Question: I have a cat named Beauty and a Chihuahua named Beast. Is it okay to apply half of Beast’s monthly flea and tick preventive to his skin and the other half to Beauty’s skin?
Answer: It’s far safer to treat Beauty with a product labeled for cats because most topical flea and tick products for dogs contain substances toxic to cats. The most common are pyrethroids, neurotoxins that paralyze and kill fleas, ticks, mites, and lice. One of the most popular pyrethroids is permethrin.
Because liver metabolism in cats and dogs differs so much, cats are exquisitely sensitive to permethrin and other pyrethroids. Therefore, canine flea and tick products that contain these chemicals must never be applied to cats.
My cats often rub up against my dogs, so I don’t use pyrethroid-containing pesticides on my dogs. If you decide to, let the product dry before Beauty and Beast snuggle or play with each other; delaying contact for 72 hours is even safer.
Ask the Vet is written by veterinarian Lee Pickett, VMD. Send questions to [email protected] and read more at saturdayeveningpost.com/ask-the-vet.
This article is featured in the March/April 2026 issue of The Saturday Evening Post. Subscribe to the magazine for more art, inspiring stories, fiction, humor, and features from our archives.
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