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Why is my puppy vomiting and has diarrhea after eating new food?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed | Male | unneutered | 2 months and 30 days old | 9 lbs

My puppy is 3 months old, he had his first puppy shots on the29th. I recently changed his dog food the day before yesterday and we have been giving him rawhides (bully sticks and new treats) he has been fine but he has had more frequent bowel movements and it has turned to diarrhea today and he vomited twice today, once food, and once foam. He’s very sleepy and I’m concerned. He won’t eat anything but he will drink water

2 Answers

Most Helpful Answer

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Answered By Ana M, DVM

Veterinarian

Published on April 3rd, 2018

Thank you for submitting your question regarding Pj. I'm sorry to hear that he is experiencing vomiting and diarrhea. If a dog is going to suffer a vaccine reaction, it typically occurs the same day as the vaccination. So this is likely unrelated. He may be experiencing GI upset secondary to all the new treats. I would stop those for now. Being so young and small, he should see his veterinarian if symptoms persist. In the meantime, encourage him to eat and drink small amounts. It will be easy for him to become dehydrated at his size. I hope this information helps!

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    Answered By Lauren Kennedy, DVM

    Veterinarian

    Published on July 16th, 2017

    I am concerned about this amount of vomiting and diarrhea. Since the vaccines were 2 weeks ago they are not likely the cause of the symptoms. I would withhold food (small amounts of water are ok) for 12-24 hours and see how he does. If the symptoms continue after fasting then I would recommend having Sam checked out by your vet. They may need to run blood work or take X-rays to determine what is going on. Your vet can also give Sam so medication to help stop the vomiting and some antibiotics to help clear up the diarrhea.

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