The Effect of Donor Packed Cell Volume and Storage Characteristics on Transfusion Efficacy in Cats.

PURPOSE: To determine whether donor packed cell volume (PCV) and storage-related changes in feline packed red blood cell (pRBC) units influence transfusion efficacy in cats. PATIENTS AND METHODS: In this prospective, observational study, 35 client-owned, transfusion-naïve, anemic cats that received a single pRBC transfusion during hospitalization were enrolled. Donor unit characteristics including age, PCV, total solids, potassium, and ammonia were measured prior to transfusion. Transfusion response was assessed as the change in recipient PCV, normalized to transfusion dose (mL/kg), measured immediately post-transfusion and at 12 and 24 hours post-transfusion. Transfusion efficacy was assessed as the change in recipient PCV at each timepoint. RESULTS: Dose-normalized response was available for 34 cats immediately post-transfusion, 30 cats at 12 hours, and 16 cats at 24 hours. Median recipient pre-transfusion PCV (17%) increased significantly at all post-transfusion timepoints (T0: 21%, T12: 23%, T24: 24%; p≤,0.002). Increasing donor unit age was associated with higher ammonia concentrations and lower donor unit PCV but not with potassium concentration. No significant associations were identified between donor unit characteristics and transfusion efficacy. CONCLUSION: Transfusion of pRBCs in cats resulted in rapid and sustained increase in recipient PCV. No association was detected between donor unit PCV or storage-related characteristics and the magnitude of this response. These findings suggest that transfusion response is multifactorial and may reflect a combination of donor-, product-, and recipient-related factors.