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Pyrethrin/Pyrethroid Poisoning in Dogs

By Renee Schmid, DVM & Ahna Brutlag, DVM, MS, DABT, DABVT Pet Poison Helpline; Updated, Ahna Brutlag, DVM, MS, DABT, DABVT, Associate Director of Veterinary Services, Pet Poison HelplineDr. Heather Handley, Staff Veterinarian, Pet Poison Helpline.

Care & Wellness, Pet Services

Pyrethrin insecticides are naturally derived from the chrysanthemum (“mum”) flower, and pyrethroids are the synthetic (artificial) versions of this chemical. Pyrethrins are rarely found in products we use on a day-to-day basis, however pyrethroids are very commonly found in products around the home for insect control. The formulations of these products depend on their intended use and vary in concentration, additional ingredients (synergists), and carriers. Some intended uses include:

  • Home and outdoor yard and garden insecticides (these typically come in liquids, sprays, granules, and foggers)
  • Over-the-counter medicated flea shampoos
  • Topical flea and tick preventatives

Common pyrethroid chemical names include permethrin, bifenthrin, deltamethrin, lambda-cyhalothrin, cyfluthrin, fenvalerate, esfenvalerate, cyphenothrin and many others.

How toxic are these insecticides to dogs, cats, and other animals?

Whether or not a pyrethrin or pyrethroid product is toxic, depends on the animal species involved, as well as the concentration, synergists, and carriers used in the product. The use of pyrethrins/pyrethroids is generally very safe in dogs; however, cats and fish are very sensitive to these products.

Fish may die from even the smallest exposure, so be sure to cover aquarium tanks (with something non-porous like plastic wrap) or remove the tanks from an area you will be treating with a product containing a pyrethrin or pyrethroid. Likewise, if you apply a topical flea and tick preventative or treatment onto your dog, do not allow him to jump into a body of water where fish may be living for at least 24-48 hours following application.

Life-threatening signs may be seen in cats with even a very small exposure to products containing pyrethroids.

How do dogs become exposed to pyrethrin/pyrethroid insecticides?

Topical flea and tick spot-on medications often contain high concentrations of pyrethrin/ pyrethroids and are commonly used on dogs without serious problems. Dogs may also be exposed to lower concentrations when these products are used inside or outside the home in the form of insect sprays, foggers and granules. Bifenthrin is frequently used in liquids and granular fire ant products.

How can I tell if my dog has pyrethrin/pyrethroid poisoning?

In a dog, signs can develop within the first hour after ingestion, and may include any or all of the following signs:

  • Excessive drooling
  • Gagging or hacking
  • Vomiting
  • Lack of appetite
  • Agitation
  • On rare occasion, dogs that may be more sensitive to pyrethrins/pyrethroids, are exposed to bifenthrin, or ingest a large or concentrated amount, can develop more severe signs such as tremors, twitching, shaking, incoordination (difficulty standing or walking), weakness, seizures, and rarely, death.

Pyrethroid based topical flea and tick products, especially spot-on formulations, may cause paresthesia or a “pins and needles” sensation of the skin. This typically occurs where the product was applied to the dog (e.g., along the back). Although this is not typically a significant concern, it can be uncomfortable and stressful to your pet. Signs of this skin reaction are listed below. These signs can develop within 15 minutes to several hours after the product has been applied to the dog’s skin:

  • Agitation or restlessness
  • Intense itchiness
  • Dogs may roll around on their backs or try to bite at their backs.
  • Vocalization
  • Crying/whimpering

What should I do if my dog is showing these signs?

If you suspect that your dog is having a reaction to a pyrethrin or pyrethroid, please call your veterinarian or Pet Poison Helpline, a 24/7 animal poison control center, at 1-800-213-6680 right away to determine if there are at-home treatments that could be performed or if immediate veterinary referral is needed. Additionally, if your pet is having a reaction to a flea/tick product, call the product manufacturer. Many animal health companies offer 24/7 support in case of adverse events.

The sooner you seek treatment, the better the prognosis and outcome for your pet!

How does my veterinarian diagnose pyrethrin/pyrethroid poisoning?

Your veterinarian will make a presumptive diagnosis if there is a known or possible history of exposure to a product containing a pyrethrin or pyrethroid, coupled with signs described above.

Is there an antidote for pyrethrin/pyrethroid poisoning in dogs?

No. There is no antidote for pyrethrin or pyrethroid poisoning. However, quick and effective treatment with decontamination, monitoring, and supportive care help to minimize the extent and severity of signs.

How does my veterinarian treat severe pyrethrin/pyrethroid poisoning?

If clinical signs have developed, treatment will be based on what active ingredient your pet was exposed to, how your dog was exposed to the product,and the signs your dog is showing. Your veterinarian may bathe your pet with liquid dish soap to remove any remaining product and prevent further exposure.

In cases involving neurological signs such as twitching, tremors, and seizures, your dog may require hospitalization for 48 - 72 hours. in some cases, signs can seem to resolve but then reoccur so it is important for your veterinarian to monitor your pet and provide supportive care.

Supportive care may include intravenous fluid therapy, muscle relaxers, and anticonvulsants. Your veterinarian will also monitor your dog's temperature, blood glucose levels, and kidney function.

What is the prognosis for recovery if a dog has severe pyrethrin/pyrethroid poisoning?

With prompt, early treatment, the prognosis is generally good.

If a dog develops uncontrolled neurological signs or develops kidney or clotting issues, secondary to severe seizures or elevated temperature, the prognosis is typically poor.

How can I protect my dog from this poisoning?

To prevent accidental exposure, read the directions for any product carefully before use.

Be cautious about the number of different flea/tick products used on your dog, as many products are not designed to be used in combination with other products. If you have a flea infestation, please call your veterinarian about proper and safe treatment for your pets and environment.

When choosing a topical flea and tick product, be sure to use a product that is appropriate for your dog's weight range. Do not use part of a larger sized dose, or multiple smaller doses, as this may result in an overdose and increased chances of poisoning. When in doubt, bring your dog to the veterinarian for a “weigh-in!”

Store all pyrethrin or pyrethroid products safely and out of reach of your pets.

Never use an insecticide on a pet that is not intended to be used on animals. Even if the concentration of insecticide is low, the carriers or other components may be harmful to animals.

Keep your dog away from any areas, both indoor and outdoor, that have been treated with a pyrethrin or pyrethroid product until it has completely dried.

With any poisoning, rapid diagnosis and treatment is imperative! It is less dangerous to your pet, and less expensive for you to treat early.

Pet Poison Helpline, an animal poison control center based out of Minneapolis, MN is available 24/7 for pet owners and veterinary professionals that require assistance treating a potentially poisoned pet. The staff provides treatment advice for poisoning cases of all species, including dogs, cats, birds, small mammals, large animals and exotic species. As the most cost-effective option for animal poison control care, Pet Poison Helpline’s fee of $65 per incident includes follow-up consultations for the duration of the poison case. Pet Poison Helpline is available in North America by calling 800-213-6680. Additional information can be found online at www.petpoisonhelpline.com

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