Neutropenia in dogs receiving vincristine for treatment of presumptive immune-mediated thrombocytopenia

Abstract

Background: Neutropenia is an adverse effect of vincristine when used in multidrug chemotherapy protocols. Objective: To determine the incidence of neutropenia, identify potential risk factors for neutropenia, and determine the effect of neutropenia on outcome, in dogs receiving vincristine for treatment of immune-mediated thrombocytopenia (ITP). Animals: One hundred twenty-seven client-owned dogs presumptively diagnosed with ITP. Methods: In this retrospective cohort study, medical records were reviewed to identify dogs presumptively diagnosed with ITP, and treated with vincristine, over a 15-year period. Logistic regression was used to identify risk factors for the development of neutropenia in dogs receiving vincristine. Time to platelet count ≥40 000 platelets/μL, survival, and duration of hospitalization were compared between neutropenic and non-neutropenic dogs. Results: Vincristine was administered to 127 dogs with presumptive ITP; 19 became neutropenic. Administration of cyclosporine was significantly (P