Osteochondrosis is a disorder characterized by abnormal calcification of the joint cartilage. It can affect primary and secondary
centres of bone growth, joint cartilage, and growth plate cartilage.
Osteochondritis dissecans is a type of osteochondrosis. The name implies that there is a lesion cutting into the joint cartilage with a secondary inflammation of the affected area and the joint.
The disorder involves a genetic, hormonal, environmental and nutritional factor.
Growth rate, conformation and level of activity may influence the development of the disease.
Genetic studies have suggested that the disease is heritable.
Overfeeding and over supplementation with calcium increase the prevalence of the problem.
Medium and large breeds are most commonly affected including the Rottweiler, Labrador Retriever, Golden Retriever, German Shepherd, Bernese Mountain Dog, Newfoundland, St. Bernard and Great Dane. OCD has also been reported in the cat.
Joints commonly affected by osteochondritis dissecans include the
shoulder, OCD shoulder
illustration), elbow (OCD elbow
illustration), stifle, and hock. Joints are often affected bilaterally.
Signs develop between four and ten months of age, although the disease may the may be subclinical.
The pattern of lameness depends on the joint that is affected and whether the problem is unilateral or bilateral.
Joints in both the fore- and hind limbs may be involved.
Dogs with mild clinical signs may show only stiffness on rising that improves with exercise.
The dog may adopt a characteristic posture, i.e. extended hocks, if these joints are involved, or there may be external rotation of the front feet if the elbows are affected.
Pain is present in manipulation, usually extension of the affected joint.
Pain may be elicited by direct pressure over the affected area of the joint, i.e. shoulder joint.
There may be swelling of the affected joint and loss of muscle size if the affected leg.