Cat Twitching After Flea Treatment

Estimated Reading Time: 2 min | Last Updated: June 26th, 2018

Cats are sensitive to Permethrin found in flea products

Permethrin (or pyrethrin) is a compound commonly found in flea products for dogs and cats that are available at supermarkets and some pet shops. Cats are very sensitive to this compound, and as such, the products made for cats have significantly lower concentrations of permethrin in them. Unfortunately, the common mistake of applying the dog flea treatment to the cat can result in disastrous consequences. Some cases of toxicity occur because the cat has groomed the dog that has recently been given this flea treatment, or the owner has diligently put two cat doses on the cat. Also, beware of insect sprays and ant sand containing permethrin, as they have the potential to cause this form of toxicity too. Look for the active ingredient pyrethrin or permethrin.


  • Ear flicking
  • Twitching, muscle tremors
  • Lack of coordination
  • Drooling
  • Panting
  • Vomiting, diarrhoea
  • Hyperthermia (increased temperature)
  • Seizures

Permethrin toxicity is life threatening, if your pet is showing signs seek veterinary attention immediately.

Emergency treatment before transport to a veterinarian

If your cat will allow it, bathe it in lukewarm water with dish washing detergent. Do not allow your cat to groom itself as it will ingest more of the toxin. Keep your cat warm after the bath on the way to the clinic.

What to expect at the vet

Intravenous medications – to control seizures, relax muscles, and bind toxin in the blood

Skin decontamination (another bath with dishwashing detergent)

Sometimes oral decontamination (i.e. activated charcoal)

Intravenous fluids to support blood pressure and to help remove the toxin from the blood

Close monitoring of temperature – which can become too high or too low if not monitored

Intensive nursing care

If treated appropriately, most cats will recover. When severe intoxication occurs, your cat may need several days in hospital with intensive nursing care and close monitoring. If left untreated it is possible that your pet will not survive.


Unfortunately, permethrin toxicity is one of the most common toxicities reported in cats, despite the fact that it is easily preventable. To avoid this toxicity, ensure you only apply flea control formulations labelled for cats, and always follow the administration instructions. It is also a good idea to mark on a calendar when you have applied the flea treatment to avoid over-dosing.

If your cat normally grooms other pets in the household (including dogs) ensure that you only use formulations on the other pets that are safe for cats. Your veterinarian can advise you further on the best and safest product to choose for flea treatment and prevention.

Pet Seizures | Insect Bites  | Pets & Toxins  | Pet CPR

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