AAEP Convention 2001: Veterinary Forums
The day before the scientific sessions started during the AAEP Convention, there was a series of forums and committee meetings. These were moderated by selected experts in those fields, and were open to anyone for a majority of the time. The last 45 minutes of the meetings were open only to AAEP members to discuss anything they felt was too sensitive to broach during open sessions. This schedule was different from last year, when all sessions were open only to AAEP members.
Reproduction and Pediatrics
The Reproduction and Pediatrics Forum began with a report on mare reproductive loss syndrome (MRLS) by Ro berta Dwyer, DVM, MS, Dipl. ACVPM, of the University of Kentucky Gluck Equine Research Center. She discussed the status of the monitoring program that will be in effect for spring 2002. At least a dozen farms in Central Kentucky will have extensive monitoring of pastures and broodmares in order to detect any changes that might mimic 2001.
Multiple research projects have continued and are being planned for spring 2002 in UK's College of Agriculture. To date, a cause for MRLS has not been determined.
The gravity of West Nile virus (WNV) in Florida was discussed by Michelle LeBlanc, DVM, Dipl. ACT, of the University of Florida's College of Veterinary Medicine. In the first week of October 2001, 18 horses (including seven foals) were admitted to the equine clinic and were WNV positive. Research is ongoing at the University of Florida on the response of horses to the WNV vaccine.
Research into Clostridium perfringens in foals was reported by Josie Traub-Dargatz, DVM, Dipl. ACVIM, of Colorado State University's College of Veterinary Medicine. Feces from normal foals were tested for C. perfringens, and 90% shed the bacteria at three days of age. However, no C. difficile was detected (possibly due to difficulty in culturing). Several types of C. perfringens exist, with type C being the most deadly, causing bloody diarrhea in foals under five days of age.
Peter Timoney, FRCVS, PhD, head of the Gluck Equine Research Center at the University of Kentucky, reported that contagious equine metritis (CEM) was detected in 15 stallions imported into the U.S. and four imported from Germany into Canada. This emphasizes the need for vigilance in post-import test breeding for CEM.
There was much discussion among veterinarians and researchers about how vaccines are tested for safety and efficacy. One consensus seemed to be that having a "challenge model" is important, although not absolutely necessary, in creating a viable equine vaccine.
"There are alternatives to challenge models," said Rocky Bigbie, DVM, with Fort Dodge Animal Health. "There are human vaccines with no challenge model, and there are vaccines for horses and other animals that have no challenge model."
There also was discussion of new intranasal vaccines for strangles (produced by Fort Dodge) and influenza (Heska). One practitioner asked about the development of abscesses following strangles vaccination and wondered if the exudates from those animals' abscesses was contagious.
Bigbie said research indicates that the organism in the vaccine won't revert to virulence, and there is no evidence that non-vaccinated horses became infected with strangles because a vaccinated horse's abscess was infective.
Veterinarians said something needs to be done about the availability of prescription medications to horse owners, and the sale of non-licensed medications. The consensus was that those companies need to be put out of business, and that state licensing boards need to become more aggressive on regulation because it is the veterinarian who is breaking the laws of his/her state by using unlicensed products.
Some veterinarians said that compounding companies that are only allowed by law to compound and ship within their own states are shipping products nationally. Also, there is no quality control over the products.
The next topic of discussion was subtherapeutic antibiotics. While this is a problem in food animals because of contamination of meat and milk, the worry in horses is that using antibiotics at a level below that needed to destroy organisms is not a good idea because it can create resistant "bugs" and make them harder to kill in the future.
The group agreed that the AAEP should encourage education of veterinarians and their clients on judicious use of antibiotics, and that AAEP members should be made more aware of the AAEP's guidelines concerning antibiotic use.
Infectious Diseases Forum
The world is keeping its eye on infectious diseases because of the terroristic use of anthrax--and the potential use of other biologics--as agents of war against humans. However, veterinarians deal on a daily basis with diseases that can have deadly effects on humans and horses. Included in those diseases is West Nile virus (WNV), which was a major topic of discussion in the forum.
WNV has been found in mosquitoes, birds, horses, and/or humans in 27 states in 2001, according to Bill Saville, DVM, PhD, Dipl. ACVIM, of The Ohio State University. Five of 44 human cases resulted in death, and the fatality rate in horses has averaged about 24% in those with clinical signs. One veterinarian said that in Florida, many more horses are dying from WNV than the official numbers indicate.
"Ohio has been very aggressive in its vector control education of the public," said Saville, who attributes the fact that Ohio has had no equine or human cases to that education process.
There are only six products licensed by the FDA to control adult mosquitoes, and the general public is wary of spraying. That is why Saville and his colleagues have focused on environmental control of breeding sites and killing of larvae. He said mosquito dunks were safe when used in water tanks, and many Ohio horse farms use them.
Timoney said the IgM Elisa test used to screen for antibodies against WNV is reliable in diagnosing recent infection, but a serum plaque reduction neutralization test should be used to confirm the diagnosis. He said there is a small population of horses which do not develop a detectible IgM response, but are positive on the serum neutralization test. Vaccinated horses do not develop a detectable IgM response, but do develop a significant neutralizing antibody response after the second dose of the inactivated vaccine.
Can humans acquire WNV without mosquito transmission? It is a remote possibility. Virus transmission is possible if the virus enters a break in the human's skin from handling an infected bird. Anyone removing dead birds should wear disposable gloves, or turn a garbage bag inside out to pick up the bird and avoid direct contact.
A Fort Dodge Animal Health representative said that of the more than one million doses of WNV vaccine that have been distributed, there have been no cases of WNV in horses which had their initial course of two doses of the vaccine administered three to six weeks apart and were at least three weeks beyond the second vaccination. This was true even in horses vaccinated in the face of the WNV outbreak in the Florida panhandle.
Equine Protozoal Myeloencephalitis
Equine protozoal myeloencephalitis (EPM) has no challenge model because of the difficulty in solving the life cycle of the causative parasite, Sarcocystis neurona. Saville said that research on developing a way to consistently give horses EPM under experimental conditions has been completed at The Ohio State, but he reserved comment until tests are completed. He says that there is a stress factor involved in whether exposed horses develop the disease. (Remember, while more than 50% of horses in some areas are exposed to the parasite and develop antibodies, only about 1% of exposed horses exhibit clinical signs of EPM.)
Another problem with EPM is proper diagnosis. While a negative Western blot test is a good indicator that the horse has not been exposed to the parasite and therefore doesn't have EPM, there isn't a definitive test to prove a horse with neurologic signs has EPM.
Bigbie, of Fort Dodge Animal Health, said that research has shown that the EPM antibody from the vaccine does cross the blood-brain barrier, yielding a positive Western blot test result.
Because so much is unknown about this disease and so many different research institutes are working on the problem, an EPM Society was formed last year to bring together all those involved in this disease.
"We've come out with a list of research priorities to send to funding agencies in the hope of having universities work together to solve the puzzle of EPM," said Saville.
There will be a half-day session at next year's AAEP convention to share the information that has been learned about EPM.
Mare Reproductive Loss Syndrome
While mare reproductive loss syndrome (MRLS) is not an infectious or contagious disease, it received attention in the forum. Management guidelines put out by the University of Kentucky can be found on www.TheHorse.com with Article Quick Find #3188 or through the university's web site at www.ca.uky.edu.
A unanimous show of hands supported a suggestion that AAEP in 2002 have a session on foreign and emerging animal diseases that can affect U.S. horses.
Purchase Exams at Public Auction
Most of the veterinarians in the forum were top practitioners who handle pre-purchase examinations of racehorses at public auction and are faced with the responsibility of making recommendations based on radiographs taken by another veterinarian. Repositories were designed to cut down on the repetitive use of radiography on the sales ground, but in this imperfect and sometimes dishonest world, not all radiographs are meant to show imperfections in sale horses.
"Part of the problem of reading the radiographs is the quality of the radiographs," said Jim Becht, DVM, Dipl. ACVIM, of Colorado State University. "If you don't know what you're doing (taking radiographs), you should leave your equipment in the car."
Not all practitioners agreed on what kind of assessment should be given to the buyer based on radiographs. Some veterinarians recommended a lengthy report on what was seen in the radiographs, and another report telling the client what the findings could mean for the future of the horse. This could minimize the chance for surprises and litigation following the sale. Other veterinarians felt that giving too much information in a report might be a bad idea, as the information might get shared freely with other potential buyers, resulting in too much weight put into one veterinarian's opinion of the horse.
Veterinarians supported the AAEP's published Position on Sale Disclosure that, "supports the position that when a horse is sold, any known invasive surgery, disease, injury, or congenital defect which is not apparent should be disclosed to the intended buyer by the owner and/or agent."
According to the veterinarians at the forum, if state law would allow it, drug tests should be handled the same way at the two-year-old sales as they are at the races. Frustration was expressed because of laboratories having different testing sensitivities, producing positives at sales that would have been passed at the track.
The group then discussed computerized (or digital) radiography (CR), and how the technology might revolutionize pre-purchase exams. Although they all agreed that CR has tremendous application in equine practice, it is not commonly used at sales at this time. "It's coming, and it's good technology," said one practitioner.
Veterinarians taking part in the Purchase Exam forum Saturday discussed a variety of topics, many dealing with the risk of litigation pertaining to purchase exams. Radiographs still play an integral part in purchase exams. Practitioners are often asked to interpret radiographs for horses they have not examined. "You can only provide a radiographic consult. If it's pathology, say what's there," explained Rick Mitchell, DVM, IVAS, a facilitator in the session.
It was suggested that a veterinarian should diagnose "a greater risk for unsoundness" rather than recommend whether the potential owner should buy the horse. Daniel Marks, VMD, said, "I'd like to see him go on the surface he's been working over. He is more likely to stay sound on footing that's more comparable."
Some veterinarians customarily take blood and urine samples to screen for drugs at a purchase exam. While some vets provide storage of the samples for future reference for a fee, others will not provide the service because of security reasons.
One veterinarian stressed that the buyer should research past performance of the horse. The horse might have been performing well with a particular fault. On the other hand, the horse might have refused jumps at the last five horse shows, signaling an imminent problem.
Finally, Marks recommended that practitioners follow a checklist while doing a pre-purchase exam. While the veterinarians agreed that it would be logical to have a standardized form for all exams, individuals pointed out that different aspects of the exam are stressed depending on the discipline for which the horse is used.
The Racing Forum at the AAEP meeting was a preview to what would be presented at a medication summit held in December 2001 during the University of Arizona's Racing Symposium. While there was some dissent among the ranks of the AAEP members during the forum about the way the medication summit was being handled (with closed meetings and invited representation), the majority of vets who voiced an opinion were in favor of trying to create uniform, nation-wide medication regulations for racehorses. (For more on the medication summit, see article Quick Find #3208 at www.TheHorse.com.)
"Challenge ideas and not personalities," encouraged Nat Messer, DVM, moderator of the AAEP Welfare Forum. Equine slaughter and the management of wild horse populations were the main topics discussed by veterinarians and welfare organization representatives in attendance.
The group debated current legislation on transportation to equine slaughter facilities, alternatives to equine slaughter, the horse's status as livestock, and carcass disposal issues. Some were very passionate about abolishing slaughter, but few outlets could be offered other than retirement farms and therapeutic riding facilities, which aren't always the right fit nor are they able to accommodate the number of horses that are currently being sent to slaughter each year. It was agreed that more education of the horse-owning public was necessary, and that more responsible breeding might help lower the numbers of unwanted animals.
Some veterinarians brought up the drawbacks of slaughter alternatives. In some states, horse burial is not allowed, and few landfills accept horse carcasses. Some owners are reluctant to pay for the costs of euthanasia and carcass disposal.
The group questioned whether there had been a noticeable change in the number of humane society calls in California since horses were reclassified as companion animals (in 1998) in that state. One representative of a humane organization pointed out that anecdotally, the law has had no impact on slaughter. "The mindset of (some) people is that they don't care that slaughter is an option--my feeling is that they will starve their horses no matter what."
Discussion turned toward wild horses, particularly after adoption. The increasing reduction in wild horse herds by the Bureau of Land Management was also discussed. Genetic viability of herds, sterilization ventures, predator management, compliance checks of adopters, and the challenge of owning these wild equids were discussed.
POLL: Rabies Vaccination