MISSISSIPPI STATE -- Although they don't carry a donor card, four-legged furry blood donors are just as essential for their kind as humans are to their's.

Dogs and cats often give blood to save other pets' lives, said Lisa Halford, the supervising technician in small animal internal medicine/ICU at Mississippi State University's College of Veterinary Medicine.

Animal trauma victims, puppies with parvovirus, chemotherapy patients, and those undergoing major surgery or amputations often need blood transfusions or blood products. As with humans, blood must be readily available or the patient dies.

Halford, a certified veterinary technician, said to meet its patients' blood needs, the CVM keeps blood donor animals available, and some workers volunteer their own pets if needed. Dog blood can be frozen in blood banks, but cat blood is difficult to maintain and usually is drawn as needed, Halford said.

MSU has three cats and eight dogs available to donate blood. The cats rarely give blood, but the dogs donate about once every four to six weeks, Halford said.

MSU blood donor dogs must at least weigh 50 pounds and be 12 to 18 months old. Dogs are typically kept three years as donors, then are adopted by screened families and usually keep ties with the veterinary college. While donors, they are given monthly mini-physicals, weigh-ins, blood checks and heartworm preventative medicine.

Health maintenance is a priority. The dogs are dewormed every three months and their teeth are cleaned every three to four months as needed. Every six months a veterinarian makes a full blood count and checks for blood parasites. Yearly, the dogs receive complete physicals and vaccinations.

Jason Peters, a certified veterinary technician who works closely with MSU's lab animals, said technicians and caregivers daily check each dog's condition and monitor exercise sessions.

When the big day arrives for a blood donation, the dogs are ready, typically having learned the routine by the second time. The dogs are placed on a table where they stretch out and lie still, Peters said.

"They know exactly what to do," he said.

It takes about 10 minutes to draw the 450 milliliters (nearly one pint) of blood from each dog, Halford said. Afterwards, the dog is bandaged, fed two cans of its favorite food and placed in ICU for two to three hours of observation.

"We don't spare any expense on these dogs because they're saving other dogs' lives," Halford said. "They even act like they take pride in what they do."

After leaving ICU, the dog is not allowed to run around and exercise for one day. A veterinarian always checks the dog's health the next day.

Halford said there are six major types of blood in dogs, but 98 percent have the "DEA4" blood type. Because of this, matching a donor's blood with the recipient's is usually easy, although a veterinarian checks to make sure the blood is compatible.

Cats have three types of blood, "A" which is very common, "B" which is not as frequent and "AB" which is rare, Halford said. When cats require blood, they are given whole blood rather than components, which dogs usually receive.

Cats must weigh at least 10 pounds to be a blood donor and can give between 40 and 50 milliliters each time. Similar health checks and observations are made for blood-donor cats.

With animal blood banks in short supply, it is important for veterinary clinics to have donor animals on hand.

"If we didn't have blood donors, we would lose a lot of lives," Halford said. "If we had a seriously bleeding animal come into the clinic, we wouldn't have the time to order the blood we need from a distant blood bank."