Causes, Symptoms

Several genes from both parents combined with other factors determine whether an animal develops osteochondritis dessicans (OCD). Which genes are involved and exactly how OCD occurs are unknown.

Nutrition is the most understood risk factor. A diet high in calcium content increases the risk for OCD. High-calorie diets and rapid weight gain at any age may also contribute to the disease.

Running and walking on hard surfaces (e.g., concrete), trauma from injury, and excessive workload or exercise can cause the cartilage to separate from bone and can result in lesions on the cartilage.

Insufficient blood supply to the joint and hormones, which regulate growth and reproduction, are also associated with OCD and affect development of the condition.

Signs and Symptoms

The most common symptom of OCD is lameness in the limb of the affected joint. Lameness may cause a slight limp or the animal may be unable to bear any weight. It may occur suddenly or it may be chronic, lasting weeks or even months. Rest helps to alleviate the lameness and exercise exacerbates it.

Other symptoms of OCD include:

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• Altered gait
• Crepitus (grating noise of bones rubbing against each other)
• Decreased range of motion
• Limb held with toes pointed outward
• Pain when joint is touched
• Resistance to full extension and flexion of joint
• Swelling

Symptoms usually develop between 4 and 10 months of age, and occasionally later. Mild, intermittent lameness may occur at onset or as late as 18 months of age. Without strict rest, the severity of the lameness increases, can become chronic, and, in severe cases, cause surrounding muscles to atrophy from lack of use.

OCD can develop in several joints. Lesions are often present bilaterally (in the same joint on both side of the body), but lameness usually occurs only on one side of the body. Degenerative joint disease can develop in severe cases.

Complications
OCD is a major cause of elbow dysplasia and commonly occurs with fragmented medial coronoid process.

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