Pyrethrin Pyrethroid Poisoning in Dogs

Pyrethrin insecticides are naturally derived from the chrysanthemum (“mum”) flower, and pyrethroids are the synthetic versions. The formulations of these products vary in concentration, synergists, and carriers depending on their intended use, which may include:

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

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 very safe in dogs; however, cats and fish are very sensitive to pyrethrins/pyrethroids.

Fish are so sensitive that they 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’ll be treating with a product containing a pyrethrin or pyrethroid (e.g., foggers, sprays, etc.). 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 instance, a koi pond or a neighboring creek) for at least 24-48 hours following application.

Cats are also very sensitive to pyrethrins and pyrethroids, because they’re unable to metabolize (break down) these agents quickly and efficiently due to their peculiar liver metabolism.

How do dogs become exposed to pyrethrin/pyrethroid insecticides?

• Topical flea and tick spot-on medications often contain high concentrations of pyrethrin/pyrethrins, but these are commonly used on dogs without serious problems.
• Dogs can also be exposed to lower concentrations when these products are used inside or outside the home (e.g., insect sprays).
• Since some fertilizers also contain these products, dogs should be kept off the lawn to prevent accidental ingestion. (Check your fertilizer packaging to see if it contains pyrethrin/pyrethroid.)

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

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

• Excessive drooling (from licking the bitter product)
• Gagging or hacking (it seems that they have something stuck in their throat)
• Vomiting
• Anorexia (lack of appetite)
• Agitation
• Tremors or shaking

Other signs of a dermal (skin) reaction to a pyrethrin or pyrethroid for a dog include the following signs below. These signs can develop within 15 minutes to several hours after exposure.

• Agitation or restlessness 
• Intense itchiness (often described as rolling around on their backs or trying to bite at their backs)
• Vocalization (crying/whimpering)
• "Paw flicking"
• Paresthesia (a local skin reaction that feels like a "pins and needles" sensation, similar to when a foot or arm falls asleep.)
• More rarely, dogs that are hypersensitive to pyrethrins/pyrethroids, or ingest a large or concentrated amount, can develop more severe symptoms such as tremors, twitching, shaking, difficulty breathing, incoordination or difficulty standing or walking, weakness, seizures, and rarely, death.

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

If you suspect that your dog is having a severe reaction to a pyrethrin or pyrethroid, please bring your dog to your regular or emergency veterinarian immediately.

If you’re not sure what you’re seeing, call your veterinarian or Pet Poison Helpline, an animal poison control based out of Minneapolis, MN, USA* (800-213-6680) immediately. 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’s a known or possible history of exposure to a product containing a pyrethrin or pyrethroid, coupled with symptoms described above. If the symptoms are severe, your veterinarian will not wait to confirm the diagnosis before beginning treatment.

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

No. There is no antidote for pyrethrin or pyrethroid toxicity. However, quick and effective treatment with decontamination (e.g., bathing with liquid dish soap), anti-seizure drugs, muscle relaxants (e.g., methocarbamol), temperature monitoring, blood work (e.g., blood glucose) monitoring, and IV fluids are beneficial. This is why it’s so important to get help immediately.

How does my veterinarian treat severe pyrethrin/pyrethroid poisoning?

• Once your dog is stable (i.e. not showing severe clinical signs), your veterinarian may start by bathing your pet with a liquid dish soap to prevent further exposure.
• If clinical signs/symptoms have developed, treatment will be based on the symptoms and route of exposure (skin, ingested, etc.). In all cases with the development of neurological signs (e.g., twitching, tremors, seizures), your dog will require hospitalization for typically 48 - 72 hours for monitoring and any supportive care that may be needed as symptoms can seem to resolve but then reoccur.
• In addition, your veterinarian’s team carefully monitors the dog’s temperature for an elevated or lowered reading. In most cases, the team will monitor blood work as well, to make sure blood sugar and kidney function remain normal.

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

If your veterinarian has a chance to provide prompt, early treatment, the prognosis is generally good if the dog does not develop further complications secondary to neurological signs.

If the dog develops neurological signs that are uncontrolled or develops clotting problems or kidney failure secondary to severe seizures or hyperthermia, the prognosis is typically poor.

How can I prevent 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. If you have a flea infestation, please call your veterinarian about proper and safe treatment for your pets and environment.
• Use the appropriate-sized product for the weight range for your dog. Do not use part of a larger size, or more than one smaller size flea and tick preventative, as this may result in a poisoning. When in doubt, bring your dog to the veterinarian for a free “weigh-in!”
• Store all pyrethrin or pyrethroid products safely and out of reach of your pets.
• Never use a product on a pet that’s not intended to be used on animals! Even if the concentration of insecticide may be low, the carriers in such products may be harmful to animals.
• Keep your dog away from any areas (indoors and out) 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’s less dangerous to your pet, and less expensive for you to treat early.

**Pet Poison Helpline, is an animal poison control service available 24 hours, 7 days a week for pet owners and veterinary professionals who require assistance treating a potentially poisoned pet. Pet Poison Helpline is available in North America by calling 800-213-6680. Additional information can be found online at www.petpoisonhelpline.com. Pet Poison Helpline is not directly affiliated with LifeLearn.