if your talking those handheld peices of crap i wouldn't use one at all on anything bigger than a squirrel....use a regular crossbow thats about 250-400 fps....
If you mean the hand held crossbow. I wouldn't recommend it. They're only about 80fps. It will prob only wound the animal and cause it pain. Go with a standard crossbow, anything above 250fps would do the job. I have both the "pistol" one and a full size. Full size will end the animal without much pain and suffering.