Red blood cell transfusion in canine and feline patients under general anaesthesia

To describe a referral hospital population of dogs and cats receiving red blood cell (RBC) transfusions during general anaesthesia (GA).

Retrospective cohort study.

Cats and dogs.

Between 2016 and 2021, animals that received RBC products during GA were identified using clinical records. Signalment, physical examination and clinical pathology findings, reason for GA, blood product details and timing of transfusion in relation to commencement of GA, American Society of Anesthesiologists (ASA) status and survival to discharge were collected. Normality was assessed using the Shapiro-Wilks test. Pearson's chi-squared or Wilcoxon-Mann-Whitney U tests was used to investigate the relationship between underlying disease, timing of transfusion and ASA status on survival; p < 0.05.

A total of 2137 animals received RBC transfusions during the study period. Of these, 332 occurred under GA and 244 patients were excluded, leaving 88 animals that met the study criteria. These comprised 18 cats and 70 dogs. The most common reason for RBC transfusion under GA was for surgical management of a haemoabdomen (23/88). Animals were significantly more likely to survive if their ASA status was I or II (p = 0.031). Overall survival was not affected by transfusion start time; however, animals with ASA status of IV or V were significantly more likely to survive when RBC transfusion was started before GA (p < 0.001). There was no significant difference in survival (p = 0.876), or length of hospital stay (p = 0.854) based on volume of RBC product administered. No transfusion reactions were identified in this group of animals in this study. Overall survival was 79.5%.

Noncritical animals (ASA I and II) were more likely to survive in this population, but more compromised animals (ASA IV and V) benefitted from starting the transfusion prior to GA.