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Can My Cat Take My Dog’s Flea or Worm Medicine?

Last Updated on December 6, 2023 by Catster Editorial Team

PillsKeith Ramsey | more info (via: Wylio)
Can a worm medicine used to treat dogs be used for cats? I use Hartz dewormer on my dogs (Chihuahuas). My cat definitely has worms but don’t have the cat dewormer on hand.

Coalport, PA

I don’t recommend it.

Many deworming medications are used both in cats and dogs. However, I absolutely never recommend self medicating a pet. There are too many ways to go wrong.

Cats have unique metabolisms. They require lower doses of many medications, and they are more prone to toxic reactions than their canine counterparts — including dogs that are cat-sized.

Also, you have mentioned the dreaded H-word. I have seen Hartz flea products cause so many toxic reactions that I suspect I will be forever prejudiced against the company’s entire product line. I don’t know what ingredients are in your particular Hartz canine dewormer, but I’d recommend that you throw that product away right now and call your vet.

Safe deworming is best done under the supervision of a veterinarian. Don’t take chances — get a prescription from him or her.

About the Author

Dr. Eric Barchas
Dr. Eric Barchas

Dr. Eric Barchas is a professional traveler who spends his spare time working as a full-time veterinarian; contributing to Dogster and Catster; walking, cooking, camping, and exploring the outdoors; skiing (when conditions permit); and reading Booker-shortlisted novels. In between trips Dr. Barchas lives and works in the San Francisco Bay Area with his wife, Denise, and his canine pal, Buster. His main veterinary interests are emergency and critical care, wellness, pain management and promotion of the human-animal bond. Dr. Barchas has to Dogster and Catster since May 2005. 

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