Guide

Never on cats

The banner on the brand's own storefront says it in four words — do not use on cats — and it belongs in every conversation about this product. K9 Advantix II contains permethrin, which dogs metabolize and cats can't: for a cat, exposure can cause tremors, seizures, and worse.

For dog-and-cat households the label's guidance is workable but strict: keep the cat away from the treated dog until the application spot is fully dry, and never let a cat groom the spot. If a cat is ever exposed, that's an immediate call to the vet or the pet poison line — not a wait-and-see.

If your household can't reliably keep a cat off a freshly treated dog, tell your vet — there are dog-and-cat-safe alternatives, and no catalog's convenience is worth the risk. This page is an owner's summary of the label warning, not veterinary advice.