Permethrin toxicity in cats usually happens when a dog flea treatment is accidentally used on a cat, or when a cat comes into close contact with a recently-treated dog. It’s one of the most common feline poisonings worldwide, with hundreds of cases reported every year in the UK. Cats of any age and breed can be affected, and even a small amount can be life-threatening if it isn’t treated quickly. 

Permethrin toxicity is a medical emergency, but most cats recover well when toxicity is recognised and treated promptly. Seek help from a vet straight away if you think your cat is at risk.

What is permethrin toxicity in cats?

Permethrin is an insecticide that’s commonly used in over-the-counter flea and tick treatments for dogs. Unfortunately, your cat’s body lacks a special enzyme needed to safely break down permethrin. Permethrin toxicity occurs if your cat is exposed to permethrin. It’s a chemical their body can’t safely remove.

• Toxicity is most often caused by dog flea treatments applied to cats by mistake.

• It can also happen through contact with treated dogs: sleeping next to or grooming a recently-treated dog.

• Symptoms can be severe and progress rapidly.

• Dog flea treatments containing permethrin include Advantix spot-on and Vectra 3D.

Call a vet immediately if you’ve accidentally used a dog flea product on your cat and/or they're showing signs of permethrin toxicity. Outlook is best following rapid identification and veterinary treatment.

Symptoms of permethrin toxicity in cats

• Drooling or salivating excessively

• Dilated (wide) dark pupils

• Vomiting

• Ear flicking, extreme sensitivity to touch, and skin rippling along their back 

• Twitching or muscle tremors all over their body, which can lead to increased body temperature (hyperthermia)

• Becoming unsteady or having difficulty walking

• Having seizures

• Collapsing or not responding to sound or touch

Cats at higher risk of permethrin toxicity

All cats are at risk because all cats are unable to detoxify permethrin. However, some will have an increased risk, such as:

• Cats living with dogs: where owners use over-the-counter dog flea treatments

• Indoor cats are more likely to be accidentally treated and/or have close contact with dogs

• Kittens: their smaller body size means even a tiny amount of permethrin can be dangerous

• Long-haired cats: potential to have more of the permethrin product clinging to their coat

How do vets diagnose permethrin toxicity in cats?

Vets diagnose permethrin toxicity based on your cat’s suspected exposure and their clinical signs, along with a full physical examination. It will help the vet if you can tell them the exact product used, when it happened and if they’ve had contact with treated dogs.

 Further tests include:

• Blood tests: to check general health, organ function/damage, and changes in blood cells

• Urine tests: to check concentration, kidney function, and colour (may be red/pink in severe cases)

• Checking and monitoring their body temperature 

What’s the vet treatment for permethrin toxicity in cats?

Permethrin toxicity is a true emergency. Treatment aims to control tremors and seizures first, then remove the toxin from your cat’s body and support their body while they recover.

Hospital emergency treatment:

• Medications to stop tremors and seizures

• Intravenous (IV) fluids: to support the circulation and organ function

• Intravenous Lipid Emulsion (ILE) Therapy: a specialised treatment for severe cases, which acts like a permethrin trap in your cat’s bloodstream, removing the toxin from vital organs

• Careful bathing to remove the product once the cat is stable

• Oxygen therapy: if needed

• Temperature regulation: cooling or warming your cat as needed

Most cats need 24–72 hours of hospital monitoring and inpatient care. 80-90% of cats who are treated promptly will recover from permethrin poisoning. Delaying treatment can lead to long-term complications and a lower chance of survival. 

How to care for a cat with permethrin toxicity at home

Home care is only suitable after your cat has been treated by a vet.

• Give prescribed medicines as directed at the correct time and dose.

• Use a buster collar if advised to prevent your cat from grooming themselves.

• Keep your cat warm, calm and indoors.

• Offer small, frequent meals.

• Encourage your cat to drink, and make sure fresh water is readily available.

• Ensure litter trays are accessible.

• Keep an eye on your cat’s appetite, movement and their behaviour, let your vet know if there are any concerning changes.

Permethrin toxicity in cats is a life-threatening emergency. Call a vet without delay, and never try to treat it at home without veterinary advice.

Tips on how to prevent permethrin toxicity in cats

• Never use dog flea treatments on cats.

• Consider alternatives to permethrin-based products for your dog if you also have a cat.

• Check labels carefully, even “natural” or “safe” over-the-counter pet products.

• Keep your cats away from dogs who’ve been treated in the last 48–72 hours.

• Store flea products safely and securely out of reach.

• Ask a vet for advice before using any parasite treatment.

Is my family at risk of catching this?

Permethrin toxicity is not contagious.

• There is no risk to people

• Risk to cats is only through direct exposure to permethrin products

• Minimise risks by washing your hands thoroughly after applying flea treatments to dogs

When to worry

Seek help from a vet immediately if your cat:

• Is drooling or twitching

• Seems wobbly or distressed

• Feels unusually hot or cold

• Has been in contact with dog flea products

• Having seizures

• Collapsed or unresponsive

Contact one of our Joii vets if:

• You’re worried you may have used the wrong flea treatment

• Your cat touched a dog that had a recent flea spot-on treatment

• You’re unsure which product was used

Safe flea treatments for cats

You should always select the dose of flea and tick treatment based on your cat’s current weight, following the weight guidelines provided on the product packaging.

Safe vet-recommended flea treatments for cats that do not contain pyrethrins include: