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.