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Can vaccinated puppies shed parvo from vaccine and infect siblings?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed | Female | unspayed | 4 months and 17 days old | 15 lbs

Hi we have a litter of puppies and recently had 2 vaccinated, after around a week one of the unvaccinated siblings has tested positive for parvo. I have been told that the vaccinated puppies could have shed the virus from the vaccine. Is this possible? The unvaccinated puppies have not left the home or been in contact with any other dogs

2 Answers

Most Helpful Answer

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Answered By Joy Fuhrman, DVM, MBA, CPA

Veterinarian

Published on August 9th, 2017

If the puppies were vaccinated with a modified live virus vaccine they can shed the virus for 7-10 days. However, the virus shed is non-pathogenic, and so will NOT cause disease. The most it would do is "vaccinate" in-contact animals.

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    Answered By Daniel Fonza, DVM

    Veterinarian

    Published on

    Hi there and thank you for posting your question! It is unlikely that your puppy tested positive for parvo due to the vaccination. I've heard of potentially weak false positives due to the vaccination but that is rare. There were some studies performed that tested dogs recently vaccinated with canine parvovirus on the snap test and they did not test positive. Any positive parvo test should be taken seriously and if your puppy is having symptoms (diarrhea, vomiting, lethargy, weakness, etc.) I would strongly urge you get the puppy in to be seen by your veterinarian for treatment. I hope this helps! Please feel free to contact me with any further questions / concerns you may have. I am also available via consultation. Remember, the puppies don't have to come into contact with other infected dogs, you can easily bring parvo virus in on your shoes, clothes and hands. I always tell clients to make sure shoes are not accessible by puppies and wash hands on a regular basis, especially if you've pet other dogs recently.

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