Prevalence of and intrinsic risk factors for appendicular osteosarcoma in dogs: 179 cases (1996-2005)

OBJECTIVE: To determine the prevalence of appendicular osteosarcoma (OSA) in Greyhounds compared with other breeds and identify potential intrinsic risk factors associated with development of OSA. DESIGN: Retrospective case series. ANIMALS: 179 dogs with primary appendicular OSA. PROCEDURES: Medical records of dogs in which primary appendicular OSA had been diagnosed between 1996 and 2005 were reviewed. Prevalence and crude odds ratios for OSA were calculated for various breeds by comparison with a reference population of mixed-breed dogs. Age and sex were examined as potential risk factors for the 3 breeds with highest prevalence. RESULTS: Breed period prevalence of OSA was highest for Greyhounds (21/339 [6.2%]), followed by Rottweilers (51/969 [5.3%]) and Great Danes (13/297 [4.4%]); all 21 Greyhounds with OSA were identified as having retired from racing. Sex was not identified as a risk factor for OSA in these breeds, but in all 3 breeds, risk of OSA increased with age. Greyhounds were significantly older at the time of OSA diagnosis (mean, 9.9 years) than were Rottweilers (8.3 years) and Great Danes (7.8 years). Rottweilers and Great Danes were more likely to have OSA involving the forelimbs than the hind limbs. The most frequent lesion sites for all 3 breeds were the proximal end of the humerus and distal end of the radius. The proximal end of the femur was also a common site for the Greyhounds. CONCLUSIONS AND CLINICAL RELEVANCE: Results of the present study suggested that Greyhounds, Rottweilers, and Great Danes had an increased risk of developing OSA, compared with mixed-breed dogs.