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My dog tested positive for distemper after vaccine. Is she contagious?

Updated on September 23rd, 2025

Pet's info: Dog | Mixed Breed | Female | unspayed | 26 lbs

Hi My adopted dog tested negative for distemper last May 28. She had her first 5in1 vaccines last July 8. Then After 2 weeks, she was tested again (needed before surgery) and it came out positive for distemper, exact result = S3 using ELISA Igm test. She had a retest after 4 days with the same S3 result and doctor said it could be the vaccines. Do you think she’s free from distemper? Is she okay to play with other dogs? I just want to get a second opinion on her result. Thank you!

1 Answer

Most Helpful Answer

Jenna Beyer, DVM, MBA, cVMA

Answered By Jenna Beyer, DVM, MBA, cVMA

Veterinarian, Certified Veterinary Acupuncturist

Published on July 28th, 2020

Since dogs can shed the virus for 4-5 weeks, I would wait at least a month from the first test before taking Manila around other dogs. As for the positive test result, your vet can call the lab and/or the vaccine manufacturer to ask about that particular vaccine reacting with the test to cause a false positive.
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