The goal of this study was to determine if cartilage lesions of the humeral head in adult dogs are the consequence of osteochondrosis dissecans or degenerative joint disease. A gross and histologic survey was performed of humeral head cartilage lesions of 155 dogs ranging in age from 1 week to 19 years. The humeral head and cartilage lesion size were measured for each dog. Cartilage lesions were classified as fibrillation, fissures, erosion, and/or eburnation. The area of each lesion was multiplied by a severity score (fibrillation and fissures 1, erosion 2, and eburnation 3) to create a combined score for each humeral head. Correlations between this combined lesion score and age, humeral head size, body weight, and body condition score were assessed using a Bonferroni-corrected alpha of .01. Twenty-six humeral heads were also evaluated histologically. Of the 155 dogs, 80 (52%) had gross lesions of the articular cartilage. The presence and severity of the articular cartilage lesions were positively correlated with age, humeral head size, body weight, and body condition score. The average age of dogs with cartilage lesions was 8.8 years, and 77/105 (74%) of adult dogs had cartilage lesions. Fifty dogs were 3 years of age or younger; 3 of those had cartilage lesions, 1 of which was osteochondrosis. These data indicate that cartilage erosion of the caudal humeral head in dogs is a common degenerative lesion acquired in adult large breed dogs; osteochondrosis dissecans does not precede the lesion in the vast majority of cases.
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