Today on Texas Vet News I am going to talk about navicular syndrome in horses as this is one of the most common causes of lameness in their front feet. The navicular bone is boat-shaped, which is why it's called the navicular bone. It is located at the back of the horse's foot and when arthritis develops in the joint or damage to the soft tissue around the bone develops, lameness occurs. One key is that horses with navicular syndrome usually respond to pain with hoof testers over the frog. Hoof testers are a sort of pliers that allows you to place pressure over certain areas of the foot, and the examiner watches for the horse's response to determine areas of pain.
To determine if the lameness is originating in the foot, nerve blocks are required to see if numbing the foot decreases the lameness and if so, you be certain at least part of the problem is in the foot. Lots of people look at a horse and say he is lame in the foot, knee or shoulder but without nerve blocks you really do not know. X-rays are important in diagnosing lameness problems but should only be used after you know the general location of the lameness. Also, especially in the case of navicular disease, x-rays can be normal and the horse can still have navicular syndrome. And just as important, horses with radiographic abnormalities may not have any lameness at all even though their navicular bones may look diseased on x-ray. The newest method of diagnosing navicular syndrome is by MRI. The advantage of an MRI is that it images soft tissue while x-rays only reveal bone disease. If you have a horse who is not performing well due to pain from the front feet, an MRI may help diagnose the problem.