P. 578

An Urban Experience
such as shoulder, sti e, tarsus and sacro-iliac joint. Osteochondrosis is thought to have a multifactorial etiology. Genetic factors that affect weight gain
and growth, behavior, sexual development and conformation undoubtedly are involved in the etiology of osteochondrosis. Osteochondrosis occurs primarily in medium to large and giant breed dogs. Rapidly growing representatives of these breeds seem to be predisposed. The genetic capacity for rapid growth and overfeeding may be in uential during the dog’s period of rapid growth. This is an important aspect in athletic dogs as often it is the largest, most rapidly growing dog that is desired. In addition the selective breeding
of performance animals may be based on performance data, conformation, and other desired qualities without knowledge of the presence of articular disease that may be subclinical in nature or affected littermates.
Biomechanical forces are another important etiologic factor in the development of osteochondrosis. Osteochondrosis lesions develop in areas of articular cartilage that are subject to increased loads. Normal joint stresses and focal trauma likely are inciting perpetuating factors involved in the pathogenesis of this condition. The strenuous activity often imposed on performance dogs
at very young ages may partially account for the high incidence of osteochondrosis in many breeds of working and racing dogs.
Overnutrition in the form of excessive amounts of food and/or nutritional supplements has been incriminated as another important etiologic factor. This is evidenced by higher caloric intake in rapidly growing animals resulting in greater incidence of osteochondrosis. Excessive calcium supplementation has been de nitively established to increase the development
of osteochondrosis. Large and giant breed dogs are predisposed to develop osteochondrosis with elevated dietary calcium intake. Hormonal disturbances have also been incriminated through experimental production of osteochondrotic lesions following the administration of thyrotropin, growth hormone, estrogens and androgens.
Osteochondrosis is usually seen in medium, large and giant breed dogs. The clinical manifestation of the disease typically occur between 4 to 9 months of age; however, it is interesting to note that in a recent review
of 626 dogs with osteochondrosis of the humeral head, 36% of the dogs presented for treatment were greater than a year of age. Osteochondrosis is usually seen more frequently in males than females. The exception
to this trend is osteochondrosis of the hock, which has been reported slightly more frequent in female dogs. In dogs, osteochondrosis most commonly develops on the articular surfaces of the humeral head, humeral condyle, femoral condyles, and the trochlear ridges of the talus. Less frequently reported sites of osteochondrosis include the femoral head, patella, distal end of the radius,
articular facets of the spine, and glenoid surface of the scapula. Multiple joint involvement is not uncommon.
A thorough physical and radiographic examination is necessary for early detection of this disease and to avoid giving an overly optimistic prognosis for return to athletic performance.
Treatment of osteochondrosis involves excision of the cartilage  ap and curettage of the subjacent subchondral bed. Osteochondritis dessicans lesions of the humeral condyle may not be as obvious as osteochondritis dissecans lesions of the humeral head. If a lesion is suspected based on the pre-operative radiographs
and is not readily apparent at arthrotomy, the articular surface of the trochlea of the humeral condyle should
be probed with a Freer periosteal elevator. In these instances the malacic cartilage will readily separate from the adjacent unaffected cartilage. All diseased cartilage should be excised and the subchondral bed curettaged. Osteochondritis dissecans lesions of the humeral condyle should be differentiated from erosive or kissing lesions
of the trochlea of the humeral condyle, which frequently occur in response to fragmented coronoid process.
Arthroscopy can be used to diagnose and treat lesions
of the humeral condyle. Routine evaluation of the joint is performed. The coronoid processes should be carefully evaluated for the presence of a fragmented coronoid process and the OCD lesion should be differentiated from a kissing lesion. Routine arthroscopy debridement of OCD lesions including removal of the  ap, curettage and micropicking as needed is performed. Novel treatment are osteochondral transfer as previously discussed in the notes.

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