Canine lymphoma: Pathological and clinical characteristics of patients treated at a referral hospital

Abstract Non-Hodgkin’s lymphomas are common canine cancers with variable demographic and clinical presentations. Their pathological characterization and treatment lag far behind those of humans. We describe consecutive lymphoma patients detected over a one-year period at the National Autonomous University of Mexico (UNAM). Of 4,512 dogs: 220 (4.9%) had a cancer diagnosis, of which 27 (0.6%) had lymphoma (12% of cancer patients). We found an association with Miniature Schnauzers, which represented 18.5% (5/27) of lymphoma patients, but it was only 6.4% (288/4,512) of the dogs studied in this time period (p< 0.011). Miniature Schnauzers and mongrels together constituted nearly half of lymphoma cases. Mean age at diagnosis was 7.5 years (3-14), with a female to male ratio of 1.7:1. We found no correlation between lymphoma and castration status. Most patients presented nodal involvement (80%), were in advanced stages III/IV (90%) and had B-cell versus T-cell tumors (64%/36%). Only two histopathological patterns were seen, both with diffuse nodal-replacement by large immunoblast and/or centroblast-like cells; one having numerous tingible-body macrophages which are suggestive of a high proliferative rate. Chemotherapy was given to 15 patients (65%) with an overall response of 73% (3 complete responses/8 partial responses) and a mean overall survival of 219 days (4-586; SD±185). One cutaneous lymphoma-patient achieved partial response (PR) with lomustine/prednisone, and treatment was still ongoing at 548 days. Earlier diagnosis, better lymphoma subtype distinction, and specific curative treatments are needed.