— Dogs always have been known as loyal companions to humans. These days, they’re increasingly helping each other — by giving their blood.

Rising demand is causing places like the University of Wisconsin-Madison’s veterinary teaching hospital to seek more dog and cat blood donors.

Six years ago, they had three donors. Now they have about 22 dogs and cats who give blood regularly.

The donors are sometimes former patients themselves. But most often, they’re companions to students or staff members.