Clinicopathological features of canine abdominal masses: 80 cases.

Introduction: Epidemiological data on canine abdominal masses are fragmentary and focused on specific diagnoses and site. The aim of this study was to describe the epidemiology, distribution and diagnosis of canine abdominal masses. Materials and Methods: Surgically-excised abdominal masses of diameter >3 cm and available histological diagnosis were collected. Dog signalment, tumour size and site were recorded. Haematoxylin and eosin-stained slides were reviewed and, when necessary, immunohistochemistry was performed. Lesions were classified as malignant (ML) and benign (BL), the latter including benign neoplasia and non-neoplastic lesions. Results: Eighty lesions were collected in dogs aged 1e15 years (median 11 years). Male to female ratio was 1.7. Forty-nine cases were splenic in origin, 14 gastrointestinal (GI), 10 intra-abdominal (without connection to any organ), four genital and three hepatic. Fifty were ML and 30 were BL, 24 of which were non-neoplastic and six were cases of benign neoplasia. Thirty-seven ML (74%) were mesenchymal (21 of which were haemangiosarcomas), seven were leucocytic (four histiocytic sarcomas and three lymphomas), three were epithelial and three were miscellaneous other lesions. ML were fewer in the spleen (55%) than in the GI-tract (86%) and abdomen (70%) (P !0.05). Difference in age or sex was not evident between ML and BL. Conclusions: The majority of canine abdominal masses were mesenchymal ML occurring in middle aged to older male dogs with a preponderant involvement of the spleen, GI tract and abdomen. The spleen was the site with the lowest percentage of ML. These data might be useful for planning the approach to canine abdominal masses in clinical practice.