Elbow Dysplasia in Dogs
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. In a dog with osteochondrosis, the cartilage
is calcified in an irregular instead of a uniform 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
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 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 at between 4 and 8 months of age. The symptoms may
resemble those of panosteitis (see this page), 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 large breeds. Lameness often gets worse with exercise. Symptoms may
appear following a traumatic episode such as jumping down stairs. Pain is
present on flexing and extending the joint. X-rays may show fragmentation of
joint cartilage or a loose piece of cartilage in the joint. The diagnosis may
not be made definitively until the dog is 18 months of age.
Treatment: Medical treatment involves restricting activity and prescribing
analgesics and chondroprotectants,as described
for the treatment of degenerative joint disease. 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.