Canine Dal Blood Type: A Red Cell Antigen Lacking in Some Dalmatians

Background:Based upon alloantibodies produced after sensitizing dogs with transfused blood, more than a dozen blood group systems have been recognized thus far, and some have been classified as dog erythrocyte antigens (DEA). Hypothesis:A new canine red cell antigen was suspected, based on the development of specific alloantibodies in a Dalmatian previously sensitized by blood transfusions. Animals:Twenty‐six Dalmatians (including 1 Dalmatian in need of blood compatibility studies); 55 canine blood donors. Methods:Serologic tests, including blood typing, crossmatching, and direct Coombs' test were performed by standard tube techniques and a novel gel column technology adapted from human blood banking. Results:By day 40 after transfusion of an anemic Dalmatian, all major crossmatch tests to 55 non‐Dalmatian dogs were incompatible. The 2 initial donors, who were compatible before transfusion, were also now incompatible, suggesting the development of an alloantibody to a common red cell antigen. No siblings were available, but 4 of 25 unrelated Dalmatians were crossmatch compatible, suggesting that they were missing the same red cell antigen. The patient was blood typed DEA 1.1, 3, 4, and 5 positive, but DEA 7 negative. Further blood typing and crossmatching results did not support an association to any of these known blood types. The alloantibodies produced were determined to be of the immunoglobulin G class. Conclusions and Clinical Importance: Based upon the identification of an acquired alloantibody in a Dalmatian, a presumably new common blood type named Dal was identified. Dalmatians lacking the Dal antigen are likely at risk of delayed and acute hemolytic transfusion reactions.