HARLEYSVILLE, Pa. - If man's best friend is a dog, then who is a dog's best friend? That would be Rover. Or Glow. Or Ivan or Raina.

The four canines recently donated pints of blood to their fellow pooches. And they did it without having to travel far from home: They visited an animal bloodmobile.

Similar to the Red Cross vehicles for humans, the University of Pennsylvania's traveling veterinary lab goes to where the donors are to make it easier to give.

"You don't really think about it until you actually need it," said Kym Marryott, manager of Penn's Animal Blood Bank. "Just like in people, dogs need blood, too."

Officials at Penn's School of Veterinary Medicine said they don't know of any other animal bloodmobiles operating in the U.S.

Theirs makes weekly rounds through suburban Philadelphia and New Jersey.

Dogs must have the correct blood type, weigh at least 55 pounds and be younger than 8 years old. Owners volunteer their pet for the short procedure, which requires no sedation.

However, Marryott said it's the dog that ultimately chooses to lie still and give.

About 150 dogs participate in the program. Each donates three or four pints a year, which can help animals suffering from illnesses like cancer or an accidental trauma like being hit by a car. One pint can save up to three dogs.

Just like people, the furry donors get a snack and a heart-shaped "U of P Blood Donor" sticker immediately after giving. In addition, they receive free blood screenings and dog food to take home.