Low-grade gastrointestinal lymphoma in dogs: 20 cases (2010 to 2016).

Objectives: To report the clinical presentation, treatment and prognosis of dogs with low-grade gastrointestinal lymphoma.

Materials And Methods: Cases were solicited from the American College of Veterinary Internal Medicine Oncology Diplomate listserv. Medical records of dogs with low-grade gastrointestinal lymphoma diagnosed via a combination of histology and immunohistochemistry with or without analysis of polymerase chain reaction for antigen receptor rearrangement were included. Signalment, clinical signs, diagnostic test results, chemotherapy protocol, response to treatment, date of first progression, rescue therapies and date and cause of death or last follow-up visit were collected.

Results: Twenty cases were included. Males and small breed dogs were over-represented. Frequent clinical signs included weight loss, vomiting and diarrhoea. Most lymphomas were T-cell phenotype (95%), and epitheliotropism was commonly described (60%). Immunohistochemistry, polymerase chain reaction for antigen receptor rearrangement or both were frequently required for definitive diagnosis. Two dogs had resection of an intestinal mass, and all dogs were treated with chemotherapy; chlorambucil and prednisone were most commonly prescribed. Overall response rate was 70%, and median survival time was 424 days (95% confidence interval: 105 to 1206 days).

Clinical Significance: Low-grade gastrointestinal lymphoma appears to be a rare condition in dogs, and treatment with chemotherapy results in a high response rate and favourable survival times. Further study is needed to determine its prevalence in dogs with chronic enteropathies.