are in need of one. There are no pacemakers made specifically for use in dogs, but human pacemaker users are often outlasted by their pacemakers, leaving behind a functioning pacemaker with less battery power left than a new pacemaker which could be implanted into a dog. One difficulty in implanting used pacemakers is the removal from the deceased human - the pacemaker leads often experience accumulation of surrounding heart muscle tissue and become difficult to remove after death. If the leads are cut in order to remove the pacemaker donation is not possible. If a pacemaker has not been used by a human but has reached its expiry date it will not be suitable for use in a human but could still be used in a dog. Blood transfusion For a blood transfusion to take place, the donor and recipient must be of compatible blood types. Dogs have eleven blood types but are born without antibodies in their blood. For this reason, first time transfusions will not have a reaction, but further transfusions will cause severe reactions if the dog has a mismatch in the DEA1.1 blood type. Because the immune systems of dogs are so fierce, cross-match tests must be performed upon each dog blood transfusion. Only about one in every 15 dogs is negative for all antigens and thus, a universal donor. 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. Policy regarding how donor animals are treated varies. In April, 2014, a veterinarian office in Fort Worth Texas, was accused of keeping dogs that had been presumed to have been euthanized, and using the animals for blood withdrawal. Heart valves Open-heart surgery for dogs requires a six- to eight-person team to carefully monitor the patient before and during the invasive surgery. The entire surgery lasts five hours, during which time the dog is