By Dr. Steve Levine, member of the Vermont Veterinary Medical
practicing at Northern Equine Veterinary Services in Danville, Vermont.
Lameness evaluation is a common procedure in veterinary practice. There are a large variety of lameness problems because of the wide range of horse breeds and their uses. Evaluation of the lame horse begins with a complete history of the animal and its particular problem. The age, sex and breed of the animal are determined and the onset, progression and duration of the lameness is described by the client. Because certain lamenesses are more common in certain breeds or ages or in their onset or progression this information is extremely valuable in determining the definitive cause of the problem. Only by making an accurate diagnosis of the problem can a rational plan for treatment be instituted.
In general, the lameness evaluation itself begins with a determination of which leg is lame. In the forelegs this is determined by the "head nod" (the head and neck nodding down on the lame leg and then up as the sound leg strikes the ground) while in the hind end the "hip hike" (the pelvis raising up as the lame leg hits the ground while the pelvis sinks with the weight of the sound limb as it hits the ground) is observed. This is best observed on a flat, firm area. If the lameness is subtle or difficult to observe then observing the horse on the longe line, on harder ground or under saddle may be necessary. It is important to note that the large majority of lameness problems occur in the forelegs because more of the horse's weight is borne here and that the large majority of these lamenesses originate from the foot.
Once the affected leg is determined than the next step is palpation or feeling of the leg. Because the majority of lameness problems involve the foot, the hoof tester examination is an invaluable part of any lameness exam. The hoof tester is an instrument that allows pressure to be put on different parts of the foot, thereby determining any sore or painful areas. The rest of the leg is then carefully felt again to determine any sore, painful, hot or reddened areas indicative of inflammation.
Local nerve blocks are also an integral part of the lameness exam. In this procedure a small amount of local anesthesia is injected around the nerves that supply a given portion of the leg thereby removing feeling from this part. If the horse is sound following this "block", then the area causing the problem has been located. If the horse is still off, then blocks are moved further up the limb until the lameness disappears. Using these local nerve blocks allows veterinarians to definitively determine at least the anatomic area of the problem.
Once the particular area of lameness is determined there are several diagnostic options available to further identify the problem. Most commonly your veterinarian will recommend radiographs (x-rays) to evaluate the particular region. Some cases require the use of the diagnostic ultrasound machine, especially if the lameness involves tendons or soft tissues as opposed to the bone.
Following determination of the precise cause of the lameness it becomes necessary to formulate a treatment plan for the horse and owner. This plan may involve rest, drugs, physical therapy, complementary therapies (chiropractic, acupuncture), trimming and shoeing changes, or any combination of these. Working with local farriers is an important part of equine health care, especially when it comes to soundness issues.