Tom Lenz ness and a decrease in synovial mem- 0.99-1.85 (or approximately one in 1,000 (DVM, then the AAEP president), and Da- brane hyperplasia (thickening of the joint starts). The metacarpophalangeal joint vid Foley (AAEP executive director) visited lining due to inflammation) compared (fetlock) was injured in 12.3% of cata- the Texas slaughter plants and found that with controls. They also experienced no strophic injuries. horses were treated humanely and eutha- adverse side effects and showed a trend “Transitions may be a factor; when a nized according to USDA/AVMA guide- toward decreased cartilage fibrillation track is dry or under a lot of rain it’s sta- lines,” she went on. “AAEP’s concerns with (softening and grooving of joint surface cartilage). Interpreting joint fluids When is a horse’s joint infected? Usually a veterinarian It’s estimated that 40,000 horses will be shipped to looks for levels of total protein, neutrophil Mexico for slaughter by the end of this year. percentage, and total nucleated leukocyte count in the joint fluid to be increased dr. Bonnie Rush with infection, but a VS study found that injection of plain saline or amikacin antibiotic resulted in temporary increases in ble, but when the rain first soaks the track the current situation are long-term place- all of these values, despite sepsis (infec- or as the track dries, inconsistencies can ment of the 80,000 unwanted U.S. horses tion) not actually being present. increase the risk of injury,” commented per year and funding for them. The Amer- “Reactive synovitis from injections can Palmer. ican Veterinary Medical Association will confuse interpretation of synovial values,” be including provisions to fund the care, explained Palmer. “Some horses had in- Horse Identification maintenance, and disposal of unwanted creases in synovial fluid values that might “Right now we’re in the midst of a vol- horses. But we need to address the root— be interpreted as sepsis even though it untary program designed to facilitate irresponsible horse ownership—not the wasn’t present. But the potential for sepsis traceback in the event of an outbreak,” symptom, which is unwanted horses going shouldn’t be ignored; veterinarians must said Palmer. “The USDA has approved new to slaughter. The Unwanted Horse Summit be careful to interpret synovial values in 134.2 KHz microchips in addition to the was held in April 2005 and the Unwanted the context of culture and sensitivity test older 125KHz chip, and they recommend Horse Coalition grew out of that summit results, and the degree of lameness. Hors- the 134.2 KHz chip from this point for- as a broad allegiance of equine organiza- es that have a mild reactive synovitis are ward.” Vets implanting the new chips will tions committed to educating the horse generally sound, while horses with infec- have to report them to the USDA. industry about the unwanted horse issue. tion are usually quite lame.” For more information, see www.Equine The goals are to reduce the numbers of Nutraceuticals for lameness Palmer SpeciesWorkingGroup.com. unwanted horses; educate owners, breed- reported on several nutraceutical stud- ers, and sellers; facilitate adoption and ies, including an equine study of avocado Slaughter donation; and establish a rescue organiza- and soybean extract (published in AJVR) “When the Horse Slaughter Prevention tion registry to facilitate adoptions.” that found that it didn’t improve lameness Act was introduced in 2005, there were “It’s a very tough situation,” Palmer con- caused by experimentally induced arthri- three slaughter plants processing about cluded. “The demand for horse meat in tis, but it did significantly reduce synovial 80,000 horses per year (two in Texas and Europe is still very high; in fact it’s at an hemorrhage (bleeding) and the severity of one in Illinois),” began Rush. After briefly all-time high due to consumer concern the articular cartilage erosion. “It doesn’t discussing the progress of that legislation regarding beef consumption in the wake provide a lot of analgesia, but it certainly and closure of the Texas plants, she noted of recent outbreaks of bovine spongiform can have a disease-modifying role in man- that in late September of 2007, the federal encephalopathy (mad cow disease). At this agement of these diseases,” he noted. appellate court upheld the constitutional- point we’re not changing anything (with re- Racing surfaces Researchers, veterinar- ity of an Illinois law banning slaughter, gards to decreasing horse slaughter), we’re ians, and others are always on the lookout effectively closing the last remaining U.S. just shifting it beyond U.S. borders.”

12 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

Medicine/Infectious Disease beforehand than internal medicine cases. their dams than those that don’t. Methicillin-Resistant Staphylococcus Attendees got quite a shock from Rush’s Treating R. equi infection with gallium aureus (MRSA) “MRSA often manifests as report of the results of a study conduct- maltolate One substance might help com- flesh-eating disease or septicemia, and it ed on veterinarians attending last year’s bat foal susceptibility to R. equi—gallium caused 90,000 cases of invasive infection AAEP convention. Nasal swabs were col- maltolate. Rush explained that it is an iron and 18,650 human deaths in the United lected and cultured at an exhibit booth mimic that exploits the iron dependency of States in 2007,” reported Rush. “Its death on 257 veterinarians from 12 countries. the R. equi bacterium to kill it. It’s highly rate exceeds that of HIV. In the past year “Recall that the general population’s car- bioavailable and has minimal side effects it’s become more community-associated rier rate is 0.8-3%, but 10.1% of us are in humans, and prophylactic (protective) than hospital-associated, with commu- carrying MRSA and 62% of the carriers administration reduces the severity of R. nity-associated outbreaks causing 32 in- were ambulatory practice veterinarians,” equi infection in mice. Side effects were fections and 6.2 deaths per year. About she stated. “The most common strain minimal or nonexistent in an AJVR study. 0.8-3% of the general population carries was USA500/CRSA5, which is normally Treatments for R. equi include immuno- it in their nasal passages without showing uncommon in humans (but common in stimulation to boost interferon (a protec- disease. Based on one study, the disease horses). Handwashing between cases and tive protein) and prophylaxis with gallium has an 83% survival rate in horses, but the farms reduces the likelihood that someone maltolate to kill the bacteria, she explained. length of the hospital stay and costs are will carry MRSA, so this is the recommen- “It will be interesting to see which strategy extensive.” dation for prevention at day cares, hospi- is more effective,” she commented. Zoonotic MRSA infection—which tals—everywhere.” Equine herpesvirus outbreaks “There jumps from humans to animals or vice ver- Do foals get Rhodococcus from their have been 25 confirmed equine herpesvi- sa—was first reported by the University of dams? Rush discussed an AJVR study of 171 rus (EHV) outbreaks since 2000, which ap- Guelph in 2004. Horse to human transmis- mare-foal pairs, 53 (31%) of which includ- proximates the number of outbreaks in the sion occurs readily (dogs can carry it, too), ed a foal affected with Rhodococcus equi previous 30-35 years,” reported Rush. “In and a study published in the Canadian pneumonia, that attempted to answer the six well-documented outbreaks, there were Veterinary Journal found that 2% of horses question of whether foals get R. equi from 119 cases and 35 deaths—resulting in high- admitted to veterinary hospitals carry the their dams. Researchers found virulent R. er-than-normal morbidity (disease rate) of bug. Penicillin and sulfa antibiotic use are equi at least once in every mare during the 26% and mortality (death rate among ill risk factors for horses, as is admission to study period, and fecal concentrations of individuals) of 29%. The disease is evolving a neonatal intensive care unit and previ- the bacterium were not significantly differ- in terms of virulence and behavior, and the ous colonization of the horse or the horse’s ent between dams of sick and healthy foals. USDA has designated neurologic EHV as farm. Undergoing surgery might reduce Thus, foals might indeed get R. equi from a potentially emerging disease. Outbreaks risk, possibly because most surgeries are their dams, but the ones that get sick don’t are caused by a specific strain of EHV-1; 30 elective and most cases get less antibiotics appear to get any more of a challenge from of the outbreaks between 2000 and 2006

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were caused by a mutant strain and only two were caused by a wild type. EHV outbreaks have had an enormous impact on the “The mutant strain causes tenfold higher viremia (level of virus in the bloodstream) performance and racing industries. than typical EHV,” she said. “A single amino acid substitution in the virus’ DNA is the dr. Scott Palmer mutation, and that viral genome is highly conserved across species. An article by American Veterinary Medical Association to 42 (0.24%) when horses euthanized or George Allen (PhD, a former professor at found that when cisplatin (in sesame oil dying in within seven days after anesthesia the University of Kentucky’s Gluck Equine emulsion) is injected into a solid tumor, were included. This rate is lower than pre- Research Center) in the Journal of Veteri- the cure rate at two years after treatment viously reported rates, noted Palmer. nary Diagnostic Investigation on a real-time was 93%, which Rush described as “as- “Familiarity with an anesthetic protocol PCR test for EHV-1 with a 24-hour turn- tounding.” One factor contributing to fail- in combination with reduced anesthetic around time showed perfect agreement ure of the first treatment included large time, emergencies of shorter duration be- with the four-day test, so diagnosis of the tumor size and residual tumor cells left in tween diagnosis and surgery, and adequate disease can be very quick now.” the area after debulking the lesion. preoperative examination appear to mini- Regarding treatment, she noted valacy- Rush also noted that a later convention mize the risks associated with general an- clovir has eight times the bioavailability of presentation would discuss the use of bio- esthesia in horses,” noted the authors. oral acyclovir, according to a study pub- degradable cisplatin beads, which result in Cervical vertebral myelopathy (CVM) lished in Antimicrobial Agents and Chemo- an 83% success rate at two years. “There’s “Most horses with CVM (narrowing of the therapy, and serum levels of the drug are obviously at least two good ways of doing spinal canal and compression of the spinal within the range of sensitivity for EHV-1. this, and I think it’s really an exciting way cord) are thought to be three years old or “I think the hope is that it will serve as a to treat these lesions,” Rush commented. less, but a study published in Journal of preventive, but it’s unclear if it will clear General anesthesia risks “Nobody likes Veterinary Internal Medicine on 22 horses clinical signs once they’re established,” to talk about it, but there are fatalities re- found a mean (average) age of 8.4 years,” Rush noted. lated to general anesthesia,” said Palmer. said Rush. Males were most often affected, “EHV outbreaks have had an enormous A study published in Veterinary Anaesthe- and Warmbloods, Quarter Horses, and impact on the performance and racing in- sia and Analgesia found that 0.12% of 961 Tennessee Walking Horses were overrep- dustries,” commented Palmer. horses (21 horses) undergoing procedures resented. Cisplatin for skin cancer Skin tumors under general anesthesia died due to fac- “In older horses with spinal ataxia (inco- are often aggravating to veterinarians and tors directly related to anesthesia, including ordination), the neck may be the problem owners due to their tendency to recur. cardiac arrest, fractures during recovery, or due to bony restructuring or degenerative But a study published in Journal of the neuropathy/myopathy. That rate went up disease,” she noted. h

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Milne Lecture Dickson Varner, DVM, MS, Dipl. ACT (a specialist in reproduction), is a self-described “renegade” when it comes to presenting papers at veterinary gatherings. He is known for his irreverent humor, po- etry, and clever turn of phrase. That being said, Varner is also a leading researcher in equine reproduction and has helped pro- pel Texas A&M University into a leadership role in that field. He was chosen to present the Milne State-of-the-Art Lecture at the convention. The lecture and award were named in honor of Frank Milne, the late and longtime editor of the annual AAEP Conven- tion Proceedings. The lecture is designed to offer in-depth information on a particular subject. r/AAEP rn e r/AAEP C o u r te sy D r. ickson Va Varner lectured on the topic: “From a Illustration of how a spermatozoon fertilizes an egg. a) The spermatozoon navigates through the Sperm’s Eye View—Revisiting our Percep- egg’s protective barrier and b) adheres to the inner layer. c) The sperm cell’s protective covering tion of This Intriguing Cell.” begins to disintegrate. d) The sperm gains entry into the egg. e) The protective covering dis- Varner said the lecture was not a com- solves, allowing the sperm cell’s DNA to merge with that of the egg (f). pilation of his work, but a presentation of the work from a great many scientists no real surprise when he announced that a song titled “Stud is a Four-Letter Word.” through the years. As if to prove that point, an animated cowboy would help him with He also whipped out his trademark har- his paper published in the Proceedings con- his message during the Milne Lecture. monica to play along, and the large crowd tained more than 1,000 references. He introduced “Dr. Dick,” an out-of-work responded with a standing ovation. Dickson’s ditty It was truly an in-depth cowboy, who would ride a sperm through Origin of the sperm With the help of “Dr. description of the sperm cell, but it also a series of slides depicting the cell’s travels Dick,” whose spermatozoal ride got rather contained Varner’s trademark brand of from the time it is formed until it ends up hectic and scary at times—especially dur- humor. He said that program chairman entering the female oocyte and establishing ejaculation—Varner described the and 2008 AAEP President Eleanor Green, ing a pregnancy. origin of the sperm within the testis “the DVM, Dipl. ACVIM, ABVP, and 2007 AAEP Everyone who knows Varner also knew sperm factory.” President Doug Corey, DVM, had frequent- he would do something unique when he The process is called spermatogenesis. ly expressed concern about what bent his arrived at the halfway point of his lecture “Spermatogenesis,” he wrote in the paper humor might take and worried that he and it was time for a break. He didn’t let he presented, “is an extremely complex might get out of line. He jokingly offered them down. He harked back to the 1998 process that involves germ proliferation, to don a dog shock collar and said they Milne Lecture presented by O.J. Ginther, germ cell differentiation, and, paradoxi- could have the remote control button and VMD, PhD, of the University of Wisconsin, cally, programmed germ cell death (termed activate it whenever he went over the edge and did him one better. During his break, apoptosis). This lengthy process, which is in the humor department. Ginther, who was presenting a paper on 57 days in the stallion, is controlled by a Among other things, Varner is a cowboy. equine pregnancy, picked up a guitar and vast array of cell-signaling messengers act- He grew up working with his parents in a sang a ditty titled “Mare is Four-Letter ing through endocrine, paracrine (when Wild West show, complete with rough stock Word.” It was a hit. target cell is close to signal-releasing cell), and trick animal acts, and he went on from Varner brought to the stage two profes- juxtacrine (cells must be in direct contact), there to be a rodeo contestant before join- sional musicians from Texas, Aaron Watson and autocrine (via secretion of a substance) ing the academic path. Thus, it came as and Dan McBride, as backup, and he sang pathways.”

March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 15 AAEP WRAP-UP 2007

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The seminiferous tubules within the tes- region, equatorial segment, post-acrosom- access into the oviduct will eventually ar- tis are where the spermatozoa are manu- al region, and posterior ring, which rive at this fertilization site. The precise factured, Varner said. If the tubules from demarcates the junctions between the mechanisms by which spermatozoa mi- two stallion testes were stretched out end head and flagellum. The posterior ring is grate to the ampullar region of the oviduct to end, he said, they would be 50 football the site of plasma membrane anchoring remain speculative, but contractile move- fields in length. As such, these tubules are to the nuclear envelope and is thought to ments of the oviduct and hyperactivated capable of producing 60,000 to 70,000 produce a tight seal that separates cytoso- spermatozoal motility are thought to play spermatozoa per second. If one were to lic components of the head and flagellum. key roles in this migratory phase.” line up the number of sperm produced by The flagellum can be subdivided into a After capacitation, the spermatozoa a stallion in a normal lifetime, Varner said, connecting piece, middle piece, principal must undergo an “acrosomal reaction” they would stretch to the moon and back piece, and end piece. These various parts before they can pentrate the vestments of more than three times. of the spermatozoon are surrounded by a the egg required for fertilization. This is a The main storage area for the sperm common plasma membrane.” rather complicated reaction that occurs within the testis is the epididymis, upon spermatozoal contact with the which if stretched out would be zona pellucida, a thick, transparent about three-fourths of a football Many of the sperm, Varner said, outer envelope that encases an egg. field in length. Each epididymis In this reaction, the outer mem- is capable of storing 40 to 45 bil- do not complete the journey brane of the acrosome fuses at mul- lion sperm. During their time in and are lost along the way, with tiple points with the overlying plas- the epididymis, the spermatozoa ma membrane of the sperm head. undergo a maturation process only about 0.0006% of spermatozoa The process enables the release of that is required for interaction enzymes from the acrosome that with the mare’s reproductive gaining access to the oviducts are necessary to enable the sperm to tract and establishment of fertil- following insemination. enter the egg. izing potential. Once that entry has been made, Prolonged storage of the sperm the sperm’s journey has come to an within the epididymis is not necessarily a The spermatozoa are virtually immobile end. And so it was for “Dr. Dick,” who was good thing and problems can arise, Varner in the epididymis, Varner told the group, able to head off into the sunset, looking for said, in the form of bent tails, detached but develop motility when ejaculated. new adventures. heads, distal droplets (abnormalities on After ejaculation, the sperm make their Stallion Fertility Varner directed the fi- the sperm flagella, or tails), and decreased way from the uterus into the oviduct on a nal two hours to a discussion of stallion motility. Normally, spermatozoa enter the journey that allows them to meet up with fertility and told the group, for example, epididymis at a constant rate in a repro- the descending egg. Many of the sperm, that morphologically abnormal sperm of- ductively normal stallion, with about 5 bil- Varner said, do not complete the journey ten do not have a negative impact on nor- lion arriving each day. and are lost along the way, with only about mal sperm. “Therefore,” he said, “the total The stay within the epididymis is from 0.0006% of spermatozoa gaining access to number of morphologically normal sperm eight to 11 days. After their stay in the the oviducts following insemination. The in ejaculates may provide more informa- epididymis, sperm are either ejaculated or remainder are lost through the cervix. Ap- tion regarding the fertility of a stallion spontaneously ejected into the urethra and proximately four hours are required for than the percentage or absolute number expelled. This latter mechanism ensures sufficient sperm to ascend from the uterus of morphologically abnormal sperm.” that viable sperm are available for fertil- into the oviduct to establish pregnancy at He also discussed ways to refine a stal- ization at the time of mating or artificial a normal rate. lion breeding soundness examination, and insemination. The ejaculated spermatozoa cannot he described newly developed laboratory A Sperm’s Tale Varner described an indi- fertilize an egg right away. Varner de- assays that might improve the predictive vidual spermatozoa as being shaped like a scribed it this way: “In mammals, freshly value of such an examination. tadpole, with a head and a flagellum. Stal- ejaculated spermatozoa are not immedi- Varner concluded his talk by telling the lion spermatozoa are about 70 to 80 mi- ately capable of fertilizing an oocyte. Early group that, while scientists have achieved crons in length. They are only about half studies showed that spermatozoa require much concerning research on sperm, more as long as mouse spermatozoa. residence time in the female reproductive study is needed. Here is how Varner described the make- tract to gain this capability, later termed “Goals might include devising methods up of the spermatozoa: “The head con- capacitation.” for long-term cooled semen preservation, tains the nucleus, overlying acrosome (a The principal location where capaci- improving the preservation of cryopre- membrane-bound compartment at the tip tation occurs, Varner said, is the caudal served (frozen) semen, and incorporation of the sperm head that contains enzymes (toward the rear) segment of the oviduct. of in vitro fertilization (both convention- to digest the outer surface of the egg), “Interactions with an ovulated oocyte, how- al in vitro fertilization—using multiple and a reduced complement of cytosolic ever, require spermatozoal migration to the sperm—and intracytoplasmic sperm injec- (fluid portion of cytoplasm) elements. The ampullar region of the oviduct, and only a tion, where only one sperm is injected in head can be subdivided into an acrosomal small percentage of spermatozoa that gain the egg) in commercial programs,” he said.

March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 17 AAEP WRAP-UP 2007

“Although these might seem to be lofty goals, a more absolute understanding of the spermatozoal structure and function would certainly take a lot of the ‘guesswork’ out of current approaches to analysis and manipulation of equine spermatozoa.”

Perinatology Traditionally, one of the stronger parts of each AAEP convention program is the time devoted to reproduction. The convention held in Orlando was no exception. It began with an in-depth session titled “Per- inatology—End of Pregnancy Through Be- ginning of Life,” during which experts in the field presented hour-long lectures on various reproductive problems, and it ended with two separate sessions of 20-minute lectures in which the presenters dealt with specific reproduction topics. In-depth presenters were Wendy Vaala, VMD, Dipl. ACVIM, who is employed by Ann e M. E Be r ha rd t Intervet Inc.; Margo Macpherson, DVM, Observation and regular check-ups of the mare and foal are recommended post-parturition. MS, Dipl. ACT, of the University of Flori- da; Regina Turner, VMD, PhD, Dipl. ACT, prolonged gestation. It is important that fluids), prepubic tendon rupture (tearing of the University of Pennsylvania’s New the practitioner has a complete history of of the ligament that supports the abdomen Bolton Center, and Robert Franklin, DVM, the mare, including whether she has been in the mare—loss of this structure makes it Dipl. ACVIM, a referral hospital veterinar- kept on fescue. There are some 35 million impossible for mares to contract muscles ian based in Ocala, Fla. acres of fescue in the United States, Vaala and deliver the foal normally), imminent Late-Term Mare, Newborn Foal Leading said, and fescue toxicosis from infected va- death of the mare because of colic or other off in the in-depth section and continuing rieties can lead to prolonged gestation and systemic illness, and maternal history of on as moderator was Vaala. She offered myriad other problems that can compro- dystocia requiring mandatory assistance “New Perspectives on the Late-Term Mare mise the foal’s chances for survival. during foaling.” and Newborn Foal.” The drug of choice in dealing with fes- The quality of the mare’s colostrum, Under ideal conditions, Vaala told the cue toxicosis, she said, is domperidone. which Vaala called “liquid gold,” should group, the late-term mare would be man- Once the foal has been delivered and be evaluated immediately after delivery, aged before birth by a specialist in repro- the fetal membranes passed (something she said. duction and after birth by a specialist in that should occur within three hours of Vaala noted in her written paper: neonatology. However, she said, in most delivery), Vaala told the group, it is very “Equine perinatology has evolved rapidly ambulatory practices, one person must important that you save and weigh the over the last two decades. However, most be prepared to fill both roles, have proper placenta. The weight of a placenta, which mares will continue to foal in locations equipment to assist in birth, and, if nec- can be 10-11% of fetal weight, can be an other than in large clinics and university essary, provide resuscitation and nursing indicator that problems might exist with hospitals. Therefore, it will remain in the care for the foal. the newborn. Heavy placentas, she said, hands of clinicians in private practice to Many problems begin within the uterus, might be associated with conditions such help improve our knowledge of the high- she told the group, and the practitioner as edema (fluid swelling), congestion, and/ risk mare by using and reporting on the must be able to monitor fetal development or infections. A light placenta might relate use of the antepartum (pre-foaling) moni- in order to determine early if something is to incomplete development of the foal, toring techniques and interventional strat- going awry. along with other conditions. egy discussed in this presentation.” When a mare, especially one in the at- Inducing labor in a late-term mare, Vaa- High-risk mare Macpherson concen- risk category, nears parturition it is impor- la said, should only be used as a last resort. trated on “Identification and Management tant to monitor her progress so that help is “Indications for induction should only be of the High-Risk Pregnant Mare” in her at hand if needed. There are many moni- limited to conditions that would seriously lecture. There are a number of conditions toring aids available, she said, but no one threaten maternal or fetal health if the that can jeopardize the pregnant mare, she aid should be considered infallible. “Noth- pregnancy were allowed to continue, or if said, and the practitioner’s challenge is to ing beats a human walking by and check- unsupervised, spontaneous delivery would identify those problems, then find proper ing on the mare,” said Vaala. occur,” she said. “Examples of such condi- approaches to resolve them. One of the problems that occur is tions include hydrops (excessive placental Three common conditions, she said, are

18 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

early udder development, acute A mare in late pregnancy that de- pain, or an unusual increase in Nothing beats a human walking velops unusual abdominal disten- abdominal size. For each condition is frequently in great jeopardy, tion, she presented the case his- by and checking on the mare. Macpherson said, and she is at risk tory of a mare that had suffered of losing the pregnancy. There are from the condition. dr. wendy vaAla several conditions that could cause She first discussed premature the problem, including hydrops, mammary gland development. Normally, of bacterial placentitis, Macpherson said, rupture of the prepubic tendon, and ab- mares undergo udder development be- involves administering trimethoprim sul- dominal wall herniation. tween two and four weeks before giving famethoxazol and pentoxifylline in con- Treatment options, she said, could in- birth. Development of the udder prior to junction with altrenogest (Regu-Mate). volve use of a supportive belly bandage, that might be an indication she is going to In a study at the University of Florida, induction of labor, and delivery by Caesar- foal early, Macpherson said. she said, 10 of 12 mares with experimen- ean section. Two of the conditions that can cause tally induced placentitis delivered live foals Three Problems Turner told the group that early udder development are the presence after treatment with this protocol. when she began preparing her presentation, of twins and bacterial placentitis (inflam- The colicky late-pregnancy mare poses she had decided to discuss her top 10 list of mation of the placenta), Macpherson told a serious challenge for the practitioner, postpartum problems in mares. Then she her listeners. Macpherson said, because it first has to realized that there wouldn’t be enough for In the case of twins in late gestation, she be determined whether the manifestation that lengthy of a presentation and cut it said, the best approach has already been of pain is from labor contractions or some back to five, then to three. missed. That would involve early detection other condition not connected with the The three problems she chose were 1) at 13 to 15 days gestation and the elimi- birthing process. hemorrhage from uterine or ovarian ves- nation of one embryo. Carrying twins to Once the diagnosis had been made, a sels, 2) uterine lacerations, and 3) retained term puts the mare at risk for a number of treatment protocol can begin. It is impor- fetal membranes. complications, including dystocia (difficult tant to have a complete health history of Hemorrhage from uterine or ovarian birth). Once twins reach the late-term stage, the mare, Macpherson said. For example, vessels usually occurs during the birth- she said, there are basically two options left if she has a history of colic when not preg- ing process, Turner said. Older mares that for the practitioner: terminate the pregnan- nant, there could be greater likelihood of have had a number of foals appear to be cies, or allow the pregnancies to continue, her having gastrointestinal disease than a at greater risk. monitor the mare, and provide assistance type of colic related to pregnancy. Treatment of the condition, she said, during delivery. Neither is particularly pal- The case study mare Macpherson de- can be difficult and confusing. The prac- atable to the practitioner, she said. scribed underwent colic surgery and four titioner must decide whether to place the A promising approach for treatment days later delivered a live foal. mare in a tranquil setting to lower stress

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and blood pressure, or whether he or she labor,” she said. “Thus, whether or not a point that measuring lactate levels can be should institute aggressive treatment that mare has a Caesarean section is not what helpful at both the diagnostic and moni- might increase stress and blood pressure. determines the outcome for the foal. Rath- toring levels (see page 21). “In most instances, as a minimum,” she er, it is how long it takes for a foal to be Franklin said in conclusion: “It is obvi- said, “we will place an indwelling venous delivered, regardless of delivery method— ous that early recognition of the high-risk catheter and begin the mare on volume this is the critical factor.” or abnormal foal is the key to a successful replacement fluid therapy.” She discussed She had this succinct advice for the outcome. Efforts and financial contribu- some of the drugs that have been used to practitioners in the room: “Refer early.” tions should be made early in the course treat the condition and others that are not Mares that undergo Caesarean section of the foal’s life to document all problems recommended. and have good postoperative manage- so that an appropriate prognosis and The prognosis for recovery is variable, ment often have pregnancy rates between treatment plan can be made. Mares with depending on the severity of the hemor- 58-68% if bred back that year. If bred back peripartum disease should be monitored rhage, she said. “Mild hemorrhage into the next year, the rate rises to about 72%. closely for foaling trouble or for the deliv- the broad ligament (a band of tis- ery of a compromised foal. Prepa- sue that helps suspend the uter- rations in terms of equipment for us within the abdominal cavity) Preparations in terms of equip- resuscitation, veterinary planning, typically is associated with a good ment for resuscitation, veterinary and foaling attendance are critical prognosis for recovery,” she said. to the successful delivery of a high- “However, severe hemorrhage in- planning, and foaling attendance risk foal.” to the abdomen or uterus can be acutely fatal.” are critical to the successful delivery Reproduction If the mare survives, she said, a of a high-risk foal. Fetal pulse Stefania Bucca, future pregnancy might result in DVM, of XY Equine Veterinary a recurrence. If the mare is a valu- Dr. Robert Franklin Services in Kildare, Ireland, re- able producer, Turner said, embryo ported on using the fetal pulse transfer should be considered. rate as an aid in determining fetal She then turned her attention to re- High-risk foal Franklin closed out the health. Abnormal patterns in fetal heart tained fetal membranes. In the mare, she in-depth session with a discussion on rate, she said, are a clear indication of fetal said, it is considered that fetal membranes “Identification and treatment of the High- compromise. The veterinarian can record have been retained if they have not been Risk Foal.” the pulse rate with the use of transrectal passed in their entirety in three hours. Early identification of high-risk foals is ultrasound, she said. The condition can occur in any breed imperative so that successful treatment Periparturient hemorrhage Carolyn Ar- but it is most common with draft mares. can be initiated in a timely manner, he told nold, DVM, Dipl. ACVS, of Texas A&M, Friesian mares, she said, are at a signifi- the group. However, identification is only reported on a study of mares treated at cantly higher risk, even after an uncom- the beginning of the process. The ambula- Hagyard Equine Medical Institute near plicated delivery. She described one study tory veterinarian should be equipped with Lexington, Ky., for periparturient (oc- where 54% of Friesian mares retained their appropriate equipment for resuscitation, curring either shortly before, during, or fetal membranes after normal delivery. assisting with breathing, and increasing shortly after parturition) hemorrhage. When membranes are retained, Turner heart rate. She said that 73 mares met criteria for said, the treatment of choice by many A valuable tool, Franklin said, is an in- inclusion in the study and that most of practitioners involves administering oxy- strument that measures lactate levels (in them had delivered a number of foals. tocin. Forceful removal is not a wise ap- the blood). High lactate level can be an Most of the mares, she told the group, proach, but gentle pressure can be helpful, indicator that the foal is in the at-risk cat- were admitted to the hospital within 48 along with uterine lavage. egory. hours of giving birth and manifested Proper management of a mare that un- One of the new approaches described at signs of abdominal pain and hypovolemic dergoes Caesarean section is important for this AAEP convention involved equipping shock (an affected horse has abnormally the mare’s survival and future reproductive attendees at some lectures with keypads low levels of blood plasma in the body, success, she said. for responding to specific multiple-choice such that the body can’t properly main- One of the problems involved with Cae- questions, which then were immediately tain blood pressure, cardiac output, or sarean section, Turner told the group, is tallied by computer. The keypad response normal amounts of fluid in tissues). The that it often is resorted to only after pro- in one instance provided evidence that very aim of treatment was to relieve pain, en- longed attempts for a vaginal delivery. De- few veterinarians attending the session uti- hance coagulation (clotting), and restore livery of a live foal after Caesarean section, lize the lactate-measuring machine. Frank- perfusion (blood flow), she said. The sur- she said, results in foal survival rates of lin made a strong pitch for its use and cit- vival rate of the treated mares was 84%. 11-42% and survival of the foal after leav- ed a number of examples where the device Mares that didn’t survive in a number of ing the hospital is lower still at 5-31%. had first identified at-risk foals, then was instances were those that hemorrhaged “The wide range in foal survival consis- helpful in monitoring their recoveries. before giving birth. tently depends on duration of second-stage A later presentation would underline his Hemorrhage in the field Charles F. Scoggin,

20 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

DVM, MS, of Pioneer Equine Hospital in used by Daels and his colleagues, adoption clinically useful. However, individual moni- Oakdale, Calif., continued the discussion was expected to be completed in five days. tors should be regularly compared with a on periparturient hemorrhage. He said Lactate levels and prognosis Imogen standard laboratory technique because of in one study it was found that rupture of S.F. Henderson, BVSc, of the Royal (Dick) variation in agreement when using horse a uterine artery frequently was the cause School of Veterinary Medicine in Scotland, blood or plasma. Understanding the poten- of death in nonsurviving mares. Scoggin reported on the monitoring of lactate lev- tial limitations of any individual monitor spent most of his lecture on various ap- els in newborn foals to help form a diag- used will aid in interpretation of the results proaches the attending veterinarian might nosis, monitor response to treatment, and produced by the meter.” take when faced with a case of hemor- form an accurate prognosis. She and her Adrenal function Kelsey A. Hart, DVM, rhage in the field. He emphasized that colleagues reviewed the records of foals of the University of Georgia, told the group periparturient hemorrhage is a severe and under 96 hours of age. It was found, she that evaluation of adrenal function is of life-threatening condition in mares and said, that nonsurvivors had significantly growing importance in equine medicine. that immediate treatment is imperative. It increased lactate levels at 12 to 36 hours Hart discussed a study where the drug co- is important, he said, to keep the mare as of age as compared to survivors. A cutoff syntropin, synthetic adrenocorticotropic calm as possible. point of 4.85 mmol/L of lactate at admis- hormone (ACTH; natural ACTH is pro- Foal adoption Peter Daels, DVM, PhD, sion correctly classified more than 80% of duced and secreted by the pituitary gland) Dipl. ACT, ECAR, of Belgium, discussed cases as either survivors or nonsurvivors, was administered intravenously (IV) when approaches veterinarians can take to in- with the nonsurvivors being foals with low levels of cortisol were identified. “The duce lactation in a mare and how to con- lactate levels above the cutoff point. When results in this study,” Hart said, “show vince her to adopt an orphan foal. Work lactate levels reached 11.3 mmol/L, she that in 3- to 4-day-old foals, the cortisol at the Keros Equine Insemination and said, there were no survivors. response to IV administration of cosyntro- Embryo Transfer Center in Passendale, Glucose and lactate monitoring Pame- pin is dose-dependent, with higher cosyn- Belgium, where he is headquartered, has la A. Wilkins, DVM, PhD, Dipl. ACVIM, tropin doses resulting in a higher peak and been going on for five years. Lactation in a ACVECC, of the University of Pennsylva- longer duration of rise in cortisol.” nonparturient mare, Daels said, can be nia’s New Bolton Center, concurred with Mathematical model Barton W. Rohr- induced during a two-week treatment pe- Henderson’s findings on using lactate levels bach, VMD, MPH, Dipl. ACVPM (pre- riod by administering progesterone, estro- in diagnosis and monitoring, but she add- ventative medicine, epidemiology), of gen, and dopamine D2 antagonist (in this ed the measuring of glucose levels as an- the University of Tennessee, presented a case, sulpride) on a daily basis, along with other valuable tool. However, she also had mathematical approach for predicting foal milking the mare regularly. Two drugs that a word of caution: “In both referral and survival. He described the approach thus- helped to arouse maternal instincts that practice situations, point-of-care (stall-side) ly: “By combining clinicians’ experience would allow for foal adoption were dino- glucose and lactate monitoring is inexpen- based on the initial assessment of the foal prost and oxytocin. Under the approach sive, easily performed, and potentially very with results of observations recorded for

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March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 21 AAEP WRAP-UP 2007

a large number of hospitalized foals, the surgically implanted and 15 of the recipi- number of treatments and seasonal factors. practitioner can provide a more precise es- ent mares had become pregnant. In the fall, fewer mares ovulate in the 24- timate of the probability of foal survival.” Making use of ICS Elaine M. Carnevale, to 48-hour window. Practitioners may con- Ovariohysterectomy DVM, MS, PhD, of Colorado State Univer- sider altering monitoring schedules based The final speaker in the Reproduc- sity (CSU), which pioneered the ICSI con- on the season, number of hCG treatments, tion-Perinatology session was David E. cept, reported on the success rate of the and changes in endometrial edema.” Freeman, MVB, PhD, of the University procedure during the 2006 breeding sea- Breeding and ovulation interval Terry of Illinois. He discussed performing an son at CSU. From 91 normal oocytes, she Blanchard, DVM, MS, Dipl. ACT, formerly ovariohysterectomy (OHE) on mares. The said, 62 cleaved into at least two cells and of the Texas A&M University faculty and surgery can be complete—involving re- were fertilized with one of the following: now a veterinarian at Hill ‘n’ Dale Farm moval of the entire uterus and ovaries—or fresh, cooled, or frozen semen. After ICSI, in Kentucky, told the group that intervals incomplete with partial removal. The sur- the embryos were transferred, achieving a between mating and ovulation of more gery, Freeman said, should be con- than two days significantly lowered sidered when a mare is suffering pregnancy rates in Thoroughbred from a condition that is life-threat- Intervals between mating and mares. It would be wise, he said, ening, such as uterine torsion, or to breed the mare again “double if she has a problem with a poor ovulation of more than two days service” (mate again on the same prognosis for resolution. Success significantly lowered pregnancy estrus) if she has not ovulated rates are high and he pointed to within two days of being bred the one study that revealed 16 of 17 rates in Thoroughbred mares. first time. mares undergoing the procedure Interpreting endometrial edema had survived. He said OHE is a vi- Dr. Terry Blanchard Juan Samper, DVM, MSc, PhD, able option in certain instances as Dipl. ACT, of Veterinary Reproduc- an alternative to ineffective medical treat- pregnancy rate of 44% at 16 days and 31% tive Services in Langley, British Colum- ment or euthanasia. at 50 days. The type of sperm injected had bia, told the group that when a mare is no effect on the outcome, she said. Using under the influence of estrogen, there is More Reproduction ICSI, Carnevale told the group, 24 late- increased blood flow to the uterus that re- One of the final sessions held at the term pregnancies were produced for stal- sults in an increase in endometrial edema. AAEP convention involved further discus- lions with poor-quality semen or limited The edema can be viewed ultrasonograph- sion on reproduction. sperm numbers. ically, he said, describing a measuring sys- Advanced approach Silvia Colleoni, FSH hormone Kory D. Niswender, DVM, tem with values from 0 to 5 to assess the PhD, of the Laboratorio di Techologie MS, Dipl. ACT, of Reata Equine Hospital edema. The bottom end of the scale would della Reproduzione in Cremona, Italy, was in Weatherford, Texas, reported on the use normally exist in mares that were in a state the first speaker and discussed advances of recombinant equine follicle stimulating of diestrus (not in heat), and the higher in ovum pick-up (OPU), intracytoplasmic hormone (reFSH) to promote follicular end is when mares are in estrus. During sperm injection (ICSI), and embryo cul- development in cycling mares. His conclu- examination there are several instances in ture in equine practice. The process in- sion was that reFSH “may be a useful tool which the veterinarian should be alerted volves collecting immature oocytes from to stimulate follicular development in the to possible problems, Samper said. He the ovaries, maturing them in vitro, in- mare.” identified them as: 1) presence of obvious jecting them with a single sperm (ICSI), Using hCG Jodyne Green, DVM, of the endometrial edema and a large follicle and implanting the embryo—either in a Western College of Veterinary Medicine at 14-15 days after ovulation; 2) presence of fresh state or after having been frozen and the University of Saskatchewan, reported hyper-edema during the normal estrous thawed—into a recipient mare. The suc- on the use of human chorionic gonadotro- period; 3) failure to reduce edema as the cess rate has not been extremely high, but phin (hCG) as a stimulant for ovulation. mare approaches ovulation and the pres- there has been success, she said. Green said results of a retrospective study ence of marked uterine edema 24 hours af- She reported on a study that involved showed: “In summary, hCG is effective in ter ovulation; 4) significant increase in the data collected from 47 commercial OPU inducing ovulation in 73% of mares ad- degree of uterine edema 12 to 24 hours af- sessions performed from 2004 to 2007 on ministered this drug. Follicular size and ter breeding; and 5) lack of uterine edema 30 donor mares ranging in age from 3 to cervical tone at time of treatment with during the estrous period. “Interpretation 24 years old. Here are the results: 808 fol- hCG are associated with ovulation within of endometrial edema,” he said, “requires licles were aspirated and 474 oocytes re- the next 48 hours. A decrease in endome- a good-quality ultrasound and evaluation covered—a mean recovery rate of 58.19%. trial edema (excess fluid swelling) score of the mare on a regular basis during the From this group, 66.05% reached a stage from the initial administration of hCG late diestrous and early estrous period un- at which they were fertilized via ICSI, to 24 hours was associated with ovula- til ovulation is detected.” which resulted in 199 cleaved embryos tion in the 24- to 48-hour window. As the Measuring progesterone Edward L. and 40 blastocysts (the stage at which breeding season progresses, there is a re- Squires, MS, PhD, of CSU discussed the an embryo is ready for transfer). At the duction in the ovulatory response rate to best approach to take when measuring time of her report, 18 embryos had been hCG administration related to increasing progesterone (hormone that supports a

22 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

new pregnancy) of the mare during early or transitional. The treated mares ceased known a paraphimosis, where the stallion gestation after nonsurgical embryo trans- cycling for the rest of the breeding season. is unable to retract his penis. The condi- fer. An appropriate progesterone level, he The next year, 88% percent of the treated tion most often surfaces in breeding stal- pointed out, is highly important in main- mares were cycling, and the year after lions, Brinsko said, but it can also occur taining pregnancy. Squires reported on that, 98% were cycling. Pregnancy rates in geldings. It begins with penile prolapse a study that involved measuring proges- for the treated mares in the first year after (protrusion or displacement), and that re- terone levels in blood that was collected vaccination were 75% and rose to 90% the sults in excessive edema and swelling of once a day, morning and night on a given following year. the penis and prepuce. Early, aggressive day, and once a day for two days. Here Oxytocin to block luteolysis Dirk therapy is important, he said, because it is the conclusion: “Because the variance Vanderwall, DVM, PhD, Dipl. ACT, of the can minimize secondary complications. was quite small between the morning and University of Idaho, reported on the use The primary goal, he told the group, is to evening samples on a given day, there did of oxytocin to successfully block luteolysis reduce swelling and replace the prolapsed not seem to be any major advantage to (destruction of the corpus luteum), thus, penis into the preputial cavity as soon as collecting samples twice in a given day. prolonging the lifespan of the corpus lu- possible. The use of anti-inflammatory In contrast, the variance was greater for teum. The importance of a functioning drugs and hydrotherapy are part of the samples collected two days in a row. This corpus luteum, he reminded the group, is treatment protocol, as is penile support to indicates that two daily samples provide the production of progesterone. Adminis- prevent further swelling. a better estimate of the mare values than tering 60 units of oxytocin twice daily on Post-mortem sperm collection Adam C. one sample. In other words, if the clini- Days 7 to 14 post-ovulation blocked luteol- Eichelberger, DVM, of the University of cian bleeds (collects blood from) the mare ysis and induced prolonged corpus luteum Florida, concluded the session by discuss- two days in a row, the accuracy of the es- function, he said. Mares with prolonged ing how to collect, handle, and process se- timate can be increased considerably over luteal function, he told the group, main- men from the epididymis of a stallion that obtaining just one individual sample. tained progesterone levels of more than has died or has been euthanatized. Being Anestrus Claire Card, DVM, PhD, of the 1.0 ng/ml continuously through Day 30. able to harvest sperm from a dead stallion University of Saskatchewan, reported on a This level of progesterone, he said, is suffi- can be important, he said, because re- study to determine whether administering cient to block estrous behavior, “therefore, productive science has produced ways in a vaccine against gonadotrophin-releasing disrupting luteolysis by administering ex- which to preserve the sperm for later use. factor (GnRF) would prevent mares from ogenous oxytocin seems to be a plausible He discussed the approaches a veterinar- coming into estrus. Mares in the study re- method of long-term suppression of estrus ian should take in first obtaining the tes- ceived two injections of GnRF vaccine four in mares.” ticles, then harvesting the sperm residing weeks apart. In the study, it was found that Paraphimosis in the stallion Steven Brin- there. He said he and his colleagues have four weeks after the second dose, 98% of sko, DVM, MS, PhD, Dipl. ACT, of Texas “collected a range of sperm from 5 to 18 the mares receiving GnRF were anestrous A&M University, discussed the condition billion per testicle.” H

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STEADFASTTM EQUINE is a product of Arenus, a division of Novus Nutrition Brands, LLC. | www.arenusperformance.com The One and Only One.TM March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 23 AAEP WRAP-UP 2007 Sponsored by Diagnostics by christy west Diagnosing Coxofemoral Sublux- ation with Ultrasound Subluxation (partial dislocation) of the coxofemoral joint between the femur and pelvis in horses is rare; only two cases have been reported in the literature. However, six cases were seen at the University of Califor- nia, Davis, in a three-year period, suggesting that perhaps this problem is somewhat more common than previously thought. Suzanne Brenner, DVM, an intern at UC Davis, discussed a technique for diagnosing these subluxations with ultrasound. Radiographs have been considered the gold standard for diagnosing pelvic disorders, she noted. But the views needed to identify subluxation require the horse to be on its back under general anesthesia, while ultrasound in the standing horse is

much quicker, carries less risk to the horse, Stepha ni e L . Chu rc h and can provide a solid diagnosis. All six Veterinarians have a plethora of diagnostic imaging tools available to help them come to a of the UC Davis cases were diagnosed with conclusion about a horse’s lameness. ultrasound. be readily and safely obtained through the used to evaluate the anatomy of the upper Affected horses were quite lame (mostly use of dynamic ultrasound in the standing limbs for a variety of reasons, such as the Grades 4/5, with one exhibiting Grade 3 horse if weight-bearing and resting views physical constraints of the horse, gantry lameness), with an acute onset of lame- are performed.” (ring around the imaging tunnel) size, X ness in five horses and insidious (slow) on- ray tube output, and difficulties in linking set in one horse. Crepitus (a bone-grinding Computed Tomography for a table strong enough to support a horse to noise), muscle atrophy, and pelvic asym- Imaging the Stifle the CT scanner,” he said. “Advances in all of metry were seen in some horses, but only The stifle joint is often implicated in cas- these areas—in addition to CT-scanner soft- one case had all three signs. No horses es of lameness, but it can be a notoriously ware and hardware improvements—have had external (outward) rotation of the dis- tough joint to image. Radiography, ultra- made the technique reported possible.” tal (lower) limb, which has been noted in sonography, nuclear scintigraphy (bone After development of CT arthrography other reports of the condition. All six cases scan), and diagnostic arthrography (joint (joint evaluation) technique via contrast showed clear displacement of the head of evaluation) all can be used, but they all media on cadaver specimens, Bergman the femur on ultrasound, and five horses have limitations. And no currently avail- described the findings and procedures had associated acetabular (coxofemoral able MRI units are big enough to accept a used to evaluate stifles on 16 horses with joint rim) fractures and severe joint effu- horse’s stifle for imaging. CT (general anesthesia is required). Horses sion (fluid swelling). Computed tomography (CT), however, were Grade 2-4/5 lame on the AAEP lame- Four of the affected horses were eutha- might be able to image the stifle with de- ness scale, and pain had been localized to nized, and only one of the remaining two tail approaching that of MRI, and with a the stifle joint by joint blocks and thorough horses is comfortable at the walk, leading shorter examination time. Erik Bergman, lameness examinations. investigators to conclude that the progno- DVM, Dipl. ECAR, a veterinarian from Diagnostic images were achieved in all sis for this condition is not favorable. Lingehoeve Diergeneeskunde, in Lienden, horses, and ultrasound-guided contrast “Coxofemoral subluxation should be the Netherlands, presented a study of the media injection for arthrography was suc- considered when a hind limb lameness is technique and clinical application of stifle cessful in all cases. Lesions were found on suspected to originate from the pelvic re- CT evaluation. CT that correlated with the clinical exam gion,” Brenner concluded. “Diagnosis can “Historically, CT has been infrequently in 14 of the 16 horses, and 12 horses had

24 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 ( your way ) ( our way )

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2629_Steadfast_TheHorse_ad_fnl.indd 1 1/22/08 4:49:13 PM AAEP WRAP-UP 2007

multiple lesions. The most common prob- DFTS specific, only desensitizing the digi- Brokken, DVM, clinical assistant professor lem was a lesion of the meniscotibial liga- tal flexor tendon sheath and its contents, of veterinary clinical sciences at the Uni- ment and/or its insertion onto the proximal or is it nonspecific, blocking more struc- versity of Florida, described a Washington tibia, which was found in six of 16 horses tures distal to (lower than) or outside the State University study of lameness origi- (37.5%). confines of the sheath itself? nating in this area. “CT was vastly superior to radiography Six horses with no pre-existing forelimb “Detection of abnormalities, specifically for evaluation of hard tissues, including lameness were studied in three trials (using desmitis (ligament inflammation) of the bone and dystrophic soft tissue miner- temporary lameness induction methods); inferior check ligament (ICL) and proxi- alization,” he reported. “Ultrasound and the first used set screws to induce solar mal suspensory ligament (PSL), has not radiography consistently underes- been possible in some horses (via timated the extent of bone remod- radiography or X rays, ultrasound, eling in these cases.” CT was vastly superior to radiog- or nuclear scintigraphy),” he ex- Bergman noted that CT arthrography for evaluation of hard tissues, plained. raphy carries two major benefits For the retrospective study, 45 over radiography and ultrasound— including bone and dystrophic soft horses with lameness localized to the ability to find lesions not previ- tissue mineralization. the proximal metacarpus/metatar- ously seen with these two methods, sus (upper cannon bone area) were and a more complete evaluation selected. Most were Warmbloods Dr. Erik Bergman of the extent of lesions seen with (20) and Thoroughbreds (12), and these methods. “In several cases, the horses ranged from 3 to 17 ultrasound accurately identified the le- pressure at the heel or toe, the second used years of age. All were lame; 22 had been sions, but the CT scan documented other endotoxin to create joint inflammation in lame for less than four months, 22 for lesions or more extensive pathology than the coffin joint, and the third used endo- longer, and one had been lame for an un- was suspected.” toxin to create inflammation in the navicu- known time. Forelimb lameness affected “In conclusion, the techniques of lar bursa. Each horse was videotaped walk- 29 horses. Thirty-one horses were Grade equine stifle CT and CT arthrography are ing and trotting toward and away from the 3/5 lame, nine were Grade 2 lame, and one feasible and clinically useful,” Bergman camera before and after lameness induc- was Grade 4. All were imaged with a high- summarized. “CT should be considered tion, then the horses were blocked at the field (1.0-tesla) MRI system. complementary to a complete clinical ex- DFTS and videotaped again at 10 and 20 “The use of MRI in this area allowed amination and other diagnostic imaging minutes after the block was applied. an accurate diagnosis in 44 of 45 horses,” modalities. In this group of clinical cases, Four investigators blinded to the video Brokken reported. “The transverse proton CT was useful to define the extent of sus- timing evaluated the videos on a 10-point density sequence was the most helpful pected or previously diagnosed injuries lameness scale. Median lameness scores in detecting subtle changes in signal and and to identify injuries that were elusive. after trial 1 (sole pain) were not signifi- size within the ICL and PSL. Having an This information allows clinicians to de- cantly improved at 10 minutes post-block, accurate diagnosis enabled appropriate velop more directed therapeutic plans or but they were significantly improved after treatment in these horses, which helped a provide a more accurate prognosis.” 20 minutes. In trials 2 and 3 (coffin joint high percentage of them to return to their pain and navicular bursa pain), there were intended use.” Specificity of Digital Flexor no significant improvements in lameness Researchers found that 23 horses had Tendon Sheath Nerve Blocks at 10 or 20 minutes after the blocks were desmitis in the upper 4 cm of the PSL—13 Diagnosing lameness in horses has of- applied. had desmitis in hind limbs and 10 in fore- ten been termed an art and a science, in “Analgesia of the DFTS using the pal- limbs. Sixteen horses had ICL desmitis; part because the use and interpretation mar axial sesamoidean approach does 12 had lesions from 1-4 cm below the up- of nerve blocks to isolate sources of pain not interfere with pain originating from per end of the cannon bone and four had is more art than exact science. In recent the sole, coffin joint, or navicular bursa if them 5-10 cm down. Of the remaining six years, several blocks have been found evaluated within 20 minutes,” Harper con- horses, one had ICL and PSL desmitis in to numb more structures than scientists cluded. “So, if pain is attenuated with the the same limb, one had desmitis in both previously thought based on research DFTS block, chances are the pain is in the ligaments but on different limbs, one had performed at Auburn University; this, in deep digital flexor tendon.” an injury to the cannon bone, one had ef- turn, impacts the interpretation of lame- fusion (fluid swelling) of the distal tarsal ness that is attenuated by those blocks. To Diagnosing Upper Cannon Area sheath of the deep digital flexor tendon help sort out one particular block, Justin Injuries (DDFT), one had a DDFT injury, and one Harper, DVM, a resident in equine surgery Pain originating in the upper cannon had no obvious abnormalities. at Auburn, presented the results of a study bone area, just below the knee or hock, is “It is interesting to note that 59% of on analgesia of the digital flexor tendon common in all types of equine athletes. De- horses that had lameness localized to the sheath (DFTS). termining exactly what structure is injured, proximal metacarpal region (forelimb) had He said the study was designed to an- though, can be difficult; some injuries can ICL damage,” noted Brokken. “Previously swer one question: Is analgesia of the only be seen with high-field MRI. Matthew it was thought that horses that block to the

26 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

proximal metacarpal region usually have a especially in the hind limbs,” Brokken oblique, paired cruciate, and paired short proximal suspensory injury,” but these re- commented. distal sesamoidean ligaments) that com- sults prove that this isn’t always the case. “In conclusion, lameness localized to prise the distal suspensory apparatus,” she Treatments ranged from a six-month the proximal metacarpal and metatarsal explained. “That apparatus resists exten- rest and rehabilitation program (33 hors- region has been a diagnostic challenge,” sion of the fetlock and holds the suspen- es) to surgery, injections, and various com- Brokken concluded. “Traditional imaging sory bones to the first and second phalan- binations thereof. Forty-three of the horses modalities don’t always yield an accurate ges. The distal sesamoidean ligaments are were available for followup: diagnosis. High field strength MRI should susceptible to overload injury from hyper- ■ Eight of 10 horses (80%) with forelimb be considered in performance horses with extension. PSL desmitis returned to full work. lameness localized in the proximal meta- “Initially, diagnosis of desmitis in these ■ Nine of 13 horses (69%) with hind limb carpal and metatarsal areas.” ligaments relied on observations of swell- PSL desmitis returned to full work. For more information, see ”Magnetic Res- ing over the palmaroproximal (upper rear) ■ Ten of 16 horses (63%) with ICL desmitis onance Imaging Features of Proximal Meta- aspect of the digit or on ruling out other returned to full work. Five of eight horses carpal and Metatarsal Injuries in the Horse,” causes of lameness in the area with radio- that had ICL desmotomy (complete cut- Veterinary Radiology and Ultrasound, Vol. graphs,” she noted. Ultrasound has been ting of this ligament) returned to full 48, No. 6, 2007, pp 507-517. helpful in some cases, but she said this work. “The success of ICL desmotomy in area is hard to evaluate with ultrasound. these horses further supports the impor- MRI for Diagnosing Sesamoidean However, MRI was found to be a very tance of making an accurate diagnosis, Ligament Desmitis good way to identify these injuries, much because (in) horses with ICL desmitis The high degree of detail seen with MRI more so than ultrasound or swelling. Af- you have a surgical option that is not ap- has made it possible for veterinarians to ter describing the anatomy and imaging propriate for horses with PSL desmitis,” find equine injuries they’ve never seen be- of these ligaments in great detail, Samp- Brokken noted. fore. One example of this—MRI evaluation son described a retrospective study of af- ■ The two horses with both ICL and PSL of desmitis in the oblique and straight dis- fected horses. Of the 27 horses, most (15, desmitis returned to full work, as did the tal sesamoidean ligaments—was described. 55.6%) were jumpers or dressage horses, horses with distal tarsal sheath effusion Sarah Sampson, DVM, doctoral gradu- and the age range of the whole group was and DDFT injury. ate student in equine surgery and MRI at 2 to 13 years. All were lame—six for less ■ Eight horses had ultrasound evaluations, Washington State University (WSU), dis- than four months, 19 for longer, and two but ultrasound findings were unremark- cussed the anatomy of these ligaments and for an unknown length of time. Seventeen able or misinterpreted as PSL injury a study of findings and treatment success horses had hind limb lameness (left, right, when ICL injury was detected instead in 27 horses. or bilateral), while the rest had forelimb by MRI. “Ultrasonographic examination “The distal sesamoidean ligaments in- lameness. of the PSL is technically challenging, clude four ligaments (straight, paired MRI confirmed injuries of the oblique

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(ODSL) or straight distal sesamoidean “Injury to the ODSL ligament (SDSL) in all study horses, but or SDSL can occur only one horse had palpable swelling in without palpable ab- the distal sesamoidean ligament region. normalities in the re- Only two horses’ injuries were detected gion,” she concluded. with ultrasound by referring practitioners “These injuries do not (four horses were reevaluated with ultra- need to be severe to sound at WSU). cause performance- Most of the horses (24/27, 89%) had in- limiting lameness in juries of the ODSL, and these were more athletic horses, and frequently in the hind limb (16/24, 67%). they should be consid- The total number of medial (inside) and ered in the differential lateral (outside) branch injuries was about diagnosis when exam- the same overall, but forelimbs tended to ining horses with lame- have medial branch injuries (87% of fore- ness that blocks out in limb injuries) and hind limbs tended to the area of the pastern have lateral branch injuries (71%). or metacarpophalan- Sampson noted that blocking the digi- geal/metatarsophalan- Ann e M. Eb r ha rd t tal flexor tendon sheath eliminated most geal region. High-field Repository radiograph quality is one issue faced by veterinarians lameness due to distal sesamoidean liga- strength MRI is a valu- evaluating sale horses. ment injury after 30 minutes. Thus, this in- able way to evaluate jury should be considered when this block ODSL and SDSL desmitis.” the wrong angle to see areas of interest. alleviates lameness. “I have a tough time being critical of col- Returning to Work The primary treat- Purchase Exam for Public leagues, but if you can’t read the films you ment for all cases was six months of rest Auction Forum can’t read them,” said one veterinarian. “It and a rehabilitation program. Twenty-two Sale description accuracy, radiograph happens enough that some attention needs horses had initial hyaluronic acid and (X ray) repositories, radiograph quality, ra- to be paid to it.” methylprednisolone acetate injections into diograph reports, medications, and genetic Sale companies often allow only one the digital flexor tendon sheath to combat diseases—what do they all have in com- study of each horse in the repository, which inflammation, swelling, and fibrous tis- mon? All of these topics were discussed makes it impossible to get new views un- sue formation. Two horses also underwent during the Purchase Exam at Public Auc- less the veterinarian takes them himself. ligament splitting. tion Forum, an open discussion session. However, concerns about maintaining the All six horses with short-term lameness The first item on the agenda was a re- integrity of the medical record complicate (less than four months’ duration) were port of what happened based on recom- the issue. sound at follow-up (one to three years after mendations from the 2006 forum regard- There were a couple of suggestions to diagnosis). Eight of 12 horses (67%) with ing statements made by announcers about improve this situation. “One, we could im- lameness for more than four months at the a horse’s condition while a horse was in the prove our educational efforts for the veteri- time of diagnosis were sound. Ten horses ring. Some felt that a veterinarian should narians so they all know it’s not just about had mild lesions, and four of the five avail- be involved in writing or reviewing these the right views, but also the right angles, able for follow-up (80%) were sound. Thir- statements to ensure accuracy, as these exposures, etc.,” opined one attendee. teen of 14 horses with moderate lesions statements can impact buying decisions. “And if the sales companies would agree to were available for follow-up, and of those Inaccuracies in sale ring announcements, have some sort of quality control in place, 10 (77%) were sound. Two of three hors- some veterinarians feel, can often have that would help, but they haven’t wanted es with severe lesions were sound (67%). the effect of glossing over or minimizing a to take the responsibility.” Finally, 16 of 21 horses (76%) that were problem. Another veterinarian suggested review- available for follow-up were competing at There wasn’t much of a result from those ing radiographs post-sale to approach the the same or a higher level of performance recommendations, said one attendee; the issue without threatening veterinarians’ than before the injury. The remaining five AAEP didn’t get involved and sales compa- relationships with their clients. The Ken- were lame and had been retired. nies didn’t either, so any further action on tucky Association of Equine Practitioners “The ability of most of these horses to re- this will have to happen on the local level. held just such an educational session af- turn to athletic performance indicates that Radiograph quality and repositories ter a Keeneland sale in Lexington in 2007, the prognosis is not as poor as previously Radiograph repositories and quality were which was well-received. reported,” Sampson noted. “High-field discussed extensively; different sales’ pro- Radiograph Interpretation Moving on to strength MRI is capable of early diagnosis cedures, handling of images, and techno- radiograph interpretation, moderator Scott of distal sesamoidean ligament injury, and logical concerns were mentioned as well. Hay, DVM, president and managing part- appropriate treatment soon after injury One concern shared by many attendees was ner of Teigland, Franklin, and Brokken in may provide a better prognosis for return- that a significant number of radiographs in Ft. Lauderdale, Fla., commented, “We need ing to performance. the repository are either of poor quality or to emphasize that it’s our responsibility not

28 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

so much to find lesions as to assess their although with the genome research ■ Grade 4: No arytenoid movement, no impact. When you start out, it’s all about completed in 2007 that number will abduction. No horses were Grade 4, but finding something wrong, and lots of good likely increase soon. She discussed hy- Pierce noted that most of these horses horses are penalized. The evolution is that perkalemic periodic paralysis (HYPP), would not be offered for sale, as they are you find a lesion, and maybe you empha- glycogen-branching enzyme deficiency usually withdrawn. size it, but maybe you don’t. It’s important (GBED), hereditary regional dermal as- Epiglottis structure (ES) to have people assess the impact of lesions thenia (HERDA), polysaccharide storage ■ Grade 0: Normal epiglottis with good rather than just filling pages with lists of myopathy (PSSM), and malignant hyper- thickness, length, and definition with anomalies.” thermia (MH). The three genetic mutations normally serrated edges. 81% of horses Attendees agreed that there is often that don’t affect Quarter Horses are severe had normal epiglottises. pressure to minimize reports of lesions to combined immunodeficiency syndrome ■ Grade 1: Slightly flaccid, with adequate help sell a horse, but the flip side of that is (SCID) in Arabians, overo lethal white syn- length and texture, but slightly thinner the trouble one can have if a lesion is not drome (OLWS) in Paints, and junctional than normal and without serrated edges reported pre-sale and is found post-sale. epidermolysis bullosa (JEB) in Belgians. (14% of horses). Most said they draw a hard line between ■ Grade 2: Mildly flaccid, with adequate reports and opinions, listing all their find- How Important Is That Airway length, thinner than normal, curled ings in a report, but not offering an opin- Exam Grade? edges, and no dorsal vasculature (4% of ion on them unless requested. Others pre- The airways of many breeds of horses, horses). fer to put their opinions on reports as long particularly Thoroughbreds, are evaluated ■ Grade 3: More severe, moderately flaccid, as the findings are not omitted. via an endoscope and graded before sale. very thin, and bent easily (1% of horses). Medications and medical records The The intent is to identify horses whose air- ■ Grade 4: Severely flaccid, extremely thin, availability of a horse’s medical records ways might have problems that could limit markedly short, and bent easily (0 hors- was also a topic of discussion; Hay noted the horses’ performance at maximal exer- es). that legislation has been proposed in Flori- cise, so buyers can consider this in their Race records for the 2-, 3-, and 4-year- da to make a horse’s entire medical history purchasing decisions. Scott Pierce, DVM, old years were collected and analyzed in public at the horse’s auction. “It’s pretty of Rood & Riddle Equine Hospital in Lex- context of the throat exam findings. Pierce far-reaching what they’re proposing,” he ington, Ky., presented a study investigating reported no difference in the number of said. “It would include any history of any the exam results and later racing perfor- starts, earnings per start, or total earn- disease, EPM, all vaccination records, any mance of 2,954 Thoroughbred yearlings ings of horses with Grade 1 vs. Grade 2a lameness, anything. It’s a little scary that in an effort to answer the question of just arytenoid function at 2, 3, or 4 years of age. some of the things written there could be- how significant airway grades are. Grade 2b horses had significantly lower to- come legislation.” The exam takes only one to two minutes, tal earnings per year at 2 and 4 years of Disclosing a horse’s entire health record and it evaluates arytenoid cartilage func- age than Grades 1 or 2a, and they almost is cumbersome and raises client confiden- tion (these cartilages should be able to ab- had significantly lower earnings at Grade tiality issues, opined one veterinarian. duct, or move completely out of the airway 3, but a few big winners in this group kept Medication usage in sale horses is an- to allow maximum airflow) on a scale of the numbers at this age from being signifi- other issue, and it’s one that’s not exactly 1-4. Epiglottises are also evaluated; a short cant. Grade 3 horses had fewer starts and clear-cut. “The problem with medication or otherwise abnormal epiglottis can con- lower earnings than Grades 1, 2a, and 2b. issues is that they vary from state to state,” tribute to dorsal displacement of the soft Forty-three percent of horses with Grade said one attendee. Several studies are on- palate, which can also obstruct airflow. 3 arytenoid function went unraced, com- going to determine typical baseline values Following are the grading scales Pierce pared to 15% of Grade 2b, 16% of Grade for several compounds and hormones; used to evaluate all study horses between 2s, and 13% of Grade 1. these will provide the basis for additional 1998 and 2001, and the results. Horses with epiglottis structure grades research to develop withdrawal times and Arytenoid function (AF) of 0-2 all performed about the same, while acceptable levels of various medications. ■ Grade 1: Synchronous movement, sym- those with Grades 3 and 4 had significantly Genetic diseases The forum ended with metrical cartilages; maximal abduction decreased earnings at ages 2 and 4. a presentation by Stephanie Valberg, DVM, easily achieved. 19% of horses (571) “So what do I tell clients?” Pierce asked. PhD, Dipl. ACVIM, director of the Uni- were in this category. “I tell them Grades 1 and 2a arytenoids versity of Minnesota’s Louise and Doug ■ Grade 2a: Mildly asynchronous, mildly function are no problem. For Grade 2b, Leatherdale Equine Center. She presented asymmetrical, maximal abduction easily there’s something there. They don’t per- new information on the inheritance, test- achieved (70%, 2,068 horses). form as good as the 1s and 2as; however, ing, and clinical signs of five equine genetic ■ Grade 2b: Asynchronous, asymmetrical, if you think the horse is really special, I diseases that affect Quarter Horses and re- maximum abduction with difficulty (9%, would buy him anyway. I can’t condemn lated breeds. Test results for these diseases 260 horses). all of these horses. Grade 3s are bad. are playing an increasingly important role ■ Grade 3: Asynchronous, asymmetrical, “For epiglottis structure, Grades 0-2 are in many sale environments. limited arytenoid movement. Full abduc- no problem, but I can’t recommend horses She noted that a DNA mutation has been tion is usually not achieved and especially with higher grades or a really flaccid or identified in only eight equine diseases, is not maintained (2%, 55 horses). short epiglottis,” he concluded. h

March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 29 AAEP WRAP-UP 2007 Foot / Lameness by Nancy S. Loving, DVM, and Christy West

Therapeutic Shoeing support and contracture. His approach foot contacts the mat until final liftoff. His The AAEP table topic on Therapeutic is to use the rail shoe to move the horse’s objective is to move the ground reaction Shoeing attracted a large group of veteri- weight back onto its heel since typically forces back toward the center of the foot narians and farriers such as Steve O’Grady, lameness moves weight toward the toe. mass, to improve phalangeal alignment, DVM, MRCVS, of Northern Virginia His objective is to engage the deep digital and by doing so, to allow every structure Equine, and Bruce Lyle, DVM, a veterinar- flexor tendon to take tension off the sus- in the foot and leg to bear its share of the ian who focuses on foot care in Aubrey, pensory ligament. load; this is especially useful to alleviate Texas, led a discussion sparked with con- In practice, he has noted that improve- repetitive stress injuries. troversy. ment of the palmar/plantar angle can Andrea Floyd, DVM, co-editor of the Questions began instantly, book, Equine Podiatry, discussed with the first topic focusing on chronic heel pain in horses. She treatment of hind limb suspen- noted that radiographs often sory desmitis (ligament inflam- show a post-like position of the mation). There was little debate short and long pastern bones, that the feet and sore suspensory then the coffin bone ends up sit- ligaments are related to one an- ting in a negative palmar angle, other. By managing the feet with such that the horse appears to a logical approach, O’Grady be- have two disparate feet. This lieves that suspensory ligament alignment often leads to heel and problems will improve. He feels quarter cracks. She stressed that the only way that shoeing direct- trimming the hoof to the widest ly affects a hind leg suspensory part of the frog does not take into ligament is related to length of account the palmar angle, and the the foot and ease of breakover. best way to improve heel growth He advocates shoes that are as is to first find the center of the wide as they are long, with no coffin bone on radiographs. extended heels. He doesn’t feel Then draw a straight line down that raising the heels is helpful, a to the distal bearing surface and

particularly if the entire back of a silv rasp the cranial-dorsal portion

the foot is “crushed” and col- au l a d of the hoof into a zero palmar P lapsed. Veterinarians in attendance all agreed that it is not always in the angle. This leaves an invisible For suspensory ligament horse’s best interest to make his foot “look” better, especially if the heel area to be filled with a flat desmitis, Lyle advocates the use horse has adapted to its unique situation. shoe applied by nailing only at of rail shoes when the plantar the toe. Soft Equithane packing, angle (the angle the wings of the hind limb transform a previously lame horse (or one taped in place with duct tape, is applied coffin bone make with a horizontal plane) that is reluctant to perform) into a sound between the heel and shoe and fills the “air is zero or negative. A rail shoe is a square- horse. gap,” and that is left for 6-8 weeks. With toed shoe with “rails” along the underside An audience participant pointed out this shoeing method, the heels still receive of the shoe. He feels many superficial digi- that most therapeutic approaches are an neurologic messages to remain stable and tal flexor and suspensory ligament prob- attempt to return weight-bearing back to grow. lems are a result of delayed or inadequate normal; for example, a navicular horse Lyle added that the position a horse function of the deep digital flexor tendon lands on its toe so it is important to move stands for hoof radiographs will affect the during the stance and propulsion phase weight loading toward the back of the phalangeal alignment, but the parameters of stride. He commented that a negative foot. within the hoof capsule relative to the cof- palmar (referring to the hind limb cof- To compute the center of force, Lyle fin bone will remain consistent. fin bone)/plantar angle of the coffin bone uses a tool called a Mat*Scan (Tekscan, Gene Ovnicek, RMF, brought up the ends up stretching the deep digital flexor Inc.) that records ground reaction forces point that in dry climates (such as the tendon to a less-than-optimal state for at 40 frames per second from the time the western United States), horses grow a lot

30 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

of false sole (the sole of a hoof that does to work. Additionally, trimming heels can differentiate a laminitic horse from a thin- not exfoliate normally), the resulting trim move the center of force sufficiently for- soled horse. The unequivocal answer from could end up with a negative palmar angle. ward to put the weight of the horse on the moderators was: “Treat as if laminitis He recommends using radiographs, hoof the navicular bone and deep digital flexor until proven otherwise.” Sequential radio- testers, and veterinary guidance to assist tendon/bursal unit, resulting in problems graphs provide objective measurements the farrier in trimming the soles in feet ranging from bursitis to necrosis and rup- for monitoring the bone to hoof capsule that are difficult to read. ture of the tendon. If there is only 3-5 mm relationship. For a reference on each in- An audience member made several re- thickness of sole based on radiographic dividual horse, compare the hoof capsule marks, including the statement that dy- measurements, the horse needs time to thickness just below the extensor process namic movement can alter perception of grow foot. A trim job should attempt to to thickness at the level of the tip of the the standing trim. He also said the impact maintain at least 15 mm of sole depth; at coffin bone. Both should be equidistant of footfall is unique to each horse, and re- sole depths of 6-7 mm or less, one should and approximately 15 mm thick. minded the audience that a standing shoe worry about bruising and lameness. If the Another question was: What is normal is not always the same as a moving shoe, sole is too thick with false sole, the result- foot landing? The speakers said ideally a nor does a horse in rehab need the same ing trim could end up with a negative pal- horse lands flat or heel first, but it should support as an athletic horse. mar angle. be considered that we don’t know if some O’Grady said that the soft tissues of the Lateral radiographs are helpful for the horses are just fine hitting toe first. Lyle foot bear weight and serve to dissipate farrier and veterinarian. O’Grady stressed noted if the horse has 6 mm digital break- concussion. O’Grady cautions against that lateral-medial hoof balance is also over and joint articulation lies in the center trimming away frog as he feels that this important and the length of heel from the of the coffin bone, then this horse is likely would alter the base of support, and prob- ground to the hairline should be similar to have a long, sound career. If the horse lems develop if the frog sits below the heels side-to-side. Radiographs taken of the dor- has a 2½ inch (65 mm) digital breakover or is receded. Lyle pointed out that even 1 sal-palmar view help evaluate balance, par- and articulation is in the caudal one-third mm of trim can make a huge difference to ticularly when using a measurement taken of the foot, he is not likely to stay sound a horse’s comfort, especially when the foot across the heels over the wings of the cof- landing toe first. is trimmed by 5-10 mm and there might fin bone. If a balance abnormality is pres- In summary, everyone agreed that it is only be 10-12 mm depth beneath the cof- ent, one must determine if it is related to a not always in the best interest of the horse fin bone. horse’s conformation or is farrier-induced to make his foot “look” better, especially a He also said there is a misconception sheared heels. Usually a horse that lands horse that has adapted to its unique situa- of trimming to the widest part of the frog: laterally will rotate the foot to land on the tion. Additionally, all parties were in favor If there is not enough depth of foot, then inside, and this must be corrected. of the idea that more critical biomechani- there isn’t a sufficient amount with which The question was asked about how to cal research with an eye to the details and

Feel better.

factors discussed would add benefit and harm can come of keeping feet in ice for audience discussed foot support. Boswell greater consensus on therapy and preven- 72 hours—as much ice therapy as possible prefers a two-part putty mixture material tion. is desirable in averting the inflammatory placed generously from the tip of the frog effects related to acute laminitis. After 72 to the back of the frog and into the sulci Managing Acute and Chronic hours, no ice is necessary and, in fact, it (grooves in the sides of the frog). This re- Laminitis might be counterproductive by softening cruits the frog and the sulci for support. To a packed room of veterinarians at the foot too much. The horse should not There was mention that “Soft-Ride” pads the 2007 American Association of Equine be walked during the acute phase. give a horse with acute laminitis a good Practitioners Convention in Orlando, Fla., DMSO (dimethyl sulfoxide) is a com- measure of relief, but these pads only con- Jim Belknap, DVM, PhD, Dipl. ACVS, an monly employed drug for laminitis treat- tact the frog, so it helps to also use impres- associate professor of veterinary clinical ment, but there is very little research sup- sion material within the sulci. sciences from The Ohio State Univer- porting its use. In an already-laminitic Lidocaine nerve blocking of the front sity’s Galbreath Equine Center, and Rob horse, DMSO might have anti-inflamma- feet on the initial visit allows assessment Boswell, DVM, a practitioner with Palm tory properties due to its being a superox- of any hind limb involvement, shoe re- Beach Equine Clinic in Wellington, Fla., ide radical scavenger (it binds to radicals moval, and radiographs. Belknap sug- opened the table topic discussion about and inactivates them), and it might work gests that veterinarians use lidocaine for prevention and treatment of laminitis. as a vasodilator. It can be given either the nerve block due to its short duration Belknap (who co-hosted TheHorse. orally or intravenously (IV) with good ab- of action. Shoes left in place could place com’s Webinar on Understanding Lamini- sorption. too much pressure on the hoof wall and tis) said the latest research points to lamin- Equioxx is a new non-steroidal anti- laminae. Removal of the shoes also allows itis as an intense inflammatory injury of inflammatory drug (NSAID) that targets the practitioner to obtain good X ray im- the foot, and it is no longer believed to be COX-2 inflammatory mediators. Belknap ages to evaluate the internal components solely a blood flow problem. It is known advised that this drug needs five to seven of each hoof. Prognosis of foot health and that even though a horse with imminent days to reach a steady state of effect, but integrity is achieved by comparative views laminitis might look normal and show no if it’s initially given at a triple dose, the of radiographs (both lateral and D-P, or lameness, inflammatory mediators are al- steady state can be reached in 24 hours. dorsopalmar, views) taken during the ready elevated by up to 1,000-fold in the Until scientists perform research on its initial 35 days of a laminitis event. Mea- laminae. effect in the early stages of laminitis, it surements of the distance from the dorsal With that in mind, Belknap is an advo- might be best used on nonacute cases due hoof wall to the dorsal border of the coffin cate of very high levels of anti-inflamma- to concerns about its potential to exacer- bone assist in evaluating the integrity of tory medications (500 mg three times per bate vascular events (such as Vioxx did in the laminae within the hoof capsule and day of flunixin meglumine, or Banamine) humans at risk) in the at-risk horse or in helping determine if there is any displace- within the first 72 hours of insult (a cause the acute case of laminitis. ment or rotation of the coffin bone. of laminitis) or onset. He said he realized Equioxx should be advantageous in Boswell suggests serial weekly radio- this high dose is more likely to lead to chronic cases, as there should be fewer graphs for four weeks. If there is a 25-30% some gastrointestinal (GI) ulceration and, side effects due to a lowered incidence of decrease in sole depth during this time, this thus, it should not be used on every horse. GI ulceration or kidney lesions when com- is not considered a good prognosis and the But he stressed that it is critical to get foot pared to other NSAIDs. However, it was laminitis is likely terminal. If there is less inflammation under control, so ulceration also mentioned that COX-2 mediators are than 6-7 mm of sole, treatment might fail might be the lesser of two evils. Once the needed to heal gastric ulcers, so there is to alleviate the crisis. If a horse is not pro- acute stage has settled down, it might be some concern on giving the drug to horses gressing well despite aggressive therapy, a desirable to switch to phenylbutazone for known to have GI ulcers. venogram might be helpful to determine better pain relief. Blood flow might not play as predomi- the circulation in the front of the hoof. If Ice might be beneficial for the same nant a role as once thought, so vasodilator circulation is absent, euthanasia might be reason that hypothermia is used in some therapy is not necessarily as important as indicated. However, not all veterinarians types of inflammatory injury in human some other treatment choices. Acepro- agree, and it was stated that some horses medicine: hypothermia is anti-inflamma- mazine only opens vascular beds for have been saved that appeared to have no tory and slows the metabolic rate (i.e., about 40 minutes following intramuscular chance on venogram results. enzyme activity) of injured tissue. There (IM) administration, so if given, it should If the shoes are left on, the back of each could be great benefit to immediately ice be administered at least four times a day. foot should be filled with cushion support the feet to decrease activity of deleterious Another possible vasodilator to use is IV substance (such as two-part putty) from enzymes such as matrix metalloproteinas- lidocaine. the tip of the frog to the back of the foot. es and to decrease inflammation. Studies Belknap and Boswell said they felt a The hoof should be placed on the ground show the best means of cooling the feet is single dose of dexamethasone in a horse so the material fills the spaces within the by using a bucket arrangement or wrap- at risk of laminitis might help decrease in- frog and any extra oozes out that would ping the hoof in a 5-liter plastic bag or flammation in the feet, but the vets are re- have caused excess pressure. truck tire inner tube filled with ice and wa- sistant to use it due to potential litigation In the early stages, a horse undergo- ter. Refresh the ice continually as needed. regarding steroid use and laminitis. ing rotation can be placed in a tempo- The discussion facilitators stressed that no Supporting the Hoof The facilitators and rary raised-heel shoe, such as the Nanric

32 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

Ultimate (taped on), but both practitio- chronic cases, and one shoe does not work ■ Applied nontraumatically (no impact ners recommend unscrewing one wedge on all cases. from nailing, as they’re attached with from this shoe to make it shorter in horses Belknap has noticed that previously screws). whose coffin bones have both rotated and 10% of laminitis cases were in horses with A thorough assessment of the foot with undergone sinking. The objective is to pasture-associated obesity; now this has lateral and dorsopalmar radiographs (side stabilize and derotate the coffin bone as increased to 60-70% of cases. He cannot and front views) is essential to design the much as possible to relieve forces, while find an explanation for that trend, nor did shoe according to what that foot needs, he providing support to internal structures anyone in the audience have any sugges- noted. of the foot. Both clinicians emphasized tions. When the shoe is constructed from a that it is important to watch the horse’s re- wood block, the sides and toe are cut at sponse to shoeing, and they should realize Wooden Shoes for Chronic about a 45° angle. This places weight bear- that there is not one type of foot support Laminitis ing directly under the bones, allows the that works for every horse. The chronically laminitic horse is often horse to easily choose the most comfort- The discussion continued onto chronic a very tough case to manage because dis- able hoof angle when standing, and de- laminitis, noting that an affected horse placement of the coffin bone within the creases torque on the laminae (which at- has a mechanical problem that can’t be foot leads to a lot of pain and damage, in tach the coffin bone to the hoof wall). The fixed chemically by this point in the dis- addition to the damage that allowed the shoe can be further modified in several ease. The best approach is using special displacement in the first place. O’Grady, ways: Its foot surface can be “routed” out shoes. discussed how to build and fit wooden in specific areas to alleviate pressure on a Audience discussion centered around shoes (clogs) to improve healing in three dropped sole, wedge pads can be added to the wooden clog shoe, using either a forms of chronic laminitis. further elevate heels, and the overall thick- homemade shoe made of 1-1/8” plywood, He listed several benefits of these shoes, ness of the shoe can be modified by adding beveled 45 degrees all the way around, or which are made out of stacked plywood or or removing layers of wood. the commercially available EDSS (Equine subfloor wood: O’Grady went on to describe the use Digit Support System) product. These are ■ Easy to build; of this shoe for three manifestations of screwed in on the side of the hoof wall, ■ Lightweight; chronic laminitis: dorsal rotation (the most and just enough cushion impression mate- ■ Dissipate energy (absorb shock) better common rotation case), medial or lateral rial is placed in the frog area to give relief than harder metals; displacement of the coffin bone (sinking without too much pressure. Such a shoe ■ Inexpensive; on the outside or inside of the foot), and absorbs concussion and allows the horse ■ Flat, solid construction allows weight dropping of the sole or prolapse of the cof- to adjust how he wants to stand, possibly bearing to be applied over specified sec- fin bone through the sole. more so than with other shoeing options. tions of the foot; Dorsal rotation In these cases, the coffin Belknap and Boswell pointed out that they ■ Easily altered according to the horse’s bone has pulled away from the hoof wall use many different types of shoes in the needs; at the toe and is rotating so its tip is closer

Jump higher.

to the ground. O’Grady recom- superior to poor quality digital mended realignment of these feet images. Attention to detail is so the bottom surface of the coffin crucial to achieve excellent qual- bone is parallel to the ground by ity images, whichever technique removing some of the heels and is used. However, excellent qual- using the increased solar surface ity computerized or digital im- for weight-bearing. Once the foot ages can potentially yield more is prepared, impression material information than conventional is applied to the foot to recruit the images and enhance our diag- sole, bars, frog, and sulci (grooves nostic capabilities. alongside the frog) for weight “I believe very strongly that bearing. Then the wooden shoe there is both art and science is applied with 1 1/2-inch drywall in lameness diagnosis,” she screws. opined. “There are rules, but O’Grady said that in some cases there are very fuzzy edges to of coffin bone rotation and pro- them.” lapse (penetration through the Keep Asking the Ques- sole), this treatment has provided tion Allen briefly discussed a a viable alternative to deep digital tough lameness case that was flexor tenotomy (cutting the deep still an enigma after extensive digital flexor tendon). He reported nerve blocks, scintigraphy a favorable response (increased (bone scan), and physical ex-

sole depth and wall growth at the Proceedings D r. Stephe n O ’ G r a dy/AAEP amination. When the horse’s toe) in 17/21 cases (81%) with this Dr. O’Grady says, “The wooden shoe (two examples are shown above) long winter coat on the leg was method. provides another very consistent farriery option when treating a horse clipped for ultrasound, a small Medial/lateral sinking Medial with chronic laminitis.” swelling was noted that turned sinking (to the inside of the foot) out to be a large lesion in the is more commonly seen, although sinking as digital radiography (X rays) and MRI superficial digital flexor tendon. to the outside has been noted in support- have given researchers the tools they need “That’s the diagnostic clipping proce- ing limb laminitis, O’Grady reported. The to look inside and learn more about lame dure,” he said with a chuckle. “A detailed approach for these feet is similar to that feet in horses. However, those tools re- physical exam is critical to these cases. You for dorsal rotation, except the heels might quire a good deal of knowledge about how have to keep asking the question, what’s not need to be taken down to realign the to interpret the results, and those results going on here? If there’s no answer on scin- foot, and a one-quarter-inch extension on have to be viewed in light of the horse’s tigraphy or clinical examination and nerve the high side is used to help lighten the clinical signs. blocks, either keep blocking or go back to load on the low side. At convention two world-renowned your imaging and ask more questions.” He found a favorable response (in- practitioners spent a half-day informing Dyson and Allen agreed that horses with creased wall growth on the low side) in attendees about the proper use and inter- significant proximal (upper) superficial 8/11 cases (65%) with this method. pretation of these imaging methods, re- digital flexor tendon lesions like this don’t Solar/coffin bone prolapse In these tough porting on recent research and a host of tend to recover full soundness for compe- cases, the coffin bone is realigned as with case studies to illustrate their findings. Sue tition-level exercise. the dorsal rotation case, heel elevation is Dyson, VetMB, PhD, FRCVS, head of clini- Palmar Process Fractures of the Coffin used to decrease the pull of the deep digital cal orthopedics at the Animal Health Trust Bone This term describes a fracture of the flexor tendon, and the shoe is routed out in Newmarket, United Kingdom, and Kent rear “wings” of the coffin bone; the inside to prevent weight bearing by the prolapsed Allen, DVM, owner of the imaging refer- (medial) wing, outside (lateral) wing, or sole and/or bone. The rear half of the foot ral facility Virginia Equine Imaging in The both can be fractured. An Animal Health is packed with impression material to help Plains, Va., presented the popular session. Trust study of 22 horses (eventers, show support the horse’s weight. Dyson described the objectives of the jumpers, and general purpose horses with He reported a favorable response (corni- presentation as follows: to present the re- an average age of 8.4 years) found that the fication of the exposed soft tissues and sults of recent studies, discuss the art and medial palmar process (back part of the hoof wall growth) in 7/9 cases (77%) with science of lameness diagnosis, provide wing) was more often affected, account- this method. practical tips, show some high-quality im- ing for 81% of fractures. Owners of many “The wooden shoe provides another ages, and demonstrate that sophisticated of the horses had not observed a sudden very consistent farriery option when treat- technology is not always required. onset of acute lameness, but horses were ing a horse with chronic laminitis,” he For example, she commented: “It is im- mildly or moderately lame upon exami- concluded portant to recognize that computerized nation at the Animal Health Trust—less or digital radiography does not necessar- severe than one usually associates with Looking Inside the Lame Foot ily equate with better. Excellent quality fractures, Dyson noted. Advances in diagnostic imaging such conventional radiographs can be vastly She reported that lameness was worse

34 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

when the horses were worked in a circle, The location of the palmar process frac- IRU was found, nor was there correlation especially on hard ground with the lame ture and whether it affects the joint surface between the angle of the coffin bone with limb on the inside. Conventional radio- (an articular fracture) doesn’t appear to af- the ground (solar angle or palmar angle) graph views showed no abnormalities in fect the prognosis in sport horses, she said. and IRU. Veterinarians found more abnor- half of the horses, but oblique (off-angle) However, concurrent injury of the collat- malities in medial palmar processes with views were able to show the fractures. eral ligament that stabilizes the coffin joint MRI than scintigraphy, and MRI grade “This highlights the need for routine use might lead to increased bone instability was significantly correlated with scintigra- of oblique projections when evaluating and delayed union of the fracture. phy grade. horses with foot pain,” she advised. More on the Palmar Processes Dyson “Focal increased radiopharmaceutical She also noted that nuclear scintigraphy also described a study that compared ra- uptake in a palmar process of the distal or bone scanning identified bone remodel- diography, nuclear scintigraphy, and MRI phalanx is not common, but it occurs most ing at the fracture site in all 12 horses that to evaluate the palmar processes of 258 frequently in the medial palmar process,” were scanned. Scintigraphy is a metabolic horses with front foot pain, in part to de- Dyson summarized. imaging modality that uses blood flow and termine if pedal osteitis (inflammation of “There’s a huge variation in radiograph- bone remodeling to produce an image. A the coffin bone) is a legitimate diagnosis. ic, scintigraphic, and MRI appearance of radioactive compound is injected intra- “I’ve always been somewhat reluctant to palmar processes,” she went on. “Focal venously and circulates throughout the use (the pedal osteitis diagnosis) unless IRU can be seen with MRI abnormalities horse, localizing in areas of injury and ac- there’s evidence of IRU (increased radio- associated with lameness or incidental tive bone remodeling. The radioactivity is pharmaceutical uptake, indicative of bone MRI abnormalities (which are present, but measured, producing an image. “Nuclear remodeling, seen on a bone scan). I still not causing lameness). Abnormalities are scintigraphy can be useful to highlight ask, is it necessarily contributing to pain more frequent in lame limbs, but are they the potential presence of a fracture and and lameness? I tend to say it’s the diagno- contributing to the abnormal loading or a prompt acquisition of different radio- sis of the diagnostically destitute,” she said consequence of it? The clinical significance graphic views to identify a fracture,” she with a grin. of these lesions has to be established. Most said. However, scintigraphy is not usually Focal moderate to intense IRU was seen horses present with concurrent lesions essential for diagnosis. in 2.8% of medial processes and 1.2% of that could also cause lameness. Thirteen of the 22 horses became sound, lateral ones. Radiographs noted multiple “So is pedal osteitis a legitimate diag- three improved but not to complete sound- radiolucent areas (of less dense bone) in nosis? Can it contribute to pain and lameness at their previous level of work, and palmar processes in 21.1% of feet, new ness?” she asked. “Yes, but in no horse was two healed but had lameness from other bone on the ventral (lower) aspect of pal- this the primary cause of lameness in this injuries, for an overall successful recovery mar processes in 11.8% of feet, and palmar study.” rate of 81%. Alteration of bone architecture (rearward) elongation of the palmar pro- “So pedal osteitis is still the trashcan di- in some horses suggested that this can be a cesses in 4.6% of feet. agnosis?” Allen asked with a smile. repetitive stress injury, Dyson commented. No correlation between sole depth and “Yes, I think it is,” answered Dyson.

Ride farther.

Enostosislike Lesions Allen described a not, you’ve got more to look at.” usually the lateral cartilage grade was 4-year-old Western pleasure gelding that Dyson described a similarly confus- more severe. presented with variable left front foot ing case, with the following conclusions: “Large medial cartilages, asymmetry be- lameness and short striding behind. When “Consider the spectrum of pathology and tween feet, and a marked lack of correla- the left front was blocked, the lameness the relationships between the cartilages tion in size between the cartilages within switched to the right front. “We gave him of the foot and collateral ligaments of the a foot may be more indicative of an abnor- a sound leg to limp on and he took the op- coffin joint; they’re connected, and if one mality,” Dyson noted. portunity,” Allen commented. is damaged, the other is likely to be as Nuclear scintigraphy (on 186 horses) Imaging results were unusual in several well. Learn the anatomy; you’re not going This imaging modality was useful to see respects, and the final diagnosis was enos- to know all of it all the time because you the level of remodeling in the cartilages of tosislike lesions (bone growths within the forget things. You need to go back to the horses with sidebone; moderate to severe central bone cavity) in all four fetlocks. anatomy textbooks and don’t be afraid to ossification as seen on radiographs was of- The horse was treated with shock wave get bone specimens, preferably with liga- ten associated with IRU. therapy and tiludronate, became sound in ments attached, so you can remind your- All fractures of ossified cartilages also 30 days, and he competed successfully at self of the attachments of these structures had IRU, indicating that moderate to se- the Quarter Horse Congress and the World to reach an accurate diagnosis.” vere ossification is a risk factor for frac- Championship Show. tures. Dyson reported that there was “This horse had a lot of bone turnover, “good correlation and excellent agreement with osteoblastic (bone-producing) and between radiographic and scintigraphic osteoclastic (bone breakdown) processes Nuclear scintigraphy grades.” happening at the same time,” he said. “The can be useful to highlight She also noted that ossification of only medication tiludronate inhibits osteoclas- one cartilage of the foot might result in un- tic activity; if you can modify this process, the potential presence balanced stresses on that cartilage and as- the osteoblastic activity should also sub- of a fracture and prompt sociated ligaments, possibly contributing side. to a greater risk of injury to that cartilage “Are these lesions always a cause of acquisition of different than in a foot with symmetrically ossified lameness? Not necessarily,” Allen said. “We radiographic views to cartilages on both sides. see these often in older horses and they’re “Some fractures were not easy to define often incidental findings.” identify a fracture. radiographically, and scintigraphy con- Distal Border Navicular Bone Fragments firmed them or sent us back to investigate What appears to be a fragment off the dis- Dr. sue dyson further and find them,” she commented. tal (lower) side of the navicular bone might “Scintigraphy may give information not actually be a fragment, noted Dyson. It about the potential clinical significance of might be a mineralization in the adjacent Sidebone The collateral cartilages of the ossification of the cartilages of the foot and distal sesamoidean impar ligament or an foot serve to dissipate shock when the foot associated lesions, thus, prompting further enthesophyte (bony growth where the liga- lands, explained Dyson. At ground con- study,” she summarized. “This study also ment attaches to the bone). Regardless of tact, they move abaxially (away from the verified the observation that marked asym- the actual structure, these apparent frag- centerline). Ossification, or hardening, of metry of the cartilages of the foot within a ments have been increasingly recognized the foot’s cartilages into bone (sidebone), foot may be a risk factor for injury.” with the advent of digital radiography. affects this function and is easily detected “I think we’re getting to some clarity Dyson noted that lameness associated on most radiograph systems. about sidebone,” commented Allen. “For with movement of the fragment relative to Several Animal Health Trust studies in- years we were told it was due to medio- the navicular bone can occur, and the frag- vestigated the prevalence and severity of lateral (side-to-side) hoof imbalance, but ments might be associated with pathology sidebone. One study of 268 horses graded there’s more to it than that. I think it really (changes due to disease) and/or adhesions ossification on a scale of 0 to 5, with 5 as does point out that we need to look at that of the digital sesamoidean impar ligament the most severe grade. Twenty-eight horses sidebone in detail and make sure we’re not and/or deep digital flexor tendon. had sidebone of some grade. just blasting past that lesion.” Figuring Out Tough Cases After present- Breed, body weight, and height to body Fracture of sidebones Ten horses with 12 ing a case where the horse’s response to weight ratio were all significantly associ- total fractures of the collateral cartilages nerve blocks didn’t entirely match the ated with sidebone grade. Large native were studied, and it was found that all of imaging results, Allen made the following ponies such as Dales, Highland, Fell, and them had at least moderate ossification of comments: “The longer I do this, the more Connemaras, along with heavier individu- the cartilages. Most (92%) of the fractures nervous I get about where local anesthetic als, were more likely to have more severe were at the base of the cartilage, and the used for nerve blocks is going. They’re still sidebone. Height to body weight ratio was medial cartilage was slightly more likely to the gold standard, but the anesthetic dif- negatively associated with sidebone grade; be fractured (58% of fractures). fuses and moves around, so you can block in other words, short, heavy horses had a “Lameness tended to be most severe on less or more structures than you intended. higher occurrence of severe sidebone. a 10- to 15-meter circle on a hard surface Take nerve blocks at face value if all of Lateral and medial cartilages had sig- with the lamer limb on the inside of the your diagnostics are falling into place. If nificantly different sidebone grades, and circle,” reported Dyson. “Lameness was

36 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

abolished by palmar (abaxial sesamoid) associated with soft tissue injuries. The pathology in the navicular bone were as- nerve blocks. most common soft tissue injuries with IRU sociated. “In some horses it was difficult to make were in the deep digital flexor tendon (13% Lesions of the distal sesamoidean im- a definitive diagnosis based solely on ra- of limbs) and in the insertion of that ten- par ligament and collateral sesamoidean diographic findings, and comparison with don on the coffin bone (14.3% of limbs). ligament were less common (38.2% and nuclear scintigraphic images was invalu- “Positive nuclear scintigraphic results 10.5%), but both were also associated with able,” she said. “Comparison of solar, lat- are good predictors of injury or disease of navicular bone abnormalities. eral, and dorsal scintigraphic images was the deep digital flexor tendon and collat- “There are close interactions between invaluable to precisely locate the site of eral ligaments of the distal interphalangeal injuries of the components of the podo- IRU.” joint (coffin joint), irrespective of the ana- trochlear apparatus, the deep digital flexor Associated trauma to the coffin bone tomical location of the lesion in the ten- tendon, the navicular bursa, and the distal Four horses with severe sidebone were don or ligament,” Dyson concluded. “But interphalangeal joint,” Dyson concluded. found to have associated trauma to the a negative scintigraphic result does not “The navicular bone can’t be considered in coffin bone, based on scintigraphy and preclude significant injuries; however, in isolation. Core lesions of the deep digital MRI imaging, reported Dyson. combination with MRI it can tell us some- flexor tendon at the level of the proximal Scintigraphy for Navicular Disease and thing about the disease process. Nuclear phalanx may have a different etiology Soft Tissue Injuries scintigraphy was not useful for detecting (cause) than lesions occurring further dis- Out of 264 horses with front foot pain, lesions of the distal sesamoidean impar tally.” scintigraphic images of 36.6% of their ligament. “ Cannon Bone Stress Fracture Dyson limbs showed IRU on a bone scan in the MRI Investigation In those 264 horses described a case of cannon bone stress navicular bone, Dyson noted. Scintigraphy with foot pain, MRI showed that 82.6% fracture, which was a subtle fracture in and MRI grades were highly correlated. of limbs had deep digital flexor tendon le- the upper rear aspect of the bone in a fore- “It was concluded that positive nuclear sions, most often near the collateral sesa- limb (just below the back of the knee). The scintigraphic results are good predictors moidean ligament (59.4%) and navicular lameness worsened with more trotting and of injury or disease of the navicular bone; bone (59%). Many of these lesions were when the horse slowed down, which she however, a negative scintigraphic result small and not clinically significant, she noted is a hallmark of this injury. A few does not preclude significant disease of the noted. of these cases have pre-existing sclerotic navicular bone,” she said. “It appears that Lesions at the level of the first phalanx changes, she noted. if bone necrosis is the predominant patho- or long pastern bone (just below the fet- The prognosis is generally a complete logical process, IRU may be normal. End- lock) tended to be core lesions (90.3%), recovery with three months of stall rest stage sclerosis (bone hardening) is also not while the aforementioned lower lesions and ascending walking exercise, she said. associated with IRU.” tended to be sagittal (front to back) splits Proximal Suspensory Desmitis A 4-year- The same 264 horses’ scintigraphic im- and dorsal (upper surface) abrasions. Le- old Warmblood was presented to Dyson ages were also evaluated to see any IRU sions of the deep digital flexor tendon and because he’d lost quality of movement. “In

Show stronger.

a young horse with loss of action, proximal injury). Medial injuries were more com- suspensory desmitis is always in the fore- mon, affecting 105 horses (93%). Ultra- front of my mind,” she said. sound found collateral ligament abnor- In this horse, no abnormalities were de- malities in only 13 horses (11.5%), and tectable with ultrasound, scintigraphy, or radiographs found no ligament problems, radiographs. However, MRI located the although they did find coffin bone frac- suspensory lesion in the lateral lobe. “MRI tures in three horses. has the potential to diagnose proximal sus- Group 3 All 11 of these horses had ultra- pensory desmitis in horses where we don’t sonographic abnormalities of the collateral see any ultrasonographic abnormalities,” ligament, and eight of nine evaluated with she noted. scintigraphy had positive findings. Coffin joint collateral ligament desmitis Bony cystlike lesions at the attachments Dyson’s last report described a study of of the collateral ligament worsened the re- coffin joint collateral ligament (CL) desmi- sponse to treatment in groups 1 and 3. tis in which horses were divided into three “Correlation between clinical findings groups: and imaging modalities is enabling us to Group 1 109 horses with primary CL in- slowly unravel the complexity of the causes jury. of foot pain and to begin to understand Group 2 113 horses with CL injury along some of the risk factors for injury, different with other injuries. pathological mechanisms, and factors in- vid Nu n ama k e r

Group 3 11 horses with primary CL in- fluencing prognosis,” Dyson concluded. “It D r. Da jury, but no MRI examination. is important to emphasize that, although Horses with cannon bone stress fractures Group 1 included 45 horses with lame- scintigraphy and MRI are hugely valuable generally complete recovery with three months ness in one forelimb (unilateral), 59 with tools, in a significant proportion of horses, of stall rest and ascending walking exercise. lameness in both forelimbs (bilateral), and a conclusive diagnosis can be reached with five with hindlimb injury (one bilaterally). a thorough clinical examination, com- for horses. Their presentations described Dyson reported that no localizing clini- bined with radiography and ultrasonogra- the specifics and challenges of stem cell cal signs were present in most horses, and phy. Clinical investigation should follow a work along with the evidence that sup- pain was not apparent when palpating or logical, stepwise progression.” ports its use for equine tendon and carti- manipulating the lower limb joints in any Allen added, “We (imaging referral prac- lage defects. horse. However, lameness was consider- tices) can’t promise a full lameness work- Stem cell background First, what is a ably worse when the horses were worked up will be cheap, but we’ll stay on it until stem cell? Even this seemingly basic an- in circles, especially on hard ground. She we have a diagnosis. There’s a real need for swer is unclear, said Fortier. “The defini- commented that horses with medial col- this in this country; too often a case doesn’t tion and identification of stem cells is lateral ligament desmitis were sometimes get a good work-up and there’s real value constantly evolving,” she noted. “There is more lame when the affected limb was to to doing this.” no current consensus on a gold standard the outside of the circle. Abaxial sesamoid assay to isolate or identify stem cells.” nerve blocks were the only ones that made The State of Stem Cell Therapy Part of the challenge is that once stem all horses go sound. Stem cell therapy has received a good cells differentiate into specific cell types The medial collateral ligament was in- deal of attention in both human and vet- (such as tendon or ligament cells), classi- jured in 73.4% of horses, and the lateral erinary medicine in recent years. It holds fying them can be ambiguous. (Is that a collateral ligament was also injured in theoretical promise for treating conditions stem cell, a tendon cell, or a stem cell that 14.5% of horses. The remainder had in- ranging from traumatic tendon and carti- became a tendon cell?) Also, no single cell juries to only the lateral ligament. Horses lage injury to liver failure, Parkinson’s dis- surface marker can differentiate stem cells that jump (including show jumpers and ease, and nerve/spinal cord damage, but it from other cells. Instead, one must iden- eventers) were overrepresented in the is still in its infancy. tify them by seeing what markers are pres- study, comprising 50 of the 109 horses. Lisa Fortier, DVM, PhD, Dipl. ACVS, ent and absent, much like a combination Ultrasound found collateral ligament associate professor of clinical sciences at lock (i.e., only a very specific combination problems in only 44% of horses, and only Cornell University, said, “Stem cells are of markers defines a stem cell). six horses had abnormalities detectable not yet living up to the hype. We’ve got a Researchers are working to develop an with radiographs. But MRI found prob- long way to go before we really know what assay combining many different markers lems in all 109 horses. we’re doing and can fine-tune these thera- to identify stem cells so they can determine Group 2 Eighty-five of the 113 horses pies.” absolute numbers of stem cells harvested (75.2%) had multiple concurrent injuries Fortier and Roger Smith, MA, VetMB, and used in therapies. This will help clarify involving the coffin joint, deep digital DEO, MRCVS, PhD, Dipl. ECVS, profes- research on their use. flexor tendon, distal sesamoidean impar sor of equine orthopedics at the Royal “To date, equine studies that have inves- ligament, navicular bursa, or collateral Veterinary College in Herts, in the United tigated the use of ‘stem cells’ contain no sesamoidean ligament (often on the same Kingdom, presented an in-depth session information regarding characterization side of the foot with collateral ligament on the current state of stem cell research of the cells before implantation or data

38 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

concerning survival or function of the (which evaluate how well stem cells can be transplanted/grafted cells,” noted Fortier. Bone marrow-derived induced to grow into different tissue types, While researchers aren’t yet in agree- such as bone, muscle, or liver). Harvesting ment on the methods and criteria for iden- stem cells have received them results in more donor site morbidity tifying stem cells, some are working on the most attention scien- (damage) than harvesting of BM-MSCs. more functional testing to find out what However, they do have their advantages; stem cells can do. To discuss this testing, tifically and, hence, are the they don’t have to be cultured for three we need to know a few additional “back- best characterized. weeks, so treatment of a lesion can occur ground basics” of stem cell therapy. These quickly—within a couple of days. Fat tis- include whether they are embryonic stem sue is harvested from the tailhead, then the Dr. lisa fortier cells (ES, cells derived from embryos or fat cells are removed and what’s left (about generated using genetic means) or adult- methodology obviates the need for genera- 50 million nucleated cells, about 2% of derived mesenchymal stem cells (MSCs). tion or destruction of embryos and it al- which are A-MSCs) is injected into the le- The latter are further broken down into lows the establishment of patient-specific sion. This approach also carries no risk of the type of tissue from which they were stem cells that would not be rejected by the rejection. harvested—whether they came from bone immune system. Several questions about stem cell ther- marrow or fat (adipose) tissue (BM-MSCs Bone marrow-derived stem cells can be apy apply to all types of cells, said Fortier. and A-MSCs, respectively). Each type and harvested from the sternum (breastbone) They include the following: location of stem cells carries specific nu- or iliac crest (part of the hip). These stem ■ What’s the best approach to using stem ances; they can’t all be lumped together. cells only comprise one in 10,000-100,000 cells? Embryonic stem cells carry a few chal- of nucleated cells in bone marrow, said ■ How many stem cells do you need? lenges. There has been a lot of political/ Fortier, but they “have received the most ■ Do we expect the stem cells to take en- ethical debate about the generation and attention scientifically and, hence, are the vironmental cues from surrounding tis- destruction of embryos to generate stem best characterized.” They are harvested sues and just turn into what’s needed, or cells, and there has been a concern about with the horse standing and sedated, then do they need some guidance? immune rejection of the cells, since they they are cultured for about three weeks ■ How important are growth factors? would contain the genetic material of an to increase their number to 10 million or ■ What’s the best way to grow stem cells in individual different from the recipient. so. They are then implanted into a lesion culture to gain maximum effect? Very current breakthroughs, however, sug- along with bone marrow supernatant (liq- “There is a lot to learn, so we need to gest that embryonic stem cells can be made uid), which contains growth factors to help pick specific areas to focus on in order to from adult somatic cells such as skin cells. heal the lesion. Since the cells come from optimize clinical implementation of stem This methodology involves the introduc- the patient, there’s no risk of rejection. cells,” she commented. “The future of stem tion of four genes that “re-program” a cell Adipose-derived stem cells have not done cell therapy is limitless for healing tendon, to become an embryonic stem cell. This as well in some cell differentiation studies cartilage, laminitis, bones, nerves, etc.”

Feel better.

Stem cells for tendon lesions “The horse training and racing) was 82% of 71 horses, cell therapies with other more estab- is a professional athlete, and tendon inju- and the success rate in 11 flat racing horses lished methods to prevent re-injury, such ries are extremely common,” noted Smith; was 50%. Twenty-four sport horses in other as desmotomy (division) of the accessory one study found that they affect 23% of disciplines had an 87% success rate, com- ligament of the superficial digital flexor National Hunt horses in training and 46% pared to a 57-77% success rate with conser- tendon (superior check ligament desmo- of limb injuries at racecourses. vative treatment in another study. tomy), makes a lot of sense and might He focused on the superficial digital He noted that horses that were re- have value. But it must be remembered flexor tendon in particular, noting that a injured had a significantly longer interval that there are still considerable gaps in large part of its function is to store energy between injury and treatment (83 vs. 44 our knowledge, although the technology via its elasticity and return that energy to days), suggesting that delayed treatment is developing rapidly.” the horse for the next stride. “That’s what resulted in more fibrosis of the lesion. He He explained the harvesting and treat- makes the horse an efficient runner,” he now recommends earlier harvesting of ment procedures in detail for the audi- explained. “The horse is estimated to be bone marrow (within one month of injury) ence. 120% energy efficient at the gallop.” The and treatment. Pre-injury harvesting and Stem cells for cartilage lesions One ad- downside, of course, is injury when the storage of cells might also prove beneficial, vantage of using stem cells to treat carti- tendons and ligaments are overstretched. as might storage of stem cells recovered lage lesions is that the cells are harvested When a tendon is injured and subse- from that horse’s umbilical cord at birth. and inserted during a single arthroscopic quently healed, the scarred tendon is less surgery; no laboratory culture time is re- elastic than normal tissue, putting it at risk quired. The technique involves removing of re-injury; one study of National Hunt Stem cells won’t any calcified cartilage, using a micropick horses found that 56% of those with super- remove fibrous tissue once to perforate cartilage and thus get growth ficial digital flexor tendon injuries suffered factors from the bone beneath, and filling re-injury. “This is the rationale behind use it’s there, so treatment the defect with a stem cell mixture harvest- of stem cells to treat tendon overstrain ed from bone marrow. The mix includes injuries—we need regeneration (of normal will be less effective on thrombin to break fibrinogen down into a tissue) rather than repair (scarred tissue),” chronic cases. fibrin scaffold, which holds the stem cells Smith explained. and growth factors in place. Equine MSCs cultured in the labora- Dr. Roger Smith “First you dry the area with helium, then tory create a matrix of tendon tissue that put in tricalcium phosphate (if there is a is “remarkably ordered,” he observed. This “Stem cells won’t remove fibrous tissue bone void underneath the cartilage), then is one of the keys to healing tendons—the once it’s there, so treatment will be less ef- put in the graft (stem cell mixture),” For- cells must be organized linearly so they fective on chronic cases,” he advised. “I rec- tier explained. “It clots immediately and can handle the linear stress placed on ommend it for first-time injury, but some- sets in 30-45 seconds, and you can sculpt them, rather than being disorganized so times it’s also been tried on horses with it so it fits in perfectly.” they can’t stretch effectively. more chronic presentation or those that She discussed one ongoing study, fund- One good thing about tendon lesions have had poor success with other treated by the Grayson Jockey-Club Research is that they generally form a closed cavity ments.” Foundation, of young (2- to 5-year-old) within the tendon. This helps hold stem Less evidence is available regarding the horses using this technique and BM-MSC cells in place and provides a vascular- value of A-MSCs in tendon injuries; Smith in 15-mm full-thickness surgically created ized scaffold (granulation tissue bed with reported that a pilot study using the col- defects. blood vessels) to help organize healed tis- lagenase model of tendon injury found im- Eight months post-surgery, treated sites sue and provide blood supply, growth fac- proved tissue organization and increased had significantly more fill of the lesions tors in the fluids present to help heal the specific gene expression compared to (more than 75% fill vs. less than 25% fill lesion, and a mechanically appropriate controls. Although this approach has been in control sites on the same horse) and im- environment. used in many U.S. horses, clinical results proved texture of the repair. Glycosamino- Smith reported that lab animal studies have yet to be published. glycan (GAG) content (which helps hydrate have found that treatment of surgically Both treatments are followed by a and lubricate the joint) was not normal in created tendon and ligament lesions with 48-week protocol of rest and controlled treated lesions, but it was better than in MSCs results in better tissue organization, exercise designed to provide appropriate control sites. composition, and mechanics, compared to mechanical stimulus to the healing cells “Stem cell therapy is an exciting technol- controls. In addition, an equine study in the without causing further damage. The pro- ogy, but it’s still developing,” summarized United Kingdom using BM-MSCs found tocol is adapted based on the individual Smith. “We must have sensible expecta- that in 82 of 168 treated racehorses that horse’s progress. tions for the therapy; this field is high on were available for follow-up after one year, “There are some encouraging aspects to emotion and low on science. We’re trying there was a 78% success rate (no re-injury) this technology, although definitive proof to readjust that balance, but certainly for compared to 43% of horses conservatively of efficacy is still lacking,” Smith said. your clients they’ll always be attracted to treated in another study—a 35% improve- “Furthermore, there have been no direct stem cells and you have to temper that ment in success rate. More specifically, the comparisons between the two techniques enthusiasm with explanation of where the success rate in National Hunt horses (in (BM-MSCs and A-MSC). Combining stem technology currently is.” h

40 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 ( your way ) ( our way )

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Doxycycline Antibiotic For to joints without hav- Arthritis? ing antimicrobial ef- Osteoarthritis is the most common fects, researchers fed human joint disorder in the world, and six healthy horses 5 in the equine industry it’s the most eco- mg/kg (half the recom- nomically important disease,” said Ashlee mended antimicrobial Watts, DVM, a graduate student at Cor- dose) every 12 hours nell University, during the 2007 American via nasogastric tube Association of Equine Practitioners Con- for two days. This vention, held Dec. 1-5 in Orlando, Fla. “It’s dosing strategy was, the primary cause of decreased athletic indeed, effective at function and wastage in racehorses.” achieving therapeutic Many medications have been tried to concentrations in the treat this common condition, and Watts joints, Watts reported; discussed the relatively new option of levels reached 0.1943 doxycycline for arthritis. Doxycycline is µg/mL by one hour af- a semisynthetic antibiotic that’s related to ter administration and tetracycline and has been used in horses increased thereafter. since the 1990s. It’s also used to treat Thus, doxycycline Lyme disease, and one study on that dis- might indeed be ther- ease noted that horses given the medica- apeutic for osteoar- tion along with other antibiotics “never thritis, laminitis, and went better,” despite being negative for neuropathy (nerve dys- D r. Na ncy S . L oving Swelling in the fetlock joint due to osteoarthritis. Lyme disease, suggesting a possible anti- function), and it might inflammatory effect. Therefore, research- be useful for prophylaxis in high-risk cas- triamcinolone acetate (TA, Vetalog), in ers decided to investigate its possible use es. Possible concerns with doxycyline use terms of two measures of joint health, against osteoarthritis. include photosensitization (horse becomes were presented. Elysia Schaefer, DVM, a Doxycycline might indeed be therapeutic overly sensitive to light) and whether it can graduate student and second-year equine for osteoarthritis, laminitis, and neuropa- be performance-enhancing in addition to surgery resident at the University of Illi- thy (nerve dysfunction), and it might be disease-modifying. nois, presented the study results. useful for prophylaxis in high-risk cases. “Further in vivo studies are warranted “Hyaluronic acid is an important com- Previous laboratory research found that to determine if MMP activity is inhibited ponent of cartilage that helps maintain hy- at concentrations as low as 0.0462 micro- in vivo and to fully elucidate a medication drostatic pressures to resist weight-bearing liters (µg/mL) in synovial (joint) fluid and protocol,” she concluded. forces,” she explained. “Corticosteroids plasma, doxycycline could inhibit the ex- (Lisa Fortier, DVM, PhD, Dipl. ACVS, inhibit the production of inflammatory pression of matrix metalloproteinases 3 associate professor of veterinary clinical mediators (some of which can break down and 13 (MMP 3 and 13). Various MMP sciences at Cornell University, was the cartilage) and leukotrienes (which sustain enzymes have been implicated in osteoar- principal investigator on the study.) inflammatory reactions), which are in part thritic and laminitic disease processes, responsible for pain. They also block pro- so inhibiting them might help slow these Treatments for Osteoarthritis duction of pro-inflammatory cytokines.” disease processes. However, antibiotics Osteoarthritis has a major impact on The study was carried out on normal shouldn’t be used at antimicrobial lev- pain and athleticism of horses, and many chondrocyte (cartilage cell) pellets from els (which are substantially higher than medications are used to combat it. At the six horses that were stimulated to break 0.0462 microliters (µg/mL) without good 2007 American Association of Equine down the cartilage matrices by using in- reason, because this might promote anti- Practitioners Convention, held Dec. 1-5 in terleukin-1 (a degadation protein). Re- biotic-resistant bacteria strains. Orlando, Fla., an in vitro study comparing searchers found that only the HA prod- To determine if oral dosing could de- commercial preparations of hyaluronic ac- uct significantly increased proteoglycan liver enough doxycycline (0.0462 µg/mL) id (HA, Hylartin V) and the corticosteroid synthesis (proteoglycan is a necessary

42 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

component of cartilage), while both prod- ounces of Myristol daily for 14 days, then every 12 hours for five days, while the oth- ucts significantly increased glycosamino- 2.67 oz daily for 28 days (42 total days of er received 2 g of Bute orally once a day glycan content of cartilage (which works supplementation). Lameness exams at for five days. Horses were exercised on a to protect against the progression of ar- Days 1, 14, 28, and 42 were used to assess high-speed treadmill daily, and lameness, thritis). the efficacy of the supplement. tissue scores, biochemical scores, and “In this study, there was no significant Researchers found that treatment with biomarker scores were used to evaluate interaction when combining HA and TA,” Myristol significantly improved lameness the efficacy of treatment. noted Schaefer. “Both a high dose of HA (2 score, lameness at the walk, response to Frisbie reported that the Bute- and mg/mL) and of TA (0.6 mg/mL) had a pro- joint flexion, lameness after flexion, and Surpass-treated limbs got significantly bet- tective effect on interleukin-1-stimulated quality of life compared to controls. ter in terms of lameness scores. The car- chondrocytes.” “We conclude that oral administration tilage glycosaminoglycan content in the of Myristol had beneficial clinical effects Surpass-treated limbs was better than with Myristol’s Effects on on horses with naturally occurring OA,” Bute (meaning the cartilage was better hy- Clinical Joint Disease said Keegan. “The most apparent benefi- drated and lubricated). There were also im- The results of a blinded, controlled study cial effects were in parameters related to provements in bone sclerosis (hardening) on the effects of the neutraceutical Myris- joint flexion. For many of these horses, of the radial carpal bone and total erosion tol on lameness caused by osteoarthritis this was a significant improvement in their scores in the Surpass-treated joints. (OA) were discussed by Kevin Keegan, quality of life.” DVM, MS, Dipl. ACVS, associate professor of equine surgery at the University of Surpass vs. Bute for Arthritis Missouri. David Frisbie, DVM, PhD, Dipl. ACVS, The product contains cetyl myristoleate, associate professor of veterinary clini- glucosamine hydrochloride, methylsul- cal sciences at Colorado State University fonylmethane, and hydrolyzed collagen. (CSU), discussed a study comparing clini- “Each individual ingredient has shown cal efficacy and joint health parameters some positive effect in either human clini- of Surpass (topical liposomal diclofenac cal trials or in vitro (in the lab) in horses,” cream) to those of the commonly used “Both Surpass and Bute had symptom- said Keegan. oral non-steroidal anti-inflammatory modifying effects, but Surpass alone had For the study, 39 horses in Missouri and medication phenylbutazone (Bute). disease-modifying (curing) effects,” Fris- Florida were selected for naturally occur- In 24 horses, carpal (knee) osteoar- bie summarized. “Diclofenac liposomal ring osteoarthritis that caused Grade 2-4 thritis was induced in one knee, and the cream (Surpass) applied to a joint with ex- lameness on a scale of 0-4. Horses were horses were split into one control and two perimental osteoarthritis provides a signifi- either in the control group (no Myristol) treatment groups. One treatment group cantly better outcome than a similar joint or the treated group, which received 4 got 7.2 g of Surpass on the affected joint treated with systemic phenylbutazone.” H

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STEADFASTTM EQUINE is a product of Arenus, a division of Novus Nutrition Brands, LLC. | www.arenusperformance.com The One and Only One.TM March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 43 AAEP WRAP-UP 2007 Digestive Health By Christy west Clearing Sand From the Gut Sand colic due to an accumulation of sand in the intestines accounts for up to 30% of all colics, often causing weight loss and chronic diarrhea. Psyllium has often been recommended as a laxative for clearing sand out of the intestines, although previous research results have been mixed as to its effectiveness. Allen Landes, DVM, of Equine Medical Service in Fort Collins, Colo., discussed the efficacy of a commercial psyllium/probiotic/prebiotic product (Assure and Assure Plus) on fecal sand clearance. “There are three risk factors leading to sand accumulation: Soil type, pasture t g e n quality, and feeding practice,” Landes noted. “As clinicians, we can only modify

one of these (feeding practice). Our sand J e nni fe r T h il content at this study location was about A study found ulcer scores were significantly lower with an alfalfa diet than with a coastal Ber- 28%, but many nearby areas are more muda grass hay diet. Ulcers tended to be worse at the end of the Bermuda hay diet study period. than 60% sand. Owners can visit http:// websoilsurvey.nrcs.usda.gov/app to get not sufficient to prevent intestinal sand ac- can be used to close incisions longer than more information on the sand content of cumulation,” he concluded. 9 cm, although this is rarely needed. their local soils and see if they have a sand The stainless steel staples are left in the problem.” Stapling the Gut colon, becoming part of the healed gut wall, Eight clinically healthy horses were These days, in many species incisions Ellis reported. No known complications or kept on pasture and/or in stalls during the are often closed with staples rather than tissue reactions have occurred from this. study, and they were supplemented with stitches—and they’re not just for external “Staple closure is as effective as hand hay to maintain body weight. Their feces use any more. Christina Ellis, DVM, a vet- sewing for this procedure, and faster,” con- were screened for sand for seven days be- erinarian with Peterson & Smith Equine cluded Ellis. fore any treatment. For 35 days they re- Hospital in Ocala, Fla., described the use ceived 30 g of Assure (probiotic/prebiotic of a TA-90 stapling device to close the large Reducing Hindgut Acidosis mix intended to improve the health of gut colon following a pelvic flexure enteroto- Acidosis (abnormally high acidity) in the microflora) followed by 226 g of Assure my (opening and removal of large intesti- hindgut (the large intestine and colon) can Plus (probiotic/prebiotic with psyllium) nal contents to treat colic). cause a number of problems in horses, in- per 454 kg (1,000 pounds) of body weight At Peterson & Smith, at least 200 horses cluding anorexia, colic, laminitis, and ste- 12-15 hours later, according to the manu- have undergone this procedure since 1983 reotypic (continuous, repetitive, and serv- facturer’s directions. No horses developed with no known complications, reported ing no purpose) behaviors such as wood colic during the study. Ellis. The advantages are simplicity and chewing and weaving. Unfortunately, this Fecal sand output significantly increased shorter surgical times—the process is ap- is often a risk when feeding today’s rich (nearly doubling) by Day 4 of treatment proximately 12 minutes faster with the concentrate feeds, and it all goes back to and remained elevated through Day 31, TA-90 device--compared to a hand-sewn, the evolution of the horse’s digestive sys- reported Landes. double-layer closure. Disadvantages in- tem. That system was designed to process “These results suggest that this product clude only the cost of the equipment (hos- large amounts of high-fiber, poor-quality may be an effective prophylactic treatment pital costs are $65 for staple cartridges forage, rather than today’s richer diets. for sand enteropathy (intestinal disease) spanning 9 cm) and the need to learn how Joe Pagan, PhD, president of Ken- and sand colic when management alone is to use the device. Multiple staple cartridges tucky Equine Research in Versailles, Ky.,

44 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

presented the results of a study evaluat- Results Fecal acidity increased in have moderate or severe gastric ulceration ing the efficacy of a protected sodium controls by six hours after feeding. In (defined as a score of 2-3 on an ulcer se- bicarbonate product in fighting hindgut contrast, the horses receiving PSB had no verity scale of 0-3). Here are some of the acidosis. This problem is common in dairy significant changes in fecal acidity during factors that increased ulcer risk: cattle on high-grain diets, he noted, and the sampling period. Horses on PSB also sodium bicarbonate is often fed to combat had significantly higher absorption of fat the resultant drop in feed intake and milk and sodium. There was a trend toward The horse’s digestive production. increased digestibility of neutral deter- “Unfortunately, in horses raw sodium bi- gent fiber (fiber content), hemicellulose system was designed to carbonate never makes it to the hindgut; it (a plant cell wall polysaccharide), and fat, process large amounts just buffers the stomach,” he noted. How- but these differences were not statistically ever, Kentucky Equine Research, along significant. of high-fiber, poor-quality with Balchem Corporation, has developed “The PSB used in this study was effec- forage, rather than a protected form of sodium bicarbonate tive in attenuating the hindgut acidosis (PSB, product name EquiShure) that was that resulted from high-grain intakes in today’s richer diets the focus of the current study. exercised Thoroughbreds,” concluded Pa- Six 5-year-old Thoroughbreds in training gan. “More research is needed to evaluate Dr. Joe Pagan on a high-speed treadmill were split into how PSB supplementation affects intesti- control and treatment groups and studied. nal epithelial health and integrity.” Cribbing/windsucking This was the most One group was fed 168 g of EquiShure (100 significant risk factor at 7.6 times higher g of sodium bicarbonate; the rest is the en- Risk Factors for Gastric Ulcers in risk. Whether cribbing might be a cause or capsulation agent) daily for a four-week Thoroughbreds an effect of ulcers is unclear. Other stereo- period, then the other group received the Up to 86% of Australian Thoroughbred typic (continuous, repetitive, and serving same treatment (the treatment and control racehorses have been reported to have no purpose) behaviors were also correlated groups were swapped for the second study gastric ulcers. Research on which factors with higher ulcer risk. period). All horses received a diet of unfor- most significantly contribute to ulcers Location of training Training in an ur- tified sweet feed, timothy hay, and 50 g of was presented by Guy Lester, BVMS, PhD, ban environment conferred a greater risk loose salt. Blood and fecal samples were associate professor of large animal medi- of ulceration (3.9 times higher risk), but it collected every two hours for eight hours cine at Murdoch University. This extensive was not retained in the final model. This on Day 15 of each period, and during week study evaluated 191 variables affecting indicated that it was factors common to four, all horses wore a complete collection 402 horses with 37 trainers in several lo- this training environment rather than sim- harness for five days so fecal and urine cations across western Australia. Thirty- ply training in the city. contents could be analyzed. three percent of the horses were found to Time in training Ulcer risk increased by

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a factor of 1.1 for every week in work, in- people seemed less likely to have ulcers. the other diet included the same amount dependent of the total time a horse spent “Maybe they know how to manage their of alfalfa hay and the same concentrate. on the property. stress—they just let it fly,” said Lester with All horses were exercised three times per Body condition maintenance Horses that a smile. week using a horse exerciser. had trouble maintaining weight were 3.4 Failing to race to expectation was highly Ulcer scores were significantly lower for times more likely to have ulcers. This fac- significant, but was not used in the final the alfalfa diet than for the Bermuda hay tor was also correlated to weeks in work. model. “Trainers are quite perceptive in diet, and the 11 horses in the alfalfa group Having a radio on in the barn Talk ra- identifying clinically affected horses and with ulcers at the beginning of the study dio was correlated with a 3.6-fold increase not racing them,” he noted. all improved their ulcer score by at least in ulcer risk, while music radio increased Diet did not have much of an impact, but two grades. However, one horse went the risk 2.8-fold (this statistic brought chuck- feeding practices didn’t vary much. other direction, developing ulcers while on les from the audience). Gastric ulceration “is a multifactorial the alfalfa diet. Only five of the 12 horses Lester noted that radio could be a sur- disease, and elimination of a single fac- starting the Bermuda diet with ulcers had rogate factor for a more urban setting tor may fail to impact disease prevalence,” ulcer score improvement, and only two of (known to increase ulcer risk), and that Lester concluded. “Don’t just go turn the those improved by the two grades or more. race radio with constant yelling of race radio off; it’s more complex than that. Ulcers tended to be worse at the end of the status might, indeed, be more stressful to Variations in the way individuals handle Bermuda diet period. horses stalled nearby. stress and ulceration make it tough to Another notable finding was that while make consistent recommendations.” ulcer scores didn’t change significantly Factors decreasing ulcer risk: Training from the end of the Bermuda diet to the on the property where the horse was Alfalfa Hay Reduces end of the pastured washout period, they housed—3.3 times lower risk. Ulcer Severity increased significantly from the end of the Turnout with other horses—3.3 times Noah Cohen, VMD, PhD, MPH, Dipl. alfalfa diet to the end of the washout pe- lower risk. ACVIM, professor of equine medicine at riod. Texas A&M University, discussed a study “So only one of 23 horses fed alfalfa Additional observations: Ulcer prevalence that found alfalfa hay reduced the severity worsened vs. 16 of 24 on coastal Bermuda,” varied widely by region, but management of ulcers in young, exercising horses. Cohen summarized. “Eleven of 12 horses within those regions likely had more of an In this study, 24 Quarter Horse yearlings on alfalfa remained ulcer-free compared to impact. were kept in small dry lots and fed two dif- only three of 12 on Bermuda.” Some trainers had no horses with ul- ferent diets for 28 days each, with a 21-day He cautioned that not all alfalfa is cre- cers, while others had ulcers in nearly ev- pasture washout period between. The first ated equal, and it’s not yet known whether ery horse in the barn. diet included coastal Bermuda grass hay older horses or those exercising more in- Horses that were aggressive toward and a 15% pelleted concentrate, while tensely would see the same benefits. h

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STEADFASTTM EQUINE is a product of Arenus, a division of Novus Nutrition Brands, LLC. | www.arenusperformance.com The One and Only One.TM 46 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by Medicine/Surgery by CHRisty west

Surgery for Triple-Level Spinal horses have undergone this procedure for have been used thusly, and two are enter- Cord Compression one or more joints since the surgery was ing training. The implant type used made Spinal cord compression in the neck, developed in 1979 for horses. no difference in outcomes. more technically known as cervical ver- In this 12-case series, the average age “Triple level fusions have similar suc- tebral stenotic myelopathy or CVSM, can of onset was two years, and all cases were cess rates to single and double fusions,” he cause notable incoordination and affects males (eight of 12 were geldings). Five said. “Affected patients can live productive about 2% of racing Thoroughbreds. Prob- were Thoroughbreds, with the rest being and/or competitive lives with no danger to ably the most well-known horse affected of various breeds. Surgery was done to sta- themselves or their handlers, and they do by CVSM was Thoroughbred champion bilize three joints on each horse, primar- not require daily medications.” racehorse and sire Seattle Slew, whose ily between cervical vertebrae C3-4, C4-5, successful surgeries were well-publicized. and C5-6 (see image below), although two Bioabsorbable Cisplatin Beads But Slew had only two affected joints horses had C6-7 fused. Five horses had the For Skin Cancers in his neck, and some horses have three original stainless-steel baskets placed, five Skin cancers are seen in horses, and joints compromised many methods and by CVSM. Only four technologies have been reports of successful used to treat them. outcomes of surgery One of the more recent on such cases had strategies is intralesion- been published as of al chemotherapy, or November 2007, but a placing a chemothera- report of 12 cases was peutic agent directly in presented at the con- the tumor to kill the ab- vention. normal cells. Christina “Affected cases have Hewes, DVM, MS, Dipl. a narrowing of the ACVS, a practitioner in vertebral spinal ca- Alamo, Calif., discussed nal (stenosis), which the newest twist on this causes incoordination, approach—placing inappropriate rigid- bioabsorbable beads of ity, paresis (impaired the chemotherapeutic C o u r te sy D r. N ic h ol a s H ggons movement), and weak- Surgery was done to stabilize three joints on each horse, primarily between cervical agent cisplatin in a tu- ness,” explained Nicho- vertebrae C3-4, C4-5, and C5-6 (shown here). mor for a slow release las Huggons, DVM, a of chemotherapy. veterinarian with the San Luis Rey Equine had Kerf Cleaning Cylinders (also known The advantages, she noted, include Hospital in Bonsall, Calif. “It’s most fre- as Seattle Slew implants), and two had greater safety for the practitioner than re- quently seen in young, rapidly growing, bone grafts. constituting and injecting a liquid solution well-fed horses. Surgical management All but one horse recovered; that horse into the tumor (cisplatin plus sesame oil aims to stop repetitive trauma to the spi- was euthanized due to incisional compli- emulsion) and the possibility that fewer nal cord. Horses that don’t receive therapy cations. One later died in a paddock ac- treatments are required (two compared have a poor prognosis because of the con- cident, but the rest improved at least one to four treatments recommended for the tinuous damage done to the cervical spi- neurological grade and 75% had improved liquid approach). nal cord.” by two grades at one year after surgery. Horses are treated every 30 days until The surgery usually consists of insert- Overall, 67% of horses returned to their in- the tumor does not regrow; most horses ing metal cylinders through the adjacent tended athletic function. Four horses were in this study received two treatments. Any bones on one side of the joint, effectively intended to race, and two did (one won a wound drainage is cleaned by a veterinar- immobilizing the joint. Huggons conser- stakes race). Three of the six other horses ian wearing chemotherapy gloves to mini- vatively estimated that more than 1,000 intended for pleasure riding or showing mize exposure to cisplatin, and materials

March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 47 AAEP WRAP-UP 2007

are disposed of in biohazard containers. procedures,” he noted. The role of the Following patient evaluation and stabili- At the Marion Du Pont Scott Equine bipolar radiofrequency device is to use zation, fracture stabilization generally con- Medical Center in Leesburg, Va., 40 of 48 high voltage to dissect away any soft tis- sists of a splint applied over a uniformly horses (83%) treated with this approach sue holding the fragments so they can be layered bandage; the splint could be made were relapse-free two years later. Hewes easily removed. The device has a ground of PVC pipe, wood boards or tool handles, reported the following success rates from electrode within the probe, so there is lit- metal rods, or casting material—anything an article published in the Nov. 15, 2006, tle risk of inadvertent tissue damage and lightweight and rigid. issue of the Journal of the American Veteri- no need for a grounding pad. “The general rule of thumb is to immo- nary Medical Association: bilize the joint above and below the frac- ■ 91% (20/22) of cases with spindle cell tu- ture,” explained Janicek. “Avoid splinting mors (sarcoids and fibrosarcomas) were Joint chips plague many up to the same level of the fracture, be- relapse-free after two years. Three cases cause that will create a fulcrum action that with regrowth at one, two, and three high-performance horses— can result in further displacement. Most of years resolved after one additional treat- up to 29% of Standardbred these materials are lying around the clinic ment. already, so bring them to ambulatory calls ■ Squamous cell carcinomas had the great- yearlings and 2% of with possible fractures.” est tendency to recur (60% success rate), Thoroughbred yearlings He divides forelimbs and hind limbs likely due to the duration of these cases into four sections when describing how to and the increased metastatic (spreading) stabilize them: potential of this tumor type. For this study, 33 cases with axial (near ■ Section 1 (forelimbs and hind limbs): ■ 93% (13/14) of melanoma cases were centerline) fragments from the upper first Fractures of the fetlock or lower regions. relapse-free after two years, including all phalanx bone were randomly selected Splints run up to just below the knee or affected gray horses. The one failure was from one year. Forty-one fragments were hock. a bay horse with malignant melanoma. removed from 36 joints in the study horses, ■ Section 2 (forelimb): Fractures from the ■ The sole cases of basal cell sarcoma and and these were primarily in the hind limbs. top of the knee to just above the fetlock. adenocarcinoma were relapse-free after Treatment consisted of arthroscopic sur- Caudal and lateral splints (on the rear and two years. gery, including use of the radiofrequency outside of the leg) run up to the elbow. ■ One horse with lymphosarcoma showed device. Once the fragment was visualized, ■ Section 2 (hind limb): Fractures of the metastasis after nine months. the device’s curved Coblation hook probe hind cannon bone. A caudal splint runs ■ Flat sarcoids don’t respond well to this was used to release soft tissue holding the up to the point of the hock, while a lateral treatment; growth stops, but the tumor fragment. Once released, fragments were splint runs up to the level of the stifle. doesn’t regress. physically removed with a rongeur instru- ■ Section 3 (forelimb): Fractures between Complications included swelling, ery- ment before curetting (smoothing) the the knee and elbow. A caudal splint runs thema (capillary congestion), wound fragment bed, if required. up to the elbow, while a lateral splint ly- drainage, subtle scarring, and a corneal “This is a very targeted approach that ing against the shoulder helps prevent ab- ulcer requiring eye removal in one horse causes minimal intra-articular bleeding, duction of the limb (pulling it away from (following treatment of an upper eyelid provides excellent visualization, minimiz- the body’s midline). tumor). es the risk of iatrogenic (physician-caused) ■ Section 3 (hind limb): Fractures from just injury, reduces surgery time, and minimiz- below the stifle joint to the bottom of the High-Tech Fetlock Joint Fragment es complications,” Kay summarized. “This hock. A lateral splint running up past the Removal instrument has become an important ac- pelvis helps prevent abduction. Joint chips plague many high-perfor- cessory for intra-articular soft-tissue dis- ■ Section 4 (forelimb): Fractures from the mance horses—up to 29% of Standard- section in this referral center (Hagyard).” elbow upward. A caudal splint helps lock bred yearlings and 2% of Thoroughbred the knee in extension, which is often yearlings. Often the chips must be re- First Aid for Limb Fractures tough for these cases to do. The injury moved, usually with arthroscopic surgery, When a horse’s leg is fractured, the is not splinted as it has extensive muscle before the horse can return to full sound- primary treatment goal is to stabilize the coverage that provides stabilization. ness. Alastair Kay, BVSc, MRCVS, a sur- fracture site so the broken bone ends don’t ■ Section 4 (hind limb): Fractures from the gery resident at The Ohio State University further separate and do more damage. The stifle joint upward. These injuries are not Veterinary Teaching Hospital, representing outcomes of these cases often have a great splinted as they have extensive muscle Hagyard Equine Medical Institute in Lex- deal to do with how well the broken leg coverage that provides stabilization. ington, Ky., described a high-tech method was stabilized in the field before a surgeon “In most cases, patient and limb stabi- for removing chips from the rearward por- ever saw the horse. John Janicek, DVM, lization followed by consultation with the tion of the fetlock joint. MS, Dipl. ACVS, of Weems and Stephens nearest surgical facility provides the best “Radiofrequency devices continue to Equine Hospital in Aubrey, Texas, pre- service to the horse and the client,” noted be used extensively in human medicine sented a review of field stabilization tech- Janicek. When transporting the horse for for both intra-articular (within a joint) niques for limb fractures in various parts surgery, he recommended the following: and extra-articular (outside the joint) of the leg. ■ The trailer should be brought as close to

48 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

the horse as possible to minimize move- or contusions of the cerebral cortex. Neuro- secondary injury may be attenuated with ment. logic signs can include contralateral (in the prompt and appropriate therapeutic inter- ■ Chest and butt bars should be used in the opposite eye) blindness, depressed menta- vention.” trailer to stabilize the horse. tion (mentality), compulsive wandering, ■ The horse’s head should be left untied to and generalized seizures. Management improve balance. Poll trauma tends to result in the most “The management of recumbent, neuro- ■ Provide hay to keep him busy. severe brain injuries. “Young horses are logic equine patients is particularly chal- ■ Haul horses with forelimb fractures fac- particularly susceptible to this because lenging and labor-intensive, often limiting ing backward, and hindlimb cases facing they tend to flip over on their heads when treatment options and duration,” she said. forward as it’s harder for horses to bal- they don’t want to do something, and the “As a result, the management of severe ance during braking than during accel- skull bones in this area don’t fuse until brain injury in horses is anecdotally reput- eration. they’re three to four years old,” Feary noted to be intensive, expensive, and associ- ed. Brainstem and blood vessel damage ated with a guarded to grave prognosis.” Traumatic Brain Injury in Horses with this injury can cause head-tilt, nystag- However, advanced monitoring tools and “Head trauma is common in horses, and mus (involuntary, rapid, rhythmic move- treatment options available today might a number of these cases will present with ment of the eyeball), depressed mentation, improve the success rates with these cases, neurologic signs consistent with brain in- tetraparesis (weakness of the extremities), she noted. jury,” said Darien Feary, BVSc, MS, Dipl. facial nerve paralysis, and bleeding into The main goals of therapy are to control ACVIM, ACVECC, a lecturer in equine the guttural pouches. intracranial (inside the skull) pressure, medicine with the University of Sydney, Brain injury takes two forms—primary keeping it below 20 mm Hg; support ce- Australia, in discussing management of and secondary. Primary injury is immedi- rebral perfusion (blood vessel pressure) at these injuries.Due to limited research on ate, direct, mechanical, or structural injury more than 60 mm Hg; minimize secondary equine brain injury, most equine recom- occurring at impact, such as concussions, injury; and treat any concurrent injuries or mendations come from human research, lacerations, edema (fluid swelling), or diseases. she reported. hemorrhage. Secondary injury encom- Additional management measures might The two most common types of equine passes “the cascade of local, then global, include inhaled oxygen therapy, non-ste- head trauma resulting in neurologic dys- cellular and neurochemical alterations roidal anti-inflammatory medication, an- function are injury to the frontal/parietal that occur in minutes to days after the ini- tioxidant therapy, anti-seizure medication brain from kicks or head-on collisions and tial injury and lead to progressive axonal in seizuring horses, thiamine (vitamin B1) poll trauma from flipping over backward, (nerve body) degeneration and cell death,” supplementation, maintenance of normal she said. These injuries are not always as- Feary explained. “In contrast to primary body temperature (i.e., cooling horses sociated with fractures. injury, which the clinician has no or mini- with fevers), and elevation of the head by Frontal trauma can result in lacerations mal control over, the deleterious effects of 10-30°.

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Brain Injury Study casting material is thick enough on the Correcting Large Colon Feary described a retrospective study bottom of the foot to effectively lengthen Displacement of 34 horses treated for primary brain in- that leg. This promotes even weight bear- Left dorsal displacement of the large jury at the University of California, Davis, ing on both limbs and aims to minimize colon isn’t the most common cause of col- between 1994 and 2004. Poll injury was muscle soreness and the risk of contralat- ic—only about 6-8% of colics are caused the most common, and 62% of the horses eral limb laminitis. by this. However, up to 21% of affected survived. Factors decreasing survival rates The study authors have applied more horses tend to displace again, even after included higher packed cell volume (the than 30 of these casts, with about two- surgical correction. These horses often portion of blood occupied by red blood thirds on hind limbs and one-third on have a deep nephrosplenic space, which cells, 40% vs. 33%), recumbency for more forelimbs, and they report minimal com- describes the area bounded by the left than four hours (18 times less likely to sur- plications. kidney, spleen, nephrosplenic ligament vive), and skull base fractures (7.5 times (supporting the spleen and kidney), and less likely to survive). Repairing Hernias with Subcuta- the body wall. Since the large colon is not “Survival rate in this study was higher neous Mesh attached to the body wall, it can move than other previously reported studies in Incisional hernias (protrusion of ab- around in the abdomen quite a bit and horses and widespread anecdotal belief; dominal contents through a gap in an inci- part of it can become trapped in this deep perhaps this is a reflection of the signifi- sion beneath the skin) occur in up to 17% space, resulting in left dorsal displace- cant advances made in the equine vet- of horses receiving abdominal surgery, ment of the large colon (also called neph- erinary profession through all levels,” she reported Gal Kelmer, DVM, MS, clinical rosplenic entrapment). concluded. assistant professor at the University of Closing/ablating (removing) the neph- Tennessee’s College of Veterinary Medi- rosplenic space with sutures can prevent How to Apply a Half-Limb Cast cine. These hernias are often repaired with recurrence of this problem. Megan Parker, and Elevated Support Limb Shoe stitches alone or with mesh implanted DVM, of Hagyard Equine Medical Institute There are many situations when cast- beneath the musculature, but Kelmer rein Lexington, Ky., described a hand-assisting a horse’s lower limb can be beneficial, ported excellent success and a lower risk ed laparoscopic technique for ablation of such as when he has a fracture of a pas- of complications by placing mesh just be- the nephrosplenic space in the standing tern bone, a tendon or ligament injury, or neath the skin, over primary suture closure horse (the technique was developed by a wound that won’t heal because of excess of the hernia defect. Dwayne Rodgerson, DVM, Dipl. ACVS, movement. During the convention a dis- also of Hagyard). cussion on how to apply a half-limb cast Other approaches to correction are and elevated supporting limb shoe was Incisional hernias more technically challenging and carry presented by Ryan Carpenter, DVM, a greater risks of organ damage, adhesions, resident in veterinary clinical sciences at occur in up to 17% of and infection, she noted. In contrast, Colorado State University. horses receiving hand-assisted laparoscopic surgery on a Compared to a bandage, Carpenter said, standing, sedated horse offers a less inva- the half-limb cast offers better immobili- abdominal surgery sive procedure with better visualization of zation, better durability, and less expense the surgical field, a shorter convalescent (the latter because it’s cheaper than mul- period, shorter surgery time, no general tiple bandage changes). However, pres- He was quick to note that not all hernias anesthesia, and a rapid return to full func- sure sores are a risk if the fetlock joint is need repair; horses with light work sched- tion. The same surgical concept is used for improperly angled within the cast. ules might not require surgery. However, removal of kidneys, ovaries, and abdomi- Carpenter described a technique in harder-working horses, such as jumpers or nal tumors, she added. which the lower limb cast is applied to the racehorses, might need this procedure. Ab- Five cases were treated with this ap- standing horse, avoiding the risks and ex- dominal bandages to support the incision proach in the past two years, with a suc- pense of general anesthesia. are used after surgery for a variable time cess rate of 100% and minimal discom- Key to this approach is placing the foot period, and patients are rested from heavy fort, Parker reported. None have had to be casted on a narrow wooden block (2 exercise for three months. recurrence of left dorsal displacement of inches by 2 inches) so the heels and toe “The advantages of this procedure in- the large colon since then, and two pa- hang off the block. This allows most of the clude secured closure with two closures in tients went back to race training, with cast to be applied with the horse standing one procedure—the primary closure with one doing quite well in races. in a normal, full weight-bearing position; sutures is backed up with mesh place- “The hand-assisted laparoscopic tech- this helps reduce poor fit and pressure ment,” Kelmer said. “The cosmetic ap- nique is very easy to perform and is as- sores. pearance is good. Sutures alone often end sociated with low morbidity (subsequent Another important part of this proce- up with several small defects, which are illness),” she concluded. “Practitioners dure is the application of a pad and frog not a problem, but they’re cosmetically should be aware that this technique pro- support material, possibly along with a not good. We’ve repaired hernias on more vides a safe, easy, and efficient way to pre- shaped wooden block, to the opposite than 50 horses with this technique and vent recurrence of left dorsal displacement front or hind (contralateral) limb if the have had a very low complication rate.” of the large colon.” h

50 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by Horse Management by christy west AND LES SELLNOW

How to Airlift a Horse prior arrangement and training session charge of physical and chemical restraint, John Madigan, DVM, MS, Dipl. ACVIM, with the pilot who is on call,” he noted. as well as precautions for personnel; director of the large animal hospital at the He described several training sessions at 7. Apply and detach Anderson sling; University of California, Davis, explained the school with multiple military branches 8. Use personnel safety equipment, how to safely airlift a horse. that might have occasion to airlift horses including ear and eye protection; “Most horses we lift are healthy, they are and mules into and out of remote areas. 9. Plan for implementation of helicopter just trapped somewhere they can’t get out of,” he noted. “We do all airlifts on standing horses.” Horses with uncontrolled movements in the air The first thing to do, he reported, is to look into all other available options of or on the ground during liftoff and landing can produce moving the horse, as they’re usually a lot significant aircraft instability. easier and less dangerous. Or, moving the horse might not be time-critical; for exam- dr. John Madigan ple, a horse in a flooded area could move to high ground and be cared for there until Madigan described the procedures, hovering, animal positioning, lift protocol floodwaters recede. training, communication, and chain of (including inspection at 10-foot hover), If it’s decided that an airlift might be command for airlifts in detail. Consulta- and landing and detachment methods; necessary, the horse’s owner makes direct tion with the on-site veterinarian before 10. Assign lift and receiving teams; contact with the helicopter operator, ap- getting involved is essential, and the over- 11. Know who will perform cable at- proves the costs, and places the helicopter all theme was that prior training and care- tachment to the helicopter and overhead on standby, pending scheduling and future ful, specific planning of procedures and frame; and determinations. responsibilities is critical to success. Two 12. Establish the timetable of events. “Live cargo transport presents numer- complete teams are required—one to send He described several airlifts with photos ous problems for helicopter safety,” Madi- the horse, and one to receive it at a safe and videos to illustrate his points, includ- gan cautioned. “Horses with uncontrolled location. ing one rescue that didn’t even result in an movements in the air or on the ground Once everything is in place and well-un- airlift because a nearby band of inmates during liftoff and landing can produce sig- derstood, the airlift itself doesn’t take long helped dig a cast horse out of a ditch. nificant aircraft instability.” To limit this if no snags are encountered; he reported “You never know where help is going to risk, he uses sedation and the UC Davis on some airlifts that took only about an come from,” Madigan commented. Anderson sling, which controls and sup- hour from start to finish. “The process of airlifting a horse still ports the head and body of the horse. His Madigan offered the following checklist carries inherent dangers for the horse and team has used this sling in 28 successful of information to be covered in a pre-res- rescue personnel,” he concluded. “Risks airlifts, and they have also used a sling cue orientation. may be lessened by a program that in- termed the UC Davis Large Animal Lift to 1. Know who is in charge of the rescue; volves regular training, including a heli- move one recumbent (down) horse. 2. Know who will perform a brief physi- copter lift when possible, to increase the The helicopter needs to be able to lift at cal examination of the animal prior to se- team’s familiarity and comfort level with least 1,200-1,500 pounds at sea level, and dation or transport; the UC Davis Anderson sling or Large Ani- the pilot needs to have longline experience 3. Orient and inspect the sling equip- mal Lift and airlift protocols.” (using long cables below the helicopter). ment and overhead support device; The horse is lifted on a 150-foot cable, 4. Organize ground-to-air radio commu- Reducing Back Sensitivity preferably one made of Kevlar rather than nications and hand signals from ground to Back pain is often suspected in hors- steel to reduce static electricity buildup. air; es, but most treatments haven’t been “If someone’s misbehaving, ask him to 5. Know helicopter safety orientation researched much or at all. Results of a go ground the sling frame,” Madigan said and grounding methods of the sling over- study designed to measure the effects of with a grin, knowing a static shock would head frame prior to human or animal con- massage, chiropractic, and phenylbuta- be the result. tact; zone (Bute) on back sensitivity were pre- “Ideally, rescue groups should have a 6. Animal restraint—know who is in sented by Kevin Haussler, DVM, DC, PhD,

March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 51 AAEP WRAP-UP 2007

assistant professor within the Department ■ All horses’ MNTs were evaluated on Day agricultural practices, what’s normal in the of Clinical Sciences at Colorado State Uni- 0 (before treatment) and at Days 1, 3, and horse world, feeding practices, etc.,” he ex- versity. 7 post-treatment. plained. “Often the primary problem is a Researchers used pressure algometry (a ■ The results of MNT evaluation on differ- change in husbandry that has encouraged spring-loaded device with a rubber-tipped ent sites on each horse were pooled for horses to seek anything edible. plunger that measures applied pressure on evaluation, and the numbers were some- “Most horses won’t touch poisonous a gauge readout) to measure mechanical what surprising, said Haussler. plants unless they’re forced to,” he stated. nociceptive threshold (MNT)—the pres- ■ The Bute group actually had a negative “Thin pasture sets them up for that. Even sure at which a horse reacts painfully— response, with 9% and 8% lower MNTs poor-quality hay might cause a horse to at several locations along the spine. This on Days 1 and 3 compared to Day 0. On look for other things to eat. And limited method of objective pain assessment is Day 7, this group had an 8% higher MNT. feeding because of weight or insulin resis- also used in humans to evaluate pain. A Bute is much more effective if given when tance worries can make the horse go look- higher MNT means more pressure is reactive inflammation is present, noted ing for more to eat.” quired to elicit a response, so the horse is Haussler. Pasture plants aren’t the only culprit, of less sensitive (less painful). ■ Massage was beneficial throughout the course; toxicity from stored feed or supple- study period, with an 8% higher MNT on ments, or a combination thereof, can also Day 1, 9% higher on Day 3, and 12% on cause clinical signs. Day 7. What signs suggest poisoning? Wright ■ Chiropractic resulted in a slight (1%) de- noted that clinical signs are often vague crease in MNT on Day 1, an 11% increase and varied, and they can include laminitis, on Day 3, and a 27% increase on Day 7 colic, hair loss, skin lesions, photosensitiv- on average. ity (a skin reaction that can look like sun- ■ Both active and inactive controls’ MNTs burn), or, at worst, death. fluctuated by about 1% across all days. In an investigation, “I start with body “We hypothesized that low-grade back condition scoring and determine whether pain or inflammation was present in ridden the horse might be looking for something horses, and we found this to be true; oth- else to eat, or if there might be a point erwise the MNTs would not have increased source of toxin,” he said. “And I’ll record in all three treatment groups relative to the feeds and feeding practices, including the two control groups,” said Haussler. “Mas- presence or absence of pasture, supple- sage was beneficial throughout the study; mental feeding, every scoop and pinch of C o u r te sy D r. Ke vin H au ssl e Pressure algometry can help researchers Bute had negative effects for 3 days, then it anything, and the feeding schedule. Man- measure pain. had a positive effect; and chiropractic had agement is also important; horses housed a negative effect on the first day, but then individually or limit fed are often at greater Researchers theorized that subclinical it had the most positive effects. risk. Bedding should be evaluated, too.” back pain is present in all ridden horses, “Pressure algometry provides an objec- Feeds are sampled and pastures are so therapy should lessen that pain and tive tool to evaluate commonly used, but carefully walked, but Wright warns that raise MNTs. Thirty-eight healthy adult unproven, treatment modalities for the pasture walks can turn up a lot more than horses with no history of back pain from treatment of back pain,” he concluded. you might think. “Most pastures and fence- four farms were used for this study, which “Future studies need to evaluate combined rows contain numerous poisonous plants,” aimed to see which treatment modality treatment effects and long-term MNT he noted. “You need to be able to recognize raised MNTs the most over the course of a changes in horses with documented back the most common toxic plants and trees in week. The horses were treated as follows: pain.” your area, and know under what circum- ■ Seven horses received Bute (1 g/500 stances they are toxic (i.e., when they are pounds orally every 12 hours) for a Investigating Horse Poisoning fresh or frozen). Sometimes horses can eat week. When an owner suspects that a horse certain weeds and be okay, and other times ■ Eight received one chiropractic treat- might have eaten something poisonous, it will really hurt them. ment using a spring-loaded mechanical the veterinarian is generally the first per- “Don’t jump to a conclusion about the force instrument at localized regions of son he or she calls. In addition to treating first toxic plant you find,” he advised. “Of- joint stiffness, abnormally high muscle any health problems, that veterinarian is ten the primary cause of the problem is tension, or pain (this mechanism en- uniquely suited to investigate the cause of poor-quality feed or underfeeding. Look at sured a consistent force/velocity of the the problem as well, said Bob Wright, BSc those things first, because the toxic weeds treatment). (Agr), DVM, of the Ontario Ministry of Ag- will often be there, but the horse might ■ Eight received one directed massage by a riculture, Food and Rural Affairs. not be eating them. In my experience, im- certified massage therapist. “Private practitioners often lack confi- proper or poor husbandry practices were a ■ Seven received no treatment, but contin- dence in their abilities to investigate these primary contributing factor to the disease ued to be ridden (active controls). cases, but we’re ideally suited because problem in more than 50% of recent poi- ■ Eight received no treatment, but were we’re on farms all the time, we have ex- son investigations. Too commonly, a single turned out and rested (inactive controls). tensive knowledge of equine behavior, plant in the pasture is blamed when an

52 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

underlying problem, such as insufficient and blue-green algae poisoning than deep with the first “wellness” examination for a high-quality feed, is the primary cause.” wells or city water sources. newborn foal. A brief visual examination “The take-home message is that you’ve might reveal problems that can be success- Feed and Weed Sampling got to know the common acute toxins in fully treated early in the animal’s life, but Wright tests all feeds, bedding, hay, vi- your area,” he said. “Take charge of the sit- they might not be as treatable later on. tamins, minerals, whole grains, nutraceu- uation and don’t rely on the lab to give you Arnott said as the horse grows and ma- ticals, pasture, water—anything the horse a diagnosis. Complete a thorough farm in- tures, regular dental exams should be con- might consume. Visual examination is the vestigation, keep an open mind, and use a ducted. “The frequency with which your start, identifying things such as whether common-sense approach to find the incit- horse should receive a comprehensive there are a lot of noncultivated plants ing cause. dental exam and dental work is dependent (weeds) in hay and what species of grass- on many factors,” he told the group. “As a es/legumes are in the hay. Then he sends Healthy Horses Workshop general rule of thumb, many equine veteri- carefully collected samples to laboratories It started as Horseman’s Day back in narians recommend at least a brief dental for further investigation. 2000 when the American Association of exam biannually until the horse reaches When walking the pasture, he prefers Equine Practitioners (AAEP) convention five years of age. During this time there is to work alone—without owners or assis- was held in San Antonio, Texas. Today it is a tremendous amount of activity going on tants asking questions—so he doesn’t miss known as the Healthy Horses Workshop, in your horse’s mouth; 24 deciduous teeth anything. He’ll look for places where trees but the basic concept remains unaltered. erupt and are shed and 36 to 44 permanent can be reached by horses near fences and During the convention for veterinarians, teeth erupt. Early identification of any po- see if any toxic plants appear to have been researchers, and veterinary technicians, tential problems allows for a faster inter- equine snacks, especially along fencelines. one day is set aside for horse owners in vention, which will hopefully minimize the the area to listen to experts in the field lec- impact of the problem over the lifetime of ture and demonstrate on specific aspects your companion.” involved in the overall wellness, training, After age five many veterinarians will and care of the horse. recommend that a dental exam be per- The presenters and their topics, were: formed on an annual basis through age 15. Rob Arnott, DVM, a practitioner in Palm From that point on, he suggested, it would City, Fla., dentistry; Heather Heiderich, be a good idea to revert to biannual evalu- DVM, associate veterinarian with Florida ations. Equine in Clermont, Fla., acupuncture and chiropractic; Jennifer MacLeay, DVM, Acupuncture and Chiropractic PhD, Dipl. ACVIM, assistant professor of Acupuncture can be effective in treating large animal medicine at Colorado State chronic pain and musculoskeletal disorders University, Understanding the Science such as lameness, Heiderich told her listen- of Natural Horsemanship; David Hayes, ers. She said it also can be beneficial for eye DVM, owner of The Pet Hospital in Merid- problems, mild colic, respiratory disorders, ian, Idaho, One Step Horsemanship; and anhidrosis (the inability to sweat), behav- Olympic gold medalist David O’Connor ior problems, anxiety, neurological issues,

C o u r te sy D r. B ob Wrig ht giving demonstrations and discussing and immune-related conditions. Photosensitization-type lesions with damage horsemanship. Following are some com- Acupuncture, she told the group, is an and peeling of the skin are sometimes a ments from some presenters. ancient technique that originated from clinical sign of poisoning. traditional Chinese medicine and involves “All plant material is suspect,” he said. Dentistry putting needles in specific points on the “Look for potential contamination from Arnott told his listeners that the equine body to treat disease or relieve pain. Those roadways or neighbors’ lawn clippings.” tooth has evolved over million of years specific places, she said, are known as acu- He noted the following common toxin to allow the horse to become a grazing puncture points and can be used to diag- sources: animal. The horse, he said, has hypsodont nose and treat certain conditions. ■ Botulism, which often occurs from hay- teeth, which means they erupt throughout These points, she further explained, are lage contamination; the horse’s lifetime—at the rate of three to specific locations on the surface of the skin ■ Clippings from ornamental yew shrubs; four millimeters per year—to compensate where pressure is applied in order to affect ■ Poison hemlock, which is common in for the wear from the daily grinding action the channels through which Qi, defined swampy areas; when eating. as life force and energy, flows through the ■ Blister beetles in alfalfa hay, which can The hypsodont tooth eventually will be body. “By stimulating these acupuncture cause severe toxicity; used up, but it can least for 25 to 30 years points, even those located far from the site ■ Oleander leaves; with proper care. Proper dental care is im- of the symptoms, the veterinary acupunc- ■ Red maple leaves portant, he said, because horses are living turist can help the animal’s body to heal Public health units can help test the wa- longer today than ever as the result of good itself by balancing its own vital energies,” ter for contamination, he said. Streams and nutrition and medical care. said Heiderich. ponds carry a higher risk of contamination Dental care should begin in conjunction Chiropractic, she said, “is a type of

March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 53 AAEP WRAP-UP 2007

holistic health care that promotes natural one of the event horses from the O’Connor However, he pointed out, this position isn’t health through adjustments of the joints of Event Team, Tigger Too. The horse had a established through force, but rather by the body in an attempt to remove interfer- portion of his colon removed in the third establishing a line of communication with ence from an individual’s nervous system,” of three colic surgeries to solve a medical the horse that leads to respect. she explained. problem, but he is still competing at a high Using his horse as a prop, O’Connor The chiropractic approach, she told the level with a young rider, although he must demonstrated how a horse can be taught group, has been around for 100 years and be kept on a special diet. what he described as “the four basics” on a involves the specific portion of the nervous O’Connor’s theme for the day was set longe line. The four basics are moving the system housed within the skull and the forth early when he said: “It is our job, out- forehand, moving the backhand, lowering spinal column. It was discovered, she said, right, to understand the horse’s language, the head, and backing. “The round pen can that a malalignment of joints (known as not for them to understand ours.” be a valuable tool,” he said. subluxation), especially the vertebrae, ad- Horse are very social animals, he said, O’Connor also told the group that vari- versely alters nerve function in those areas. and if we take them out of an environ- ous disciplines in equine competition The goal of the chiropractor is to put the ment where they can socialize with other should keep open minds about what others joints back into proper alignment. horses, such as in preparation for a ma- are doing, rather than ignoring everything Heiderich emphasized that chiroprac- jor event where they spend much of their but that in which they are involved. He said tic care does not replace traditional vet- time isolated in a protective box stall, the dressage riders, for example, could learn erinary medicine, but it works very well in normal environment must be replaced from cutting horses. He explained that conjunction with it. “The chiropractic ad- and “you are it.” You should spend time many dressage horses are keyed up and on justment,” she said, “is designed to restore with the horse in a relaxed setting, such edge much of the time. The cutting horse, correct alignment and full working order, as grooming, rather than just in training he said, moves in quiet, slow motion when thus, restoring the proper function of the sessions. going into the herd and bringing out a cow, nervous system.” When horses are in a group setting, he but when it starts cutting, it is an exploding said, there is always one that is the “buck- dynamo of energy and action. The moment The Language of Gold et” horse. He described that horse as be- the horse is signaled to cease work, it re- O’Connor put on a three-hour clinic at ing the one that, if you were to set out a verts immediately to a calm state. the end of the day, complete with dressage bucket of grain, would always be the horse O’Connor said he learned much about and jumping demonstrations and coupled that took possession of the bucket because communicating with an equine compan- with advice on how to be successful with it was number one in that group’s pecking ion when he was 11 years of age. He, his your horse. He stayed to autograph copies order. mother, and his 13-year-old brother set out of the book Life in the Galloping Lane that O’Connor said in learning to commu- on horseback from their home in Mary- he and his wife, Karen, authored. nicate with—and relate to—horses, “you land and rode on a cross-country odyssey Helping him during his presentation was have to be the bucket horse, the leader.” to Oregon. h

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Measuring Titers with a history of endemic Ashley Boyle, DVM, Dipl. R. equi infections. There ACVIM, assistant professor in equine field were 338 foals involved science at the University of Pennsylvania’s in the study. Chaffin said School of Veterinary Medicine, discussed the number of R. equi- SeM-specific antibody titer levels as a affected foals was signifi- possible indicator for deciding whether cantly higher in the group to vaccinate horses against Streptococcus that was not administered equi infection (strangles). (SeM-specific Zithromax, compared to antibody titers refer to the concentration the treated group—21% of of antibodies in the sera that recognizes the nontreated foals were one of the surface proteins—called an M affected, compared to 5% protein—of S. equi.) of those treated. No ad- Some horses suffer an adverse reaction verse effects from the drug when vaccinated against S. equi, she said, were detected in the treated in the form of purpura hemorrhagica. This foals. Use of the drug did is an overzealous immune response to S. not eliminate R. equi on the equi by the horse’s body that results in endemic farms studied, he pinpoint hemorrhages along the mucous said, but it did curtail the membranes, as well as areas of firm, pit- incidence. ting edema on the lower abdomen and He also said that more a

lower limbs. research will be necessary a S ilv

Purpura hemorrhagica appears more before this approach can au l a d P frequently in horses with high titers of S. be recommended for wide- While equine influenza is usually not fatal, it can spread quickly equi antibodies. Boyle said a horse’s age spread application in the and cause long periods of down time. and breed can have an effect on titer levels. field. Warmbloods and Thoroughbreds gener- Flu Vaccination ally have higher titers than other breeds. Enrofloxacin Paul Lunn, BVSc, MS, PhD, of Colo- She also pointed out that the likelihood Thomas J. Divers, DVM, Dipl. ACVIM, rado State University (CSU) reported on a of having a high titer—1:1600—increased of Cornell University told the group that study involving Recombitek equine influ- with each year of age. “Both age and breed persistent Leptospira spp infection of the enza vaccine marketed by Merial. Twenty- should be considered when determining eye has been confirmed in some horses three unvaccinated ponies were involved whether or not an ELISA test to measure with recurrent uveitis (moon blindness). in the study. Eleven were placed in a con- SeM-specific antibody levels or titer should He reported on a study aimed at deter- trol group and 12 were vaccinated twice be conducted before vaccination.” mining whether the intravenous (IV) ad- at 35-day intervals. Six months after the ministration of enrofloxacin, an antibiotic second vaccination, ponies in both groups Azithromycin marketed as Baytril 100 by Bayer, would were challenged with (were exposed to) M. Keith Chaffin, DVM, MS, Dipl. AC- provide high enough levels of the antibi- a flu virus. Lunn said ponies in the vac- VIM, professor of medicine in the College otic in the aqueous humor inside the eye cinated group demonstrated “significant of Veterinary Medicine at Texas A&M to help clear up the infection. protection from challenge infection as University, reported on a study involving In the study, six affected adult horses determined by duration and extent of py- the use of azithromcyin (a lipid-soluble received 7.5 mg/kg IV every 24 hours for a rexia (high fever), clinical score (of signs antimicrobial), marketed as Zithromax total of four treatments. The conclusion, of disease), and body weight. Viral shed- by Pfizer Laboratories as a preventive he said, was the levels of enrofloxacin in ding occurred in both groups, but shed- treatment for Rhodococcus equi infection the eye were high enough to suggest that ding occurred at a significantly lower in foals on endemic farms. (R. equi can this therapy may be a useful adjunct treat- level in the vaccinated group.” He said cause deadly pneumonia in foals.) ment for recurrent uveitis associated with the unvaccinated ponies demonstrated The study involved 10 breeding farms persistent Leptospira spp infections. severe clinical signs, and seven of the 11

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required therapy with non-steroidal anti- inflammatory drugs and antibiotics.

West Nile Virus Vaccine Leonardo Singer, DVM, MS, of Me- How To: Dentistry rial Ltd. reported on a recombinant canarypox-vectored equine West Nile by LES SELLNOW virus (WNV) vaccine, marketed by Merial under the trade name Recombitek Equine Bitting is formed. It occurs more often in older West Nile Vaccine. Involved in the study Dwight Bennett, DVM, PhD, a retired horses. He then went into detail on a sur- were 20 mixed-breed horses, ranging in professor from Colorado State University gical approach to remedy the problem. age from 18 months to 14 years. Horses and a longtime student of bits and their were housed in a single pasture at a re- effects on horses, opened the How To ses- Maleruptions of Premolars in search facility in Montana until Day 42 af- sion on dentistry. He focused on bits used Miniatures ter an initial vaccination. They were then in driving horses. Edward Earley, DVM, of Laurel High- transferred to CSU. There, the test horses “Familiarity with the unique bitting re- land Farm and Equine Services in Wil- received a single dose (1 mL) of the vac- quirements for draft horses, light horses liamsport, Pa., told the group that some cine on Days 0 and 35. On Day 49, all of the shown in harness, horses driven in mul- Miniature Horses are prone to malerup- horses in the study were challenged with tiple hitches, and harness racing horses tion of the upper fourth premolars, which WNV by direct intrathecal injection (into is important to the equine veterinar- are the last cheek teeth to erupt into the the space in which cerebrospinal fluid cir- ian dentist,” he declared. “The diagnosis, arcade. Horses at risk should be moni- culates around the brain and spinal cord). treatment, and prevention of many dental tored with regular oral examinations, he The results of the test indicated the vaccine problems require a basic knowledge of the said, along with radiographs. Maleruption did, indeed, protect the horses from WNV use of driving bits, overchecks, and side can be the cause of periodontal disease. and led the researchers to this conclusion, checks. The type of driving and the bitting Earley also described steps that the equine as stated by Singer: “The result of this study system used are important parts of a driv- dentist can take to solve the problem. and previous studies show significant pro- ing horse’s dental history.” tection data from a single dose of vaccine Bennett then proceeded to describe var- Dental Malocclusions and protective immunity lasting for one ious bits and the effects they have on the Bayard Rucker, DVM, of Lebanon, Va., year after a course of two injections.” horse’s mouth, including overcheck and discussed “How to Detect Reoccurring side check reins. A careful examination Dental Malocclusions Caused by Enamel Lawsonia Infections of the lips and mouth can reveal a horse’s Insufficiency.” He said abnormalities of Michele Frazer, DVM, Dipl. ACVIM, of bitting history and the reason for bitting wear, such as ramps, hooks, and a wave or Hagyard Equine Medical Institute in Lex- problems, he said. “For example, chafing step mouth, might be caused by a number ington, Ky., discussed ways to diagnose at the corners of the lips may indicate that of problems, including enamel hypoplasia and treat infection with the bacterium bridle checks need to be loosened or that (lack of enamel). Simply correcting the Lawsonia intracellularis, a disease that, in a team is improperly aligned. Tenderness malocclusion doesn’t necessarily solve the the past, has been much more common in the lower interdental space (between problem, Rucker said, as the lack of enamel in pigs than in horses. The disease most the incisors and the molars of the lower will result in overworn areas in the future. commonly manifests in equine weanlings jaw) may be a sign of mandibular perios- “Maintenance shortening of the oppos- 6 to 7 months of age. Clinical signs range titis (inflammation of the periosteum, the ing teeth will be needed annually or bian- from mild to severe and include weight connective tissue that sheathes the bones), nually,” he said. loss, rough hair coat, diarrhea, ventral which indicates that either the bit or the edema, a pot-belly appearance, and poor driver’s hand is excessively harsh. Sores Chewing Motion body condition. The goals of treatment are on the upper interdental space or on the Hilary Clayton, BVMS, PhD, MRCVS, elimination of the bacteria and supportive hard palate may indicate that the check- of Michigan State University, is better care. Recent clinical experiences, she said, rein is set too high or that the overcheck known for discussing gait analysis than have indicated that good results can be ob- bit is too severe.” chewing motion. However, using some of tained by administering the antiprotozoal the same technology used for gait analysis, metronidazole combined with either of Sinus Problems she described how a series of cameras was the antibiotics oxytetracycline or chloram- Palle Brink, DVM, Dipl. ECVS, of Swe- utilized to record the motions of a horse’s phenicol. Alternate choices include doxy- den, discussed the formation of an oro- mouth when chewing hay and when chew- cycline, erythromycin, clarithromycin, or maxillary sinus fistula. It is a complication ing pelleted feed. The results of the study azithromycin. Frazer said although the that can occur in 7-33% of horses after proved that when a horse chews hay, the disease has shown up in horses during the loss or removal of the caudal (rearward) mandibular motion is much greater than past 10 years and has become increasingly four maxillary (upper) teeth in horses, when chewing pelleted feed. The greater common, the source of infection is not yet in which an abnormal passageway from range of motion helps reduce the threat of known. H the oral cavity to the paranasal sinuses dental overgrowth. H

March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 57 AAEP WRAP-UP 2007 Nutrition by Nancy S. Loving, DVM

Endocrine Disorder Feeding Tips Finos and Arabians. Generally, these hors- pathways, or glucose transport systems. Nicholas Frank, DVM, PhD, Dipl. es have a higher-than-normal blood insu- To compensate, many horses will secrete ACVIM, associate professor of large ani- lin concentration. An ECD horse is typi- additional insulin, thereby worsening the mal clinical sciences at the University of cally an older or aged horse with pituitary problem. An obese horse has lipid accu- Tennessee, spoke about equine endocrine dysfunction that results in excess secretion mulation within adipose (fat tissue) and disorders that are the most manageable of ACTH (adrenocorticotropic hormone), skeletal muscle tissue that interferes with by dietary control: equine metabolic syn- alpha-MSH (alpha-melanocyte stimulat- insulin signaling, leading to insulin resis- drome (EMS) and equine Cushing’s dis- ing hormone), and other hormones. These tance. Frank described some basic con- ease (ECD or pituitary pars intermedia horses have delayed or patchy hair coat cepts that are important for a horse owner dysfunction, PPID). shedding, and there is noticeable muscle and veterinarian to consider: An EMS horse tends to be fairly young, loss. Often there is excess drinking and uri- Obesity predisposes to insulin resis- might have some genetic predisposition, nation, which might go undetected. tance; and has pronounced fat deposits, espe- Frank said insulin resistance can devel- Insulin resistance is a diabeteslike cially on the neck, shoulders, and but- op in either EMS or ECD individuals. In- state; tocks. These horses are considered “easy sulin resistance results from impaired tis- Sugars exacerbate insulin resistance; keepers.” Some breeds are more likely to sue responses to insulin due to problems Insulin resistance makes horses develop EMS than others, such as Paso with insulin receptors, insulin-signaling more prone to laminitis; ordis h Su s a n K An insulin-resistant horse in good body condition should be fed to improve insulin sensitivity.

58 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by

It is important to avoid laminitis trig- with elimination of grain and pasture The second diet Frank considered is a gers such as intestinal abnormalities, sea- grass from the diet. Then, hay is lowered weight maintenance diet that is predomi- sonal variations, and dietary changes. to 1.5% of current body weight, then of- nantly forage-based (hay) with less than A goal for managing an obese horse is fered at 1.5% of ideal body weight. For ex- 12% NSC. Hay is fed at a rate of roughly to induce weight loss. In a horse that is in ample, you’d give 15 pounds of forage to a 2% of body weight to maintain weight. Vi- good body condition, yet has insulin resis- 1,000-pound horse. The horse is fed at this tamins, minerals, and protein are provided tance, you should aim to maintain its cur- level until an ideal body condition score is as needed. High-glycemic feeds should be rent weight with the objective of improving achieved. In some cases, a hay-only diet completely avoided, such as sweet feed insulin sensitivity. A thin Cushing’s horse might provide insufficient protein; a diet with molasses, as this challenges glucose with insulin resistance should gain weight of 8% protein is acceptable. If more pro- and insulin metabolism and exacerbates and improve its insulin sensitivity. tein is needed, a small amount of alfalfa insulin resistance. A horse experiences a Of three possible diets to manage in- higher glycemic response (blood sugar) if sulin resistance, the first Frank described carbohydrates are digested in the small in- is a weight loss diet in which all grain is A horse needs testine, so it is best to feed small amounts eliminated and access to pasture is elimi- nutrients for healing and of food more frequently, (so lesser amounts nated or restricted to less than two hours of carbs ferment in the small intestine at per day or to a small area of strip graz- immune function, but one time) and to feed hay before concen- ing. A grazing muzzle is useful to control loading the bowels with trates. Always avoid sudden changes in consumption of grass. Dynamic phases of feed so the bacterial flora in the bowel can grass growth (i.e., following drought con- feed might increase the adjust gradually to various feed materials. ditions) should be avoided. Soaking hay Frank stressed that “a safer feed is not for 30 minutes before feeding lowers its chance for intestinal shut- necessarily a safe feed.” General recom- sugar content. Hay should be analyzed for down and colic relapse mendations apply to most, but not all, its nonstructural carbohydrate (NSC) con- insulin-resistant horses since insulin re- tent, and hay should be selected that is low or for breakdown of the sistance varies in severity and there are (less than 10-12%) in NSC. Frank notes abdominal incision individual variations in responses to feed. that it is impossible to identify NSC con- Body condition should be assessed ev- tent (simple sugars and starches) from ap- Dr. Ray Geor ery two to four weeks, and blood insulin pearance, and content varies by grass type, should be monitored. rainfall, soil type, season, cutting, and time hay or soybean meal can be substituted for The weight gain diet relies on low-NSC of day. (As a comparison to forage, oats a portion of the diet. (less than 12%) hay fed free-choice along have a value of 50% NSC.) Exercise is important for weight loss, with molasses-free beet pulp and rice bran Initially, the fat horse should be fed 2% provided laminitis or lameness does not or corn oil. Soaked molasses-free beet pulp of its current body weight in hay along preclude physical activity. is mostly digested in the large intestine.

Ride farther.

Presoaked, one cup is equivalent to one- stressed that how a horse should be fed de- quarter pound. Start with one-quarter to Pelleted mashes pends on the underlying cause of the colic one-half pound of pre-soaked beet pulp incident, as well as the horse’s appetite and and feed this twice a day, increasing grad- and slurries combined extenuating complications that might arise ually to 1 pound daily. Beet pulp should with high-fat supplements in the recuperative phase. A horse with a be rinsed twice in warm water to remove simple colic might have feed and water simple sugars, then soaked for 10 to 30 can be offered to geriatric withheld during the episode, but as soon as minutes in warm water before feeding. the colic has resolved, the horse can return Commercial low-NSC pelleted feeds horses with poor dentition to a normal diet. Many practitioners advo- are also recommended for weight mainte- or missing teeth cate elimination of the grain portion of the nance or gain. Advantages of these prod- diet for a few days to allow restoration of ucts include the ease of feeding, regular Dr. David Pugh hindgut microbial function. testing of ingredients to ensure a lower In contrast, following intestinal surgery sugar content, and addition of ingredients feed should not be introduced until there that affect absorption and palatability. It has been common practice to withhold is evidence that intestinal motility has feed initially and provide only water and been restored, and, even then, only small Feeding After Colic possibly intravenous fluids and electro- amounts (1 pound) of forage are offered at Nutritional support of horses following lytes to a horse that suffered from colic or frequent intervals (four to six times a day). a bout of colic is important, especially for colic surgery, then slowly re-introduce feed Increase the amount gradually and steadi- hospitalized horses following colic sur- at a rate that allows the GI system to ac- ly based on the horse’s response. gery, noted Ray Geor, BVSc, MVSc, PhD, commodate forage. Another tactic is to offer pasture grazing Dipl. ACVIM, professor, Paul Mellon Dis- Geor advocated feeding a stall- for 20-40 minutes intermittently through- tinguished Chair, and director of Virginia maintenance ration (approximately 70% out the day or to offer pelleted senior feed, Tech’s Middleburg Agricultural Research of maintenance needs; a maintenance diet which is digestible and low-bulk. For the and Extension Center in Middleburg, Va. accommodates basic physiologic func- two weeks following surgery, it is best not There are arguments as to how much tions without the added demands of exer- to offer grain so as not to further disrupt to feed following a colic attack or colic cise, etc.) for two to four days after horses hindgut (large intestine) microbial activity. surgery. A horse needs nutrients for heal- have colic surgery, increasing the ration Reinstitution of grain begins with small ing and immune function, but loading continually until reaching a maintenance amounts (2 pounds or less per day) and is the bowels with feed (and the weight of intake of digestible energy. increased gradually. the feed) might increase the chance for Three avenues of nutritional support are By the second or third day following intestinal shutdown and colic relapse or available: 1) voluntary feeding, 2) assisted surgery a horse should voluntarily con- for breakdown of the abdominal incision. feeding, and 3) parenteral nutrition. Geor sume at least 75% of stall-maintenance

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requirements in forage, i.e., 8 pounds of calories can be obtained through high-fat example, a 1,000-pound horse should not hay for a 1,000-pound horse. A horse that concentrates (oil, rice bran, or supple- receive more than 5 pounds of concentrate won’t eat this amount of hay will need ments especially high in fat) with avoid- at a meal. appetite stimulation with grass or other ance of grains and sweet feed. Body condition might be difficult to palatable, but highly digestible, feed, par- maintain in some older horses due to in- ticularly if the horse is in poor body con- Feeding the Geriatric Horse adequate intake of feed, poor digestive ca- dition. If this fails to induce an appetite, A horse kept healthy and disease-free pacity, dental disease, metabolic disease, then assisted feeding is necessary. This in its younger years has the potential to endocrine disease, or infection. A complete relies on administration by stomach tube live well into its 20s and 30s, stated David physical exam and blood work should be of energy-dense pelleted feed, slurried and Pugh, DVM, MS, Dipl. ACT, ACVN, of Fort performed on a geriatric horse to rule out supplemented with fats. The volume given existing problems. by stomach tube four to six times per day Before protein is increased, it is impor- is slowly increased over several days to a Maintaining tant to examine liver and kidney function. target amount. Careful clinical monitoring In general, dietary calcium should be kept is important to avoid stomach distention, stability of the hindgut below 1% due to the potential for kidney intestinal shutdown, or laminitis. microbial community is stones in aged horses. Thus, the use of al- The third strategy for nutritional sup- falfa must be considered carefully. In these port is that of parenteral nutrition that of paramount importance cases increased protein needs might be is given intravenously through a catheter to GI health provided with soybean meal. dedicated only to this purpose. This form A horse with kidney disease should re- of nutrition is particularly valuable for Dr. Ray Geor ceive less than 8% protein and will do best horses recovering from enteritis (intesti- on grass hay supplemented with fat and/ nal inflammation) or from small intestinal Dodge Animal Health. In the senior horse, or corn oil if more calories are needed. surgery, particularly if a portion of small routine medical management should be Digestion of phosphorus seems to decline intestine has been removed. implemented, including parasite control, with age, and it is valuable to monitor the Once intestinal motility is restored with dentistry, and dietary modifications to ac- calcium to phosphorus ratios. A horse with no gastric reflux, it is recommended to commodate existing problems. liver disease should not be fed a high-fat feed a highly digestible diet using fresh Dental disease is a common problem in or high-protein diet, and that horse might green grass or soft first-cutting hay and/ aged horses, so the teeth should be checked benefit from vitamin B supplementation. or pelleted feed mashes, offering only very at least twice yearly to minimize the risk Support of a geriatric horse’s immune small meals every three to four hours. of choke and to avoid weight loss. Pelleted system could be helped by supplemental Regarding large intestinal disorders, mashes and slurries combined with high- vitamin C and vitamin E, along with main- such as an impaction, feed should be fat supplements can be offered to geriat- taining a good body condition score. Pitu- withheld until the impaction has cleared. ric horses with poor dentition or missing itary adenomas (benign tumors in glandular Grain should not be fed until it is evident teeth. If an older horse is able to maintain tissue) and/or obesity elicit glucose intoler- that manure is passing regularly and in ap- good body condition on a regular mainte- ance and insulin resistance, making feed- propriate quantity and consistency. If large nance diet, then no extra supplementation ing of such individuals a real challenge. If a intestinal surgery was performed, it is im- should be necessary. Some aged horses horse requires additional calories and does portant to monitor for diarrhea, as Geor require “safe” feeding areas to avoid herd not have a liver problem, these are best of- reported the risk of diarrhea is increased competition, especially if afflicted with ar- fered as high-fat supplement. twofold in horses with large intestinal thritis or failing eyesight. disorders as compared to other intestinal Pugh noted that nutrition for aging hors- Managing Carbs in Horses problems. This risk increases if the large es and young, growing horses is similar in How is feeding carbohydrates related colon has undergone direct surgical inva- the protein and energy needed to support to gastrointestinal (GI) disease? Geor dis- sion. There appears to be some mitigating their metabolism. An old horse might not cussed the conflict between GI physiol- effect on diarrhea when grass hay is fed. digest dietary fiber efficiently, and he also ogy and the way horse owners tend to fed Hay can be offered starting 12 hours post- might need a higher (12-14%) protein in- modern horses, especially those with high surgery, with small amounts of soft first- take because he can’t digest protein as well. athletic demands. The propensity to feed cutting grass hay given every two to three It is important to ensure adequate intake high-grain and high-concentrate diets in- hours. Grain should be withheld for 10-14 of specific amino acids, such as lysine and stead of relying on high-fiber diets has in- days, but pelleted feed can be fed due to threonine. In many cases including alfalfa creased the incidence of colic. its low bulk. in the diet helps to limit loss of muscle One study from 1997 indicated that on Following extensive large colon resec- mass and weight. A high-fat supplement 31 farms, the risk of colic increased 4½ tion (removal of a section), Geor noted (vegetable oil and/or rice bran) is useful to times when horses were fed moderate to that transit time of nutrients is altered so provide calories, as are beet pulp mashes large amounts of grain (5-10 pounds). low-bulk feeds, such as pelleted feed, can or pelleted feeds. Pugh recommends that An increased risk of colic also is related be offered initially, followed by legume for- concentrates be restricted to no more than to a change in diet; particularly in the first age or a grass-legume hay mix. Additional 0.5% of body weight per feeding, as, for week after a diet change, there is a chance

March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 61 AAEP WRAP-UP 2007

of simple colonic obstruction or disten- Acidosis also results from large grain con- Minimize the flow of rapidly ferment- tion, but risk diminishes 15-28 days fol- centrate meals, lush spring pasture graz- able carbs to the cecum and large colon; lowing dietary changes. ing, or from forage that is high in nonfiber Limit amount of grain, sweet feed, or Geor stressed that other contributing carbohydrates, such as what occurs with pelleted feed per meal to no more than 4½ factors should be considered, such as level rich legume hay. pounds of starch for a 1,100-pound horse; of physical activity, breed, age, season, and Studies indicate there is a stepwise de- Increase the number, not the size, of the area’s weather, but, in general, there is crease in cecal pH relative to increasing meals to at least three feedings per day and an increased risk of colic with high-grain amounts of grain and the size of a starch provide free-choice hay when possible; concentrate diets and with recent dietary meal. Larger grain meals increase risk of Feed starch sources high in pre-cecal changes. So, the question is, “Why?” starch bypass of the small intestine with digestibility, such as oats. If using corn or Geor said there is a disturbance of the rapid fermentation in the large intestine. barley, these need heat treatment, such as hindgut ecosystem related to delivery of The effects of this depend on the horse’s extrusion, popping, or micronization; undigested starch and other rapidly fer- adaptation to the types of starch and size Slowly introduce changes in cereal mentable carbohydrates to the hindgut. A of meal. or sweet feed to increments of less than 1 limited capacity for starch digestion in the pound per day over seven to 10 days; small intestine contributes to overflow of Use alternative concentrated energy starch to the hindgut. There is also a lag or One study from 1997 sources, such as oils, or rice bran, or high- transition time in the speed of microbial ly digestible super fibers, i.e., beet pulp or adaptation to dietary changes. He point- indicated that on 31 soya hulls; ed out that maintaining stability of the farms, the risk of colic Encourage long-stem forage intake to hindgut microbial community is of para- at least 1-1½% of body weight, i.e., 12-17 mount importance to GI health. increased 4½ times when pounds per day for a 1,000-pound horse; There are three types of carbohydrates: and Hydrolyzable Starches and sugars are horses were fed moderate When switching hay batches, blend digested in the small intestine to generate to large amounts of grain over seven to 10 days. glucose, but these ferment rapidly in the Geor also mentioned how diet affects stomach or the large intestine. (5-10 pounds). equine gastric ulcer syndrome (EGUS), Rapidly fermentable Fructans and oligo- which is reported to have an incidence saccharides (saccharides of a small num- of 60% in pleasure and show horses, and ber of component sugars) that rely on Lac- Cecal acidity is associated with feeding 85-90% in racehorses. tobacillus, Streptococcus, and Clostridium grain starch of low digestibility, such as is The “trickle” feeding pattern of pastured spp, with lactate production as a byprod- seen with corn. The higher digestibility of horses (small intake of feed over a long pe- uct. oats mitigates this effect, whereas barley riod of time) might have a protective effect Slowly fermentable Cellulose that relies and corn starch are more resistant to di- that is coupled with the high-fiber diet of on Fibrobacter and Eubacterium spp that gestion and lead to acidosis. pasture grass. Saliva production doubles consume lactate. Oats are about 84% digested before when eating hay and is continuous when If a large load of rapidly fermentable car- reaching the cecum as opposed to corn at grazing; saliva has a powerful buffering ef- bohydrates enters the hindgut, overgrowth 45% or less digestion. Heat treatment or fect on stomach acid. of lactate-producing bacteria leads to in- reduction in particle size (micronization Alfalfa has an additional buffering effect creased lactate and gas production, acidity or extrusion) is needed for improved pre- on stomach acid, whereas recent findings of the hindgut, a die-off of Gram-negative cecal digestibility and retention of normal do not support any benefits from corn bacteria, and the release of endotoxin and cecal pH. or rice oil in preventing development of other substances. The result is disruption As for probiotics (dietary supplements EGUS. Overall, it is important to remem- of the mucosal layer of the intestinal lin- containing potentially beneficial bac- ber that a horse has a small stomach and ing, absorption of endotoxin, more gas dis- teria or yeasts), Geor pointed out that large hindgut and a limited capacity for tention, and altered gut motility with the data is lacking due to the absence of well- starch digestion in the small intestine. In potential for an intestinal volvulus (twist). designed scientific studies. In addition, general, the best strategies rely on feeding This sequence of events results in an acute there are issues regarding product quality, smaller and more frequent meals with less and severe colic. and some studies show adverse effects in reliance on cereal or sweet feeds. A more chronic and less severe intesti- foals receiving probiotics containing Lac- Other supplements were discussed, such nal disruption develops from a decrease in tobacillus pentosus. as “stabilizing” products for the hindgut fiber-fermenting, acid-utilizing microbes. Another new supplement (made by Ken- ecosystem. A live yeast preparation or This leads to chronic acidosis, digestive in- tucky Equine Research) that is advertised prebiotic (a food substance intended to efficiency, weight loss, altered fecal consis- as a hindgut buffer is purported to miti- promote the growth of certain bacteria in tency, and the development of stereotypic gate moderate decreases in cecal pH fol- the intestines; 10 grams per day of Sac- behaviors such as cribbing. lowing a grain meal or when grazing lush charomyces) mitigates the decrease in pH Hindgut acidosis develops subsequent pasture. that occurs with high-starch meals, but of to sudden introduction of grain feeding or Geor summarized his recommendations greater importance is the feeding of high an abrupt increase in amount of grain fed. to reduce colic risk: dietary fiber, i.e., forage. H

62 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 Sponsored by Ophthalmology by nancy s. loving, dvm

Eye Examination Dennis Brooks, DVM, PhD, Dipl. ACVO, of the University of Florida veterinary school, led the panel at the in-depth session on ophthalmology. He was excited to share many developments from the last six months that allow veterinarians to save eyes and sight. He stressed that in most cases an eye exam does not require special equipment, but it does require a “lack of fear” in addition to a bright light, a direct ophthalmoscope or otoscope (an instrument for examining ears), and skills to perform a thorough exam. Brooks pointed out that a veterinarian is limited by the nature of the beast in examining eyes. Assessment of a menace reflex from hand motion is a crude measure, making it hard to determine if the horse is reacting to the feel of air or to hand motion. The best equine test for vision is the “dazzle reflex,” a sensitive test for retinal function. An observer determines if the horse squints in response a bright light shined into the injured eye. Although there might be a variable pupillary response to the light, squinting denotes the perception of light. If the horse’s cornea is opaque, yet

he squints, then the retina is still working. c ha d me nd e ll Another useful test is the “flashlight test” Veterinarians are limited by the nature of the beast in examining eyes. or indirect papillary reflex that stimulates the bad eye with light while observing for blocks to anesthetize branches of cranial through the nasolacrimal duct (the duct pupillary reaction in the other eye. Often nerves to curtail blinking or sensation of that connects the eye to the nasal passag- inflammation is confined to the front of pain and to facilitate careful examination es) can take up to 10-15 minutes. an eye, and a positive indirect pupillary re- of eye structures. Use of Rose Bengal stain evaluates sta- flex indicates that there is a chance to save With wry humor, he noted there “are bility and integrity of the tear film. Nor- sight and the damaged eye. really only two eye diseases: corneal ul- mally, the tear film takes 10-15 seconds to Brooks also pointed out that, in general, cers, and everything else.” Staining the break up, but rapid dissipation indicates the upper eyelashes of a painful eye tend to eye with fluorescein dye identifies defects roughening on the corneal surface that point down. This droopiness of the lashes in the corneal epithelium (the outer layer won’t allow the tear film to hold together. is one of the last things to return to a nor- of the cornea) and the extent of an ulcer. Dry eye is one cause of a roughened cor- mal position as an injury heals. It might be The corneal epithelium is eight layers neal surface, and this can occur with viral necessary to view the eyes from a distance, thick, but the dye will be picked up with or fungal diseases. even with binoculars, for a horse that is loss of only one to two layers. The Seidel’s An observant veterinarian can tell a lot protective of examination of the eye and test detects a corneal perforation when from color changes within the cornea: tends to close when a person approaches. the fluorescein changes color as it leaks white might indicate an abscess, blue Brooks described helpful regional nerve into a hole. Normal passage of fluorescein discoloration is consistent with edema

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expected with an ulcer, red indicates blood ing it; IOP increases 87% with the head in ciliary body become leaky. White blood vessel entry for healing, while a dark col- the down position. Looking at the drain- cells enter the eye along with their in- or is of concern for imminent rupture. A age angle (the gray band on the lateral, flammatory cytokines and enzymes. She pigmented iris will change color, becom- or outer, portion of the eye), one should explained that molecular mimicry could ing dark with inflammation from uveitis, see minute holes. If these holes collapse play a role—an antigen might trigger the melanoma, or hemorrhage. The size of and close and appear solid, there is an in- immune system, then similar antigens of the pupil also gives specific information— creased risk of glaucoma. the horse can subsequently trigger the im- a large pupil might indicate glaucoma or mune system, which causes the clinical retinal or optic nerve disease; small pupil Treatment of Uveitis signs of ERU. size is symptomatic of uveitis. Aqueous Mary Utter, DVM, PhD, Dipl. ACVO, of ERU is like an autoimmune response, flare is visible as little white spots seen the University of Pennsylvania veterinary tending to be a dynamic process with shifts with a slit lamp; this results from protein school, stressed that equine recurrent in immune-reactivity that cause a waxing leaking from blood vessels of the iris and uveitis (ERU) is the leading cause of blind- and waning of uveitis episodes. is another sign of uveitis. ness in horses. The prevalence of uveitis Suspected stimuli that might incite an For a corneal ulcer, Brooks recom- in the United States horse population is attack of ERU are bacterial, viral, and mends obtaining a bacterial culture first, about 8% based on a 2005 study—this parasitic diseases, including leptospirosis, then evaluating cells with cytology. Once means there could be 736,000 horses with onchocerciasis, strangles, brucellosis, tox- he removes superficial debris, he gathers moon blindness in the United States! oplasmosis, equine herpesvirus, and Lyme a deep scraping at the edge and base of an Utter pointed out that this is a syndrome disease. Some breeds have a predilection ulcer, using the handle end of a metal scal- of many subsets rather than being a single for developing ERU, including Appaloosas pel blade. disease. She compared it to laminitis in and Warmbloods. Brooks stressed that even after treatment that both are inflammatory processes in- While leptospirosis is the most signifi- kills bacteria, white blood cells (neutro- volving multiple tissues in key functional cant cause of uveitis in all species world- phils) die and dump enzymes (proteases) areas, and both occur due to a variety of wide, Utter feels there also might be a into the tear film that continue to worsen triggers. She noted, “Both of these diseases “lepto link” in horses. Leptospirosis is a an ulcer. One objective in treatment is to are poorly understood, both have a vari- bacteria that penetrates mucous mem- return the tear film proteases back to nor- able response to therapy, and both are bad branes in the mouth and settles in the mal. Blood vessels grow from the periph- for the horse.” kidneys, causing an animal to shed the or- ery at 1 mm/day, while white blood cells A horse can have a genetic predisposi- ganism in urine for 2-3 months. Although move in at a rate of 8 mm/day. tion to develop uveitis, but in most cases the serum titer elevates within 4-8 days The horse has the highest intraocular the disease process begins as some com- following infection (antibodies are made pressure (IOP) of any land mammal, and promise to the blood-ocular barrier in by the horse), the virus persists for the ani- the horse’s head must be up when measur- which the blood vessels of the iris and mal’s life.

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Initially, the illness is mild and clinical signs might be missed; months later the eye disease begins, with increasing damage with each flare-up. Horses with the highest risk are those with access to carrier species, such as cattle, deer, rats, or rac- coons, and especially in close proximity to water sources since this organism can live for months in ground water. A leptospirosis vaccine is approved for cattle, but its’ use in horses is considered off label. The vaccine should only be used on “at risk” farms and only on horses with normal eye exams and negative serum titers. Utter reported on breed predilection for ERU, saying 80% of uveitis cases occur in Appaloosas, and generally both eyes are affected. The individuals most at risk are those with coat patterns with overall roan or light coat color, little pigment around the eyelids, and sparse manes and tails. In Germany, some lines of Warmbloods are at risk. In an Appaloosa with a positive lepto titer, 100% will lose sight in one eye and 50% go completely blind. If an Appaloosa c ha d me nd e ll has had no exposure to leptospirosis, there Eye injuries can be very serious and warrant an immediate call to your veterinarian for possible treatment, such as this horse above who scratched his cornea. is a 70% of losing sight in one eye and a 29% chance of total blindness. In non- education so subtle clinical signs can defect. Initially, this forms a single layer of Appaloosa breeds, a horse with a positive be recognized early to enable timely cells, but eventually a multilayered sheet lepto titer has a 50% chance of losing sight implementation of treatment. Treatment of cells will cover the corneal wound. The in one eye and 17% risk of complete blind- goals focus on preserving vision, control- epithelial cells migrate at a rate of 0.6 mm/ ness, while if the horse has no previous ex- ling active inflammation, and minimizing day if there is no concurrent infection; it posure to lepto, the non-Appaloosa has a discomfort and permanent damage. takes at least six weeks for the epithelium 34% chance of loss of vision in one eye and to securely attach once it has crossed the only 6% chance of going blind. Corneal Ulcers defect. An indolent ulcer is one that won’t Utter described how a horse with ERU Caryn Plummer, DVM, Dipl. ACVO, as- heal either due to an abnormality of the will have an acute attack alternating with sistant professor at of the University of basement membrane or a problem of ad- periods of quiescence, yet damage is ongo- Florida veterinary school, described the herence. ing despite a lack of outward clinical signs. outer corneal layer (epithelium) as the A defect in the stroma requires a bal- Each episode results in more permanent windshield of the eye, and explained that it ance of resorption and remodeling, which damage. During a flare-up, there is tearing, is protective and supportive to underlying takes longer than healing of more superfi- pupillary constriction (miosis), conjunc- corneal tissues. Beneath the epithelium is cial ulcers. Any imbalance in this restor- tivitis and redness, decreased intraocular the stroma, the thickest layer of the cor- ative process can lead to “melting” of the pressure, and other signs of inflammation. nea, comprised of collagen and fibroblasts. cornea. Chronic cases can have evidence of “foot- Beneath that is the thin basement mem- This can occur due to upregulation of prints” of previous episodes, such as iris brane (Descemet’s membrane), and at enzymes of bacteria or white blood cells adhesions, increased pigmentation of the the bottom of the cornea is the single-cell that cause “housekeeping cleanup” to ex- iris, and scarring on the optic disc. endothelial layer that serves as a pump to ceed the rate of repair. Normal tear fluid Cataracts are a common sequela, with move accumulated fluid from the interior contains soluble proteases essential to the potential to lead to glaucoma. Other of the cornea. corneal health. Disproportionate amounts indications of chronic inflammation and Plummer noted that ulcers are classi- of these, as produced by inflammatory damage might be present, including band fied according to their depth, cause (etiol- cells, lead to pathologic degradation. Nor- keratopathy (deposition of calcium just ogy), and response to treatment. She not- mal repair also requires corneal blood ves- beneath the epithelium), phthisis bulbi ed that following an injury, mitosis (cell sels, which move at the rate of 1 mm/day, (degeneration and atrophy of the globe), division) stops, and the cells at the edge yet they are slowed by therapy with non- or retinal detachment. of the wound enlarge and lose their at- steroidal anti-inflammatory medications Utter stressed the importance of client tachment, allowing them to slide over the (NSAIDs).

March 2008 The Horse AAEP Wrap-Up TheHorse.com/AAEP2007 65 AAEP WRAP-UP 2007

White blood cells invade the cornea of necrotic debris surrounding the mar- anticoagulant and as a chelator) slows pro- at 8.6 mm/day, so they are the first to gins of an ulcer allows epithelium to cover teolytic activity (cleavage of proteins by respond to injury. Epithelial cells move at the defect. Plummer said it is important proteases) by 99.4%. Plummer noted there 0.6-1.2 mm/day. to keep in mind that “sterility does not might be advantages in obtaining serum A melting ulcer is not always due to equate with healing.” Dilation of the pupil from another horse on the property. Other bacterial influences, and this is a true deters internal damage, and NSAIDs quiet enzyme-inhibiting products are available emergency due to the possibility of pro- the uveitis and lessen pain. with similar effects. The objective is to stop lapse of internal eye tissues within hours Enzymes are responsible for collagen corneal melting, restore drainage, sterilize or days. It is always prudent to do a bacte- destruction, so medications that inhibit the wound, provide structural support for rial culture and sensitivity and cell cytol- destructive enzymes are critical for suc- ulcer repair, decrease pain and inflamma- ogy, in addition to implementing aggres- cess. Equine serum reduces enzymes tion, and prevent secondary damage to the sive treatment with topical antibiotics by 90%, while 0.2% EDTA (ethylene di- interior of the eye. Treatment might be re- and possibly antifungal agents. Removal amine tetra acetate, a chemical used as an quired every two to six hours. Surgery and placement of a subpalpebral (beneath the eyelid) lavage tube might be necessary to facilitate healing. Required Reading Contributing Authors Contributors to the AAEP Wrap-Up are: Christy West, TheHorse.com Web Mas- for Responsible Horse Owners. ter and freelance writer. Nancy Loving, DVM, owns Loving Equine Clinic in Boulder, Colo., and has a special interest in managing the care of For over 10 years The Horse: Your Guide to Equine sport horses. Her newest book, All Horse Health Care has been essential reading by responsible Systems Go, is a comprehensive veterinary horse owners. care and conditioning resource in full col- or that covers all facets of horse care. She Subscribe today, and along with your full access to has also authored the books Go the Dis- TheHorse.com, you’ll receive 12 issues of The Horse tance as a resource for endurance horse filled with essential information you need to know to owners and Conformation and Perfor- keep your horses healthy and strong. Order now and mance (both available at www.Exclusive- SAVE OVER 72% off the cover price. Plus, you’ll get the lyEquine.com or by calling 800/582-5604), next edition of The Horse Source FREE. as well as many veterinary articles for both horse owner and professional audi- NO RISK. NO OBLIGATION. ences. Her next book, First Aid for Horse and Rider, is due out soon. Your satisfaction is absolutely guaranteed. If you’re Les Sellnow, is a freelance writer based not completely satisfied, we’ll send you a refund for all near Riverton, Wyo. He specializes in ar- unmailed issues! ticles on equine research, and he oper- ates a ranch where he raises horses and livestock. He has authored several fiction and nonfiction books, including Under- standing Equine Lameness, Understanding SUBSCRIBE NOW! The Young Horse, The Journey of the West- ern Horse, and Happy Trails, published by CLICK HERE or Eclipse Press and available at www.Exclu- sivelyEquine.com. call 1-800-582-5604 Special Thanks Many professional writers and veterinarians contribute to making this Wrap- Up possible. All articles are reviewed by the presenter or moderator of a session without compensation. We are grateful to these dedicated veterinarians, research- CQ06Z236TH ers, and other professionals for their assistance. H

66 TheHorse.com/AAEP2007 AAEP Wrap-Up The Horse March 2008 ( your way ) ( our way )

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