Romiplostim for treatment of thrombocytopenia in dogs: A retrospective assessment and clinical outcomes

Abstract Background Romiplostim, a thrombopoietin analog, is commonly used to treat immune‐mediated thrombocytopenia (ITP) in humans, but its use in dogs remains limited. Objectives Evaluate the effects and adverse events of romiplostim administration in dogs with thrombocytopenia caused by various underlying diseases. Animals Forty‐two client‐owned dogs with naturally occurring thrombocytopenia at 2 referral animal hospitals. Methods Retrospective, multi‐institutional analysis to evaluate the outcomes of romiplostim treatment in dogs. Results Among the dogs treated with romiplostim, 27 experienced an increase in platelet count and 26 maintained a platelet count within the reference range. Platelet count improvement was observed in various conditions: primary ITP (90%, n = 18/20), pancytopenia of unknown etiology (42.9%, n = 3/7), chemotherapy‐induced thrombocytopenia (50%, n = 3/6), babesiosis (100%, n = 1/1), radiotherapy‐induced thrombocytopenia (0%, n = 0/1), and disseminated intravascular coagulopathy (33.3%, n = 2/6). The median time for platelet recovery (>50 000/μL) after romiplostim administration was 4 days, and the median time for platelet count normalization was 7 days. Median hospitalization time for the improvement group (I) was 5 days. The survival‐to‐discharge rates were 85%, 40%, and 28.6% for dogs with primary ITP, secondary thrombocytopenia, and thrombocytopenia of unknown etiology, respectively. Conclusions and Clinical Importance Romiplostim is a well‐tolerated and promising treatment for primary ITP in dogs, suggesting its potential as a valuable therapeutic option for dogs with thrombocytopenia caused by various underlying conditions. These findings emphasize the need for further research to optimize romiplostim dosing and understand its role in treating secondary thrombocytopenia and pancytopenia of unknown etiology.