Prevalence and Mode of Inheritance of the Dal Blood Group in Dogs in North America

BACKGROUND The Dal blood group system was identified a decade ago by the accidental sensitization of a Dal- Dalmatian with a Dal+ blood transfusion. Similar Dal-related blood incompatibilities have been suspected in other Dalmatians, Doberman Pinschers, and other breeds. OBJECTIVES To determine the prevalence and mode of inheritance of the Dal antigen expression in dogs. ANIMALS A total of 1130 dogs including 128 Dalmatians, 432 Doberman Pinschers, 21 Shih Tzus, and 549 dogs of other breeds including 228 blood donors were recruited from North America between 2008 and 2015. METHODS Prospectively, dogs were blood typed for Dal applying a gel column technique using polyclonal canine anti-Dal sera. Pedigrees from 8 typed families were analyzed. RESULTS The prevalence of the Dal+ blood type varied between 85.6 and 100% in Dalmatians and 43.3-78.6% in Doberman Pinschers depending on geographical area. Dal- dogs were identified mostly in Dalmatians (15/128; 11.7%), Doberman Pinschers (183/432; 42.4%), and Shih Tzus (12/21; 57.1%), and sporadically in mixed-breed dogs (3/122; 2.5%), Lhasa Apsos (1/6) and Bichon Frises (1/3). Only 6/245 (2.4%) blood donors were found to be Dal-, including 5 Doberman Pinschers. The mode of inheritance of the Dal+ phenotype was determined to be autosomal dominant. CONCLUSIONS AND CLINICAL IMPORTANCE The high percentage of Dal- Doberman Pinchers, Dalmatians and Shih Tzus increases their risk of being sensitized by a blood transfusion from the common Dal+ donor. Extended Dal typing is recommended in those breeds and in dogs when blood incompatibility problems arise after initial transfusions.