Cats have A, B, and AB blood types with specific factors, but there is no universal donor type Recipient and donor blood must be properly cross-matched. Red cells from the donor are mixed with the serum of the recipient in major cross-matching. In a minor cross-match, the recipient's red cells are compared with the donor's serum. Blood donors must meet specific requirements in order to qualify to donate. They must weigh at least 50 lb for dogs and 10 lb for cats, have high enough blood component values, and have no infectious diseases. One donation could be used by up to two animals.