Reprinted from Active Dog Edition 1
OCD (short for osteochondritis dissecans) is a condition involving faulty development of cartilage in growth plates and joint surfaces. The normal process of bone formation is retarded while the cartilage continues to grow, resulting in abnormally thick regions. Due to mechanical stress, cracks can develop in this thickened cartilage, that eventually lead to the formation of a cartilage flap.
OCD is mainly seen in young dogs of the large and giant breeds. OCD is most often diagnosed in the elbow and shoulder joints, but can affect the hocks. It can occur on both sides of the body, but the lameness is usually more noticeable on one side than the other. The signs of OCD are usually noticed at around 4 to 6 months of age, but may not be obvious until the dog reaches 8 months or older. Males are more often affected than females. Typically a dog with OCD looks stiff when rising from rest, and has a mild lameness which gets worse after exercise. The affected joints appear to have a limited range of movement and may be swollen and sensitive to touch. The signs usually get worse with age, and can lead to painful arthritis.
There are many causes of lameness in young dogs, so your vet will need to give your dog a full physical exam and take detailed X-rays of the affected joints before arriving at a diagnosis of OCD. Depending on how severe the problem is, treatment may involve surgery and/or drugs to reduce the joint inflammation and pain. While the exact causes have yet to be identified, we know that there is no single cause of OCD. Multiple factors are often involved including: the dog's genetics, nutritional and physiological factors and sometimes a history of traumatic injury.
Genetics appear to be important in some cases. OCD is more prevalent in some breeds of dog than others, and sometimes OCD tends to run in families. Preventing OCD should be a priority for breeders, especially if the puppies are destined for an active lifestyle. To limit the occurrence of OCD, select only healthy parents, and do not breed from affected dogs. If certain dam and sire crosses produce puppies with OCD they should not be repeated. Nutritional and physiological factors that may influence some cases of OCD include excessive calcium intake, growing too rapidly and excess calorie intake. Excess weight during the period of rapid growth is thought to affect the normal development of the skeleton. The abnormal stresses caused by this excess weight on the major weight-bearing joints, especially the stifles and elbows, are thought to increase the risk of OCD.