Safe Use of Flea and Tick Treatments
on Dogs and Cats

The FDA and the EPA noticed an increase in the number of problems reported with flea and tick treatment "spot-on" products in 2009. In April 2009, they issued an advisory on about 70 of these products (I suspect that they issued the advisory on all spot-on products). Both over-the-counter (OTC) and veterinary products were then examined by the EPA. Their findings are now available to any who wish to know about them.

I would like to encourage you to review all of the information available for you here. I would also like to encourage you to try to remain calm and objective as you sift through all of this material, which is plentiful. Lastly, I wouldlike to encourage you to resist the impulse to lump all pet parasiticides into a group of "not good".

The message I would like you to take from this today is that you should be aware of what you are using on your dog or cat, and be sure that you are as safe as you can be in your parasite control measures.

Reactions to Spot-On Flea and Tick Treatment Products

ALL medicines, and supplements, have the potential to cause undesired effects. In 2008, there were 16 reported reactions per 100,000 doses of spot-on parasiticides applied to dogs and cats. 97% of these reactions were non-life threatening and self-limiting. 1.4% of these reactions were fatal. The remaining 1.6% of reactions were somewhere in between. This incidence rate (16/100,000) increased in 2009 (I don't know by how much), drawing the attention of the FDA and the EPA.

Summary of EPA Report

The EPA released their "Review of 2008 Incident Reports for Pet Spot-On Parasiticides" March 12, 2010. Their major findings are summarized as follows:


** Small dogs, between 10-20 pounds, were more at risk of having a reaction to a topical parasiticide. It was noted that Chihuahua, Shih Tzu, Miniature Poodle, Pomeranian, Dachsund and Bichon Frise breeds were more commonly affected than other breeds. Mixed breed dogs were also noticed in high numbers, likely because of the large number of mixed breed dogs in our population.

** The ingredients that seem to be causing the problems in small breed dogs are called cyphenothrin and permethrin.

** In general, dogs that had reactions were under 3 years old. It is believed that this age may represent the first time a flea or tick product was applied (older dogs who had reacted in the past were likely not given the product again, and so were not represented/reported).

** There is a concern that pet owners are either applying the wrong size dose to their small dogs (mis-reading the packaging), or that some product dose sizes are incorrect for these small dogs. There is also a concern that owners of small dogs may be purchasing large doses and then attempting to split them into smaller doses themselves for their pet. This is not recommended.


** Most cat reactions to a product labelled for cats was due to application of a dose meant for a larger cat. It may be that owners were estimating their cat's weight, rather than actually weighing them.

** Nearly all of the serious, often fatal, cat reactions were due to the application of a dog product.

** The main ingredient to cause problems for cats was permethrin. Some of these cat reactions were in a cat who had not had any product applied, but who were near/grooming their dogs who had had a permethrin product applied.

The "inert ingredients" should also be investigated, as they may also play a role in toxicity of spot-on flea and tick treatment products.

Please feel free to read the entire EPA report yourself. (This is a 29 page PDF file, and will open in a separate window.)

My Opinions....

In the fifteen years that I have been a veterinarian, I have had few and minor problems with the veterinary flea and tick treatment spot-on products. In those same fourteen years, these same flea and tick treatment spot-on products have provided countless pets and their people with comfortable, healthy, external parasite-free lives.

I have seen more problems with the OTC products, and most of these problems have been with owners using dog products on their cat.

Do not use dog flea and tick treatment products on cats!

Products Containing Either Cyphenothrin or Permethrin

To the best of my knowledge, each of these products contain one or both of the EPA implicated ingredients. I do not know if this list covers all of the flea and tick treatment products available - please check the "active ingredient" list on your package! I do not know how much of the EPA implicated ingredients is in each product.

Sergeant's Spot-On products

Bio-Spot Spot-On for Dogs


Defend EXspot

K9 Advantix

Adam's Spot-On

Zodiak Flea Trol

Vectra 3-D

Good Educational Links:

Read the Label First: Protect Your Pets - courtesy of the EPA

Taking Care of Fleas and Ticks on Your Pet - courtesy of the EPA

Safe Use of Flea and Tick Treatment Products on Pets - courtesy of the FDA

Your Guide to Reporting Problems to the FDA - courtesy of the FDA


Love + Knowledge = Healthy Happy Pets.

Unleash Yourself!

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Page last updated 2/25/14.


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