Lameness in the Racehorse Table Topic (AAEP 2011)

Malcolm J. Borthwick, VMD, practiced on Standardbreds in New Jersey and Pennsylvania for 30 years, and in his retirement continues to enjoy owning and driving racehorses. In his introduction to the Lameness in the Racehorse Table Topic presented at the 2011 American Association of Equine Practitioners Annual Meeting, held Nov. 18-22 in San Antonio, Texas, he emphasized the importance of the foot and felt that it is overlooked as a common seat of lameness in the racehorse. He also asserted the importance of the veterinarian having a good relationship with the trainer and groom, which facilitates reaching a diagnosis and ensures more effective follow-up care.

Melissa McKee, DVM, is a partner at McKee-Pownall Equine Services in Toronto, Canada. Her caseload is 70% Standardbred and 30% Thoroughbred/racing Quarter Horse, and she focuses primarily on lameness diagnosis and advanced imaging, including MRI. She also believes that a good relationship with the trainer and groom is vital, because a detailed history from those working closely with the animal provides important clues to the underlying problem. She also mentioned several subtle findings such as abrasions in the mouth, shoe wear, and various areas where a horse might interfere with himself while trotting or galloping, that are important details to notice during a workout. Both veterinarians agreed that a very thorough physical exam was essential before moving toward any type of imaging or treatment.

Attendees addressed several issues concerning the foot. Horses without a notable lameness or respiratory issue, but that were unwilling to pass other horses or finish the race strongly, often have bilateral (affecting both limbs) foot pain that saps their desire to be competitive on the track. Both Thoroughbred and Standardbred veterinarians in attendance commented on the long toe/low heel conformation as contributing to deep-seated foot soreness despite reasonably normal radiographs (X rays). All felt this was frequently related to soft tissue injuries within the hoof, particularly to the deep digital flexor tendon as it inserts on the bottom of the coffin bone. McKee confirmed she has noted that type of lesion on MRI scans of affected horses. All agreed this type of foot conformation was often acquired due to typical shoeing techniques encouraging a long toe, because it is erroneously assumed this will lengthen the horse's stride. Unfortunately, crushed heels are a difficult problem to fix, and wedge pads will worsen the issue. Shortening the toe and trimming the crushed heel, while adding various types of pad to redistribute the weight, is often the best solution. Most veterinarians stated they would also perform injections or shockwave therapy to help treat local pain and inflammation.

Attendees discussed club feet and the question of whether to perform an inferior check desmotomy (cutting of the ligament) in a yearling with club feet. All agreed that a club foot in an older horse should not be corrected through shoeing, as dramatically lowering the heels would create lameness by altering the established limb mechanics. There was some debate over performing surgery on young horses, but most veterinarians felt the resulting adhesions could be quite problematic later on.

All agreed that wherever a synthetic track surface had been installed, there was a dramatic change in the type of lameness problems that occurred. Several Thoroughbred veterinarians had noticed an increase in condylar fractures, sore shins, and pelvic issues. Improper conditioning of the racing surface might be part of the problem. A physical therapist commented that she often sees horses that train on dirt go on to develop significant body soreness when they move to synthetic surfaces, probably due to the increased traction. Once they become accustomed to it the soreness dissipates.

Several veterinarians agreed that back and neck pain was underdiagnosed in the racehorse. McKee has found several abnormalities in the neck and pelvis on both radiographic and ultrasound examinations and has had good results treating specific lesions with ultrasound-guided injections and other therapies. Elevating the head with an overcheck in the Standardbred can aggravate existing cervical facet arthritis, and spinal impingement, lumbar pain, and sacroiliac (SI) disease are evident in both breeds. The power with which a racehorse breaks from the gate places significant strain on the SI region (where the spine joins the pelvis), and many also have pelvic asymmetry from gate/stall door mishaps. While many back problems result from compensation for chronic lower limb lameness, primary back injuries do exist, and both require treatment.

Equine protozoal myeloencephalitis (EPM) was discussed and--particularly among veterinarians from the Northeast--was felt to be "at least a minor contributor in the majority of poor performance problems." Since this disease tends to cause vague and variable clinical signs and a diagnosis is difficult to confirm, many horses are treated preventively with various available products. Many veterinarians have observed affected horses to be sensitive to high doses of potent corticosteroids, and this affected their medication choices when treating these horses.

This table topic was moderated by Malcolm J. Borthwick, VMD, a practitioner from New Hope, Pa., and Melissa McKee, DVM, of McKee Pownall Equine Services in Toronto, Canada.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.

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