A Prospective Randomized Clinical Trial of Vincristine versus Human Intravenous Immunoglobulin for Acute Adjunctive Management of Presumptive Primary Immune-Mediated Thrombocytopenia in Dogs

Background Dogs with immune-mediated thrombocytopenia (ITP) are at risk of hemorrhage when platelet count is <50,000/L. Treatment with vincristine (VINC) or human intravenous immunoglobulin (hIVIG) decreases platelet recovery time compared with treatment with corticosteroids alone. Objectives To compare the effect of hIVIG versus VINC on platelet recovery in dogs with ITP. Methods Prospective, randomized study. Twenty dogs with idiopathic ITP (platelet count <16,000/L) were enrolled. All dogs were treated with corticosteroids. Dogs were randomly assigned to receive a single dose of hIVIG (0.5g/kg) or VINC (0.02mg/kg). Outcome measures were platelet recovery time, duration of hospitalization, and survival to discharge. Results There was no significant difference in age, sex, weight, or initial platelet count between dogs treated with hIVIG (n=10) and dogs treated with VINC (n=10). Median platelet recovery time for both groups was 2.5days (P=.51). Median hospitalization time for all dogs that survived to discharge was 4days and not different between groups (P=.29). Seven of 10 dogs in the hIVIG group and 10 of 10 in the VINC group survived to discharge. Survival analysis did not identify any significant difference between the groups at discharge, 6months, and 1year after entry into the study. No adverse effects were reported in either group. Conclusions and Clinical Importance Vincristine should be the first-line adjunctive treatment for the acute management of canine ITP because of lower cost and ease of administration compared with human intravenous immunoglobulin (hIVIG).