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Dog Flea Treatments - Commercial


Flea infestation, both on our dogs and in our house, is probably one of the worst nightmares we have when bringing a new dog into our family. We all want to keep our new best friend happy and comfortable, and seeing her constantly itching and chewing trying to rid herself of that pest is very painful. So, naturally, we pay heed to all those commercials, and perhaps even our vet, about the spot-on flea treatments. They are touted as both safe and effective, but are they really?

All pesticides (including insecticides) contain chemicals that can be harmful, and not just to the dog. The manufacturers of these products tout the safety, especially when compared with the flea collars and foggers of yesterday. However, remember that they also touted the safety of those collars and foggers when they were popular. So, let’s examine some of the more popular brands of spot-on flea treatments. First we will discuss the limited information available on the ingredient label, and give potential problems with some of the active ingredients. Then we will discuss the mysterious “other” ingredients.

Popular Flea Treatments for Dogs and Their Ingredients

Below are some of the more popular spot-on flea treatments, with their ingredients. ingredients that are potentially harmful are highlighted and in a bold red font. Prepare to see a lot of color!

Product Ingredients
Adams Spot-on Flea & Tick Control Etofenprox 30.0%
S-Methoprene 3.6%
Piperonyl Butoxide 5.0%
Other Ingredients 61.4%

Product Ingredients
Advantage II Imidacloprid 9.1%
Pyriproxyfen 0.46%
Other Ingredients 90.44%

Product Ingredients
BioSPOT Spot On Defense Etofenprox 50.0%
Piperonyl Butoxide 9.1%
N-octyl bicycloheptene dicarboximide 0.91%
Pyriproxyfen 0.45%
S-Methoprene 0.23%
Other Ingredients 39.31%

Product Ingredients
Frontline Plus Fipronil 9.8%
S-Methoprene 8.8%
Other Ingredients 81.4%">

Product Ingredients
K9 Advantix II Imidacloprid 8.8%
Permethrin 44.0%
Pyriproxyfen 0.44%
Other Ingredients 46.76%

Product Ingredients
Pet Armor Flea & Tick Topical Fipronil 9.7%
Other Ingredients 90.3%

So What Harm Can These Chemicals Cause?

Poisonous ingredients

The ingredients highlighted above have been researched at great lengths, and severe consequences for use have been discovered. However, realize that not all dogs exposed to these chemicals will exhibit any of the problems listed for those chemicals. The results are a small portion of all the dogs treated. But do you want to test your luck with your dog’s health? While chances are good that your dog will live a long healthy life, there is also the chance that she will succumb to one or more of the problems associated with that chemical.


Fipronil is suspected to be a human carcinogen. It is a neurotoxin that can also cause thyroid cancer in dogs, Other potential consequences of contact include liver toxicity, damage to the kidneys, thyroid hormone changes, and increased cholesterol levels. For pregnant bitches, it can cause miscarriages and smaller puppies. The EPA states that Fipronil has the potential for nervous system and thyroid toxicity after long term exposure at low dosages.


Laboratory testing indicates that Imidacloprid can be neurotoxic, causing incoordination and labored breathing. It can also cause thyroid lesions, reduced birth weights, and an increased frequency of birth defects.


Permethrin is suspected to be a carcinogen, having caused both lung cancer and liver tumors in laboratory animals. This pyrethroid insecticide is also suspected to be an endocrine disrupter, which can cause cancerous tumors, birth defects, and developmental disorders.


Pyriproxyfen inhibits the growth of juvenile fleas, and causes them to lose their reproductive abilities. While considered safer than earlier versions, Pyriproxyfen has still been known to cause enlarged liver and kidney degeneration.


S-Methoprene is similar to Pyriproxyfen, both in purpose and in potential side effects.

Other Ingredients

In 1949, Congress passed the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), which basically allowed the insecticide manufacturers to label some of their ingredients as “Trade Secrets”. These ingredients did not have to be listed on the packages, but could be grouped in an anonymous group. Until just recently, these were labeled as “inert”, but are now listed as “Other Ingredients”.

The problem with these Other Ingredients, is they are not considered “Active Ingredients”. While the EPA requires fairly extensive testing on the potential hazards of the active ingredients, the “Other Ingredients” only require cursory testing for acute toxicity. There is also no requirement to list these “Other Ingredients” on the label.

Even though they are not listed on the label, some of these ingredients can be found on the product Material Safety Data Sheet (MSDS). Looking at these, you will find some scary things, like ethanol, polyvinlpyrrolidone, diethylene glycol monoethyl ether, and butlyhydroxanisole.

So What Else Can I Do, If Not Commercial Spot-Ons?

We discussed the ingredients and their potential affects on your dog and you, but limited our discussion to the spot-on products that are popular. But the internally processed flea products (tablets, chews, etc.) share many of the ingredients listed above, and carry similar risks. So where do we go from here?

Fortunately, we can be just as effective in eliminating the flea problem in a more natural, holistic way. We will discuss these methods to control our flea problem naturally on another page. See you there!

Visitor Comments

This is your chance to add your feedback. Do you have more questions about commercial flea control products and their ingredients that either Dog Nation or another of our visitors might be able to help you with? How about additional stories of harmful affects to your dog when using commercial flea products? Please feel free to add your comment or question below.

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