October, 1997

Edited by Judy Benoit

Contributors: Sue Brightman, Toni Davies, Mark Eastman, Kayt Edwards, Frankie Rubel

Osteochondritis Dessicans, or OCD, is a problem with the cartilage in a young dog. To better understand what OCD is, it helps to understand the structure of the long bones in the legs. The bones consist of three main parts - picture the drumstick bone of a chicken or turkey. The central area, the long round hollow shaft, is called the diaphysis (to grow between). This part of the bone is rigid and made of dense bone cells. Toward each end of the bone, a slightly flattened area is called the metaphysis (to grow beyond), and the small knob-like structures at each end (4 in all) are called the epiphysis (to grow upon). Both the metaphysis and the epiphysis are made of bony material that looks like a sponge with air pockets, and yet it is still very strong. Separating the metaphysis and the epiphysis in a young growing dog are the growth plates, or epiphyseal plates, made of cartilage and bone-forming cells. Covering the outside surface of the epiphysis is a layer of cartilage, or articular cartilage, which helps to minimize friction and wear of the bone when the joint moves.

In a young dog, sometimes a piece of the articular cartilage will tear away from the epiphysis and form a flap. This is OCD. The flap may reattach to the bone on its own, or it may tear away, becoming a joint mouse in the joint cavity. This joint mouse can cause pain if it is not ground into small pieces and absorbed. The flap may remain unchanged, causing pain and arthritic changes to the joint.

There are three things associated with causing OCD. Trauma can cause damage to the cartilage resulting in OCD. Genetics are thought to predispose a dog to OCD. Diet for the growing dog is also thought to be a factor. Excessive weight gain, calcium supplementation, and an overly nutritious diet are all to be avoided.

The signs of OCD are usually noticed in a dog as early as 4 - 10 months or as late as 12 - 18 months. It occurs more frequently in males. Although it can occur in almost any joint (hock, stifle, and elbow), it most commonly occurs in the shoulder. It is first apparent as mild limping, the affected joint can stiffen after resting, and the limping is aggravated by exercise. If OCD is left untreated, arthritic changes in the joint may cause permanent lameness.

Radiographs usually aid diagnosis, but manipulation of the joint will generally cause a pain response. Radiographs should be taken of the opposite joint as well, since OCD often occurs bilaterally.

Once the problem is diagnosed, the course of treatment is generally to allow 4 - 6 weeks of rest and restricted activity to give the joint a chance to heal on its own. Medication is not advisable because it causes the dog to feel better and more like playing. It is uncommon for the joint to heal on its own, but it is certainly worth a try. Some vets advocate moderate exercise in order to help the flap break away and get ground down and absorbed. If, after 6 weeks of rest no improvement is seen, surgery is the only other standard option.

If the OCD occurs on the humerus - the long bone in the upper foreleg - then the surgery has an excellent chance for a full recovery. Surgery for OCD in the elbow, hock, or stifle has more unpredictable results. The surgical procedure consists of cutting away the cartilage flap, removing any loose unattached cartilage, and searching the joint in order to remove any fragments that have already torn away. Activity is restricted for 1 - 2 weeks after surgery, after which time normal activity may resume. Within a month the dog's shoulder should be as sound as it was at the time of the surgery, and should continue to improve thereafter. There may be some arthritis in the joint eventually, but it will not always become symptomatic.

Preventing OCD may not be possible, but there are many things thought to help. A diet minimizing rapid growth, supplementation with vitamin C, and shark cartilage have all been used by list members with varying degrees of success.

From the List:
Sue Brightman's 1-year-old Whimsy started showing episodes of limping. When it did not get better, in she went to the vet. In true Berner style, Whimsy seemed perfectly sound at the vet. It took 2 visits and a full set of x-rays to reveal the OCD. The first thing that was tried was severely restricting Whimsy's activity level. Several weeks went by with no change. Then they tried allowing exercise to cause the flap to break loose and be ground down and absorbed. This worked! A few months later, new x-rays showed no sign of OCD, and Tess has not had any problems with the joint since.

Toni Davies' Budson fell and injured himself at 4.5 months. His limping worsened. When he was x-rayed at 7 months, the vet diagnosed OCD. Surgery found a lession the size of a nickle. Immediately after surgery, his pain seemed better and any pain was likely a result of the surgical trauma rather than from chronic pain. To avoid buildup of fluid in the joint, his exercise was severely restricted for 2 weeks, and leash walked for an additional 4 weeks. After 2.5 weeks, there was no sign of any problems.

Mark Eastman's Eli had OCD on the humerus bone in each shoulder. After a great deal of trepidation, Mark went ahead with the surgery on the shoulder that was causing Eli to limp. The surgery cost just over $800. Just 3 weeks later Eli was doing great!

Kayt Edward's Tess was about 6 months old when she started limping. Although the x-rays didn't show anything, the vet suspected joint mice from OCD. He operated and found loose cartilage in both elbows. At age 4, Tess has an occasional bout with arthritis, but is otherwise just fine.

Frankie Rubel's Matt started limping at 9 months. The limping came and went, but eventually stayed around most of the time. X-rays pointed to a probable OCD problem in one shoulder. Matt was referred to a surgeon and had the loose cartilage removed. $900 later, he came home. Three days later, he came down with something resembling parvo (no doubt caught from one of the 2 vet hospitals). The problem was shown not to be parvo, but the culprit was never definitively diagnosed. $1190 later, thanks to a wonderful, dedicated vet that tried everything in the book, he recovered from near death. He has shown no further problem with the shoulder in the last 3 years.

References:
Genetics of the Dog, Malcolm B Willis, Howell Book House, 1989.

Small Animal Orthopedics, Marvin L Olmstead, Mosby Year Book, 1995.

Saunders Manual of Small Animal Practice, Stephen J. Birchard, DVM, Robert G. Sherding, DVM, W. B. Saunders, 1st edition, 1994.

Veterinary Medical Terminology, Dawn E. Christenson, W. B. Saunders, 1997.

The Merck Veterinary Manual, Merck & Co., 7th edition, 1991.

Back Digests of the Berner-List, 161, 167, 168, 387, 388, 782, 784, 785, 791, 812, 836