Veterinary Medicine - February 2008 - (Page 79) Research Updates The prevalence of and risk factors for canine appendicular osteosarcoma Effect of the moon on emergency room visits I n this retrospective study of dogs treated at a veterinary teaching hospital, the prevalence of appendicular osteosarcoma in greyhounds compared with other breeds was examined, along with the potential risk factors for developing the disease. Primary appendicular osteosarcoma was diagnosed in 179 dogs; prevalence was highest for greyhounds (6.2%), rottweilers (5.3%), and Great Danes (4.4%). All of the greyhounds were retired from racing or training. Body weight and sex were not risk factors for osteosarcoma in these breeds; however, risk did increase with age. Greyhounds were significantly older at the time of diagnosis (mean = 9.9 years) than were rottweilers (mean = 8.3 years) and Great Danes (mean = 7.8 years). Rottweilers and Great Danes were more likely to have osteosarcoma in the forelimbs than in the hindlimbs. The most frequent sites for osteosarcoma in all three breeds were the proximal end of the humerus and distal region of the radius. In greyhounds, the proximal aspect of the femur was also a common site for osteosarcoma. The authors recognized the limitations of a retrospective study involving low osteosarcoma case numbers and potential geographic bias (a state with the largest number of greyhound racetracks and retired animals in the country). Nonetheless, the three breeds listed were shown to have an increased risk for osteosarcoma compared with mixed-breed dogs. COMMENTARY I Greyhounds may also be at risk for developing osteosarcoma. Bone neoplasia is a morbid and common condition encountered in small-animal practice. Osteosarcoma is the most common primary bone tumor in dogs; large and giant breeds, such as Irish wolfhounds, Scottish deerhounds, and Borzois, have an increased risk for developing osteosarcoma. The lesions most frequently involve the proximal end of the humerus and distal end of the radius. The results of this study reveal that another sight hound, the greyhound, may also be at risk for developing osteosarcoma and that the proximal aspect of the femur may be another frequent location for the lesion. In the three most commonly affected breeds of this study, age was a risk factor while body weight and sex were not. To their credit, the authors cited numerous previous studies both in agreement and in conflict with this data. Furthermore, the speculation of trauma-induced neoplasia in racing greyhounds could not be ascertained because of the absence of a control (nonracing, nontraining greyhounds). Theoretically, the greater weight carried by the forelimbs (60%) and the increased stress on the right limbs in dogs racing counterclockwise could be factors in the development of osteosarcoma. Interestingly, the greyhounds in this report did not have an increased risk in the forelimbs or in the right vs. left limbs. n this retrospective case series from a university veterinary medical center, the frequency of canine and feline emergency visits were noted with respect to the lunar cycle. Emergencies were classified as animal bite, cardiac arrest, epilepsy, ophthalmic, gastric dilatation-volvulus, trauma, multiple diseases, neoplasia, or toxicosis. Of the 11,940 cases seen during the 11-year period, 9,407 involved dogs and 2,533 involved cats. The lunar cycle was classified into eight phases, ranging from new moon to full moon to waning crescent moon, and lasted 29.5 days. The effect of the lunar phase on the emergency visits was evaluated by calculating relative risk. The results of the study revealed that the number of emergencies on full moon days was not significantly different from nonfull moon days for either dogs or cats. However, significant differences existed in the number of emergencies for both animals observed on fuller moon days (waxing gibbous, full moon, and waning gibbous phases) compared with other days. The risk was 28% greater in dogs and 23% greater in cats. According to the authors, these slight increases would probably not be recognized by attending emergency clinicians. They also acknowledged the limitations of this low caseload study and concluded that further investigations at other clinical facilities with greater patient numbers are warranted. COMMENTARY Rosenberger JA, Pablo NV, Crawford PC. Prevalence of and intrinsic risk factors for appendicular osteosarcoma in dogs: 179 cases (1996-2005). J Am Vet Med Assoc 2007;231(7):1076-1080. The effect of the lunar cycle on animal and human medical conditions has always been a source of interest and VETERINARY MEDICINE February 2008 79
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.