Rectal lymphoma in 11 dogs: a retrospective study

To retrospectively evaluate the clinical behaviour and immunophenotype of lymphoma of the rectum in dogs.

Eleven dogs diagnosed with lymphoma of the rectum on histopathology were retrospectively reviewed. Immunohistochemistry with CD3 and CD79a antibodies was performed at diagnosis or retrospectively.

Treatment protocol varied with six dogs undergoing surgery and adjuvant chemotherapy, two received chemotherapy after only incisional biopsy, one had surgical resection only, one was treated symptomatically and one dog was not treated. Chemotherapy treatment consisted of either a -low-dose COP (cyclophosphamide - prednisolone - vincristine) protocol (four dogs) or a six-week CHOP-based (cyclophosphamide - vincristine - -prednisolone - anthracycline) protocol (four dogs). Dogs that received chemotherapy lived significantly longer than dogs that did not receive chemotherapy (2352 versus 70 days). Median survival time was not reached, and there was an overall mean survival time of 1697 days. Immunohistochemistry was performed in 10 of 11 samples, and was consistent with B-cell -lymphoma in all cases.

Canine lymphoma of the rectum is associated with a favourable prognosis. Immunohistochemical evaluation of these lesions was consistent with B-cell lymphoma in all cases in which it was examined.