Tag Archives: toxicity

Pyrethroid Toxicity in a Cat

Last week we saw a cat with a toxic reaction to an over-the-counter flea/tick prevention product.  The owner had utilized the company’s cat product, at the appropriate dose, applied per the instructions.  This cat, however, developed the most obvious and common of the signs associated with a toxicity to one of the ingredients in the product.  The video below shows you what we saw when the owner brought the cat in.



Flea and tick topical products use a pretty wide range of ingredients.  There are a LOT of different products out there.  For most owners, knowing what might be problematic is almost impossible.  Given that a company is marketing a product for a particular species, age, and weight range, a consumer would generally believe that it’s safe and effective.  Sadly, we see often enough that safety and efficacy are lacking in some products.


In this case, the prevention contained a product that belongs to a  class of pesticides known as pyrethrins/pyrethroids (Pie – reeth – rens).  They’re modeled after a naturally occurring toxin in chrysanthemums.  These chemicals cause nerve cells to malfunction, leading to paralysis of the affected organism.


Most animals can break down the toxin fast enough that it doesn’t cause them any trouble.  The liver is responsible for a lot of the breakdown of the chemical.  However, cats lack a specific enzyme that the liver uses to destroy the toxin molecules.  This makes cats far more sensitive to the effects of pyrethroids.


Pyrethroids are used in many dog products, including some that we recommend and use.  Dogs aren’t anywhere near as sensitive to these products as cats, so we feel that the dog products are safe for use in dogs.  Owners have to be VERY careful, however, to never apply the dog products to cats, nor to let cats lick the freshly applied product off the dog.  Serious, potentially lethal toxicity WILL result from the use of dog products on cats.  No doubt about it.  I haven’t seen a cat show toxicity simply by living with a dog that has a pyrethroid-containing product on its skin.


There’s no direct antidote to pyrethrin toxicity.  We decontaminate the animal by washing them in dish soap.  This strips the oil and product off the skin, so no more is absorbed into the animal’s body.  If the tremors are severe, a muscle relaxant can be given to lessen the twitching and tremors.  I don’t think death from pyrethroid toxicity is very common, but it’s definitely possible.


I’m deliberately not mentioning the name of the product used on this cat, nor the specific names of the products we use.  I’m doing so to avoid libel/slander claims.  Contact your veterinarian for specific recommendations for your pet and your home environment.  Regional variations in which products are needed to control fleas/ticks are also something we have to acknowledge.  What we use up here in Michigan may not be effective in Florida, for example.


Avoiding products with pyrethroids is the easiest way to lower the risk to your cat.  We recommend products that do not contain pyrethroids for our feline patients.




Filed under case report, cats, medicine, toxicology