Dear Straight Dope: My friend and I were wondering, where exactly do they get the blood for operations on dogs? You never hear of doggie blood drives or anything, but dogs need surgery sometimes and they sometimes need transfusions, right? I wouldn't think human blood would work, but where else does the blood come from? Same for kitties or hamsters — where do the vets get blood for all these poor animals? Ashley Carter, Phoenix

SDSAB Jill replies:

I used to work as a veterinary technician and to be honest with you, I had never heard of this before. Turns out animals donate and receive blood transfusions from others of their species, and the process is very similar to human transfusions. But you can’t exactly call the donors “volunteers” and they probably aren’t offered juice and cookies.

Just as with humans, animal donors are checked for infectious diseases and must meet a weight requirement. They can only donate once every couple of months. Apparently some veterinarians used to keep a few dogs and cats in their facilities for the express purpose of blood donation in emergency situations. There are now national, regional and local veterinary blood banks. And some people make their pets available as local donors.

Dogs have about a dozen blood type groups and cats have three groups with some variation within each group. Generally the donor and recipient animals must be matched, though dogs with A negative blood are universal donors. Cats have no universal donors, but almost all domestic shorthair cats have type A blood. Certain purebred cat varieties tend to have Type B blood or, rarely, type AB.

Horses have more than 15 different blood types, way more than humans. “Beevo,” a horse who lives at Oklahoma State University Veterinary Medicine College, is very valuable as he’s one of only 5% of horses who has a blood type that makes him a universal donor. You can read about him at www.horsenet.com/news/pr/blood_2. 21.html.

“When needed for medical emergencies and other equine surgical procedures requiring blood replacement, veterinary assistants load Beevo up and transport the horse a few miles south to the OSU Veterinary Hospital on campus. The horse has donated blood up to nearly three quarts a pop when necessary for a single complicated surgery scores of times during the past several years.”

Apparently he doesn’t balk too much at the procedure. They do sedate him a bit while they draw blood from his jugular vein. He weighs 1,900 pounds, so it’s probably not a good idea to tick him off.

There is now an artificial blood on the market for dogs. “Oxyglobin” is derived from cattle blood and costs $150 a unit. The FDA approved it in 1998 and at some point such a product may be available for humans, too.

As for hamsters, I hate to sound cold but a replacement hamster costs about six dollars and fifty cents.

SDSAB Jill, Straight Dope Science Advisory Board

Send questions to Cecil via cecil@straightdope.com.

STAFF REPORTS ARE WRITTEN BY THE STRAIGHT DOPE SCIENCE ADVISORY BOARD, CECIL'S ONLINE AUXILIARY. THOUGH THE SDSAB DOES ITS BEST, THESE COLUMNS ARE EDITED BY ED ZOTTI, NOT CECIL, SO ACCURACYWISE YOU'D BETTER KEEP YOUR FINGERS CROSSED.