Call ASPCA Poison Control: (888) 426-4435 or go to your nearest emergency vet. Do not wait for symptoms.
Permethrin, found in many dog flea treatments and yard insecticides, is acutely toxic to cats. Cats lack the liver enzyme (glucuronyl transferase) needed to break it down. Even small amounts — including exposure from a recently treated dog in the same household — can cause fatal neurological toxicity.
Why Is Permethrin Toxicity Toxic to Cats?
Permethrin disrupts sodium channels in nerve cell membranes, causing constant nerve firing. Cats metabolise pyrethroids far more slowly than dogs or humans, leading to rapid accumulation in neural tissue and prolonged, severe neurological effects.
Cats are particularly vulnerable due to their unique metabolic profile — they lack certain liver enzymes that other mammals use to process many compounds, making them more sensitive to a range of toxins than dogs or humans.
How Much Permethrin Toxicity Is Toxic to Cats?
These thresholds are general guidelines. Always use your cat's actual weight and contact Poison Control for a personalised risk assessment.
| Cat weight | Mild signs | Serious signs | Potentially fatal |
|---|---|---|---|
| Any cat | Any exposure: TOXIC | Any exposure: TOXIC | Any exposure: potentially FATAL |
ℹ️ ⚠️ Even second-hand exposure — sleeping near a dog that was recently treated with a permethrin product — can cause toxicity in cats.
Symptoms of Permethrin Toxicity in Cats
Onset: 30 minutes – 6 hours. Watch for these signs:
Treatment window: Urgently. Tremors and seizures can escalate quickly. Bathing to remove permethrin and immediate IV anticonvulsant therapy are critical.
What to Do If Your Cat Was Exposed to Permethrin Toxicity
- Stay calm and note the exposure details — what was consumed, how much, and when. This is critical information for the vet.
- Call ASPCA Poison Control immediately — (888) 426-4435. Available 24/7. They will tell you whether emergency care is needed.
- Do not induce vomiting unless specifically instructed by a vet or Poison Control. Incorrect induction can cause additional harm.
- Go to an emergency vet if symptoms are already present or Poison Control advises it. Find a 24-hour emergency vet near you.
- Bring the packaging or a sample of what your cat was exposed to if safe to do so.
Frequently Asked Questions
Yes. If your dog was treated with a permethrin flea product and your cat grooms the dog or sleeps against them, the cat can absorb enough permethrin to become severely ill.
The most recognisable sign is severe, constant muscle trembling — often starting in the face and spreading through the body. Seizures can follow rapidly.
There is no specific antidote. Treatment focuses on controlling tremors and seizures with methocarbamol or diazepam, cooling, IV fluids, and supportive care. Early treatment dramatically improves outcomes.
Many dog-specific spot-on flea products contain permethrin. Always check labels before applying any flea product to dogs in multi-pet households with cats.