Pyrethrin and Pyrethroid Toxicity in Dogs

Not only do fleas and ticks cause intense itching and skin irritation, but they can also transmit various diseases like tapeworm, Rickettsia (both from fleas), Rocky Mountain Spotted Fever and Lyme disease (both from ticks). Because of these potentially serious illnesses, ridding your dog, and your home of these pests is important and very desirable. Prevention in the first place is a necessity also, and the routine use of prescribed insecticides is the method that works the best. However, toxicity from the improper or careless use of these products is a valid concern.

Flea and tick medicines contain insecticides (also called ectoparasiticides) that can be toxic if not applied correctly, if applied in larger doses than are safe, or if they are accidentally ingested. Most products used to eliminate fleas and ticks are topical applications and are applied to the back of the neck.

The are a great number of pesticides used in the products typically applied on dogs; they can cause varying degrees of toxicity. Most of the time, flea and tick medicine poisoning occurs due to the ingestion (whether accidentally or intentionally) of the medicine, as opposed to the application. However, poisoning can occur due to application only. A small sample of the ectoparasiticides is listed here.

• Pyrethrins and pyrethroids
• Vomiting
• Tremors
• Difficulty breathing
• Profuse drooling
• Weakness
• Tearing of the eyes
• Diarrhea
• More severe cases of poisoning from pyrethrins and pyrethroids can show these additional symptoms:
• Depression
• Fever
• Low body temperature
• Disorientation
• Respiratory failure can be followed by death

Symptoms of Indoxacarb and Organophosphates include:

• Indoxacarb
• Excessive drooling
• Weakness
• Depression
• Abnormal walk and movement
• Inability to stand
• Head tilt
• Organophosphates
• Profuse drooling
• Small pupils (miosis)
• Frequent urination
• Muscle contractions (fasciculation)
• Lack of coordination
• Weakness
• Difficulty breathing
• Nervousness
• Diarrhea
• Vomiting
• Collapse can precede death

We must stress that products designed to be used as repellents or eliminators of fleas and ticks in dogs can not be used on cats. The reaction is much more severe, and the consequences can be dire.

Types

• Pyrethrins and Pyrethroids
• Pyrethrum, used to make these compounds which are used in flea and tick medicines, is extracted from the chrysanthemum plant
• Indoxacarb (Oxadiazines)
• This compound is in a chemical class use in crop pesticides
• It is used alone in products for flea control, and in combination with permethrin in tick control
• Organophosphates
• These are derivatives of phosphoric, or phosphoric acid, and vary greatly in residual degree and toxicity
• Flea collars can contain this product

The list of compounds used in flea and tick medicine is extensive, with others included being isoxazolines (the first oral flea and tick product), and chlorinated hydrocarbon compounds (used in dipping treatments), to name just two.

The reaction your pet may have to flea and tick medicine depends on many factors.

• Age can be a factor if the medicine is used on puppies that are under the recommended age for safe use
• Combining products in hopes that “more is better” can be a bad idea due to contraindication of the medicines
• Poisoning can happen when the label is not read properly, and directions are ignored
• Using too high a dosage for the size of the dog can cause a toxic reaction
• Some pet owners may use a small amount of a tube meant for large dogs on their small dog to save money, not realizing that the dosage and strength can be wrong for a small canine
• Ingestion of flea and tick medicine, whether by eating oral tablets or licking off a topical application, can be dangerous
• Using an insecticide meant for humans (such as DEET for ticks and mosquitoes), in hopes that it will kill fleas or ticks on your dog can be a critical mistake
• If an unregulated over the counter medicine is used or an out of date product is used, the regulations of the usage and safety could have changed

The onset of signs that your dog has been poisoned by a topical, dip, oral, spray, or collar flea and tick medicine can range from a few hours to a few days. When you use a substance containing an ectoparasiticide on your canine family member, always record the amount, day, and time of use. A reaction can occur at any time, even if your pet has had the product used on him before.

When you bring your pet to the veterinary clinic, the care team will ask for the history of what product was used, and when it was applied or given. If possible, bring the container or packaging with you.

Your veterinarian will base her diagnosis on clinical signs, a urine sample, and a serum blood test. Detection through urine or blood is not always definitive. This is why bringing the packaging is so important. At the very least, be aware of the name of the product and how much you used, if possible.

The protocol for the poisoning remedy will depend on many factors.

• The degree of toxicity your pet is experiencing
• Which product was used to eliminate or prevent the fleas and ticks
• How long ago the medicine was applied or given orally
• The age and the health of your dog before the poisoning occurred

Many of the hundreds of compounds used in flea and tick medicines adversely affect the nervous, muscular and respiratory systems of your pet when overdosed. Treatment will depend on which systems have been disturbed, and what functions are in need of correction. Some of the methods and medications used for detoxifying your dog are listed below.

• If the toxicity is affecting the skin, a bath to remove the product will be done
• Some compounds require inducing vomiting, where others are best not to have vomiting brought on
• Medication to empty the bowel is sometimes given
• Seizure drugs or muscle relaxants may be appropriate
• Active charcoal is often used to bind and eliminate stomach contents
• Intravenous access for fluids and medication administration could be necessary
• Oxygen might be required if your dog is having trouble breathing

Using flea and tick medicine for the elimination and prevention of these pests is a necessity in order to keep our beloved animal family members (and us) healthy and happy. However, caution is key to preventing poisoning.

Always purchase flea and tick products from your veterinary clinic. Doing so will ensure that you are using regulated, tested medicines. This will also give you the added security of safe dosage amounts because your veterinarian will tell you how much to use based on the age, health condition and weight of your dog.

Follow the directions of your veterinarian to the letter. Never use dog flea and tick products on other animal family members. Do not combine medicines in the hopes that the flea or tick problem will be resolved sooner.

Wash your hands after handling or applying flea and tick medicine, and be sure to store the medicines safely, out of the reach of pets and children.