Do not make him vomit whatever you do unless he is under veterinary supervision as he could choke. This happened to a friend of ours whose dog ate a slipper. Dog survived as wife was a nurse but had throat damage for quite a while. Monitor to see what comes out in your dogs poop. But unless you can gather all the piece you may have to take the dog for xrays etc and possible surgery as any foreign body stuck anywhere in the digestive track can lead to rupture or blockage and death. Pets are wonderful but you have to always be prepared that they will do crazy things and it will cost money.