And is it possible he pooped outside without you seeing it?Most things pets eat will pass through their system in 24 hours. Sometimes foreign objects can get stuck in places and not pass. Most times if there is a foreign body in the intestinal tract we will see symptoms in a pet such as vomiting, decreased appetite, lethargy, and abdominal pain. It doesn't sound like your dog is showing these, but it does make me concerned that it has been 3 days and the shell hasn't shown up. Sometimes the foreign object doesn't cause a complete blockage, so things can still pass through around it, but it can cause problems down the road. Luckily a mussel shell should be easy to pick up on an x-ray, so if you can get your dog in for an x-ray they should be able to tell right away if it is still there (it is much harder with something like a piece of fabric). If you want to try something at home, I would consider feeding
a few bulky meals today (such as whole grain bread or brown rice). If your dog doesn't pass the shell in the next 24 hours, and you are pretty sure he ate the shell, I would take him for an x-ray. Depending on where the mussel shell is, they may want to do different things. If it is still in the stomach
, it may be removed with a scope, if it is in the colon, he may need an enema or stool softener, if it is in the small intestines, then surgery may be needed.