A Prospective Multicenter Observational Study Assessing Incidence and Risk Factors for Acute Transfusion Reactions in Cats

ABSTRACT Background The reported incidence of blood product transfusion reaction (TR) in cats varies greatly. Objective Evaluate the incidence and practices surrounding acute TRs in cats receiving feline blood products, using Transfusion Reaction Small Animal Consensus Statement (TRACS) definitions. Animals Cats (n = 444) that received feline blood products (n = 608) between March 2022 and January 2024. Methods Prospective, multicenter observational study at referral hospitals (n = 14) in the United States, United Kingdom, and Australia documenting the incidence of acute TRs in cats receiving allogenic blood transfusions. Results Acute TR incidence was 7.8% (95% confidence interval [CI], 5.6–10.6) for red blood cell (RBC)‐containing products and 1.1% (95% CI, 0.0–5.9) for plasma products. Febrile nonhemolytic transfusion reactions (FNHTRs) were the most common in RBC‐containing products (incidence, 5.7%; 95% CI, 3.8–8.1). Age of RBC unit (adjusted odds ratio [aOR], 1.04 per day; 95% CI, 1.00–1.07) and administering a RBC unit with an infusion pump rather than a syringe driver (aOR, 4.7; 95% CI, 1.43–15.54) were associated with an increased odds of FNHTR. Of transfusions discontinued (n = 28) because of a potential TR, 46.4% did not fulfill TRACS criteria for any TR. Death occurred within 24 h of a transfusion event in 18.3% but was not associated with the development of a TR (odds ratio [OR], 0.76; 95% CI, 0.29–1.99). Conclusions and Clinical Importance Transfusion reaction incidence in cats, as defined using TRACS guidelines, is reported. Febrile nonhemolytic TRs were the most common and were associated with increasing RBC unit age and administering RBC via an infusion pump.