A Controlled Study of Human Intravenous Immunoglobulin in the Treatment of Canine Primary Immune-Mediated Thrombocytopenia
We have previously reported (JVIM 2007; 21: 694-699) that human intravenous immunoglobulin (hIVIG) was well tolerated and associated with rapid platelet count recovery in an uncontrolled study of canine primary immune-mediated thrombocytopenia (pIMT). In the present clinical trial, we used a prospective, randomized, double-masked, placebo-controlled study design to test the hypothesis that early adjunctive therapy with hIVIG in pIMT dogs treated with corticosteroids would be a safe therapeutic intervention to improve survival rate to discharge, accelerate platelet count recovery, and shorten hospitalization time without increasing the cost of treatment. Eighteen client-owned dogs with pIMT were enrolled beginning in August 2006. The population consisted of 16 purebreds and 2 mixed breed dogs with a mean age of 8.3 +/- 1.7 years and a mean body weight of 20.9 +/- 2.8 kg. There were 14 spayed female and 4 neutered males.
Dogs were randomized to receive either a single infusion of hIVIG (0.5 g/kg) or placebo on day 1 from initial admission. Groups did not differ with regard to age, body weight, platelet count, hematocrit, or albumin on presentation. The placebo group consisted of 9 dogs, and 2 dogs (22.2%) were lost from the study because of death due to pIMT. The hIVIG group consisted of 9 dogs and has not lost any dogs. Two dogs, one for each group, experienced an episode of relapse within six months from the initial diagnosis. The median lag time from the start of treatment until platelet count increased to >40,000/µL for placebo group dogs was 7.5 days (mean +/- SD, 7.8 +/- 3.9 days; range, 3-12 days) and 3.5 days (3.7 +/- 1.3 days; range, 2-7 days) for hIVIG group dogs. The median hospitalization time for placebo group dogs was 8 days (8.3 +/- 0.6 days; range, 4-12 days) and 4 days (4.2 +/- 0.4 days; range, 2-8 days) for hIVIG group dogs. There were no identifiable immediate or delayed adverse events associated with hIVIG administration.
Analysis of the data revealed a significant (<0.05) reduction in platelet count recovery time and length of hospitalization in hIVIG group dogs. There was no significant difference between groups with respect to costs of initial hospitalization. Although the population sample size is small, early adjunctive therapy with hIVIG appears to be safe and beneficial in dogs with pIMT.