Bone lengthening is a continuous process in which rapidly growing cartilage at the ends of bones becomes calcified and is gradually incorporated into the bone. Osteochondrosis is a disease caused by a defect in the calcification process of this growing cartilage.
Osteochondrosis most often involves the head of the humerus in the shoulder joint. It also occurs in the elbow, where it is responsible for many of the defects of elbow dysplasia. Osteochondrosis occurs less commonly in the stifle and hock joints. In the stifle, Osteochondrosis involves the femur at its articulation (movement point) with the tibia. Symptoms of intermittent lameness may look like luxating patella. In the hock, Osteochondrosis involves the articulation between the tibia and the talus (the first bone of the hock).
Osteochondrosis is a common disease of rapidly growing, large-breed puppies. The first signs show up between 4 and 8 months of age. The symptoms may resemble those of panosteitis, another disease that causes lameness in growing puppies.
The typical presentation is gradual lameness that seems to stem from the shoulder, elbow, stifle, or hock in a young dog of one of the larger breeds. Lameness often gets worse with exercise. Symptoms may appear following a traumatic episode such as jumping down stairs. Pain is present on flexing ans extending the joint.
In a dog with osteochondrosis, the cartilage is calcified in an irregular fashion. This creates areas of uncalcified, defective cartilage over the ends of the bones. With stress on the joint, the defective cartilage breaks into loose fragments called joint mice. This process, which is accompanied by joint pain and swelling, is called osteochondritis dissecans.
The diagnosis is made by X-ray and may not be definitive until the dog is 18 months old. X-rays may show fragmentation of joint cartilage or a loose piece of cartilage in the joint.
Medical treatment involves restricting activity and prescribing analgesics and chondroprotectants. Preparations that contain polysulfated glycosaminoglycan (such as Adequan) may be of benefit in limiting further cartilage degeneration and relieving pain and inflammation.
In most cases, surgery will be required to scrape away defective cartilage and remove any joint mice. The best results are obtained in the shoulder and elbow joints. The results are less favorable for the hock, which is a small joint, and for the stifle, which is a more complex joint. In the hock and stifle, degenerative joint disease is likely to occur over time.
Please contact your veterinarian for more information regarding this condition.
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