Can dogs and cats eat Dog flea treatment on cats (permethrin)?
Many dog flea spot-ons contain permethrin, which is very toxic to cats. Cats can be poisoned by being treated with a dog product or by close contact with a freshly treated dog.
Why
Permethrin (pyrethroid insecticide; cats metabolise it poorly)
Signs to watch for
- twitching, tremors
- seizures
- drooling
- wobbliness
- high temperature
- dilated pupils
Good to know
Only for use on the skin exactly as directed on dogs; if a dog licks or eats the product, call your vet. Never use dog flea products on cats; keep cats apart from a treated dog until the product has dried. If it has been applied to a cat, wash it off with mild washing-up liquid and lukewarm water and go to the vet immediately.
If you think your pet has been poisoned
If you suspect your dog or cat has eaten or touched something poisonous, contact your vet or the nearest emergency veterinary clinic immediately, even if your pet seems fine – some poisons take hours or days to show signs, and early treatment works best. Do not try to make your pet vomit unless a vet tells you to, as this can cause more harm. Take the packaging, label or a piece of the plant with you, and note what was eaten, roughly how much, and when.
Sources
Sources
- PDSA – Permethrin toxicity in cats
- International Cat Care – Cats and poisons
- Cornell Feline Health Center – Poisons
Checked against these sources in October 2026.