Single agent chemotherapy with doxorubicin for feline lymphoma: a retrospective study of 19 cases (1994-1997).

Medical records of 21 cats with confirmed lymphoma treated with single-agent doxorubicin were reviewed. Nineteen cats met the inclusion criteria for this retrospective study. Doxorubicin was given at a dosage of 25 mg/m2 (n = 8) or 1 mg/kg (n = 11) IV, every 3 weeks for a total of 5 treatments. Four of 16 tested cats were positive for feline leukemia virus (FeLV) and all 16 cats tested negative for feline immunodeficiency virus. Eight of the 19 cats (42%) responded to doxorubicin for a median duration of 64 days (range, 35-575 days). Five cats (26%) achieved a complete response (CR) to doxorubicin for a median duration of 92 days (range, 54-575 days). Partial response was observed in 3 cats. Institution was the only significant prognostic indicator for response, with cats treated at Colorado State University being more likely to achieve CR than cats treated at Tufts University. Cats that achieved CR to doxorubicin and FeLV-negative cats had significantly longer survival times. Loss of appetite was the most common toxicity, observed in 9 cats (47%), and was severe in 5 cats (26%). Other toxicoses were less frequent and included vomiting, diarrhea, and myelosuppression. Doxorubicin was not very effective at inducing and maintaining remission in the cats in this study. Therefore, if doxorubicin is used for the treatment of feline lymphoma, it should be combined with other effective chemotherapeutic drugs in a combination protocol.