February 15, 2000

 

 Treatment advances reported at equine meeting

Posted Feb. 1, 2000

Keeping current on new medical and practice information was paramount in sessions attended by equine practitioners during the American Association of Equine Practitioners annual convention, Dec 5-8, 1999 in Albuquerque, NM. Practitioners acquired information on advances in research and tools with which to operate, in practice and in business.

Lowell Catlett, PhD, futurist and New Mexico State University economist, delivered the keynote speech. He said, "The demand for animal services will increase." In today's economy, people can afford tangible goods (eg, televisions, cars) and still be in a financial position to spend money on services.

The Frank J. Milne State-of-the-Art Lecture was delivered by Dr. I. G. Joe Mayhew, Department of Veterinary Clinical Studies, Royal School of Veterinary Studies, and Large Animal Hospital, Easter Bush Veterinary Centre, University of Edinburgh, Edinburgh, Scotland.

Dr. Mayhew's lecture, "The Equine Spinal Cord in Health and Disease," reviewed the healthy spinal cord and identified specific conditions associated with spinal cord injuries and diseases.

"Many variations exist for all equids. You won't know if an animal has 17 vertebrae. From a radiology point of view, that can be important," he said, adding that most of the understanding scientists have about the equine spinal cord is assumed from work in other species and derived from observations of equine neurologic diseases.

Outlining methods of performing neurologic examinations of horses with potential spinal cord problems, Dr. Mayhew encouraged the audience to test for muscle atrophy as well as gait abnormalities, weakness, ataxia, and posture deficits.

Dr. Mayhew gave descriptions and suggested treatment of such diseases as cervical vertebral malformation, occipitoatlantoaxial malformation, neonatal Thoroughbred foal ataxia syndrome, and such physical defects as spinal cord trauma and discospondylosis.

With spinal cord trauma, Dr. Mayhew said, "We must not manipulate necks of horses without a definitive diagnosis. One horse was brought to a chiropractor, and this made the situation worse."

The clinical signs of equine protozoal myeloencephalitis can vary so much that some horse owners may jump to conclusions when their horse has a spinal cord problem. "But don't rule out other diseases," Dr. Mayhew said. Toxic disorders and nutritional conditions also cause horses to stagger as if they have spinal cord injuries.

Back by popular demand was the second annual Kester News Hour; emceed by Dr. Larry Bramlage, equine veterinary surgeon, Lexington, Ky, and Dr. John Madigan, professor, Department of Medicine and Epidemiology, University of California-Davis School of Veterinary Medicine. They reviewed the most pertinent news in the eyes of many equine veterinarians — the West Nile virus outbreak situation (see www.avma.org or www.aaep.org for status reports).

Dr. Mayhew visits with audience member
Guest lecturer Dr. I. G. Joe Mayhew visits with an audience member.

Dr. Bramlage discussed use of equine nasal strips (trade name: Flair) in sport horses. Dr. Bramlage said 25 percent of the Breeders' Cup runners and three of the eight winners wore them.

"Early research shows [the nasal strips] decrease oxygen consumption and decrease carbon dioxide production," Dr. Bramlage said. "It is proposed that [the strips] reduce the work of breathing. The promising thing is that in research it showed decreased bleeding. ... Is a nasal strip a piece of equipment or something that should be deemed illegal? The jury is still out on this."

According to Dr. Madigan, one recent development in California is the opening of the Kenneth L. Maddy Equine Analytical Chemistry Laboratory. The 29,000 square foot, $7.4 million building opened in February 1999. "[Laboratory employees] will begin screening up to 12,000 post-race drug-testing samples on behalf of the California Racing Board this spring. ... The equipment that is in this laboratory will hopefully bring state-of-the-art testing to the area."

Because alternative therapies are becoming acceptable to an increasing number of veterinarians, the AAEP is looking into developing appropriate terminology. "Use of alternative therapy has been exploding. AAEP is investigating the use of the term chiropractor, and it may be limited [legally] to humans. There are some regulations that say the term chiropractor means a person working on another person," Dr. Madigan said. He mentioned that two studies are looking at acupuncture efficacy and the ability of nonveterinarians to use acupuncture on animals.

"One concern is where ineffective [alternative] therapies [are] prescribed in lieu of effective ones that are in the literature and published and shown to be effective. Some liability concerns have come up as a result of that," Dr. Madigan said.

Racing of two-year-olds has been a debated topic, so veterinarians have tried to study the effects of this practice. According to one study, Dr. Bramlage said, "The first race at a younger age was a statistically significant factor at making the horses have a longer career. The next time a person comes up and says you're shortening a horse's career by racing them as two-year-olds, this is the first hard, objective [data you can cite] on a large population of horses that negates that [theory]. This shows that if they race younger, they race longer. More days between races also was associated with a longer career."

Another study revealed that wild horses could acquire degenerative arthritis similar to that of racehorses. "These injuries are not something that we are creating that the horses would not have sustained on their own. These horses got it, and they never had a bridle on," Dr. Bramlage said.

A JAVMA study (see Sept 1, 1999, page 630) determined that furo-semide (trade name: Lasix), administered in racehorses, significantly reduced peak mean pulmonary artery pressure. "I think a lot of the data from the study are good, but there are things that could be looked at," Dr. Bramlage said.

Because of another new study, the age-old question of proper cooling of a hot horse has been answered. "[Dousing a horse with cold water] is a safe, effective means for facilitating heat dissipation of horses after exercise even in a hot, humid environment where there's not much evaporation," Dr. Bramlage said. No cramping or muscle problems resulted from cold-water baths.

A timely topic at the inaugural Kester News Hour in 1998 and again this meeting was equine protozoal myeloencephalitis. "There certainly needs to be some improvement in how to interpret the western blot positive, Dr. Madigan said. Michigan State researchers have developed a new western blot test that they think will be more sensitive and specific. They believe that some of the false-positive CSF results can come from nonspecific bands. They say there are nonspecific bands in the standard western blot test that do not represent exposure to the causative organism of this disease, which is Sarcosystis neurona."

Dr. Madigan attributed a prevalence of false positives to measurement of the wrong antigen, contamination of CSF with serum, latent infection, and prior treatment of the disease, of which the attending veterinarian is unaware.

The 1999 AVMF Bayer Excellence in Equine Research Lecture on equine strangles was given by recipient Dr. John F. Timoney, Gluck Equine Research Center, University of Kentucky. Dr. Timoney described the pathogenesis of the disease, tracking the organism as it enters through the mouth or nose via feed and water and attaches to lingual and palatine tonsils.

Equine nasal strip
Nasal strips are becoming commonplace in equestrian events.

Dr. Timoney said the disease travels to the lymph nodes within hours. "Basically the disease is an outpouring of neutrophils in the lymph nodes," he said.

Clinical signs of Streptococcus equi include fever 12 to 28 days after exposure, abscesses 13 to 34 days after exposure, and shedding from nasal passages 17 to 40 days after exposure.

Immunity generally results after a natural occurrence of the disease. Strangles vaccines can cause inflammation and abscess formation and can trigger systemic responses in vaccine recipients. "The disease itself does stimulate some type of immunity. This is something we would like to mimic in a successful vaccine," Dr. Timoney said.

Several other timely scientific presentations were given. An afternoon of sessions was devoted to a modified-live equine influenza virus vaccine (trade name: Flu Avert) that received USDA approval Nov 18, 1999. Dr. Robert E. Holland, Gluck Equine Research Center, University of Kentucky, reported on the efficacy and safety of the vaccine in young equids, finding it was effective in preventing clinical signs for type II influenza virus strains. Other veterinarians reported their findings on the vaccine during the meeting, concluding that protection was demonstrated at five weeks and at six months after administration, establishing the vaccine as safe.

Dr. Paul Lunn, Department of Medical Sciences at the University of Wisconsin School of Veterinary Medicine, reported, "It is best not to give other safe, live vaccines within the same 10-day period. We were not aware of any contraindication of administering killed and live vaccines on the same day."

New findings on equine monocytic ehrlichiosis, commonly known as Potomac horse fever, were reported by Dr. Madigan. The causative agent in equine monocytic ehrlichiosis (ie, Ehrlichia risticii) was found to be transmitted by trematodes from freshwater snails.

"This is a disease with clinical signs that are fairly common and no specific hematologic signs," Dr. Madigan said. Horses that contracted the disease generally had a history of exposure to or consumption of water from streams with infected snails.

In addition to scientific sessions, new officers and directors were installed, and awards were given to deserving veterinarians and members of the equine industry (see related stories, page 470 and 471).

The 2000 AAEP annual convention will be held Nov 26-29 in San Antonio, in conjunction with the Society for Theriogenology.