AAEP Preview: Convention Topics Preview

The latest information on a wide range of horse health topics will be presented at the 2002 AAEP convention. While we can't give you a preview of them all, we wanted to bring you a representative sample of the educational opportunities. Look for in-depth coverage following the convention in our AAEP Wrap-Up--which mails with the February 2003 issue--and online at www.TheHorse.com during and after the convention.

Lameness: Thoroughbreds, Peruvian Pasos, and More

 At some point, lameness plagues nearly all horses regardless of breed, discipline, and age. Practicing veterinarians and researchers are continually learning more and more about what causes lameness and how to treat it. The annual Dolly Green Lameness series on Sunday, Dec. 8, features the latest on their efforts to learn how to keep horses sound and return them to full use.

Effectiveness of an Oral Supplement for Joint Health--World-famous biomechanics researcher Hilary Clayton, BVMS, PhD, McPhail Endowed Dressage Chair at Michigan State University, will be presenting the results of her study on the effectiveness of an oral joint health supplement on lameness caused by tarsal degenerative joint disease. This double-blind study (in which those evaluating the horses didn't know which horses had been treated, then the treatment groups were switched and horses re-evaluated) involved gait analysis with Clayton's digital video analysis of reflective markers on particular areas of the horse as well as analysis of ground reaction forces collected via force plate.

Shock Wave Therapy--Two studies examined the usefulness of radial extracorporeal shock wave therapy (ESWT) in treating Thoroughbred racehorses and mature competition horses. Scott Palmer, VMD, Dipl. ABVP, of the New Jersey Equine Clinic in Clarksburg, N.J., will present the results of a study that used radial ESWT on 50 Thoroughbreds with bucked shins which had been unresponsive to conventional therapy for at least two months. Oliver Crowe, a veterinarian from the Royal Veterinary School in London, will discuss the other study's findings on treatment of hindlimb proximal suspensory desmitis (ligament inflammation present for at least three months) with radial ESWT.

Rupture of the Peroneus Tertius Tendon--This tendon helps flex the hock and is part of the reciprocal apparatus that locks the hindlimb in extension so the horse can sleep standing up. Rupture of this tendon might or might not spell the end of a productive career. Find out when Judith Koenig, DVSc, a staff veternarian in large animal surgery at the University of Guelph, presents a study of 25 horses with this condition.

Degenerative Suspensory Ligament Desmitis in Pasos--Many veterinarians specializing in Peruvian Pasos have noticed a relatively high frequency of degenerative suspensory ligament desmitis in these horses. Jeannette Mero, DVM, associate veterinarian with Starland Veterinary Services in New York and head of DSLD Research, Inc., will discuss a review of 20 affected Pasos in which ultrasound, gross examination, and histopathological data were compared in an effort to find any predisposing factors to this problem.

Enlarged Superficial Digital Flexor Tendon--Should you purchase a colt for racing which has an enlarged superficial digital flexor tendon? Many consignors and buyers balk at buying immature Thoroughbreds with this problem, even though there are more questions than answers regarding their future performance. Johanna Reimer, VMD, Dipl. ACVIM, Dipl. ACVC, of Rood and Riddle Equine Hospital in Lexington, Ky., will discuss the findings of a study on whether this condition affected racing performance at two and three years of age.

Curb--This is a syndrome characterized by swelling in the plantar (rearward) aspect of the hock, and can be caused by quite a few particular injuries within the hock. Michael W. Ross, DVM, Dipl. ACVS, in the Department of Clinical Studies at the University of Pennsylvania's New Bolton Center, will present a study in which ultrasound and scintigraphy were used to describe and differentiate between the myriad of injuries that all cause curb.

Desmitis of Distal Interphalangeal Collateral Ligaments--The horse's foot is a complicated structure, and a problem with any one of its components can cause lameness. The trick is figuring out which one is problematic so you treat the right one.

Tracy Turner, DVM, MS, Dipl. ACVS, a professor of equine surgery at the University of Minnesota, will present a study that evaluated desmitis of the distal interphalangeal collateral ligaments (the ligaments holding the coffin bone to the second phalanx and lateral cartilages). This problem should be considered as a differential diagnosis for foot lameness, and can be confirmed or ruled out with diagnostic imaging. Turner will present images and discussions of 22 horses with this problem.


 In addition to the Dolly Green section, the convention will feature a radiology panel on Saturday, Dec. 7, to discuss optimal usage of X rays in diagnosing hoof and leg problems.

Sue Dyson, MA, VetMB, PhD, DEO, FRCVS, of the United Kingdom's Animal Health Trust, will present a study on the value of magnetic resonance imaging (MRI) in diagnosing the cause of lameness in 18 horses with palmar foot pain. The MRI images obtained in these cases helped differentiate core lesions from tears and splits in various soft tissue structures, and helped clarify navicular bone abnormalities.

William Widmer, DVM, PhD, Dipl. ACVR, will review foot radiology with an emphasis on the navicular region, with an eye to better understanding the radiographic changes associated with the syndrome.

Mark Martinelli, DVM, PhD, Dipl. ACVS, Associate Surgeon (Orthopedics) in the San Luis Rey Equine Hospital in Bonsall, Calif., will present the clinic's experience with using special radiographic views, scintigraphy, and ultrasound to diagnose difficult lamenesses in performance horses.


 On Thursday, Dec. 5., three speakers will give presentations during an in-depth session on Current Concepts in Equine Nutrition. The first talk will be by David Pugh, DVM, MS, of Auburn University, who will discuss nutritional problems of older horses and how to develop a feeding program for the older horse.

These horses are not able to assimilate phosphorus and nitrogen as well as younger horses, are at risk for liver and kidney disease, are more prone to colic, lose weight easily, have dental problems, or might be faced with arthritis. Pugh will discuss how diet can help the older horse through his golden years, even if health issues are present.

After his talk, Ginger Rich and Les Breuer will discuss recent developments in equine nutrition that can be applied on the farm and in the clinic.

Mules and Donkeys

 The Friday afternoon session will be devoted to four presentations on mules and donkeys. It is appropriate that time be devoted to mules and donkeys because of the changes that have occurred concerning the type of animals being bred, says Tex Taylor, DVM, of Texas A&M, who is a donkey breeder. His topic is "Donkey and Mule Scenarios: When to Stop, Think, Read, or Call." In the past, he explains, mules were mostly used as draft animals. Today, that has changed, with mules being asked to perform in many of the same disciplines as horses--reining, roping, cutting, dressage, jumping, and even racing. As a result, Taylor says, medical problems are now surfacing that weren't an issue before.

Yet, he is quick to point out, mules often have to be handled in a different manner when being treated or trained. Restraint is one example. When a twitch is applied to the horse, he says, the animal usually submits to the restraint. When the twitch is applied to a mule in the same manner, it might work, but then again, it might not. "That mule just may wander off, taking the twitch and the handler with him." Taylor will inform his listeners on the proper approaches to take when dealing with mules.

The session will open with Suzanne L. Burnham, DVM, of Graham, Texas, discussing "Anatomical Differences Between Donkeys, Mules, and Horses." She will be followed by Nora Matthews, DVM, of Texas A&M, who will talk about "Anesthesia of Donkeys and Mules: How They Differ From Horses."

David G. Pugh, DVM, of Auburn University, also a donkey breeder, will discuss "Donkey Reproduction." Pugh will tell his listeners that there are some basic reproductive differences between the donkey and the horse. He says that some of those differences are obvious, while others are subtle. For example, the gestation time for a donkey can be as long as 375 days. The normal gestation period for a horse ranges from 343-353 days.

Jacks (male donkeys) also have larger testicles and a larger penis than the horse, he says. Correspondingly, the jenny (female donkey) has a larger vagina when compared with the mare on a per pound basis. The jenny often remains in a state of estrus for a couple of days longer than the normal mare. One of the subtle differences between a jenny and a mare, Pugh says, involves the cervix, which is somewhat smaller in diameter in the jenny than in the horse.


 A variety of topics will be covered in the two medicine sessions to be held Friday afternoon and Saturday morning. For some talks, new research will be presented.

For instance, Emily Graves, VMD, an equine medicine resident at Michigan State University, will speak on the newly described endocrine disorder Peripheral Cushing's Syndrome (PCS). Graves said the veterinary community is just beginning to understand this disease, which is typically seen in middle-aged, overweight, or obese horses presented with laminitis. Horses often have excess body fat in the crest of the neck and near the base of the tail. She will present the results of a clinical study that assessed thyroid function in PCS-affected horses. Researchers used the overnight dexamethasone suppression test (DST) and the thyrotropin releasing hormone (TRH) suppression test to assess pituitary-adrenal and pituitary-thyroid axis function, respectively. To be included in the study, subjects had to show normal responses to the DST. Graves will present the results of the study, which provided useful information about diagnosis of this disorder and the thyroid gland's role in this syndrome.

Other topics include:

  • Exertional rhabdomyolysis in foals;
  • Rhodococcocus equi foal pneumonia;
  • Botulism in foals;
  • Treatment of Clostridium difficile toxins and Clostridium perfringens enterotoxin;
  • Clostridial myositis;
  • Urinary tract problems;
  • Antimicrobial resistance;
  • Cartilage degeneration;
  • Treatment of Cushing's Syndrome;
  • Prevention of equine protozoal myeloencephalitis (EPM);
  • Possible environmental sources of positive drug tests;
  • Joint lameness treatment; and
  • Exercise-induced arterial hypoxemia.  

Inflammatory Airway Disease

Respiratory specialists in recent years have researched methods to diagnose and treat inflammatory airway disease (IAD), a frequent contributor to compromised athleticism in the horse. An in-depth session on inflammatory airway disease will be held Dec. 7 at the AAEP Convention.

Laurent Couëtil, DVM, of Purdue University, will discuss "IAD: Cough, Poor Performance, Mucus in the Airways--What is So Important About That?"

Couëtil explains that, "Studies have shown that there is a strong association between finding mucus in the airway when you scope the horse's trachea after a race and poor performance. Hopefully, there will be a lot of healthy debate at AAEP through questions from the floor and interacting with the practitioners about new directions for research. We're trying to determine how to treat, prevent, and essentially decrease the incidence of IAD."

Andy Hoffman, DVM, DVSc, Dipl. ACVIM, head of the Lung Function Lab at Tufts University, will present the "Newest Diagnostic Methods for Inflammatory Airway Disease."

Bonnie Rush, DVM, MS, Dipl. ACVIM, associate professor of equine internal medicine at Kansas State University, will discuss "Treatment of IAD: Aerosol Delivery Devices and Medications Case Studies." Rush contributed to the development of Torpex, an inhaler device that allows metered-dose administration of albuterol sulfate (a bronchodilator) to the horse's airways through the nostril. She will discuss the advantages and disadvantages of the drugs and systems used by the veterinary community through a review of the literature based on the subject.

"Torpex improves pulmonary function by 70% in five minutes," she explains, adding that it can be used to open the airways for administration of another aerosol drug. "This treatment is not appropriate for the backyard horse--it is not economically feasible," she adds. "These products are for the client who makes their living off of the horses."


Computers and Ovulation

A hallmark of each AAEP convention has been an in-depth look at the latest developments in equine reproduction. A topic that will likely draw the interest of many veterinarians will be presented by Elaine Carnevale, DVM, MS, PhD, of Colorado State University. Her topic is "Use of Computer-Assisted Image Analysis to Determine the Interval Before and After Ovulation."

The computer, says Carnevale, can do a much better job than the human eye can in interpreting ultrasound images. The human eye can differentiate between only a few shades of gray, while the computer can analyze 256 variations. What all this means, she says, is that the computer can be a very helpful assist in determining when a mare will ovulate and the elapsed time if she has already ovulated. The technique she will discuss can be a real boon for veterinarians when close synchronization is required, and it can be extremely helpful to veterinarians who do not have a lot of experience with reproductive ultrasound.

EPM Treatment and Stallion Fertility

Treatment of stallions for EPM can cause reproductive after-effects. Steven Brinsko, DVM, PhD, Dipl. ACT of Texas A&M University, will discuss "Effects of Ponazuril on Reproductive Function of Stallions."

The purpose of the study on which he will report, Brinsko says, was to determine if the medication Ponazuril (used to treat horses with EPM) would have any negative effects on a stallion's reproductive functions, as has been the case with other EPM medications. While Ponazuril is more expensive than some other treatments, the recommended treatment period is shorter. Veterinarians and horse owners want to know if the drug has negative effects such as lower semen quality, or if it causes mounting problems. The study results on Ponazuril will be revealed at the convention.

Keeping Mares Out of Heat

Konnie Wendt, DVM, of Texas A&M University, will report on a study that looked at "The Effects of Deslorelin Administration in Vulvar Mucosa, with Removal in two Days, in Foal Heat Mares."

The negative aspect of deslorelin--mares sometimes having a delayed return to estrus after its use--have pretty much been negated by implanting the hormone in the vulva, then removing it. The question of this study was whether deslorelin would result in a predictable ovulation with mares in foal heat. Hear the results at the convention.

Other Topics of Interest

Other topics in the reproduction session include:

  • Relationship Between Estradiol 17-beta and Endometrial Echotexture During Natural and Hormonally Manipulated Estrus in Mares;
  • Mares Susceptible or Resistant to Endometritis Have Similar Endometrial Echographic and Inflammatory Cell Reactions at 96 Hours Post Infusion with Frozen Semen and Extender;
  • Induction of Lactation and Adoption of Foals by Non-Parturient Mares; and
  • Comparison of Three Holding Solutions for Cooled Storage of Equine Embryos.

Advances in Equine Surgery

One of the surgical topics of interest involves a study that started small, but has grown with time and still continues. The presenter is Debra Sellon, DVM, PhD, of Washington State University. She will report on research that examined the effects of "Continuous Butorphanol Infusion for Analgesia in the Post-Operative Colic Horse."

Her interest in equine pain management, Sellon says, began 10 years ago when she was at North Carolina State University. Research had shown that humans and dogs recover more quickly from surgery when they are not suffering from pain. She wondered if the same would be true with horses.

The second of two studies at Washington State, Sellon says, involved 31 horses admitted for colic surgery. (All of the owners consented to having the horses involved in the research.) In the study, some of the horses were administered the pain reliever butorphanol intravenously on a continuous basis for 24 hours, while the other group received saline.

Sellon will go into detail on the results during her presentation, but she did find that one group recovered more quickly, lost less weight, and spent fewer days in the hospital. But, as with every study, there were some downsides.

Beth Kraus, DVM, of the New Bolton Center at the University of Pennsylvania, will discuss "Laryngoplasty and Ventriculectomy or Ventriculocordectomy for the Treatment of Laryngeal Hemiplegia in 104 Draft Horses." The procedures to be discussed are for treatment of "roaring," a condition involving laryngeal dysfunction that quite frequently shows up in draft horses, Kraus says.

The procedures are performed while the horse is under anesthesia, and a key question the study was designed to answer involved recovery rates. She wanted to know which treatment approaches resulted in the most improvement. Also, she set out to discover which were able to compete after surgery. Many of the horses involved were competing in draft horse hitches, and one of the requirements is that there be no undue breathing noise.

One finding was that out of 111 surgeries performed, 11 draft horses had some complications, but only one failed to overcome the complication.

Other topics to be discussed in the surgery section include:

  • Transendoscopic Laser Cauterization of the Soft Palate as Treatment for Dorsal Displacement in the Racehorse as an Adjunct Treatment;
  • New Perspectives on Diagnosis and Treatment of Progressive Ethmoid Hematomas;
  • A Review of Conditions of the Equine Temporomandibular Joint;
  • Results of Plate Fixation of Third Metacarpal and Metatarsal Diaphyseal Fractures;
  • Equine Meniscal Injuries: A Retrospective Study of 14 Horses; and
  • Correlation of Lesion Size with Racing Performance in Thoroughbreds After Arthroscopic Surgical Treatment of Subchondral Cystic Lesions of the Medial Femoral Condyle: 150 cases (1989-2000).
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