As you may already know the concern is the plastic becoming obstructed in the intestinal tract. Inducing vomiting is not indicated as the sharp edge can damage the esophagus on the way out. This is what you can do:
1- Do not give things like Pepto Bismol.
2- Do not induce vomiting.
3- Change his diet for the next 2-3 days to rice (75%) and boiled boneless chicken or ground beef (25%). The idea is for the rice to help move the plastic out in the feces while protecting the intestinal tract. Make sure you check his stool for the next 48 hours, if you do not find the plastic I would have him checked by your vet for x-rays with barium.
4- If during the next few days you see the following symptoms: lethargy, anorexia, vomiting, constipated or diarrhea, etc. follow up immediately with a veterinarian. These are all signs of a possible obstruction or perforation of the intestinal tract. In the meantime, observe him and change diet as above then wean him back into his regular diet.
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