Saturday, June 11, 2011

No foot, no horse

Yesterday's theme was lameness. Lameness is a huge part of equine practice, particularly sporthorse practices. The term "no foot, no horse" describes the fact that whether on the trail, on the flat, over jumps, or in front of a cart, a horse's purpose in life is to perambulate in some way.

Not having grown up on the back of a horse, lameness is mysterious to me, and an area in which I am honestly not sure I will ever be comfortable. In referral practice (like at the vet school) it is the realm of the surgeon, whereas my nascent interests tend toward internal medicine. Nevertheless, I was in the presence of an expert yesterday and within the context of lameness I had a revelation about systematically approaching a problem.

A lameness exam, put simply, consists of watching a horse move through all of its gaits, palpating tendons and joints, performing flexions, and watching it go some more. Depending on the character of the lameness and the resources of the owner, it may involve nerve blocks, radiographs, or ultrasound. To the inexperienced observer, abnormalities in the horse's gait are almost impossible to see unless they are extraordinarily severe.

Dr. C's first exam was a flea-bitten gray (think red-freckled) Hanovarian-type gelding. The horses in my life seem to be getting bigger; I remember my grandma's Morgans being much smaller than the thoroughbreds I ride now, and the Hanovarian was bigger still, with withers that were level with the top of my head. I had the job of jogging him up and down while Dr. C evaluated his gait both going and coming. The horse may have been jogging, but I was definitely sprinting. Dr. C flexed each of the horses joints as hard as he could, and then watched him trot more to see if he could elicit a lameness that way. After he had formed preliminary opinions based on these flexions, and his palpation of all of the major tendons in each leg, Dr. C requested to watch him go on a longe line. I was deemed too inexperienced to longe the horse, which hurt my pride. The outcome was positive, however, since Dr. C did what nobody ever had before, and explained to me what he was looking for as the exam took place.

Even most horse owners watching a lameness exam would see only this picture: a horse moves in a large circle around a handler holding the line and walking in a smaller circle to keep the horse moving forward. The vet stands and watches, occasionally requesting changes of pace to the walk, trot, or canter, and changes of direction. After twenty minutes or so, he will describe what he saw and how that bears on the horse's soundness. He may perform more flexions or watch the horse go in a straight line again. He may block certain nerves in the legs to try and localize where the pain is coming from.

Leaning on the paddock fence, Dr. C described to me what he was looking at. On some rounds he looks at the head for any bobbing. He looks at how far each hind leg moves cranially during the canter, and compares it with the length of the stride on the other lead. He evaluates whether they canter comfortably in either direction, or whether they tend to break from the canter due to discomfort. I will not describe the exam in any more detail because I know I could not do it justice. I will need to be coached through dozens more lameness exams if I am ever to really understand it. What was a revelation to me, however, was the systematic approach. When Dr. C described his approach, it dispelled one layer of the mystery of lameness for me. I saw that, with practice, it was not so much different than learning to read a radiograph; you have a set series of steps to go through to ensure you evaluate everything and don't miss any abnormalities. I believe that there is a true art to lameness evaluation, but yesterday's experience convinced me that perhaps it is a skill that can be learned.

The idea of systematic approaches to diagnostic problems has been a theme of my veterinary education so far. Before starting school, I was daunted by the prospect of cramming enough knowledge into my head to ever successfully diagnose an animal. To my mind, not terribly systematic naturally, it appeared that veterinarians were walking compendiums of animal disease who could look at an animal, lay hands on it, and know how to treat it. I now realize that only a savant could function this way. In reality, an animal is examined, a list of differential diagnoses is created, and this list is sorted and refined systematically. After years in practice, one gets used to clinical signs that are most often correlated with certain disease processes, and this can give the impression of encyclopedic knowledge. Systems, however, help prevent diagnostic mistakes.

After so much jogging I fear I have come up lame. I think I'll spend my weekend afternoon reading and resting my feet in preparation for tomorrow's jaunt up to the East Bay!

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