Flea and Tick Medication Poisoning (Pyrethroid Toxicosis) in Dogs

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Last updated on
6 min read

Key takeaways

Organophosphates and chemicals from the pyrethroid family are the most common active ingredients of pesticides associated with flea and tick products and is one of the most common types of poisoning in dogs.

  • Symptoms of poisoning from flea and tick medication range from drooling, vomiting, and diarrhea, to lack of coordination, weakness, and seizures
  • Pyrethroid or organophosphate poisoning is an emergency.
  • Diagnosis is mainly based on history and physical examination.
  • The goals of treatment for pyrethroid or organophosphate toxicoses are twofold: remove the product from the skin and symptomatically treat the signs of poisoning
  • The outlook for a dog who has been poisoned following exposure to a flea and tick medication depends on the type of product and amount used as well as the dog’s size and health status
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A closer look: Flea and Tick Medication Poisoning (Pyrethroid Toxicosis) in Dogs

There are hundreds of pesticides, repellents, and insect growth inhibitors that are sold to protect dogs from flea and tick bites. These include pills, spot-ons, collars, dips, sprays, shampoos, and powders. Seeking professional advice from a veterinarian is the best way to avoid the potential hazards associated with pesticide use on and around pets.

A chemical smell is often present on the fur of a dog who has been exposed to these types of pesticide products.

Pyrethrin-based and organophosphate pesticides have a low margin of safety. This means there is a narrow dosage range where the products are effective without being harmful to the dog. Standard dosages are based on averages, and some dogs are more sensitive than others. As a result, these products can end up being harmful to some dogs even when used as directed.

Risk factors

Any dog using an pyrethroid or organophosphate based external parasite control is at risk of poisoning related to this class of product. Always consult a veterinarian when selecting external parasite control, and use the product exactly as directed by the prescribing veterinarian. Veterinarians are the best resource to help pet parents choose the safest medications for dogs.

Poisoning from flea and tick products is common in dogs. Pyrethroid and organophosphate toxicoses can cause severe symptoms and lead to death, so emergency care is indicated.

The severity of the symptoms increases with the quantity, concentration, and type of pesticides involved.

Immediate veterinary care is needed for the following if pyrethroid toxicity is expected.

Immediate veterinary attention is also necessary for dogs who have ingested pyrethrins/pyrethroids or organophosphates as these are intended for topical use only.

Possible causes

This type of poisoning is caused by exposure to pyrethroids and/or organophosphates in flea and tick control products. Symptoms in dogs may be related to mishandling or misuse, incorrect dosing, or because the product has not been regulated as safe for use on a dog.

Pesticides must be used exactly as directed to minimize the chances for toxicosis. Ingestion of a topical product or using the wrong product at the wrong dose on the wrong schedule can lead to toxicity.

Main symptoms

Testing and diagnosis

A dog displaying typical symptoms following pyrethroid or organophosphate exposure is given a presumptive diagnosis of toxicosis. There is no specific diagnostic test and urine samples or serum blood tests are not definitive.

Steps to Recovery

There is no specific antidote to the active ingredients.

In some cases, emergency life-saving treatment to stop seizures or provide ventilatory support is required to stabilize the dog before decontamination. Decontamination involves removing the medication from the skin by bathing. In cases where ingestion has occurred, gastrointestinal decontamination may be performed in the first two hours following ingestion. GI decontamination may include induction of vomiting or administration of activated charcoal. Induction of vomiting and administration of activated charcoal should only be performed by a veterinarian. There is no safe way to induce vomiting at home.

In mild cases, skin decontamination may be the only treatment required.

More serious cases may require a combination of decontamination and:

  • Medications to relieve associated symptoms like seizures, nausea, and muscle spasm
  • IV fluids
  • Providing supplemental oxygen if the dog is having difficulty breathing
  • Monitoring of vital signs; temperature, blood sugar levels, kidney function

The prognosis is determined by:

  • The type of flea or tick product used and the amount and method of administration
  • The length of time since the product was administered or applied
  • The health and age of the dog before the poisoning

Prognosis is poor if the dog has severe symptoms such as seizures or if there is kidney damage. Milder signs like excessive drool, paw flicks/scratches, and ear twitches usually resolve within three days of treatment.


This type of poisoning is prevented by using a vet-recommended flea and tick control product exactly as directed by the prescribing practitioner. It is important to notify a vet of the presence of all animals and children in the home when choosing external parasite control. All medications should be stored out of reach when not in use to prevent accidental exposure between doses.

Is Flea and Tick Medication Poisoning (Pyrethroid Toxicosis) in Dogs common?

Pyrethroid and organophosphate toxicoses are among the most common poisonings in dogs.

Typical Treatment

  • Skin decontamination
  • GI decontamination (if exposure was through ingestion)
  • Supportive care


No Author - Writing for U.S. Food and Drug Administration
Barri J. Morrison, DVM - Writing for PetMD
Hannah Hollinger - Writing for Wag!

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