Did you find any pieces of cloth? If so, were they small pieces? If so, hopefully the rest of the collar went down in small pieces. The dog may vomit it up. You may find it in poop in a day or 2. Or worst case scenario, it could cause a blockage. If any of the dogs start to act off, even in a week or 2, bring them to the vet, because the blockage could show up later. Keep on the look out, hopefully it comes out soon and painlessly.