Why Permethrin is Dangerous for Cats: What You Need to Know

Permethrin is a synthetic insecticide that is used in agriculture, forestry, home pest control, and in the treatment of head lice in humans. Permethrin is a neurotoxin, meaning it attacks the nervous system of insects causing over-excitation and death. It is found in a wide range of topical flea and tick products that can be purchased in the grocery store, pet store, and large retailers. Although these products are safe when used on dogs they are toxic to cats and cause feline permethrin toxicosis.

Many pet owners believe that cats are very similar to dogs and think that it is okay to treat them the same way when it comes to feeding and administering medications. This false assumption could not be more wrong or deadly. Cats are quite unique and have some very important physiological and metabolic differences that make them distinct from dogs. In most mammals, like dogs, permethrin is quickly broken down by the liver into harmless compounds and this prevents it from having a toxic effect on the body. Cats however, lack the ability to break down permethrin in their livers and as a result they display the same signs of nervous system over-excitation as insects.

In most cases, uneducated pet owners apply permethrin containing flea and tick products to cats because they did not read the label, mistakenly assume cats and dogs are treated identically  or because they think that applying a small amount of the product will not hurt the cat. In other cases, cats come into contact with permethrin because they have licked or groomed a dog that had permethrin containing flea and tick products applied. Either way, the results are disastrous.

Signs of feline permethrin toxicosis are convulsions, seizures, vomiting, uncoordinated movements, drooling, and disorientation. Cats exhibiting these signs are likely to die if emergency veterinary treatment is not sought. The sad reality is that even with aggressive treatment, many affected cats will still die. Prevention is the key!

It is therefore CRUCIAL for cat owners to read the labels of the medications they buy for flea treatments. Major brands containing permethrin for flea treatment for dogs do tend to have warnings on their labels saying NOT to use the product on cat’s but sometimes these warnings are in small print.

Although once a month topical flea and tick products are very convenient and easy to use, it is imperative that pet owners are educated about the risks associated with their use. Be on guard for products that contain the insecticide permethrin. Although they are safe when used responsibly on dogs, they are deadly to cats and should never be applied to them. If a product containing permethrin is applied to a dog and there are cats in the household extra care and caution should be taken to ensure that the cats do not come into contact with the product. The best advice is to apply the product in the evening, separate the dog from the cats, and allow the product to dry over night. Once the product has dried it is no longer a danger to cats or children.