Vet Tip of the Day: High & Low Ringbone
Key Words: Pastern, arthritis
Continuing our examination of the leg, let's look at another disease that is common in the foot/pastern region. Remember that there are three pastern bones located below the fetlock: the long pastern bone (P1), the short pastern bone (P2) and the coffin bone (P3). Ringbone is a common degenerative joint disease that occurs in two locations: high ring bone results when the joint surfaces between the first and second pastern bone become irregular and eventually proliferative (arthritis). Low ring bone occurs when similar changes take place at the joint between the second pastern bone and the coffin bone.
Horses with short, upright pasterns and narrow feet are predisposed to ringbone, as are those whose occupations involve repeated concussion on hard surfaces. Because the joint between the second pastern bone and the coffin bone is inside the rigid hoof capsule, low ring bone is more difficult to manage than high ring bone.
Ring bone is diagnosed using a combination of diagnostic nerve blocks and radiographs. It is a chronic progressive disease that is treated with corrective shoeing, injections of anti-inflammatory medication into the affected joint, administration of chondroprotective (joint protecting) medications and oral supplements such as chondrotin sulfate and hyaluronic acid, and administration of non-steroideal anti-inflammatory drugs such as phenylbutazone. In severe cases of high ring bone, the joint between P1 and P2 can be surgically fused.
