Evaluation of the University of Florida lomustine, vincristine, procarbazine, and prednisone chemotherapy protocol for the treatment of relapsed lymphoma in dogs: 33 cases (2003-2009).

Objective: To evaluate the toxicity and efficacy of a modification of a previously evaluated combination of lomustine, vincristine, procarbazine, and prednisone (LOPP) as a rescue protocol for refractory lymphoma in dogs.

Design: Retrospective case series. Animals-33 dogs with a cytologic or histologic diagnosis of lymphoma that developed resistance to their induction chemotherapy protocol.

Procedures: Lomustine was administered on day 0 of the protocol. Vincristine was administered on day 0 and again 1 time on day 14. Procarbazine and prednisone were administered on days 0 through 13 of the protocol. This cycle was repeated every 28 days.

Results: Median time from initiation to discontinuation of the University of Florida LOPP protocol was 84 days (range, 10 to 308 days). Overall median survival time was 290 days (range, 51 to 762 days). Overall response rate with this protocol was 61% (20/33), with 36% (12) having a complete response and 24% (8) having a partial response. Toxicosis rates were lower than for the previously published LOPP protocol.

Conclusions And Clinical Relevance: The University of Florida LOPP protocol may be an acceptable alternative to the mechlorethamine, vincristine, procarbazine, and prednisone protocol as a rescue protocol for dogs with lymphoma.