Fleas are a pain (literally) – a nightmare that all dog owners face at some point.
Lots of people turn to chemical spot-on treatments to combat the problems. The bigger issue is, these flea and tick treatments for dogs often do more harm than good.
If you’re thinking about using Frontline Plus, a topical pharmaceutical used to kill fleas and ticks, on your own dog, you’re going to want to read this first.
Frontline Plus: Typical Cases & Impacts
A five-year old Golden Retriever is brought to the veterinarian with ear and eye discharge three weeks after receiving a dose of Frontline Plus. The symptoms go away within a month.
When the dose of Frontline Plus is repeated, the dog develops an ear infection that improves after about six months, but never goes away. The dog dies from liver cancer two years later.
This is a typical story about Frontline Plus that led Dr. Jennifer Ramelmeier to change the way she looked at the treatment. Ramelmeier stopped using Frontline flea treatment after seeing a connection between its use and cases like this.
Dr. Ramelmeier says the owners would often complain when their animals developed an oily and sticky coat soon after applying the product.
Dr. Christina Chambreau is another vet from Maryland who has seen similar cases and has a similar attitude towards using Frontline flea and tick for dogs – and cats.
She told the story of a friend’s cat who had received Frontline Plus two or three hours earlier and went missing while she was visiting. They found him under a bench “looking like a puddle,” Dr. Chambreau said. On examining the cat, she found him to be very lethargic and when he started to walk, he had a very uncoordinated gait.
Dr. Chambreau advises her patients to avoid using Frontline. She’s only recommended it on three occasions in her 30 years of practice. She has strong concerns over its toxicity to the pet and she has confidence in the efficacy of alternative methods.
She’s found that after she treats an animal for any type of problem, particularly behavioral or neurological, if the owners apply Frontline or other similar pesticide products, the symptoms that she’s treated come back.
The Controversy Over Frontline Plus
Despite the cases that are well known, some conventional vets disagree with concerns over the safety of Frontline.
“There is no evidence to suggest that Frontline causes cancer or other serious diseases,” says Dr. Deborah Lichtenberg, a vet from Massachusetts. With regard to allergic reactions, “most of these reactions are mild and don’t require treatment” she added.
Dr. Lichtenberg warns that by choosing to use more natural protection against ticks or fleas, your dog will get more ticks and be at a greater risk for developing tick-borne illness. Tick-borne illnesses are Lyme Disease, Ehrlichia, anaplasmosis, Rocky Mountain spotted fever or babesiosis.
Frontline Plus Ingredients & Background Details
The main active ingredient in Frontline Plus, fipronil, was developed between 1985 and 1987 by Rhone Paulenc AG as a broad-use insecticide. It was introduced into the market in 1993.
Since then, it has been integrated into a wide variety of products including “pesticide products, granular products for grass, gel baits, spot-on pet care products, liquid termite control products, and products for agriculture,” the National Pesticide Information Center (NPIC) says.
Frontline Plus is produced and owned by Merial, the animal subsidiary of Sanofi, a multinational pharmaceutical company. Frontline Plus also contains S-methoprene, a compound that has been in use since 1977 that stops juvenile insects from turning into adults.
Merial also produces Heartgard to prevent heartworm, NexGard, a chewable flea and tick poison that was released in 2013, and a series of vaccines for cats.
Altogether, Sanofi reported a net profit on these products of $706 million in 2015.
Frontline Plus is used monthly on dogs and cats. If you have a rabbit or other pet, note that Frontline is highly toxic to rabbits and Frontline is labeled “Do Not Use On Rabbits. Do Not Use On Other Animals.”
It’s applied by breaking open the plastic vial and dispensing the oily liquid between the animal’s shoulder blades. The idea is that the animal won’t be able to reach back and ingest the liquid, but at the same time, the liquid will spread over the body and be absorbed into the oil glands of the skin where it is gradually released.
Frontline Side Effects
There are many concerns about the possible side effects of using Frontline, the most common being skin reactions like hair loss, itching, and redness, and neurological issues like uncoordinated movement and lethargy. However, these side effects are not addressed anywhere on the US website for Frontline.
Interestingly, the New Zealand and United Kingdom websites for Frontline Plus do address safety concerns on their Q&A pages.
“Frontline Plus has a long established and wide margin of safety and your cat should be fine,” was the response from the New Zealand website to an owner who was concerned about whether her pet would see problems from her inadvertent over-application of Frontline.
When asked about side effects, the UK website’s response was, “side effects could occur but these tend to be mild and temporary in the majority of cases.”
[Related] Are oral flea and tick meds any better? Read about the dangers of using Nexgard, Bravecto and Simparica preventives here.
Research by the Environmental Protection Agency (EPA)
The EPA’s Pesticide Division has found that fipronil enters the body and into the fat, organs, urine and feces of dogs.
Research by the EPA in 2009 examined incident data for spot-on pesticides used on dogs, including fipronil products for dogs and cats. The report on Frontline Plus for Dogs shows that of a total of 2469 incidents, they classified:
- 1,872 (76%) as minor
- 51 (21%) as moderate
- 47 (2%) as major
- 39 (<2%) were deaths
The EPA found that most of the reactions to Frontline involved systemic, application site, digestive, neurological and behavioral disorders. The most common clinical signs were:
- pruritus (itching)
- erythema (reddening of the skin)
- alopecia (hair loss)
- hair changes at the application site
Other commonly reported clinical signs were lethargy and vomiting (possibly from ingestion).
There were also symptoms reported from exposure to fipronil by humans, including nausea, vomiting and headache.
The EPA’s study also covered many other spot-on pesticides for dogs, and while some incidents were classified as minor, it’s important to note there were major incidents and deaths associated with every product.
How Frontline Works
Of the Frontline Plus ingredients, fipronil is the most dangerous. Fipronil acts by disrupting the central nervous system (CNS), which contains the brain and the spinal cord. It also blocks a receptor, GABA, which has a similar form in mammals, and a receptor called GluCl, which doesn’t exist in humans.
Fipronil inhibits the insect GABA receptor much more effectively than the human receptor, making it more toxic to insects than mammals. The net effect is over-excitation of the CNS, which causes the death of the insect.
Although fipronil is more active on insects than mammals, there’s a difference between the activity of a manufactured chemical and the activity of that chemical’s metabolite – meaning what the chemical turns into inside the body.
This is where the danger to pets arises.
In the bodies of dogs and other mammals, fipronil primarily converts into fipronil-sulfone.
According to the NPIC, fipronil-sulfone is twenty times more active on the mammalian receptor than on the insect receptor and is six times more effective on the mammalian receptor than fipronil.
This means that fipronil-sulfone is many times more toxic to mammals than fipronil itself.
This increased toxicity to mammals includes humans – so your child can absorb the chemical when she cuddles with your dog who’s been treated with Frontline.
A Safety Review of Frontline
A review of Frontline Plus side effects and the safety literature on fipronil was done on behalf of the Australian Pesticides and Veterinary Medicines Authority (APVMA).
The review said that despite the increased toxicity of fipronil-sulfone, it’s unlikely there would be any adverse effects because there is a rate of passage of less than 5% fipronil through the skin. This suggests the metabolite isn’t concentrated enough to cause problems.
However, the studies on fipronil’s rate of passage through the skin only look at animals with healthy skin. The reviewers commented that further research might find fipronil is absorbed at higher levels through damaged or unhealthy skin.
Even so, the review concluded that fipronil-containing products are generally safe to use with correction application. This is because the NOAEL (no observed adverse effect level), which was calculated from a daily oral dosage of fipronil, was much higher than would normally be used on a biweekly or monthly basis.
The article states “Individual variation in response to fipronil is to be expected.” It warns that adverse reactions should be a sign to stop using it.
Also, it advises care when applying Frontline to damaged skin. Finally, it emphasizes the importance of following the label on the products, especially in using the correct drug for cats or dogs, and to use the correct dosage.
Holistic Vets Disagree That Frontline Is Safe
Dr. Chambreau, Dr. Jennifer Ramelmeier and many other holistic veterinarians are critical of studies like the ones in the APVMA review. These studies only look at immediately visible symptoms and fail to account for long-term effects that are often harder to see.
These vets provide clients with recommendations on flea and tick prevention without Frontline Plus.
Here is some of the best advice:
- Maintain the health of your pet. This means a healthy diet and physical activity. Also minimize the use of unnecessary pharmaceuticals. Healthy animals have lower body temperatures and cooler animals attract fewer fleas.
- To actively repel fleas, she recommends products like neem oil.
- Use Shoo tags
- Feed garlic
- Apply geranium oil to the collar of your dog to prevent fleas and ticks
Want to know how you can keep the fleas and ticks away naturally? To learn more, visit this article for natural flea and tick repellent recipes for your dog.