Effectiveness and Adverse Events of Cyclophosphamide, Vincristine, and Prednisolone Chemotherapy in Feline Mediastinal Lymphoma Naturally Infected with Feline Leukemia Virus

SIMPLE SUMMARY: Feline leukemia virus (FeLV) infection is considered a poor prognostic factor for feline lymphoma. Cyclophosphamide, vincristine and prednisolone (COP) chemotherapy is a standard protocol treatment of feline lymphoma. This retrospective study involved 92 cats diagnosed with mediastinal or mediastinal plus other anatomical sites of lymphoma and treated with COP chemotherapy. Clinical signs and adverse events were observed after the 1st, 2nd, and 3rd inductions. Clinical signs improved after the 3rd induction of COP chemotherapy. The response rate was 96.74%. The overall median survival time was 338 days (range 62–1057 days). This study found that cats aged <4 years had longer survival than those aged at least 4 years. Anemia (before COP), azotemia (after 2nd induction) and elevated alanine aminotransferase (after 1st induction) was associated with an increased chance of mortality. ABSTRACT: Feline leukemia virus (FeLV) infection is considered a poor prognostic factor for feline lymphoma. This study investigated the prevalence of cats suffering from feline lymphoma with natural infection of the feline leukemia virus, as well as clinical signs, adverse events, and survival time after cyclophosphamide, vincristine and prednisolone (COP) chemotherapy. This retrospective study involved 92 cats diagnosed with mediastinal or mediastinal plus other anatomical sites of lymphoma and treated with COP chemotherapy. FeLV-antigen-positive was observed in all cats. Clinical signs and adverse events were observed after the 1st, 2nd, and 3rd inductions. Clinical signs improved after the 3rd induction of COP chemotherapy. The response rate was 96.74% (81.52% complete response, 15.22% partial response, and 3.26% no response). The overall median survival time was 338 days (range 62–1057 days). The overall response rate and median survival time of cats with feline lymphoma that were FeLV-antigen-positive and treated with COP chemotherapy were higher than from other studies. This study found that cats aged <4 years survived longer than those aged at least 4 years. Anemia (before COP), azotemia (after 2nd induction), and elevated alanine aminotransferase (after 1st induction) were associated with an increased chance of mortality.