Ideally, we'd like to see Chewy visit your vet today due to the potential battery ingestion. For these, we don't usually recommend inducing vomiting because of the high risk involved in damaging the esophagus if battery acid comes back up. Since you bear confidence that he did not chew on it, this may be of minimal risk. My recommendation to you would be to give him 1/2 cup of milk to drink and present him to your vet's office. They may either induce vomiting there or give you instructions on how to treat this at home.
If you choose to avoid the vet's office, I would give the milk as suggested and then follow up with the following GI protocol. Famotidine will be used to keep the stomach calm and the bland, higher fiber diet will help to move the item through the GI tract.
The first step is to administer a dose of regular pepcid (famotidine) every 12-24 hours. This should help with GI symptoms. You will want to give 0.5mg/pound of body weight (a 10# ***** would receive 5mg, a 5# ***** would receive 2.5mg, etc). For this, you can visit any human pharmacy and buy the OTC brand name Pepcid, or you can use the cheaper, off-brand “famotidine” that’s available. Either will be useful. For a pet avoiding taking medication readily, you will likely need to using a pilling technique like this one: https://www.youtube.com/watch?v=-P6NfbxeLX0
Following this, feed 2-4 meals per day of the following diet: Combine white or brown rice, boneless, skinless chicken breast and sufficient water for cooking in a stock pot. Boil on medium until it turns to mush and the breast is easily flaked. If your companion requires a more palatable food, try adding in pureed baby food in chicken, turkey and similar flavors. Avoid those that contain onion or garlic in the ingredient panel. Work up to feeding exclusively until he passes the item in his stool. After this, work on slowly switching back to the regular food that your companion typically eats over the course of 7-10 days.
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