Yet another of the many arthritic conditions that can disable your dog is one known as OCD, which stands for either osteochondritis dissecans or osteochondrosis dissecans. OCD is a disease that affects the cartilage - the spongy tissue that cushions the space between joints and allows them to work smoothly together.

Anything that damages or erodes this cartilage can lead to arthritis, resulting in joint pain, swelling and lameness. In the case of OCD, the cartilage is either damaged or grows abnormally. Instead of remaining attached to the bone that it's cushioning, the cartilage either separates or develops cracks. Sometimes pieces of cartilage will break off and float freely within the joint itself, where they continue to grow. All three of these problems cause extreme pain for the affected animal.

About 15 percent of all dogs will develop OCD. It can appear in any breed, but is more often seen in large and giant breed dogs. Males are stricken two to five times more frequently than females, probably due to their larger size and increased stress on the joints. Most cases begin when the dog is still a puppy, between four and eight months of age, although it can strike older dogs as well.

Any type of dog can develop OCD, but for unknown reasons, some larger breeds are NOT affected as often, including the Collie, Doberman Pinscher and Siberian Husky. Dogs that are more susceptible include Golden Retrievers, Labradors and Rottweilers.

Genetics, injuries, trauma to the joint, unusually rapid growth (possibly caused by nutritional supplements or a high-protein, high-fat diet) and/or a restricted blood flow to the cartilage are all factors that can lead to the development of the condition. It is recommended that any animal's parents be screened against the disease before the dog is bred, to avoid passing on the problem. Owners whose animals are in a high-risk breed sometimes are advised to feed them a low-fat, low-protein diet that will produce sustained, steady growth during the first year. However, this strategy has not yet been proven effective.

Dogs with OCD will first exhibit lameness in the affected leg. The symptoms run the gamut - some dogs have a barely noticeable limp; others are unable to bear any weight on the affected leg. For obvious reasons, the pain and limping will be noticeably worse after exercising and improve after sleep or rest. Nearly three-fourths of all cases occur in the shoulder joint. Another 11 percent occur in the elbow joints, and the final 4 percent appear in the hock. Dogs with an affected shoulder often exhibit a shortened step or almost a hop, because of their reluctance to flex and extend the damaged joint.

As with all types of arthritis, treatment is done through both medication and, in severe cases, surgery to repair the joint. Rest, anti-inflammatory medications and painkillers often are prescribed. Cartilage-repairing supplements like glucosamine and chondroitin may be prescribed, but these have not yet been scientifically proven as effective against OCD. With proper care, most animals with the disorder can be successfully treated and their pain either eliminated or minimized.