Canine bladder cancer: epidemiologic features.

A retrospective study of medical records from 13 veterinary university hospital clinics yielded 114 dogs with microscopically confirmed primary malignancy of the bladder. When matched to controls, there was no increased frequency to suggest an association of urogenital tumors or anomalies with neoplasms of the bladder. The majority of tumors seen in this study were transitional cell carcinomas. Four breeds were identified with excessive risk for bladder cancer and may serve as models for further research into genetic determinants, such as abnormal tryptophan metabolism. The epidemiologic features of canine bladder cancer were compared with the disease in man. An excess among female dogs may be the result of less frequent urination as compared to male dogs. Assuming an etiology from urine-borne carcinogens applies to spontaneously occurring bladder cancer in dogs, then monitoring the frequency of occurrence of canine bladder cancer may provide an early warning of emerging environmental hazards to man.