Tape worms cause this! Be sure he had a de-wormer that also kills tapes! Some of them don't! BTW, tapeworms are caused by fleas, so also use a flea treatment on him. BE CAREFUL to use a good brand ... NOT HARTZ ... and make sure he is old enough for it. I would advise using Advantage ... available through your vet or an online pet supply company!

NOTE: a good dewormer that includes all worms (tapes included) is Drontal tablets! Three wormings about 2 to 3 weeks apart is a good rule of thumb! Don't get confused with Droncit ... that does tapes ONLY.