Retrospective study of canine gastrointestinal tumors in Tokyo, Japan, 2012-2024.

Gastrointestinal (GI) tumors are common neoplastic diseases in dogs. However, epidemiological data on canine GI tumors in Japan are limited. The present study aimed to investigate the prevalence of GI tumors in Japan and assess the association of canine breed, age, sex, and anatomical location with the development of common tumor types. A total of 1,310 canine GI tumors that were histopathologically examined between 2012 and 2024 were retrospectively analyzed. The statistical methods included a contingency table analysis, multivariable logistic regression analyses, and Mann-Whitney U tests. The most frequent GI tumor was lymphoma (58.9%), followed by adenocarcinoma (16.2%) and adenoma (15.0%). Statistical examination revealed that Shiba dogs were predisposed to T-cell lymphoma, Miniature Dachshunds to colorectal B-cell lymphoma and colorectal adenoma, Jack Russell Terriers to adenoma, acinar adenocarcinoma, papillary adenocarcinoma and tubulopapillary carcinoma, French Bulldogs to gastric signet-ring cell carcinoma and plasmacytoma, and Shih Tzus to tubulopapillary adenocarcinoma. These breed predispositions to specific tumors may be unique to the Japanese canine population. To the best of our knowledge, this is the first large-scale epidemiological investigation of canine GI tumors in Japan. The epidemiological information from the present study will serve as a useful reference for clinical veterinarians to establish the differential diagnoses of canine GI tumors.