Osteochondritis Dissecans (OCD): What Is It? This disorder of immature long bones is seen primarily in the human, horse and dog. Due to a various set of circumstances which include diet, trauma, genetics and body size and weight, growing long bones may develop cracks in the cartilage of the weight bearing surface.These cracks may extend deep to the soft (cancellous) bone beneath the cartilage and eventually a section of the joint cartilage will separate from the underlying structure. This cartilage flap, varying in size from less than a quarter of an inch to over and inch in diameter, acts as an irritant in the joint. Subsequent inflammation and attempts at healing can lead to scar tissue and calcium deposits in the affected joint. Not a happy situation for a creature who is growing and active!
The normal humeral head has a very regular and smooth surface which slides forward and backward under the joint surface of the scapula bone.
In the x-ray image above, the scapula bone (shoulder blade) can be seen above the head of the humerus (upper arm bone). The rear surface of the humeral head has a pitted area instead of continuing the smooth round surface line of the joint. You can see the thin line that is the flap of cartilage which has lifted off the surface of the head of the humerus. We are seeing the circular cartilage flap edge-on so it appears as a thin white line. This particular flap was about the size of a dime. Every time this dog would move the joint or bear weight on it, the flap would irritate the underlying tissue and create pain and discomfort. That's why a dog limps with this condition. Plus there often is inflammation and nerve irritation simply due to the fact that the cartilage flap shouldn't be there! This loose object in the joint can float about and create what is termed a "foreign body" reaction. The joint capsule is actually a sealed chamber that contains lubricating joint fluid. Any loose cartilage fragments are trapped in this space and can really create pain if wedged between the two bones forming the joint. Most cases of Osteochondritis Dissecans create low grade discomfort in the dog. Extra joint fluid builds up, nerve endings are irritated, scar tissue and calcium deposits can result from the body's defense mechanisms that are trying to heal the defect.
Osteochondritis Dissecans (OCD): The Causes
In truth, there are theories as to the causes but since this disorder seems to be spontaneous and not so easy to predict, no one knows for sure why some dogs get OCD and some don't.
It is much more prevalent in Labrador Retrievers, Golden Retrievers, German Shepards, Rottweilers and other large breeds. It is uncommon in the small breeds.
OCD almost always shows up during the growth phase of a young dog's life... usually six to nine months of age. OCD can affect the shoulder, ankle or elbow joint.
It may start as an intermittent limp in one front leg, or the dog may "hold it out" or point the toes away from the midline more than the normal front leg.
Many young dogs with Osteochondritis Dissecans will run and play with gusto; buy when their activity has slowed they recall that the limb hurts and then return to favoring the leg. When laying down they will take care to be gentle with the affected limb. Some people believe that an overweight, growing dog will be much more likely to acquire Osteochondritis Dissecans than one that is trim.
Physical impact on the limbs, such as would occur in a dog that repeatedly jumps off of a deck or from the back of a truck, may be a predisposing cause.
Repeated impacts to the surface of the humerus may separate the cartilage from the growing soft bone beneath. Once the cartilage has detached, it takes very special conditions of rest for any chance of the non vascular cartilage to reattach. Non vascular means that there is no direct blood supply and nutrients are transferred via a fluid medium. Does diet play a role in OCD? Yes! Diet plays a major role in everything a dog does or is! An over fed pup who is carrying more weight than optimum has a greater statistical chance of developing OCD than a lean pup. That is NOT to say that you should underfeed a growing pup just to avoid skeletal deformities! That line of reasoning has been proven to be in error. Rather, be certain to feed high quality meat-based diets that do not have grain as their first ingredient. Diets with high protein and fat seem to be a better choice for dogs and cats than those diets high in carbohydrates like corn, wheat, soybean meal.
Osteochondritis Dissecans (OCD): The Cure.
Rather than a cure, there is a treatment for Osteochondritis Dissecans. One treatment method requires the dog to be confined to a pen for a number of weeks where activity and jumping will be kept
to a minimum. After four to ten weeks of confinement there is about a sixty percent chance that the cartilage defect on the humeral head will heal and the dog will return to normal activity.
This may be termed the conservative approach. The most direct approach and the one that returns the pup to normal activity the soonest is the surgical approach.
In surgery the veterinarian makes an incision over the shoulder and accesses the shoulder joint. Opening the joint space the surgeon inspects for any loose cartilage pieces and rotates the humerus
to expose the back side of the head of the humerus where the defect comes into view. Usually the cartilage flap can be grasped with forceps and lifted away from the humerus.
Some surgeons gently scrape the bed where the flap was situated in order to stimulate faster healing and some leave the area as it is. The joint is flushed again and closed with sutures.
The dog is rested for about ten days and then gradually returned to activity. In successful cases some dogs return to normal within two weeks.
Other dogs will take longer depending upon the size of the defect, how deep into the head of the humerus the bed was eroded, the dog's weight and diet, and other undefinable factors.
Many veterinarians believe it is better to do surgery rather than hope that weeks of rest will solve the problem (how DO you make a young pup rest, anyway!?) .
Once the surgery is done the dog begins the healing process immediately. Any dog that develops a limp that does not improve within fourty eight hours should be checked by a veterinarian.