In vitro compatibility of type-B feline blood with canine blood of different DEA 1 phenotypes and with type-A feline blood

Canine xenotransfusion may be a temporary emergency option for type-B cats when compatible feline blood is unavailable, but the in vitro compatibility of type-B feline blood with canine blood has not been fully characterized. This study evaluated and compared the slide-agglutination crossmatch compatibility of type-B feline blood with canine blood with different dog erythrocyte antigen (DEA) 1 phenotypes and with type-A feline blood. Blood samples were obtained from 70 type-B cats, 17 type-A cats, 26 DEA 1-positive dogs, and 18 DEA 1-negative dogs. Among 300 major crossmatches, incompatibility was detected in 66/230 (28.7%) canine tests and 69/70 (98.6%) type-A feline tests; type-A feline blood carried a significantly higher risk of major incompatibility than canine blood (RR 3.4, 95% CI 2.7–4.2; P < 0.0001). Among 287 minor crossmatches, incompatibility occurred in 186/218 (85.3%) canine tests and 26/69 (37.7%) type-A feline tests; canine plasma carried a higher risk of minor incompatibility than type-A feline plasma (RR 2.2, 95% CI 1.6–3.0; P < 0.0001). No significant differences in incompatibility were found between DEA 1-positive and DEA 1-negative canine blood or between weakly positive and normal/strongly positive DEA 1-positive blood. These in vitro findings suggest that, in selected emergency cases, a single transfusion of canine packed RBCs may be cautiously considered as a short-term rescue option for type-B cats when compatible feline blood is not immediately available, following compatibility testing and careful individual risk–benefit assessment. Canine plasma should not be considered suitable because of the high rate of minor incompatibility.