Internal medicine

Packed red blood cells

Surgery

Intensive care medicine

ABO blood group system

Blood type (non-human)

Hematocrit

CATS

Blood transfusion

Anesthesia

Medicine

Journal of Veterinary Internal Medicine

Background Recognition of the feline red blood cell (RBC) antigen Mik and the presence of naturally occurring anti‐ Mik antibodies resulting in acute hemolytic transfusion reactions prompted the recommendation to perform a crossmatch before a cat's first RBC transfusion, but this guideline has not yet become a standard practice. Objective To determine the prevalence of naturally occurring non‐AB alloantibodies detectable by tube crossmatch, and to compare transfusion outcomes in cats with and without a crossmatch performed. Animals Three hundred cats that received an RBC transfusion, with or without a major crossmatch performed. Methods Retrospective study. Results Major crossmatch incompatibilities were documented in 23 of 154 transfusion‐naive cats (14.9%) and in 15 of 55 previously transfused cats (27%; P = 0.042). Type‐specific packed RBCs (pRBCs) were administered to 167 and 82 cats with and without a crossmatch, respectively. Median volume of pRBCs administered during the first transfusion was 5.3 mL/kg (range, 2.4‐18 mL/kg). Median change in PCV scaled to dose of pRBCs was +0.8%/mL/kg; administration of crossmatch‐compatible pRBCs was not associated with a greater increase in PCV. Febrile transfusion reactions occurred more often in cats that received non‐crossmatched (10.1%) compared to crossmatched (2.5%) pRBCs ( P = 0.022). Seventy‐six percent of cats that received pRBC transfusions survived to hospital discharge. A crossmatch was not associated with improved survival to discharge or at 30 or 60 days posttransfusion. Conclusions and Clinical Importance The prevalence of naturally occurring non‐AB incompatibilities is sufficiently high to justify the recommendation to perform a crossmatch before all (including the first) RBC transfusions in cats.

Prevalence of naturally occurring non‐AB blood type incompatibilities in cats and influence of crossmatch on transfusion outcomes