TUMORS OF LOWER ALIMENTARY-TRACT

  • 1 January 1976
    • journal article
    • research article
    • Vol. 53  (2-3) , 167-186
Abstract
This classification is presented in 2 parts: tumors of the gastrointestinal tract; and tumors of the anal canal and margin. In the gastrointestinal tract the tumors are classified as adenoma, adenocarcinoma and undifferentiated carcinoma, with several subtypes. Most polyps are nonneoplastic, hyperplastic or regenerative rather than adenomatous. Carcinoma of the stomach occurs in dogs, but is a rare tumor in all parts of the world. Moderately differentiated, tubular adenocarcinoma of the small intestine with excessive fibrosis occurs in all 6 species. In some geographical locations it may occur frequently in sheep and cattle. The adenoma/carcinoma sequence in the rectum of the dog is similar to that in man but is encountered less often. Carcinoid tumors are rare in domestic animals. Among the soft tissue tumors, those of smooth muscle and adipose tissue are found fairly frequently and congenital mesothelioma in the peritoneum of calves occurs occasionally. Tumors of the hematopoietic and related tissues are the most common gastrointestinal neoplasms in all species and most belong to the lymphosarcoma group. Tumors of the anal canal and margin are common in the dog and 90% of these are tumors of the hepatoid (perianal) glands.