I’ve been using the topical tick/flea preventative Frontline Plus on my dog Quinn for about 3 years now. I do this so that he won’t become infected with diseases carried by ticks or suffer the misery of flea bites – I use this medication to keep him healthy. Then why do I feel a bit nauseated and guilty when admitting to using Frontline? Because there are well-informed people out there telling me about serious and potentially fatal side effects associated with the use of topical tick/flea preventatives on dogs, including a whole host of cancers, liver disease, thyroid disease, and even death. But, to make matters more complicated, there are equally well-informed people on the other side of the aisle telling me there isn’t a causal link between topical tick/flea preventative treatments and the development of cancer (or other series diseases) in dogs. ARGH!
One thing I know for sure though is that the active ingredient in Frontline Plus is fipronil and the EPA categorizes fipronil as a carcinogen, which means that fipronil is absolutely involved in the development of cancerous cells.
I’m gravely concerned about using topical tick/flea treatments on our pets, but let’s take a look at some research. Here’s a link to results from a study done by the American Veterninary Medical Assocation looking at bladder cancer in Terriers titled “Topical flea and tick pesticides and the risk of transitional cell carcinoma of the urinary bladder in Scottish Terriers”
- The results and conclusions stated in the abstract:
- Results — After adjustment for host factors, Scottish Terriers treated with topical spot-on flea and tick products containing fipronil or imidacloprid did not have an increased risk of TCC [transitional cell carcinoma], compared with Scottish Terriers that had never been exposed to any flea and tick products.
- Conclusions and Clinical Relevance — Results suggest that use of topical spot-on flea and tick products does not increase the risk of TCC [transitional cell carcinoma] in Scottish Terriers. ( J Am Vet Med Assoc 2004;225:389–394)
Okay, so this study concludes there is no increased risk of bladder cancer, but what about the development of other cancers? When I searched for more studies looking at topical tick/flea preventatives and cancer in dogs I came up dry. This is likely because I wasn't using an academically-focused search engine, so maybe I'll take a trip down to the library or Portland State University for some more thorough digging.
Lizi Angel has some very enlightening points in a recent blog post liziangel.blogspot.com, one being that that dogs in general are more at risk for developing cancer than humans, so maybe this means we need to be overly cautious about the levels of carcinogens they’re exposed to? Angel then states,
- “According to the Journal of Pesticide Reform, ‘In tests with laboratory animals, fipronil caused aggressive behavior, damaged kidneys, and ‘drastic alterations in thyroid function.’”
Lizi contacted me and provided some great information regarding the above study. Please see the Insecticide Factsheet for more information explaining the above conclusions. These results are enough for me to stop using the topical flea treatments, but I’ll continue for the sake of sharing as much information as I’ve found so far. Because the important things are covered by the link Lizi provides I’ll remove my concerns about the Journal of Pesticide Reform, because that’s not the focus here.
The National Pesticide Information Center provides results of research done on fipronil and its effects on rats, dogs, humans, and other animals. Here are some relevant excerpts:
- “Researchers fed dogs 0.2 mg/kg/day fipronil (length unknown) and observed no adverse effects. In the same study, researchers observed clinical signs of neurotoxicity at 2.0 mg/kg/day.2″. Not much help here though because the length of time dogs were exposed to fiponil is unknown.
- “Data from short-term and long-term toxicity studies with fipronil in rats, rabbits, mice and dogs ‘do not suggest any endocrine disruption activity’.” Okay, well this would mean that there was no casual evidence found linking fipronil to the development of cancerous cells in rats, mice, or dogs.
Back in 2009 the EPA began to look more closely at the risks associated with these topical tick/flea preventatives. From the American Veterinary Medical Assocation’s (AVMA) site:
- “In April 2009, the Environmental Protection Agency (EPA) issued an advisory concerning approximately 70 spot-on flea and tick control products because of an increase in the number of reports of adverse reactions to the products. Reactions reported included skin irritation, skin burns, seizures, and death. In May 2009, the EPA met with the manufacturers of the products to discuss the issue. In a July 2009 advisory, the EPA and the Food and Drug Administration (FDA) cautioned consumers to be cautious when using these products and to consult with their veterinarian. On March 17, 2010, the EPA announced it was taking steps to increase the safety of spot-on pesticide products for flea and tick control for cats and dogs.” The AVMA has a great list of FAQ regarding this investigation here: www.avma.org Clearly there are issues here that I hope are addressed soon, but until then I won’t be using a topical tick/flea preventative on Quinn the Dog!
I’m wondering if these studies are considering long-term exposure to these topical tick/flea preventative treatments? Is this whole fiasco a case of the drug companies dragging their feet on the results and we’ll be the ones looking back saying “Why didn’t we just stop using these topical preventives?” And, let’s not forget, the subjects that suffer during these studies are DOGS! For now I’m looking into tick and flea preventatives that are taken orally, like Trifexis, and I’ll let you know what I find. It would be great to hear your reactions, thoughts, concerns, questions!