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My puppy is sick after vaccines. Why is he lethargic and not eating?

Updated On September 23rd, 2025

Pet's info: Dog | Pit Bull Terrier | Male | unneutered | 2 months and 27 days old | 7 lbs

Our puppy is very lethargic and shaky. He won't eat or drink since 7. He has diarrhea. He had his 2nd set of shots on Saturday afternoon.

2 Answers

Most Helpful Answer

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Answered By Ricardo Fernandez, DVM

Veterinarian, Veterinary Oncology Resident

Published on January 28th, 2018

Thanks for using Petco Pet Education Center, formerly Petcoach! Possible side effects after vaccines include pain at the injection site, lethargy, inappetence, diarrhea and general discomfort. I am concerned that Pepper is not drinking water and could become dehydrated. For this reason, I recommend you have Pepper evaluated by a veterinarian for further assessment and treatment. They would also be able to make sure that there is nothing else concerning going on. Pepper will likely start feeling better shortly. Good luck and best wishes!

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Other Answers

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    Answered By Ricardo Fernandez, DVM

    Veterinarian, Veterinary Oncology Resident

    Published on December 3rd, 2018

    Thanks for using Petco Pet Education Center, formerly Petcoach! Possible side effects after vaccines include pain at the injection site, lethargy, inappetence and general discomfort. This should subside within 1-2 days. If it does not improve or it worsens, have Pru evaluated by a veterinarian for further assessment and treatment. Otherwise, Pru will likely start feeling better shortly. Good luck and best wishes!

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    1Pet Parents found this answer helpful

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