(The following article, written by Gail Burgess, is an excerpt from "Peak Performance: Coaching the Canine Athlete", a two-day seminar given by Chris Zink, D.V.M., Ph.D on May 9-10, 1998. It is printed with Dr. Zink's permission.)
You, as the owner and working teammate of your dog, are the best evaluator of any alterations of your dog's health or behavior. Lameness is an indicator of pain; it can indicate injury to soft tissue, bone, tendons or ligaments, muscles, nerves, presence of a foreign object, or it may be a mechanical problem. Lameness may not be apparent when the dog is excited, but it is important that the dog not work until an evaluation is made in order to prevent further injury. If the handler can assess the dog and give the veterinarian as much specific information as possible, it saves time, expense, and stress on the animal.
Evaluation is best done when the dog is standing, walking, and trotting.
The dog should be in a natural position, unstacked, without any pressure on the collar. If you know what to look for, this can give you the most information. Look at the position of the feet, and whether one foot appears smaller than the others. This will be a non-weightbearing foot. A foot placed ahead of the other will also not bear as much weight. Note whether the tail hangs off to one side (away from the injured side). Look for asymmetry in how the dog stands. A pelvis or withers higher on one side indicates unequal weight distribution. Move the dog forward a few steps and look again. How easy is it to move a foot out of position? A non-weightbearing foot will be easier to position. Examine the toenails for uneven wear; a foot that is not picked up will have nails worn down further. Move and stand several times until you have consistent clues to the injury site.
It is best to observe the dog from the front, side, and rear. Flexing the legs before having the dog move can make lameness more apparent. If the dog moves after rest resulting lameness is indicative of arthritis. If a front leg is affected, the dog's head moves UP when weight is on that leg to minimize weightbearing. It's easier to watch a moving dog's head come DOWN when he uses his good leg. If the affected leg is a rear limb, it can be assessed by standing behind the dog and watching the pelvis rise when weight is placed on the injured leg. Length of stride may also be affected.
One of the most helpful tests to detect lameness is the cornstarch test: sprinkle cornstarch on some paper and coat the dogs paws with it, then walk him across a dark, solid surface. The resulting tracks will inform you of shortened or lengthened stride lengths and degree of weightbearing on each limb. Measure left and right strides; the injured side often has a shorter length. The injured limb's pawprint may appear dramatically lighter, or the opposite limb may leave very clear marks.
If the symptoms are too subtle to detect walking, move the dog down and back at a trot and look for head-bobbing, lopsided pelvis, and uneven stride length under this greater demand. Try pivoting your dog; dysplastic dogs won't do this well, and will avoid pivoting on the affected side. However, dogs normally pivot better in one direction than the other (handedness), so don't expect the dog to be able to pivot in both directions equally well, even on a good day.
Once the affected limb is identified, palpate for further information. Dr. Zink stressed the importance of "educating your fingers", as they are extremely sensitive diagnosticians. Palpate as many dogs as possible to begin to learn normal shapes, textures, and consistencies, as well as subtle variations. Learn the muscular anatomy of the dog. While many vets are taught to "press hard and see if it's painful", this is an inefficient and uninformative maneuver.
Sit or squat behind the dog, having him stand squarely. Starting at the ears, gently feel down the dog's neck and shoulders, using fingers and thumbs. It's easier to detect subtle changes if your eyes are closed. You are feeling for normal, symmetrical muscle, bone, and soft tissue. Swelling on one side indicates inflammation or internal bleeding; lack of muscle on one side may indicate atrophy and a long-standing problem. Leg size difference may indicate either one of these. Heat is not a reliable indicator, since petting the dog generates friction and localized heat. Crunching sounds, grinding (a symptom of arthritis or fracture), and degree of muscle tension are important.
Nerve damage is often found by a proprioceptive deficit symptom: a dragging foot, knuckling over a standing foot, uneven wearing of nails. Test front legs for this by holding the dog under his belly and lightly brush his front legs just under a table edge at the same time; when they brush they should reach up. A damaged leg won't reach as quickly.
Evaluation in Action:
During the seminar observers examined a German Shepherd and a Sheltie, both with lameness that wasn't immediately apparent. Using these assessment tools and tests, the seminar participants were able to identify the affected limb; with palpation, Dr. Zink was able to describe a chronic condition in the Sheltie. While this assessment process sounds like simple observation, it was amazing how much information about these two dogs was available by using these common-sense guides.