When a pet develops a lameness which involves both hind legs there is a whole group of possible causes that need to be considered and ruled in or out. Hip dysplasia, intervertebral disk disease, bilateral cruciate ligament ruptures, bilateral ly torn meniscal cartilage, lumbo-sacral stenosis, spondylosis, fibro-cartilaginous infarcts, and spinal cord tumors are a few of the possible causes for such a lameness. Although cruciate ligament tears cam be diagnosed using the “drawer test” while hip dysplasia can be diagnosed using xrays , and torn meniscal cartilage can be diagnosed when a “click” is heard upon flexing and extending the knee, most of the other above causes mentioned requires an MRI. Unfortunately an MRI is very expensive and many pet owners can not afford this diagnostic procedure. So the question then becomes—How can a veterinarian decide what therapeutic approach to take without having an MRI to distinquish whether the lameness is due to an intervertebral disk disease, spondylosis, lumbosacral stenosis, a spinal cord tumor, or a fibrocartilaginous infarct, all of which produce similar symptoms?
The answer is, that a veterinarian has got to play the odds and treat the problem that is most likely to cause the symptoms. Spinal tumors and fibro-cartilaginous infarcts are relatively rare so we need put our efforts where we are most likely to reap the benefits. Intervertebral disk disease and spondylosis are both high up on the list when playing the odds. Therefore, without an MRI to figure out the true cause of the lameness we, as veterinarians, treat the dog or cat for disk disease and/or spondylosis. This gives us the greatest chance of success. Granted we may be wrong but we have a better than average chance of being right.
Now if we decide to play these odds and treat for disk disease we still have to decide, without an MRI, where the ruptured disk is likely to be. In this case a veterinarian uses symptoms to narrow the choices. If the damage is in the neck the dog may hold his head still and turn his whole body. Ruptured disks in the neck are usually very painful and the patient will scream out if the neck is turned. If the damage disk is in the mid to lower back the dog may walk with an arched back and may cry out upon moving in the wrong way . A ruptured disk in the neck can cause both front and back leg gait abnormalities where a ruptured disk in the the lower thoracic or lumbar will only produce hind leg problems.
Once a veterinarian decides whether the problem is in the lumbar spine or the neck the veterinarian must further narrow down the location of the damage. If the veterinarian has determined the disk problem is somewhere in the back but he can’t more speciificly localize a tender area he will play the odds that the damaged disk is between T11 and L4. So this the general area where acupuncture would be applied. Again playing the odds is not the best way to determine where to treat but is the best we can due if the money is not available for an MRI.