AAEP Convention Wrap-Up 2004: Sports Medicine
Shock Wave Therapy
Several studies have been conducted on extracorporeal shock wave therapy (ESWT) at various institutions this past year. One presented by C. Wayne McIlwraith, BVSc, PhD, DSc, FRCVS, DrMedVet (hc), Dipl. ACVS, director of Colorado State University's Gail Holmes Equine Orthopaedic Research Center, involved ESWT's effects on osteoarthritis. In a model of induced osteoarthritis in horses, ESWT decreased lameness and synovitis, and it improved joint fluid and soft tissue quality. Anti-inflammatory activity continued for 42 days after the last treatment, when the study concluded.
Susan Holmcombe, VMD, PhD, Dipl. ACVS, ACVECC, associate professor in the department of large animal clinical sciences at Michigan State University, said mucus in a racehorse's trachea can prevent him from utilizing oxygen to the fullest. Accumulation of airway mucus, she said, is common in young horses and often stems from inflammation. The number of racehorses affected approaches 33%.
In an effort to find definitive answers, a study was conducted at Thistledown Racetrack in Warrensville, Ohio, from April to December in 2002 and 2003. Each of the 527 horses in the study was checked via endoscopic examination of the nasopharynx, larynx, and trachea on a monthly basis. Here are Holmcombe's conclusions:
"The results of this study suggest that moderate to severe tracheal mucus accumulation is a risk factor for poor racing performance in Thoroughbred horses. Indeed, horses with little to no tracheal mucus placed nearly twice as well in a race compared with horses with moderate to large amounts of tracheal mucus.
"Infectious agents can cause airway inflammation and mucus accumulation. Tracheal mucus is also a symptom of inflammatory airway disease, hypothesized to be a response to the contaminants found in the air of stables. These contaminants include small particulates, antigens from molds and fungi, dust from hay and bedding, air pollutants, dust from the arena, and endotoxins.
"Therefore, recommendations to improve airway health and minimize tracheal mucus in horses may lead to improved racing performance. Emphasis should be placed on reducing environmental antigens by improving stable ventilation, decreasing dust in feed and bedding, and isolating horses with infectious disease."
More information: www.TheHorse.com/ViewArticle.aspx?id=5442.
Performance Horse Forum
Performance horse veterinarians treat everything from the cutting horse to the dressage mount, but when it comes to issues pertinent to their practice, they are much alike. Online and traveling pharmacies, clients administering medications, drug testing at shows, and compounding were discussed at the Performance Horse Forum. Midge Leitch, VMD, Dipl. ACVS, of Londonderry Equine Clinic in Cochranville, Penn., and Darrin Kelley, DVM, of Redmond Veterinary Clinic in Redmond, Ore., moderated the session.
Practitioners attending the forum have had clients request prescriptions to be filled by discount online pharmacies. "Online pharmacies sometimes present an ethical problem for us," said one practitioner. "I make it very clear to my clients that (the medication from these operations) is not coming from my clinic, and we're not responsible (if something goes wrong)."
One veterinarian said he handles these inquiries from clients differently: "If a client requests a prescription for a bottle of Banamine, then I tell my clients that if their horse is colicky and it needs Banamine, then they need me."
Veterinarians could refuse to write the prescription, but that touched another issue, because in some states (i.e., Pennsylvania), if the client requests it, a veterinarian must provide a prescription for a drug he has indicated the horse needs.
"Write prescriptions and don't stock (major amounts of product), rather than let requests rattle you," suggested one vet. "Make your money on diagnostics and purchase exams. You cannot compete with those dot-com deals."
Vets mentioned the current availability of traveling pharmacies at horse shows from which owners can purchase medications. Leitch and many vets in the room expressed concern that a veterinary-client-patient relationship is not cultivated in these transactions, and that relationship must exist for a drug purchase to be considered legal.
A racetrack practitioner pointed out that there should be an effort on the backside of racetracks to watch the way medications are prescribed. "If we dispense a bottle for the trainers, they are going to use it any way they please," said the veterinarian. "Sometimes the convenience factor, the fear of losing the client, and the economics of selling that bottle" keep veterinarians from refusing to supply some drugs in quantity.
Another track practitioner said he had clients "that I know their horses need a tranquilizer to clip. I train that client, then dispense an appropriate amount of tranquilizer with a prescription label on it. But that's it, no bottles go out."
Other veterinarians pointed out that practitioners don't have the credentials and training to certify people in venopuncture and questioned whether instructing owners on how to give shots would be fostering them to practice veterinary medicine without a license. Most veterinarians agreed that the administration of shots by horse owners is a hard situation to avoid.
One veterinarian suggested that maybe the veterinary community should try to establish the legality of having vet techs administer injections so veterinarians don't have to spend so much time driving long distances to give a few shots. Currently, it varies from state to state as to whether vet techs can give injections.
Drugs in Competition--Drug detection has become more sensitive in recent years. One vet pointed out that positive drug tests might sometimes be an honest mistake, while other times it's cheating. "(Federation Equestre Internationale, or FEI) vets don't know how far out (how long before competition) to give the drugs now. What was perfectly applicable last month might not be today," he said.
Several performance horse vets are trying to put together a guide for "10 emergency drugs" for circumstances such as colic that require immediate treatment. Unfortunately, these necessary drugs will be detectable weeks later on drug tests. "Anything right now is too much (FEI has a zero tolerance rule); we know that's not practical," said one attendee.
The real issue is what qualifies as a therapeutic dose of medication and what is just a trace dose. "What affects the playing field?" asked one veterinarian, "and what's just left over in the horse?" It bothered some veterinarians that "horse show people have to practice under a no-foreign-substance rule, while there is a controlled medication program in racing."
Vets can get withdrawal times for specific medications by contacting the United States Equestrian Federation (information on drugs and medications can be found at www.usef.org/content/drugsMeds).
More information: www.TheHorse.com/ViewArticle.aspx?id=5419.
EIPH and Race Times
K.W. Hinchcliff, BVSc, PhD, Dipl. ACVIM, visiting fellow at the University of Melbourne in Australia, discussed the effect of exercise-induced pulmonary hemorrhage (EIPH) on race times when furosemide was not given. The study involved examinations of horses competing in events where furosemide is not allowed, and it involved Thoroughbreds competing at races in Victoria, Australia, between March 1, 2003, and June 18, 2003.
In the wake of examinations for EIPH, the Australian horses were graded from 0 to 4 for degree of severity of EIPH. A horse with zero grade meant there were no signs of EIPH, while a grade 4 designation meant the horse was a serious bleeder.
The study showed 322 horses were grade zero, 273 were grade 1, 101 were grade 2, 25 were grade 3, and 13 were grade 4.
Hinchcliff said the researchers concluded that "Horses with EIPH, defined as grade 2 or higher, were four times less likely to win, 1.8 times less likely to finish in the top three places, and finished 1.8 meters farther behind the winner than did unaffected horses. Horses with grade 4 finished an average of 3.4 meters farther behind the winner than horses with grade 0."
Hinchcliff said the results demonstrated that EIPH has a significant negative effect on race performance of Thoroughbreds, and that the more severe the affliction, the more profound is the effect.
More information: www.TheHorse.com/ViewArticle.aspx?id=5444.
P. Morley, DVM, PhD, Dipl. ACVIM, assistant progessor of epidemiology and biosecurity in environmental health and clinical sciences at Colorado State University, reported on a study involving the effects of furosemide (Salix) on the performance of Standardbred racehorses. He said the goal of this research was to use a large number of Standardbreds to determine whether first-time use of furosemide had a beneficial effect on racing performance.
He said that furosemide is administered to counteract EIPH--a malady that affects up to 75% of all racehorses to some degree.
Race records for horses at 82 tracks were included in the analysis. Of this number, he said, furosemide was administered to 4,631 horses (22.35%). The study showed more males than females were given furosemide, and the proportion of horses given furosemide increased with age.
Overall, Standardbred mares given furosemide finished 0.18 seconds faster than untreated mares; treated geldings finished 0.05 seconds faster than untreated geldings; and treated stallions finished 0.11 seconds faster than untreated stallions.
However, it was found that horses given furosemide for the first time did not have faster race times than untreated horses.
More information: www.TheHorse.com/ViewArticle.aspx?id=5443.
Evaluating Saddle Fit
Tracy Turner, DVM, MS, Dipl. ACVS, in discussing saddle fit, said, "Back problems are a significant cause of altered gait, poor performance, and misbehavior in the horse, particularly in English disciplines. The complexity of the back--its vertebrae, ligaments, and muscles--can make diagnosing, imaging, and treating problems very challenging. Musculoskeletal issues of other regions, particularly the hind limbs, can create secondary back issues; thus, a primary lameness must first be ruled out. Then the veterinarian should scrutinize saddle fit as part of the diagnostic work."
Problems that indicate saddle and/or back problems might include resistance to saddling such as tail switching, girthiness, and/or ear pinning. "If the horse resists, that's an abnormality," he stated. Other possible indicators of saddle pain are resistance to mounting, unresponsiveness to the rider's aids, and bucking.
The initial saddle fit examination begins with evaluation of the horse's back, including a fingertip exploration of the entire area under the saddle to identify any areas of localized pain or swelling, he said. Also, the horse should extend and flex his back willingly, and his vertebrae should be palpated.
Once this is done, saddle fit is subjectively evaluated. "The rider should be allowed to position the saddle and pad as he/she normally does," Turner said. "Many place the saddle too far forward, where it can interfere with the scapulas (shoulder blades) and the withers and tipping the saddle up so the rider sits too far back. After the saddle is positioned, the examiner should grab the pommel and give a sharp tug down and back. If the saddle moves and 'locks in,' it wasn't positioned correctly. If it doesn't move, then it was OK."
Then put the saddle on the horse without pads to check its balance, wither clearance, panel evenness, and width of the gullet. "Identify the lowest part of saddle (set a pencil on the seat crossways and let it roll down to the lowest point)," he directed. "It should be centered between the cantle and pommel. Otherwise, it affects the rider's balance, pushing them toward the low side."
Next check withers clearance (there should be 2 1/2-3 fingers' width there) and the position of the saddle points (the projections at the front and side of the saddle tree). These points shouldn't interfere with the scapulas' range of motion, and their angle should conform to the withers' shape. Mold a malleable ruler to the horse's back and seeing how well the saddle matches it. Many horses are asymmetrical and a malleable ruler is best for visualizing this, he said. Re-assess all parameters with the girth tightened.
Next, Turner instructed, press lightly on the seat center with one hand and run your other hand along the angles of the points and under the panels front to back, looking for rocking, pressure points, or bridging (gaps in saddle contact). Stand back and above the horse (perhaps on a mounting block), to make sure the saddle fits between the withers and the last rib, or it's too long. Also look at gullet clearance; the gullet should clear the spine and its ligaments regardless of pressure on the seat.
High-Tech Saddle Fitting--Turner described evaluating saddle pressure with
pressure-sensitive saddle pads and thermography. "The subjective elements of saddle fit are easy to perform and are useful in detecting gross problems," he said. "However, the identification of subtle fit problems may go undetected with these methods.
"With pressure-sensitive pads, you can see pressure points that interface that saddle and the pad (with or without a rider)," he said. "They're very accurate and give you great information. Thermography gives you a new dynamic interaction between the saddle and the horse's back, so you can see the heat generated by friction."
For thermographic evaluation, Turner said the horse is saddled with a simple cotton pad and lunged for 20 minutes at normal gaits in both directions, then the saddle and pad are removed and a thermograph is taken of the horse's back and the saddle's panels. Repeat with a rider.
"Thermography is one of the best methods of identifying back problems in the horse," he stated. "Abnormal pressure and/or friction will create a 'hot spot' that the thermal imaging camera can detect with at least 10 times more sensitivity to temperature than the human hand.
"A well-fit saddle shows symmetrical heat patterns, without localized hot spots (showing more pressure and friction) or cold spots (which might indicate intense muscle spasms or severe pressure damage and swelling)," he explained.
He also described his analysis of CAIR interchangeable tree saddles on a few horses using thermography. "The CAIR panel system worked better for some horses (with fewer pressure points) than their custom-fit saddles," he reported. Other observations following riding sessions were that heavier riders tend to use the cantle more than lighter ones. Regarding pads, Turner commented: "I think they make a lot of difference. Some put a lot of pressure on the withers, and some riders put on far too much padding. That just creates different kinds of pressure points."
What about treeless saddles? "We have some thermography data," he said. "The ones I've seen created more pressure on the center line, in my opinion. There may be more pressure and friction than riders think."
One vet asked about dry spots on a sweaty back. "I think wet and dry spots tend to be related to peripheral nerve injury produced by the saddle," Turner answered.
"In conclusion, saddle fit is an important aspect of evaluation for poor performance," he stated.
More information: www.TheHorse.com/ViewArticle.aspx?id=5393.
One key to enabling horses to perform at maximum is getting oxygen to tissues via red blood cells. Trainers and owners have used several approaches to do this, but one can have fatal consequences, according to C. Schwarzwald, DVM, Dipl., ACVIM, graduate student in the department of veterinary clinical sciences at The Ohio State University.
Schwarzwald said some administer recombinant human erythropoietin (rhEPO) to horses in an effort to increase red cell mass, which would increase the amount of oxygen carried to muscles and decrease fatigue. When the compound was administered three times a week to test horses, he said, it did increase the red cell mass, "suggesting the potential of this compound to improve the athletic capacity."
Then Schwarzwald dropped this bombshell: "Adverse effects of administration of rhEPO to horses are potentially fatal." It might induce production of anti-EPO antibodies that attack the horse's natural EPO; it is associated with severe anemia (lack of red blood cells) secondary to red cell aplasia (underdevelopment) that can cause death.
In one stable with 115 horses, Schwarzwald said, 14 were given rhEPO. Anemia was detected in eight of the 14 after treatment, and five of those eight died.
More information: www.TheHorse.com/ViewArticle.aspx?id=5441.
BY STEPHANIE L. CHURCH; ROBERTA M. DWYER, DVM, MS, DIPL. ACVPM; LES SELLNOW; AND CHRISTY WEST
About the Author
POLL: University Equine Hospitals