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Permethrin Toxicity in Cats - Symptoms and Treatment

Laura García Ortiz
By Laura García Ortiz, Veterinarian specialized in feline medicine. Updated: February 28, 2024
Permethrin Toxicity in Cats - Symptoms and Treatment

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Permethrin is a type of insecticide which can be used in medical applications as a deworming agent. It is found as an active ingredient in numerous antiparasitic and insecticide products. Its use is safe and effective for use on canines, but it is highly toxic to cats. Due to the high levels of permethrin toxicity in cats and its widespread household use, it is one of the most common causes of poisoning in cats. Permethrin intoxication can cause serious symptoms and threaten the life of the cat.

At AnimalWised, we look into more detail at permethrin toxicity in cats. Specifically, we look at the symptoms and treatment of permethrin poisoning in cats to help you know what to expect if your cat is affected.

You may also be interested in: Common Cat Poisons - Symptoms and Treatment


  1. What is permethrin?
  2. Why is permethrin toxic in cats?
  3. Symptoms of permethrin poisoning in cats
  4. Diagnosis of permethrin poisoning in cats
  5. Treatment of Permethrin Poisoning in Cats

What is permethrin?

Permethrin is included in the drug group known as pyrethroids. These compounds are frequently used as external antiparasitic and insecticides in dogs. They are marketed in products such as flea collars, pipettes, shampoos and sprays. They can be used alone or combined with other active ingredients. They are also used in farms, homes and gardens. Specifically, pyrethroids are characterized by:

  • Being compounds obtained from Chrysanthemum spp., so its origin is natural, pyrethrum being known since ancient Persia and China
  • They have high cuticular permeability, so they are very topically absorbed well by the skin
  • They present very little toxicity in mammals (with the exception of cats)
  • They do not create resistance in insects
  • Up to 25% of marketed insecticides contain pyrethroids

Specifically, permethrin is a first-generation pyrethroid. It is characterized as having cyclopropane carboxylic esters and being lipophilic, the latter meaning they are distributed in tissues with a greater amount of lipids. These tissues include the liver, nervous tissue, fat and kidneys. Other pyrethroids include cypermethrin, which is a second generation pyrethroid and has a cyano group.

Why is permethrin toxic in cats?

The toxicity of permethrin in cats is due to the fact this species metabolizes it poorly. Specifically, permethrin is metabolized in the liver by the microsomal system, followed by oxidation and conjugation processes with glucuronic acid. Cats have a deficiency in glucuronidase transferase, which is involved in the conjugation of the compound with glucuronic acid. This causes detoxification of these compounds to be greatly delayed, resulting in toxic effects.

How can a cat be poisoned with permethrin?

A cat becomes poisoned when it absorbs permethrin through its skin, by licking its fur, or by accidental ingestion. Despite not being indicated for cats, poisoning frequently occurs when:

  • The cat lives with dewormed dogs: the feline lives with a dog that has recently been dewormed with this product. Close contact with the dog results in intoxication.
  • A dog pipette has been administered: usually due to ignorance of the product, some cat guardians administer a permethrin pipette with the false belief it will be just as affective as other deworming agents.

For more information, you can consult this more general guide to poisoning in cats.

Symptoms of permethrin poisoning in cats

The high levels of permethrin toxicity in cats makes poisoning by this active ingredient a serious medical problem. As a neurotoxin, it affects the cat's brain and results in neurological symptoms. It acts on the voltage-dependent sodium channels of neurons, causing hyperexcitation or continuous nervous excitation.

The effects of permethrin poisoning appear between 3 and 72 hours after exposure, and the following clinical signs may appear:

  • Tremors
  • Muscle fasciculations (contractions)
  • Incoordination
  • Seizures
  • Vocalization (meowing)
  • Depression
  • Bradycardia (reduced heart rate)
  • Dyspnea (breathing difficulty)
  • Mydriasis (pupillary dilation)
  • Hyperesthesia (painful increase in tactile sensitivity)
  • Hyperthermia or hypothermia
  • Vomiting
  • Diarrhea
  • Pruritus (itching)

In the event that a topical permethrin spray is used in a cat, they will show paresthesia (prickling or burning sensation) on the area to which it is applied. If they ingest the toxic permethrin sialorrhea (excessive salivation) will appear after ingestion.

learn more with our article on why a cat is drooling.

Permethrin Toxicity in Cats - Symptoms and Treatment - Symptoms of permethrin poisoning in cats

Diagnosis of permethrin poisoning in cats

Laboratory tests are not very useful for the diagnosis of permethrin toxicity. Only positive samples sent from fat tissue, the liver, skin or brain indicate exposure. In some cases, these are only obtained from the dead animal if a necropsy is performed. Permethrin poisoning can be confused with anticholinesterase poisoning, so an anticholinesterase test can help rule it out. In permethrin intoxication, acetylcholinesterase activity should be normal.

The diagnosis of permethrin intoxication in cats is made from the clinical history and the clinical signs the feline presents. It is suspected when a cat appears with tremors, agitation, convulsions, discomfort, incoordination, changes in behavior or body temperature, as well as when an affirmative answer is obtained when asked if the cat has been dewormed with a pipette for another species or if they have had contact with an animal dewormed using a permethrin pipette.

A blood test, a biochemistry and a urinalysis can be performed, where the following may appear:

  • Azotemia (increased creatinine and urea)
  • Hypoproteinemia (low protein)
  • Hyperkalemia (high potassium)
  • Increased transaminases, especially alanine transaminase (ALT) and aspartate transaminase (AST)
  • Hematuria (blood in urine)
  • Proteinuria (proteins in urine)
  • Bilirubinuria (bilirubin in urine)

These symptoms are not permethrin specific, another reason why providing the veterinarian with as much information as possible is so important. Find out other conditions with some of these symptoms by reading our articles on blood in a cat's urine and azotemia in cats.

Permethrin Toxicity in Cats - Symptoms and Treatment - Diagnosis of permethrin poisoning in cats

Treatment of Permethrin Poisoning in Cats

Treatment of permethrin intoxication in cats will depend on various factors, including the amount involved and its route of introduction into the body. For example, primary treatment according to route of intoxication includes:

  • Oral treatment of permethrin poisoning: if less than 2 hours have elapsed since ingestion, emetics such as xylazine can be used to induce vomiting. If this has not been effective, gastric lavage (stomach pump) should be performed. Activated charcoal can also be used in the first 4 hours, the porosity of which will adsorb part of the permethrin's toxicity and preventing it from passing into the blood.

  • Treatment of permethrin intoxication through the skin: if the intoxication has been through the skin, the cat should be bathed with mild dish detergent or with a keratolytic shampoo. After bathing, the cat should be kept in a warm and safe place.

Symptomatic treatment

In addition, supportive treatment should be carried out to control the clinical signs of permethrin intoxication, which include:

  • Oxygen administration in cases of respiratory distress
  • Fluid therapy if there have been losses due to vomiting and/or diarrhea
  • Diuretics such as mannitol or furosemide to increase glomerular filtration (kidney flow) and stimulate diuresis to favor its elimination (as long as the animal is hydrated)
  • Atropine at low doses if there is hypersalivation (high doses stimulates the already overstimulated central nervous system).
  • Warm them if hypothermic
  • Keep the cat cool if there is hyperthermia or heat stroke
  • If they have tremors, methocarbamol can be given as a muscle relaxant
  • If they have recurrent seizures, methocarbamol and diazepam will be administered as an anticonvulsant
  • If the seizures and neurological signs are very severe, the cat can be anesthetized by inhalation with isoflurane


Cats poisoned by permethrin can have seizures that are difficult to control. If left untreated, the cat can die within 24 hours. Most cases are not usually so serious and the clinical signs are short-lived, with the cat usually recovering between 24 and 72 hours after intoxication.

It is essential to deworm your animal with products specially marketed for them. Products from other species should never be used to deworm them, especially if we do not know their active ingredients. As permethrin proves, the wrong ingredient for the wrong purpose can seriously threaten your cat's health. Senior cats and kittens are more at risk of adverse effects due to weaker immune systems.

Find out some of the other products you can find in your home with result in poisoning in cats with our video below:

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Permethrin Toxicity in Cats - Symptoms and Treatment, we recommend you visit our Other health problems category.

  • Roder, J. D. (n.d.). Manual of Veterinary Toxicology. Retrieved from: http://www.rednacionaldeveterinarias.com.uy/articulos/farmacologia%E2%80%8F/Manual_de_toxicolog_a_veterinaria.pdf
  • Editorial team. (2017). Small Animal Toxicology. Veterinary Portal. Retrieved from: https://www.portalveterinaria.com/animales-de-compania/articulos/16833/toxicologia-en-pequenos-animales-apunte.html
  • MA Daza. (2004). Most frequent intoxications in small animals . AVEPA Available at: https://ddd.uab.cat/pub/clivetpeqani/11307064v24n4/11307064v24n4p231.pdf
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Permethrin Toxicity in Cats - Symptoms and Treatment