Get to the closet vet or pet shop for professional care. Until you get to the vet, find a small CLEAN cloth and dampen it with lukewarm water. DAB the the blood off the area so you can see the wound. Do NOT rub hard-- blood must clot before it can start healing; if you break the clotting, the animal will bleed again. Consult a vet as soon as possible; it might need stitches.