Flea control for cats comes with a warning that owners of both species must take seriously: many dog flea-and-tick products are toxic, sometimes fatally, to cats. Each year cats are poisoned because a well-meaning owner used a leftover dog spot-on or let a treated dog groom the cat.
The permethrin problem
Many dog spot-on products contain permethrin at concentrations cats cannot metabolise. In a cat it can cause tremors, seizures and death within hours. Even a small amount — from licking a treated dog or rubbing against them — is dangerous. If a dog product ever gets onto a cat, wash it off and call your vet immediately.
What to use instead
- Only ever use a product clearly labelled for cats and dosed for their weight.
- Ask your vet to recommend a cat-specific spot-on, tablet or collar.
- In multi-pet homes, keep treated dogs separate from cats until the application is fully dry.
Do indoor cats need it?
Often, yes. Fleas hitch a ride indoors on shoes, on other pets, and through windows. An indoor cat with a sudden scratching habit or flea dirt in the coat needs treatment too. Talk to your vet about a sensible year-round plan rather than reaching for whatever is in the cupboard.
What poisoning looks like and what to do
Twitching, drooling, tremors, or seizures after any flea product application is an emergency, not a "wait and see." Wash the affected area with dish soap and lukewarm water and get to a vet immediately — don't wait for symptoms to worsen before acting.
