If the toenail is cut too short, you can use a styptic pencil containing silver nitrate to stop blood flow, although many animals object to the styptic pencil as much, or more, than toenail cutting. The black end of the stick is held to the bleeding nail and gently rotated until bleeding stops.
Even without any treatment the nail should stop bleeding in about 5 minutes or less
http://www.vetmed.wsu.edu/clientED/dog_nails.asp