Tumours of the urinary bladder.

Tumours of the urinary bladder are uncommon in all domestic animals except cattle in certain regions. Where cattle eat bracken (Pteridium aquilinum) there is a high incidence of these tumours. Epithelial tumours are the most frequently encountered neoplasms in cattle and in dogs-the two species most studied. They are described under the following names: papilloma, adenoma, transitional cell carcinoma (with variants), squamous cell carcinoma, adenocarcinoma, and undifferentiated carcinoma.