Humans have long been implored to give blood – rewarded with a cookie, a glass of orange juice and the satisfaction of knowing their donation of vital fluid could help save a faltering patient.
Now an increasing number of dogs and cats are being pressed into service as blood donors to keep up with advances in veterinary medicine, such as open-heart surgery and the removal of tumors and aggressive treatment of traumas that require blood transfusions.
Veterinary blood centers sometimes feel the squeeze, with periodic shortages and no big sponsors stepping in to help defray the cost of animal blood banks, said Dr. Jean Dodds, a veterinarian who is founder and head of HEMOPET, a non-profit canine blood bank in Irvine, Calif.
"The last two years have been about the same, maybe worse," Dodds said of her supplies of donated blood. "It's worse in the sense that all of us are trying to expand – we're chasing a shadow. We're doing more sophisticated care today, and it's also because of awareness. People want to have the best for their pets."
Blood Banks Reward Donors
Many blood banks and animal hospitals reward a pet owner for a donation with packages of goodies: pounds of pet food, free exams, dog or cat treats and toys, and a free blood transfusion if it's ever needed. Their pets are also likely to be given a thorough physical, including intensive blood analyses.
Federal standards for human blood donations don't apply to animals, but veterinarians follow some general standards. To donate, dogs must be healthy and weigh at least 35 pounds, be between the ages of 9 months and 7 years and be up-to-date on their immunization shots. They cannot be in heat or pregnant and must be free of blood-born parasites.
Donation Depends on Size
Depending on a dog's size, blood banks will draw between 250 milliliters, the amount a child would donate, and 500 milliliters, about the human adult standard. Dodds draws much of her blood from retired greyhounds who are waiting to be adopted – one of the largest of breeds – and prefers to take only 250 milliliters.
Cats should be between the ages of one and nine, weigh at least 10 pounds and be free of illness or pregnancy. Cats will also be tested for feline leukemia, feline AIDS and other diseases. They generally donate no more than 50 milliliters at a time.
The process for dogs and cats is painless and is complete in a matter of minutes.
Dogs can give blood as often as every several weeks, and many blood banks encourage dog owners to bring back their pets from time to time, especially if the dog takes well to the procedure and has a sought-after blood type.
Dog blood types are quite different from human blood types. Dogs can have up to 9 parts to their blood type, each named for the antigen DEA followed by numbers 1 through 9. Since dogs can be positive or negative for each of the nine parts, there are thousands of different alternatives. A dog can be a "universal" blood donor if he tests negative for all parts of the blood type except for DEA 4. These dogs are the most sought after donors but, unfortunately, are uncommon.
The antigen that causes most reactions to canine blood transfusion is DEA 1.1. Many veterinarians and small community-based blood banks are able to test only for this antigen, especially in emergency situations. The test results are available in minutes.
Cats have three blood types, A, B or AB, the last of which is very rare. Most cats in the United States are type A, so it's usually not too difficult for a veterinarian to find a blood donor – in fact, some animal clinics keep a type-A cat around as a mascot and possible donor, in case a transfusion is needed on the spot, said Dr. Jane Wardrop, associate professor of veterinary medicine at Washington State University.
If your cat is among the 5 percent of felines with type B blood, you need to make sure you know where you'll be able to get a transfusion if it's needed. A cat with type B – usually found in several specific cat breeds, like the Devon Rex or British short-hair – has an antibody in the blood that rejects type A, so that cat must be given type B, Wardrop said.
As with dogs, veterinarians can test for a cat's blood type in just a matter of minutes.
Four Canine Blood Banks
Over the years, four large canine blood banks have been founded around the country to meet the animal blood needs of their regions. They operate independently. One of those, Midwest Animal Blood Services Inc. in Stockbridge, Mich., accepts only donations of the universal dog blood type, said associate director Valerie Cortright. There are also many small, community-based donor programs across the country.
One ray of hope for ending the periodic blood shortages came two years ago from the Food and Drug Administration, which approved the use of a substance called Oxyglobin, an artificial hemoglobin that's being used to replace natural blood in animal transfusions and may one day be given to people, said Wardrop.
Oxyglobin can be used with any blood type, she said. Yet until such substitutes become cheaper and more universally available, she said, pet lovers and veterinarians will face the problem of getting enough blood to ailing animals.
"It's a major problem to tackle," she said. "We'll get there, but it will take time."