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Does K9 Advantix II prevent heartworm in puppies? Is dosage safe?

Updated On September 23rd, 2025

Pet's info: Dog | Goldendoodle | Male | unneutered | 2 months and 7 days old | 10 lbs

I am looking into purchasing heartworm medication for my puppy. I have already purchased K9 Advantix II which prevents fleas, ticks and mosquitoes. Knowing that mosquitoes transmit heartworm, do I still need to purchase heartworm medication for my pup? Or, will the K9 Advantix II prevent heartworm? If yes, is generic brand as good as heartguard? Also, if the K9 Advantix II is for medium dogs (11-20lbs) and my pup is only 8/9 lbs when I need to apply it, is it safe to use? Thanks in advance!

3 Answers

Most Helpful Answer

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Answered By Megan, DVM, CVA

Veterinarian

Published on June 26th, 2018

I would still use a heartworm prevention. The K9 advantix may repell mosquitoes but it will not prevent 100%. I have a lot of people who uses the generic heartgard and don't have any breakthroughs. I would not give the 11-20 lbs Advantix to a dog less than 11 pound. My only concern is that is may cause him to be really lethargic due to being a little higher dose than he needs. I would see if you can buy one dose for a smaller dose of Advantix or a different flea preventative like frontline. I hope this helps!

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Other Answers

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    Answered By Andrea M. Brodie, DVM

    Veterinarian

    Published on April 12th, 2018

    Advantix II will kill mosquitoes which transfer heart worm larvae before they can bite your dog, however it is not effective against heart worm larvae in the blood. So while it may protect your dog from mosquito bites, it will not directly attack heartworm. If your vet thinks, that in your area, Advntix II is sufficient protection against heartworm, then I would not worry. If the information did not come from your vet, then I suggest you discuss this with your vet, as each area carries a different risk for infection.

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    Answered By Dr. Melanie, BVSc MS

    Veterinarian

    Published on June 4th, 2019

    Infected mosquitoes inject heartworm larvae when they bite your dog's skin. By killing mosquitoes before they can bite, you may help decrease your pet's chance of contracting the disease. That being said, it's best to use a heartworm medication as well, and I recommend Heartgard.

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