Lameness issues are one of the most common reasons owners call veterinarians about their horses. Equine veterinarians use a 5 point scale to rate lameness:
0- Lameness not perceptible under any circumstances
1- Lameness is difficult to observe and is not consistently apparent, regardless of circumstance
2- Lameness is difficult to observe at a walk or when trotting in a straight line but consistently apparent under certain circumstances such as weight-carrying, circling, inclines, hard ground, etc
3- Lameness is consistently observable at a trot under all circumstances
4- Lameness is obvious at a walk.
5-Lameness produces minimal weight bearing in motion and/or at rest or a complete inability to move.
Sometimes the cause of the lameness is obvious and an owner may only be seeking a treatment plan. This is often the case with acute injuries, however, many of the lameness cases we look at are more subtle and often of a chronic nature.
A complete history relating to the lameness concern is where we begin and no detail is too small.
Next, we will look at the horse at rest to see if any abnormalities can be visualized.
Unless the horse is grade-5 lame, we will now want to see him/her move. How lame is the horse? (Grade 1-5)
In what way does it move abnormally? Which leg is the lame one? Sometimes we will need to see the horse being ridden to observed the lameness.
Next step is a thorough HANDS ON EXAM. This is a practiced skill where we palpate the horse checking muscles, joints, bones, tendons and ligaments for evidence of heat, pain or swelling or other abnormalities.
A huge percentage of horses we see are lame due to foot pain. Hoof testers are used to assess foot pain.
Flexion tests of various joints may be the next step to evaluate pain in joints or adjacent structures.
If after these steps the source of the lameness cannot be determined, the horse may need to be evaluated under special circumstances such as in a circle, on hard ground, being ridden, etc.
If after all of the above being done and no diagnosis is to be found, then further diagnostic procedures will be needed to locate the source of the pain. Remember, while a human patient can simply tell the doctor where it hurts, our equine patients cannot, so the very first thing we need to determine is WHERE DOES IT HURT. We often must use diagnostic nerve blocks to find the source of the pain. We do this by injecting short-acting local anesthetic around a nerve, or into a joint to numb that area. We do this in a sequential order usually starting with the foot and working up the limb. If the lameness improves after a particular nerve block, we then know that this is the GENERAL area where the pain is coming from.
Now comes the question: So this is where it is----but what is causing the pain here?
We look "inside" the area identified as being the source of the pain with a variety of electronic diagnostic equipment including radiographs (x-Rays), diagnostic ultrasound, nuclear scanning, CT scanning, and MRI. The last three of these are only available at specialty referral practices and university veterinary teaching hospitals and we do send complicated lameness cases on to these facilities.
Only when we have figured out WHERE IT IS, and WHAT IT IS, can we formulate a treatment plan.