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Does Hartz kill roundworms?

Species: Dog
Breed: lab mix
Age: 1-2 years
well, this one time when I had a lab mix puppy that wasn't vetted or wormed or anything because she came from a super rural farm in MN. She was 12 weeks old and I used those flea and tick drops on her (they were from Wal-mart...Hartz brand) and the next morning I went to take her outside to potty, and there were dead worms all over the crate floor! there were A LOT! sp I was wandering.....the fleas and tick drops can kill worms too?...because it sure looked like it to me....

Related Article: How to get rid of fleas!


Online vet, Dr. Marie

Dr. Marie replied:

Thanks for an interesting question!

Hartz flea drops are not supposed to treat roundworms (which is most likely what you saw). The ingredients in Hartz flea and tick drops are mostly phenothrin and some methoprene. Both of these have some effectiveness against fleas. (I say some because I find that these products do not work well for fleas.)

There is no claim on the label that they work for intestinal parasites. I did some research for you to see if there was any connection but could not find any.

However, my theory is that the ingredients do have some effect on roundworms. Many of the topical medications do get absorbed through the skin and can have systemic effects as well.

It is definitely a good idea to repeat a treatment with a dewormer that is meant for roundworms as there may still be more there. You will also want to repeat it in 10-14 days to make sure that you cover all the life stages.

As an additional note, I really don't recommend over the counter flea products like Hartz. I have seen so many cases where they don't work and in some cases they can be toxic especially if applied to a young puppy or to a cat.

I hope that helps!

Dr. Marie

---This question was asked in our Ask A Vet For Free section.---


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Disclaimer: Although Dr. Marie is a qualified veterinarian, the information found on this site is not meant to replace the advice of your own veterinarian. AskAVetQuestion.com and Dr. Marie do not accept any responsibility for any loss, damage, injury, death, or disease which may arise from reliance on information contained on this site. Do not use information found on this site for diagnosing or treating your pet. Anything you read here is for information only.

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Dr. MarieDr. Marie is a veterinarian who practices in a busy animal hospital in Ottawa, Ontario. She created Ask A Vet Question as a resource for good, accurate veterinary advice online. Dr. Marie treats dogs, cats, hamsters, guinea pigs, and rats. She has been a vet since 1999.

Is an online vet visit just as good as a trip to your veterinarian? No! But, many times, asking an online veterinarian a question can help save you money. While Dr. Marie can't officially diagnose your pet or prescribe medications, she can often advise you on whether a vet visit is necessary. You can also ask Dr. Marie for a second opinion on your pet's condition.