Exploration of risk factors for non‐survival and for transfusion‐associated complications in cats receiving red cell transfusions: 450 cases (2009 to 2017)

Objectives To describe red blood cell transfusion practices and short‐term outcomes in anaemic cats. To determine clinical variables associated with non‐survival and transfusion‐related complications. Material and Methods In this retrospective study, blood bank records from the Ontario Veterinary College Health Science Centre (OVC‐HSC) were reviewed to identify cats that received packed red blood cells or whole blood from 2009 to 2017. We extracted cause of anaemia, history of previous transfusion, pre‐ and post‐transfusion packed cell volume, pre‐transfusion compatibility testing, volume and dose of blood product, age of red blood cell unit, transfusion‐associated complications and patient survival. Results A total of 450 transfusion events were recorded in 267 cats. Blood loss was the most common indication for blood transfusion (44.9%), followed by ineffective erythropoiesis (37.5%) and red blood cell destruction (22.5%). Transfusion‐associated complications occurred in 10.2% events and there was a 20.2% mortality after transfusion. Mean increase in packed cell volume 24‐hours after transfusion was greater in cats undergoing major cross‐match testing before transfusion (7.2%) versus those that did not (4.0%). Non‐survival was associated with higher packed cell volume before transfusion, low patient body temperature before transfusion, anaemia due to blood loss and number of transfusions administered. Older age of transfused blood units was associated with non‐survival and transfusion‐related complications. Clinical Importance This study was observational and so our analyses were exploratory, but suggest that major cross‐match before transfusion tended to have greater transfusion efficacy and transfusion of older blood products might have detrimental effects on survival.