HM07 - Identification of a Novel Common Red Blood Cell Antigen Lacking in a Boykin Spaniel

Abstract:
Background- Canine blood groups were identified through transfusion-induced alloantibodies. High-frequency RBC antigens pose significant clinical challenges, as rare negative patients risk sensitization, making finding compatible blood thereafter difficult.
Hypothesis: Suspect identification of a new canine RBC antigen due to alloantibody development in a transfusion-sensitized Boykin Spaniel.
Animals: Ten Boykin spaniels; four Dal− dogs; 34 canine blood donors.

Methods: Serologic tests, including blood typing, crossmatching, agglutination titers and direct Coombs’ test were performed by standard tube methods and gel column technology.

Results: A DEA 1+ Boykin Spaniel with Coombs negative non-regenerative anemia was first transfused with DEA 1- packed RBCs (pRBCs). She received a second and third DEA 1+ crossmatch-compatible pRBC transfusion, both uneventfully, 2 weeks and 11 months later. Nine days later, all major crossmatches with 47 dogs were strongly incompatible (graded 4+; auto-controls negative), including 9 Boykin Spaniels (one half-sibling), 4 Dal− dogs, and 34 blood donors (22 DEA 1+ ; 12 DEA 1−). The alloantibodies were identified as immunoglobulin G, with agglutination titers of 1:128 on neutral gel but exceeding 1:8,192 on antiglobulin-enhanced gel. Notably, three dogs exhibited weaker incompatibility (graded weak to 2+; titer < 1:16). The patient was blood-typed as DEA 1, 4, 5, 7 and Dal positive. Further typing and crossmatching revealed no clear association with known blood types.

Conclusions: A new, presumably common RBC antigen was identified in a Boykin Spaniel with an acquired alloantibody likely capable of hemolytic transfusion reactions. Rare weak reactions suggest some antigenic polymorphism. Antiglobulin-enhanced crossmatches significantly improved sensitivity.