Yes. Today, the veterinary community has not only recognized the many different blood groups for canines, but our understanding of what exactly happens to an animal when a transfusion is administered has revolutionized how we can be certain we are providing the right therapy for patients. There are over a dozen blood group systems that have been recognized in dogs; however, only six are clinically significant. These are referred to as dog erythrocyte antigens, with the abbreviation DEA followed by a number. So far, the recognized blood types in dogs are DEA 1:1, 1:2, 3, 4, 5, and 7. Basic blood types include DEA 1:1 negative and DEA 1:1 positive, while complete blood typing reveals if a canine is also positive or negative for the remaining antigens 3-7. DEA negative is the most common blood type; however, only one of the negative types is a true universal and that is DEA 4.  For this reason, DEA 4 is the most beneficial blood type and the main blood type we screen for.  Both positive and negative dogs are still eligible to donate.  However, because positive blood types are not as common, we only need a limited number of positive donors.  Cats on the other hand, have just two basic blood types, type “A” and “B.” Type “A” is much more common; 95% of housecats in America have type “A” blood. A third, type “AB,” is extremely rare.