Seresto Flea & Tick Collars: The New Satanic Panic?

Like many vets around the country, I’ve had a sudden wave of panicked calls and emails from clients about a dramatic article that appeared in USA Today yesterday. The article essentially claims that the Seresto flea and tick collar is injuring and killing huge numbers of dogs and some humans. Despite all the weaselly linguistic tricks to imply neutrality and plausible deniability if called out on making this accusation, no reasonable person could read this article and not get the message that this product is deadly and that the EPA is callously ignoring the danger, likely because they are in the pocket of Big Pesticide. 

This article is an example of the horrifyingly bad journalism that we see all too often concerning the safety of pet healthcare products. It is full of anecdote and innuendo and guilt-by-association, but devoid of the kind of actual data that might tell us whether the fear the author wants to incite is justified. As veterinarians, we have all been through this before. The web sites, Facebook pages, sloppy journalism, and even lawsuits claiming the pets are being harmed by Rimadyl and other NSAIDs, and TrifexisFebreezeSwiffer, and of course vaccines are a fact of life for anyone in pet health professions. 

It is easy to blame a particular product or treatment for something bad that happens to our pets. We naturally search for explanations when our companions are sick, and we tend to fixate on concrete things we can see and touch and potential causes we are primed to be suspicious of. Both reports of the real dangers of some pesticides, industrial chemicals, and medicines as well as the irrational demonization of all of these by opponents of mainstream medicine have implanted an automatic anxiety about the safety of such products in all of our minds. 

When a pet falls ill suddenly, we look around for a reason. The food or medicine or vaccines or pest control products we may be using come readily to mind. Invisible viruses and bacteria, internal causes inside the body that we can’t see, and other common but intangible causes are less noticeable, and so less likely to be blamed. This availability bias is a classic psychological quirk that impedes our ability to accurately assess risk and identify the causes of undesirable events. It’s why we are more afraid of airplanes and sharks than cars and mosquitoes, even though the former are a lot less likely to hurt us than the latter.

Finally, there is an unfortunate tendency in the media to shock and disturb rather than inform, which this article illustrates. Such media coverage can easily lead to excessive and inappropriate panic about risks that are smaller than made to appear in the media or even entirely unreal. The Satanic Abuse panic of the 1980s is a classic illustration of this. Hysterical and dramatic reporting of individual claims that people had been ritually abused by Satan worshippers went from fringe publications to mainstream media. Despite years of widespread coverage and the ruining of people’s lives by unfounded allegations, hard evidence never emerged to substantiate these claims. While some individuals undoubtedly did experience abuse of some kind, the media generated both a fictional cause to blame and a surge of unreliable anecdotes by presenting the initial reports in a melodramatic and irresponsible way. Sadly, finding and fixing the really dangers behind such claims was only hampered by this media coverage, and the same is often true of health scares such as those I mentioned earlier.

The Claims
Before we try to answer the question whether or not the Seresto collar is safe for our dogs, let’s look at the claims of this article and what they are based on. The writer begins, as usual in these kinds of scare pieces, with a heartbreaking anecdote of a pet dying. The owner believes this death was caused by the flea and tick collar she used, and the writer of the article jumps right from that to the claim that this product has been  “linked to hundreds of pet deaths, tens of thousands of injured animals and hundreds of harmed humans.” The emotional setup here is clear, and the message that the product is dangerous probably doesn’t require any actual evidence for most people at this point. But the author does provide a link to support this claim. So what is that about?

The link is to a collection of reports on the EPA web site of illnesses and deaths in dogs using the Seresto collar. Seems pretty damning, doesn’t it? Here’s the trouble: Those numbers are simply collections of spontaneous reports made to the agency. Zero investigation has been done to show the reports are accurate or that there really is a connection between the product and the events described. The purpose of such reporting sites is to create a place for people to raise concerns. Agencies in charge of various public health areas collect and monitoring these spontaneous reports for signals suspicious for a problem that merits investigation. If a pattern is seen that suggests there might be a safety issue, the agency can investigate to determine if there is a real concern or not.

This is what happened with the issue of grain-free diets and heart disease that I have written about several times. The FDA saw a change in the number of reports received and began an investigation. Two years later, the nature of any association between these diets and the disease is still being studied, and their role, if any, in causing heart disease is still unclear. The fact that people reported their observations about heart disease and what they were feeding their dogs isn’t proof of a causal role, just a collection of anecdotes that may or may not signal a real problem. Rigorous scientific investigation is how we find out if health products are causing harm, not simply accepting every scary anecdote as true. 

The same issue has come up innumerable times over many years with regard to vaccines and the Vaccine Adverse Event Reporting System (VAERS), managed y the CDC and the FDA. VAERS collects unsubstantiated anecdotal reports about possible harm from vaccines. Despite the overwhelming evidence for the safety of vaccination in general and most vaccines in common use, these reports are frequently cited by antivaccine activists to “prove” that vaccines are causing tremendous harm. One doctor actually submitted a report that a vaccine caused him to turn into the Incredible Hulk, and this report would still be in the VAERS database if he had not allowed the government to delete it.

Such databases are useful surveillance tools that can provide early signals of real problems, but they are also full of uncorroborated and inaccurate reports and speculation. They are not reliable evidence for a causal role of any product or medicine in harm done to people or animals. This, again, requires appropriate scientific investigation.

What else does this article rely on to support the clear claim that Seresto collars are killing dogs and injuring people? There are several strategies at play here. One is the use of unrelated cases of harm from pesticides to poison the well and imply that claims about the dangers of Seresto must be true since other pesticides have caused harm. The fact that claims have been made about harm from other pesticides (some true and some also unproven) aren’t relevant at all to the question of whether Seresto is safe or not, but they exacerbate the general anxiety or fear about pesticides to strengthen the reader’s willingness to accept negative claims about it. Clever rhetorical technique, I suppose, but not a legitimate form of argument that leads to the truth.

The citation of experts is also used to suggest Seresto is unsafe and the EPA is failing to protect the public. Quotes are provided from a “senior scientist… who has a doctorate in cell and developmental biology” at an environmental watchdog group and a “retired EPA employee… who worked as both a scientist and communications officer.” Noticeably absent from the expertise consulted is anyone with a specialty in veterinary toxicology or parasitology. Since assessing the safety and effectiveness of parasite control methods and the impact of toxins on veterinary patients is the central area of expertise for people in these fields, such individuals would have been far more likely to have relevant and informed opinions on the scientific question of whether or not Seresto is safe. Not including them is a pretty transparent technique for building a one-sided argument. I have heard from two veterinary toxicologists, a parasitologist, and a veterinarian with a national poison control center, and none of them found the allegations of widespread serious harm from the Seresto collar credible. Hopefully, people with appropriate expertise will weigh in on this issue publicly soon. 

The Science
So is there scientific evidence and, if so, what does it tell us? There are published studies and reviews of the safety of both active ingredients in Seresto, imidacloprid and flurmethrin, as well as studies of the combination in the product itself. As usual, these provide a much more nuanced picture of the risks and benefits. It would be implausible and unreasonable to claim that no dog had ever experienced adverse effects from this or any other parasite preventative. As I point out forcefully and often, no medical intervention that does anything at all is without risks, so the important issue is understanding what the risks and benefits actually are and how they compare.

Imidacloprid is a common pesticide that has been used and studied extensively for decades. This EPA document provides a relative recent overview of the available evidence. Research in dogs and cats has shown extremely low risk, and this product has been used extensively for many years without any consistent or reliable evidence of the kinds of extreme harm depicted in this article. As always, some adverse effects from excessive or inappropriate use or in unusually susceptible individuals can occur, but overall there is nothing in the evidence concerning imidacloprid to justify the level of anxiety directed at Seresto in this piece.

The other ingredient, flumethrin, is a synthetic pyrethroid pesticide, a class that has also been studied and used extensively for a long time in dogs. Cats are especially sensitive to this class of agents, and they are not typically recommended for this species, but dogs are much less likely to experience adverse effects when pyrethroids are used properly. Those cases of harm that do occur are typically associated with improper dosing. Studies of flumethrin in dogshave found limited evidence of toxicity at doses well above recommended use for parasite prevention.

More importantly,  there is published research evidence investigating the use of the combination of these ingredients in the Seresto collar. These have shown some adverse effects, but nothing even approaching the kind of common and devastating effects suggested by this article:

Stanneck 2012

In cats, a total of 28 events were suspected to be related to study medication… 23 in the [Seresto] (9.0%) and 5 in the control group (5.6%) [using a different parasite collar]. This difference was not statistically significant (p > 0.4; Fisher’s exact test). [These events were] were generally mild dermal reactions (alopecia, pruritus, mild contact dermatitis).

In dogs, in the [Seresto] group 3 events (alopecia, hair coloration, dermatitis) and in the [control] group 4 events (alopecia, flea infestation, pruritus, aggressive behaviour towards a collar wearing animal) were scored as being related to the study medication. The difference between the two groups was not statistically significant (P > 0.16; Fisher’s exact test)

Krudewagen 2015

Small Non-Controlled Clinical Safety Study
No clinically relevant adverse event related to der- mal or systemic safety occurred and no abnormalities concerning general health were noticed during the course of the study. 

Controlled safety studies – Seresto®/ Advocate®
All dogs tolerated the treatment well. Two out of 51 treated dogs showed transient skin alterations in the region of collar application, namely a crusty spot (approx. 1 cm diameter) on one day, respectively a moderate erythema of small (< 1 cm) to medium size (1 – 4cm) for about two days. Further findings in the treated group that were considered unlikely to be treatment related were conjunctivitis and a congested nasolacrimal duct in one dog, and a hot spot in the tail region of the same dog that showed erythema in the collar region. In the control group one dog also showed wounds and crusts in the neck region. No further clinical signs were present. 

Blood hematology and clinical chemistry 
No clinically relevant changes were detected for any parameter in the dog or cat study.

There are neither dermal nor systemic safety issues with the particular combination of the three actives imidacloprid, flumethrin and moxidectin in adult cats and dogs…

There is also research evidence showing that this product is effective in reducing flea and tick infestations, which can have the benefits of reducing allergy symptoms and protecting dogs against infectious diseases (and 23) spread by these parasites. These benefits have to be weighed against any potential harm. 

Finally, in terms of safety the available data has been evaluated by public agencies in many countries and found not to support claims of significant health risks. While the article accuses the EPA of a gross failure and dereliction of duty in not acting aggressively on the anecdotal reports it has received, as I pointed out earlier, such reports appear with many healthcare products, and these often turn out not to be accurate. It is possible that the risk here has been underestimated, but the burden of showing that with hard evidence remains on those making the claim.

One more issue that this article ignores is the subject of knockoff or lookalike products. Unfortunately, if a veterinary product is successful, it is common for other companies to make products that appear similar but have different ingredients in order to capture some of this market. It is also not unusual for fake replicas of a brand-name product to be produced in some countries and sold online as if they were the original product. These knockoffs have not passed the regulatory safety testing required of properly approved products. They may very well be less safe, and this can confound efforts to assess the accuracy of adverse event reports for these products. Such fake Seresto collars have made their way into the market, and it is possible some reports of harm may involve these rather than the original product.

Bottom Line
So what’s the bottom line? Is Seresto a perfectly safe and effective parasite preventative or a poison decimating the dog populations? The truth, of course, is between these extremes. There are undoubtedly some risks to this product, and it is possible that they are greater than has so far appeared in the scientific literature. The research done on this product has mostly come from companies and investigators with a financial interest in it, and that always raises some concern about the potential for bias in the data. On the other hand, such concern doesn’t somehow make collections of unsubstantiated anecdotes a reliable source of data. The fact that some people think Seresto has harmed them or their dogs is not, alone, evidence that it has. 

I don’t personally recommend Seresto for my patients because I find other parasite preventatives more convenient to use. I do have clients using it, and some doctors at my practice do prescribe it, and none of us have seen the kind of terrible effects depicted in this article. That is, of course, only more anecdote, but before we panic because of scary stories, it is worth remembering that there are many veterinarians and pet owners who have not had any negative experience with this product. 

I hope that additional research shows that the concerns raised in this article are unfounded, but if it turns out the risks are greater than we currently realize, that will be important information. Unfortunately, rigorous scientific investigation takes time; a lot more time and work that sensationalist medial reporting. My hope is that reasonable people will respond to this latest example of poor-quality reporting in a reasonable way. We likely should take a careful, objective look at the safety data for this product, and perhaps conduct further research if warranted. We should not panic and blame every bad thing that happens to us or our dogs on the latest media bogeyman. 

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28 Responses to Seresto Flea & Tick Collars: The New Satanic Panic?

  1. Jody says:

    What medications do you recommend? We live in an area where ticks are a big problem on our dogs. We have been using these collars on our dogs but my last dog died suddenly after having a seizure and I had recently started using the collar. I’d like some alternatives.

  2. Kelsey says:

    My dogs haven’t had any issues with their seresto collar, but just out of curiosity, What are some of the flea and tick preventatives you do recommend?

  3. skeptvet says:

    There are many alternatives, though of course they all have potential risks as well as benefits, like every medical tool. I typically recommend Nexgard or Simparica, though I have no specific objections to any of the other products available.

  4. skeptvet says:

    I typically recommend Nexgard or Simparica, though I have no specific objections to any of the other products available.

  5. Julie Levy says:

    Thank you so much for this prompt and comprehensive response. You are the Snopes of veterinary medicine.

  6. M A says:

    “ Mr M fed his dog at 6 pm every evening for years with no ill effects whatsoever. Until one evening he left the gate open , dog ran out and onto the road and got hit by a car, minutes after eating his dinner. Clearly eating his dinner directly caused his being hit by a car, as it happened only minutes after eating that dinner. Mr M warns everyone out there of obvious and undisputed dangers of feeding your dog at 6 pm and does not want other people and pets to suffer the way he and his dog did”

  7. Claire says:

    Our dog had a horrible horrible seizure 2 months after starting Seresto. we had to put her down at the vets after a day filled with seizure after seizure. She didn’t even recognize us. She did not ever have a seizure before that 3:30 am horror. I. NOw feel like we made the decision that killed her.

  8. Carla Bowen says:

    Thank you for the information regarding the seresto collars. Because ticks are so bad in the pastures of northern/Bay Area California, I have recently combined two collars and use on my large horses. Wikipedia shows the main ingredient is also in wipe on/spray fly and tick repellent for dogs, cats, horses, cattle, sheep. However the wipe/sprays are irritant to my hands as well as greasy on the horses. Peremethim for animals and barn walls. Fly collars are available for horses. Therefore I made a decision to try and carefully monitor my horses. Both of my horses have contacted and survived tick disease erlichee in the past. That disease is devastating to a horse and required heavy antibiotics and red cell iron to recuperate. They are vaccinated annually for west Nile, etc without incident. Each animal like each human is different in reaction but I am hopeful for success. Will be happy to share results.

  9. skeptvet says:

    What happened to your dog is terrible, but it is even more terrible that irresponsible reporting like this has made you feel responsible. There is simply no believable evidence that this product can cause the symptoms your dog experienced, and feeling this way only hurts you. There are many other possible causes, and I see patients with seizures all the time who have never used this product. Please try and remember that and not take blame you don’t deserve.

  10. greg nutt says:

    Thank you for your work in teasing out the truth.

    Greg

  11. Jill says:

    @claire that is what the purveyors of these scare tactics want you to feel. Listen to the doc’s advice above.

    Also remember that “holistic” and “wellness” are BIG BUSINESS and there are people out there who stand to gain a lot by convincing you that conventional medicine and science-based products are evil. They literally cannot make money any other way.

    You did not kill your dog with a flea collar. It’s very sad that she died but it’s very unlikely that the collar had anything to do with it.

  12. Lewis faulkner says:

    After reading the sensational USA today article I went to the EPA web site to see what kind of signs to look for . The incident reports are just that . Someone used the collar and thought it caused a problem . I found some of the “many ” cases of harm to people laughable . One lady applied a collar to her animal , 6 months later experienced eye pain redness and swelling . An eye doctor examined her and diagnosed an eye infection ( but it was caused by the collar if you take the press at face value . Thank you for a well thought out objective look at this report .

  13. I tend to be very alert to the use of language, and to small details in an article. In this article I was struck very early on by this: “An officer helped her lift the dog into her car, and she rushed him to the hospital.” A police officer helped her lift a *Papillon* into the car?! I have owned and worked with Papillons and Papillon breeders for decades, and the biggest Papillon I have ever seen weighed about 15 pounds.

    When I saw that I was already skeptical about the article, and became increasingly so as I continued to read, and the bit about a police officer helping someone lift a Papillon into her car seemed like quite a long reach for sympathy.

  14. Jo says:

    “The other ingredient, flumethrin, is a synthetic pyrethroid pesticide, a class that has also been studied and used extensively for a long time in dogs. Cats are especially sensitive to this class of agents, and they are not typically recommended for this species”
    Please can you explain why this collar is also made for cats to wear given the above statement. Thanks

  15. skeptvet says:

    Dats are more sensitive to permethrin generally that dogs, but flumethrin has been specifically tested in this species and found to be safe. It’s an additional indicator of how low the risk is for these ingredients.

  16. CWebb says:

    I have had a pateint come in to clinic in status. They had a knock off Seresto, that they had picked up at either Sam’s or Wal-Mart. Consider how the USA Today article claims so many purchases of this product from Amazon. How many third party suppliers (from countries such as China) are selling ‘Seresto’ collars?
    How many of these people are picking up knock-off products. We have been seeing knock offs for years.
    Want to be sure your product came from the manufacturer and not someone out to get your pet care dollars? Get it from your vet who gets it direct from Elanco/Bayer.

  17. L says:

    @ art malernee

    Thanks for the link. I have had no problem with the Seresto collar.
    Out of fear I went back to the Preventic collar (Amitraz), for now. Hopefully it will work as well.

  18. v.t. says:

    In all fairness (to pet owners and some vets) – the EPA does not exactly have a stellar reputation regarding product investigations and requirements (studies) of flea/tick product manufacturers. Has everyone forgotten the years-long fiasco with certain spot-on treatments? It took several years for the EPA to take action for those products, all the while only requiring manufacturers to change labeling (which the EPA admitted and continues to admit, does not reduce the number of reports or reduce the number of adverse reactions – one manufacturer changed labels up to three times, IIRC). Btw, the national poison control centers, veterinarians, as well as advocate groups all submitted reports to the EPA for years and nothing was done.

    Manufacturers as well as the EPA also blamed pet owners for misuse and error in application for spot-on treatments, yet they also failed to investigate the reports in a timely manner and in the end, those products were eventually taken off the market (too late for many pets), or new products were developed. The same applied to certain flea collars containing known carcinogens in years past.

    If anything, whether the reports regarding Seresto are true or not, should serve as a warning that pet products containing pesticides are not without risk, and if the reports start mounting as they did a decade ago, manufacturers (and the EPA) have an obligation to investigate promptly.

    Let us also not forget the accumulated exposure that pets are exposed to when using any flea/tick product, or a combination of products over the course of their lives. There is one manufacturer (who I will not name), who actually promoted the use of the company’s collars, baths, spot-ons, powders/sprays used in the home etc and claimed multi-product use was completely safe – imagine for a moment, just how much exposure that really is for pets and children.

  19. skeptvet says:

    All of what you say is true, but of course it doesn’t bear directly on the safety of the ingredients in the Seresto collar. While it is understandable that past problems create a sensitivity or suspicion, whether it is of government, vets, pet food companies, etc., this is also a big problem. Every advocate for alternative therapies uses this to generate suspicion of specific people, groups, or treatments even if there is no evidence that these are unsafe. Understandable suspicion may be understandable, but it is also exploitable.

    How many people feed raw diets because of the melamine tragedy? How many people buy into the nonsense about organic produce because of DDT, PCBs, and other real environmental problems? This kind of natural suspicion is easy to generate and target in attacking something, but it isn’t a reliable guide to the truth about specific interventions, and in my opinion it does more harm than good. Of course pesticides are not without risk, but as I take pains to point out all the time, nothing is. All the people turning to limonene or eschewing flea and tick control altogether as a result of this histrionic article will be exposing their pets to risk as well, they just won’t know it.

    The core of skepticism as an approach is to reserve judgement in the absence of evidence and to proportion the strength of our judgements and claims to the strength of the available evidence. This kind of journalistic fear-mongering makes such rational assessment of risks nearly impossible, and that is not in the best interests of our pets. 🙁

  20. v.t. says:

    I agree, skeptvet, there is a lot of opportunity to cry foul when no foul is evident.

    The spot-on product situation started in much the same way, however. By reporting. Granted, many of the reports mounted significantly in a short amount of time (which prompted the concern, but certainly not the quick action from the EPA). Of course, such reports require validating, I just wanted to point out, that we should not forget how we got to the conclusion of the harm of spot-on treatment products back then, to a potential new problem again (whether it’s Seresto or any other product). I would hope the manufacturer(s) in question and the EPA would be on high alert and act accordingly as opposed to their failures in the past.

  21. lt says:

    groomer here- as a personal anecdote, serestos make me sick. When exposed ( dog wearing one, or if owner removed it ) I get a migraine, my chest feels tight, heart races and I garble my speech. I have had migraines, but the other symptoms are only when exposed to a seresto. Other groomers report reactions too. I know it’s seresto exposure because my dogs don’t wear them and my symptoms start within a minute of handling a dog who does. It’s easier for groomers to pinpoint exposure than for a person living with a pet wearing the collar, I noticed a pattern, started keeping notes, and that confirmed it. I think there’s a need for more research.

  22. skeptvet says:

    Unfortunately, it’s impossible to know what that means, Obviously, the vast majority of people and dogs don’t show any symptoms, so how would that work? And remember, tens of thousands of people have reported muscle aches with statins, but in blinded studies when they don’t know if they are getting the drug or a placebo, this doesn’t happen, so almost all of those people are experiencing a nocebo effect. This happened to me, where I was sure I had aches taking these drugs, and once I realized it was a nocebo effect, it went away. We do, of course, have to investigate claims like this, but we have to remember that the observations themselves don’t actually tell us if there is a real problem or not.

  23. Carol Beechey says:

    At this time myself and several friends have cut off the Secresto on their dog(s). You have a lot “fancy” sounding reasons why the collars are safe but why should we believe you more than the article. My vet has put out a post telling his clients if they feel uncomfortable using the Secresto flea tick collars then Do Not Use One On Your Dog. I would say that is the best advice. Until more proof of the dangers or no dangers to your pet – just do not use. one.

  24. skeptvet says:

    If by “fancy” reasons you mean scientific arguments and evidence, that’s exactly the difference between my analysis and that of the USA Today article. If you prefer anecdotes and fear over a critical, evidence-based analysis of the risks and benefits, that’s up to you, but I don’t agree that the best approach is to act on ill-founded anxiety.

  25. Steven Sohn says:

    I have been using Seresto collars on my Old English Sheepdogs for two generations, with nothing but excellent results. The only reason I occasionally consider an alternative is that my male, Rufus, has the unpleasant habit of tearing off the Seresto from my female, Mopsey, during play and rough housing, and I have to search the grounds to find the blasted thing.
    Wonder what USA Today would make of that? “Seresto causing destructive and aggressive behavior in dogs?” Likely.

  26. R.D.S. says:

    Kinda of like today with Covid right? They stop using the Johnson and Johnson vaccince because six people had adverse reactions and died. Six people out of SEVEN MILLION doses. There are, and always wull be people, and animals wgo have bad reactions that’s call life.
    We use seresto collars on all five of our dogs, and nonevof them have had any issues with them. Short of just being expensive they work perfectly for our pets.

    As for folks who fear this product that’s fine as one stated above about past alarms over the spot treatments we have been there and done that. We used Pet armor from walmart on our two rots. A week later our female was dead. Seemingly healthy dog before the drops dead a week later. Coincidence? Maybe, but you have to consider everything I mean she was within her lifespan she was ten. Rots live between 9 and 12 on average. Maybe she was ill with no visible signs to make us think otherwise. But as i said we used the drops on our rot(s). Mind you most are colored black with some brown. Our male rot turned grey. All the black went grey over his whole coat. The brown stayed brown. He lived another five years. Who fathered the dogs we have now. So unless you plan to live with fleas and ticks you have to find the product that works for you and your pet family.
    We will continue to use the seresto collars which have no ill effects on our 5 dogs, 3 cats, nor my wife or myself. Goodluck to you all.
    R. D. S.

  27. R. D. S. says:

    Sorry for some of the typeo’s. I suffer from fat fingers, and small phone syndrome.

    R. D. S.

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