Flea and Tick Medication Poisoning (Pyrethroid Toxicosis) in Cats

With moderate to severe cases of pyrethroid toxicosis, cats may experience more severe symptoms.

Certain flea and tick medications are potentially fatal to cats, even in small amounts and even if they are labeled for use in cats. If a cat has been exposed to the following drugs, they require immediate medical attention:

The active ingredient in the flea and tick medication can be found on the product packaging, usually under the brand name.

Left untreated, cats can suffer from severe complications including brain damage, muscle damage and kidney failure.

Most cases of flea and tick medication poisoning in cats are from exposure to permethrin-based products, so the clinical syndrome is often called “pyrethroid toxicosis”. Cats are highly sensitive to permethrin, and even small amounts are potentially fatal.

Cats often develop this toxicosis when owners mistakenly give dog-only medications to their cat. It is critical to follow all instructions on the label, and to only use veterinarian-approved medications in cats. Never use a dog product on a cat.

Cats may also be exposed if a pyrethroid product is applied to the skin of a dog living in the same home. To prevent this, select cat-safe medications for dogs living with cats and separate the dog from the cat(s) until topical flea medications are dry.

It can take up to 72 hours for symptoms to develop after exposure to medication.

Diagnosis of pyrethroid toxicosis typically relies on a known exposure to these medications. It is uncommon to conduct a specific test to confirm exposure.

Treatment may involve any or all of the following:

• Bathing the cat to remove the medication, if applied to the skin
• Anti-seizure medications
• Muscle relaxants
• Fluid therapy
• General anesthesia when seizures cannot be controlled through medication alone
• Intravenous lipid emulsion (ILA) therapy

When serious symptoms are present, they are managed prior to bathing because bathing can make tremors worse or trigger a seizure.

Symptoms of pyrethroid toxicosis in cats generally resolve within 2-3 days with prompt and aggressive treatment and the prognosis for full recovery is good. Pyrethroid toxicosis is life-threatening, so without treatment, brain damage, muscle damage, kidney failure, and death may result.

Pyrethroid toxicosis is prevented by keeping cats on a vet-approved flea control medication specifically for use in cats. It is also prevented by ensuring the treating veterinarian is aware of the presence of cats in the home when sourcing flea control products for other animals, especially dogs.

Pyrethroid toxicosis is rare in cats receiving veterinarian-approved flea and tick products specifically for feline use.

It is commonly reported when cats exposed to pyrethroids in/on:

• Over-the-counter products
• Products labeled for dogs
• Dogs treated with pyrethroids

• Bathing
• Anti-seizure medication
• Muscle relaxants