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My dog tested borderline positive. Will prevention affect heartworm retest?

Updated On September 23rd, 2025

Pet's info: Dog | Beagle | Male | 8 years and 8 months old | 36 lbs

He was diagnosed with border line positive for heartworm our vet too a micro test that showed negative he has him on sentinel pills he wants to redo the regular heart work test again would it show negative if he is on heartworm pills

1 Answer

Most Helpful Answer

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Answered By Dr. Strydom, DVM

Veterinarian

Published on October 11th, 2018

Yes, it would show up even if on prevention. The test is only checking for the presence of the adult heartworms in the heart. It takes approximately 6 months from the time the dog is bitten by a positive mosquito to the time they would show up positive on a test. I suggest you not wait and get a confirmatory test now. If Shiloh truly is heartworm positive you should have him treated. The prevention is only going to keep him from getting more worms. It does nothing for treatment. Hope this helps. Best wishes.

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