Can I Use Dog Flea or Tick Treatments on a Cat?

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  • Fleas and ticks are common ectoparasites (a parasite that lives outside its host) that affect both dogs and cats.   Regular preventative treatment is necessary to keep these parasites under control. But is it ever okay to use a dog flea treatment on a cat?

    The short answer is no, treating a cat with a dog flea treatment can potentially cause death.

    The active ingredient in most spot-on (products that are applied to the back of the neck) dog flea treatments is permethrin, a synthetic compound that acts like natural extracts from the chrysanthemum plant.  It affects the nervous system in insects, by interfering with sodium channels to disrupt the function of neurons. This causes muscle spasms, paralysis and death. Unfortunately, it is also highly toxic to cats. Our beloved felines aren’t a small dog (or human); they have an entirely different liver metabolism when it comes to many drugs, including permethrin. Even a tiny amount of permethrin can be deadly to cats.

    Do other flea and tick products contain permethrin?

    Topical flea treatments are the most common source of permethrin poisoning in cats, but other dog products which may contain the toxin include:

    • Flea collars
    • Shampoos
    • Sprays
    • Foggers

    Deliberate or accidental exposure to this product causes neurotoxicity with a range of symptoms, including:

    • Ear flicking and facial twitching which progress to full body twitches or tremors
    • Seizures
    • Vomiting
    • Crying
    • Loss of appetite
    • Elevated body temperature (pyrexia)
    • Ataxia (wobbly gait)
    • Dilated pupils
    • Respiratory failure
    • Coma

    How does poisoning occur?

    • Deliberate administration of a dog flea product on a cat. It is never a good idea to buy a dog flea treatment and to save money, split the pack between dog and cat, or treat several cats with a single dose meant for a dog.
    • Accidental administration of a dog flea product on a cat.
    • When a cat comes into contact with a dog who has recently been treated with a dog-flea treatment that contains permethrin.

    What should I do if my cat has been exposed to permethrin?

    Immediately wash the affected area using warm water and dishwashing soap (the type you use in a sink, not a dishwasher such as Dawn or Fairy Liquid). Apply a drop or two of dishwashing liquid, lather with a small amount of lukewarm water, rinse. Keep water away from the cat’s face to prevent accidental water aspiration. Apply detergent, lather and rinse three times, then wrap the cat in a warm towel to prevent hypothermia. If you are not confident enough to bathe the cat, don’t waste time, proceed immediately to the nearest veterinarian who can bathe the cat for you.

    Rinsing the product off the coat will help to reduce toxicity; however, some of the flea-product will have still made it into the cat’s system. Therefore urgent veterinary care is necessary. Call ahead of time to let them know you are on your way. This is a critical situation that can not wait until the morning. If possible, bring along the packaging of the product the cat has been exposed to.

    How is permethrin poisoning treated?

    There is no antidote to permethrin poisoning. The goal of treatment is to manage symptoms and provide supportive care; this can include the following:

    • Muscle relaxants such as methocarbamol
    • Propofol where tremors and seizures are present
    • Gas anesthesia may be necessary for refractory seizures (seizures that do not respond to seizure medication).
    • Intravenous fluids


    • Always store cat and dog medications separately to prevent accidental administration of a dog flea/tick product.
    • Keep cats away from dogs for 72 hours after they have received a flea or tick product that contains permethrin.
    • Better still, avoid the use of flea and tick products on dogs that contain permethrin if there is a cat in the home. I prefer to give my dogs chews instead.
    • Speak to your veterinarian about the safest flea and tick products for your dog and cat. Avoid supermarket flea and tick treatments.
    • Always check the active ingredient on cat or dog flea and tick treatment packaging. Some cat flea treatments also contain permethrin in much lower doses, but it is always safer to avoid the use of permethrin on cats altogether, even if they are at so-called safe levels. There are far safer flea and tick treatments on the market for cats. If you are in any doubt about the safety of a flea and tick product, speak to your veterinarian or vet nurse.

    Common which contain permethrin:

    If you have a  home with both dogs and cats, avoid the use of the following products.

    • Advantix
    • Bio Spot Spot On (for dogs)
    • Virbac Knockout Fogger
    • Proticall for dogs
    • Vectra 3D


    • Julia Wilson, 'Cat World' Founder

      Julia Wilson is the founder of Cat-World, and has researched and written over 1,000 articles about cats. She is a cat expert with over 20 years of experience writing about a wide range of cat topics, with a special interest in cat health, welfare and preventative care. Julia lives in Sydney with her family, four cats and two dogs. Full author bio