Dr. Latimer flexing a horse duringa lameness exam
Each lameness exam is different depending on the history, presentation and physical exam findings of the lame horse, however commonly you can expect the veterinarian to palpate the horse’s body and limbs, observe the horse at a walk, trot and canter, place hoof testers on the horse’s hooves, perform limb flexions, nerve and/or joint blocks.
To block a horse means to inject a small amount of local anesthetic around nerves that innervate certain structures or directly into joints so that if lameness resolves pinpointing of the origin of pain is accomplished. Typically, if nerve blocks are to be performed first they are done from the bottom up, so that for example the hooves are blocked first, then the pastern, then the fetlock, and so on. This is because once a nerve is blocked at a certain point the local anesthetic diffuses downwards and anything below that area is consequently also blocked. This is not the case when blocking joints, since the local anesthetic does not diffuse out of the joint. Most veterinarians work with a combination of nerve and joint blocks to work up complex lameness’s but this can vary depending on the case. A full lameness exam including all the necessary blocks can take from 40 min to up to several hours.