Flea and Tick Medication Poisoning (Pyrethroid Toxicosis) in Dogs


Poisoning as a result of exposure to flea and tick products 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. This type of poisoning has the potential to be lethal. 

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. Organophosphates and chemicals from the pyrethroid family are the most common active ingredients of pesticides associated with this type of poisoning. 

Pyrethroid and organophosphate toxicoses are emergencies. While some minor cases of poisoning with slight or subtle symptoms can be managed by washing the product off the dog at home, dogs showing more severe symptoms need emergency veterinary attention.   

The goals of treatment for pyrethroid or organophosphate toxicoses are twofold: remove the product from the dog (decontamination) and treat the signs of poisoning. Dogs with seizures, for example, are given anticonvulsants.  

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.  Severe exposures can be fatal.

Risk Factors

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

Seek immediate veterinary care if symptoms like ataxia (trouble walking), severe drooling, vomiting, diarrhea, tremors, seizures, collapse, or loss of consciousness are present. 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. 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.

Main Symptoms

Typical symptoms of pyrethroid and organophosphate toxicoses include: 

Excessive drooling (ptyalism)VomitingCoughing, gagging, hacking • Agitation and restlessness

• Flicking of paws and twitching ears • Excessive urination • Watery eyes  • Appetite loss • DiarrheaTremors

Difficulty walking (ataxia)  • WeaknessSeizures

Detailed Characterization

A chemical smell is often present on the fur of a dog who has been exposed to these types of pesticide products. The severity of the symptoms increases with the quantity, concentration, and type of pesticides involved.

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. 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.

Steps to Recovery

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 problems with their kidneys and seizures. 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 Common in Dogs?

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

Typical Treatment

Immediate first aid upon observing symptoms is to decontaminate the dog using soap and water to wash off topical products. This may be the only intervention required if the dog’s symptoms are mild and serious neurologic symptoms like seizures or loss of consciousness are not present. 

Typical treatment for more serious cases involves a combination of: 

• Inducing vomiting (only if appropriate and under medical supervision) 

• Administering medication to empty the bowel

• Giving activated charcoal to bind toxins. 

• Administering medications to relieve associated symptoms like seizures, nausea, and muscle spasm

• Adminsitering IV fluids 

• Providing supplemental oxygen if the dog is having difficulty breathing

• Monitoring of vital signs; temperature, blood sugar levels, kidney function

Want to speak to a vet now?

Book an appointment
Book online vet feature photo

Time for a check-up?

Start a video chat with a licensed veterinary professional right now on Vetster!

Book an online vet