Keeping Cats Safe: Permethrin

Hi everyone,

Please find below the latest entry in the icatcare spotlight on science entry:

Permethrin is generally used as an insecticide and is found in some flea spot-on products made for dogs, however, for cats, exposure to concentrated permethrin can result in serious illness and death.

Why can permethrin be used in products for dogs but not for cats?

Cats lack certain proteins (enzymes) in their liver that break down some chemicals into harmless forms, which means that the chemicals can accumulate in the cat’s body and cause serious illness. It’s this difference in drug metabolism that means we should never assume a product that’s safe for dogs is also safe for cats.

How are cats poisoned by permethrin?

Most commonly this is through owners using a dog flea product on their cat by mistake. This could be because they assume that the product for dogs is simply a stronger version of that for cats, and a smaller quantity is needed. This isn’t the case and even a very small amount of permethrin can make a cat very unwell.

Poisoning can also happen through contact with a dog that has recently been treated by a spot-on product containing permethrin. The cat may rub against the dog, or even sit on the same furniture, and the permethrin can be transferred to its coat and then be poisoned.

Permethrin is sometimes impregnated in clothing to deter ticks, mosquitoes and flies, and though there is no evidence to show that cats have been poisoned through exposure, if there is a specific concern it’s always best to contact the manufacturer of the product. 

What are the signs of permethrin poisoning?

The chemical affects the cat’s nervous system, causing:

  • Tremors
  • Shaking
  • Twitching
  • Oversensitivity to touch and sound
  • Walking as though drunk

In severe cases:

  • seizures or fits

Less commonly cats may have trouble breathing and may even become blind.

What should I do if I believe my cat has been exposed?

If you think you may have applied a flea product containing permethrin you need to contact your vet IMMEDIATELY. The same applies if you think your cat has been in contact with a treated dog.

Can cats recover from permethrin poisoning?

If veterinary treatment is received promptly, the majority of cats will thankfully make a full recovery.

More severely affected cats, especially those suffering from fits that are hard to control, unfortunately have a poorer prognosis and sadly may die or be put to sleep.

How can we prevent cats suffering from permethrin poisoning?

Fortunately most cases of permethrin poisoning are preventable.

  • Never use a dog product on a cat.
  • Ensure flea treatments are solely designed for cats. Take extra care when choosing from a shop where dog and cat treatments may be displayed together.
  • Be careful when shopping online. Many descriptions don’t include active ingredients and warning logos or signs aren’t always prominently displayed on webpages.
  • Always read product descriptions and take note of warnings
  • If you have both dogs and cats in your home, use a treatment for the dogs that doesn’t contain permethrin.
  • If dogs are treated with a product containing permethrin, they should be kept away from cats for 72 hours.
  • If you have any concerns about a product, contact your vet for advice.
  • Whenever permethrin poisoning is known or suspected, it’s important to let the manufacturer know, as well as the local drug regulatory authorities (your vet can help with this). Unless cases of poisoning are reported, the scale of the problem can’t be determined.

Keep up to date with the rest of the Keeping Cats Safe campaign here.

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