Recently an article was published in USA Today that raised concerns about the safety of Seresto collars. I’d like to take a few moments to discuss the article and its implications for your pet. Firstly I want to say that you do NOT need to immediately remove and destroy the Seresto collar your pet is wearing if they have had no problems with it. What we want to discuss here are the few pets who do have sensitivities. Just like ANY medication (or vaccination), there is no way to predict in advance how pets will react. We don’t know if your pet will have a vaccine reaction until we administer a vaccination. We don’t know if your cat will have a flea allergy until they meet a flea. We don’t know that your dog has an allergy to bee stings until they try to play with a bee. The same goes for people. So what do we do? We prepare ourselves to recognize adverse reactions and understand the steps needed to treat them.

So what are the concerns with interpreting the recent news articles?

Unfortunately the authors elected NOT to seek the advice of a veterinarian or veterinary toxicologist (yes, they exist!) before publishing the article. If they had they would find that the toxicologists agree that the active ingredients in Seresto collars are safe for pets and they find no reason to expect that the synergistic effect (meaning both ingredients together are more potent than the individual ingredients) that would explain the severe adverse reactions described in the article.

The article fails to differentiate between correlation and causation. Correlation is when two things happen at the same time. Causation is when the first thing causes the second. It’s always sad when a pet passes away, oftentimes owners elect not to pursue a necropsy (which is a pet autopsy) that confirms the cause of death. When this is declined we never know the true underlying cause of death. This means that while the Seresto may have been worn when the pet died we have no way to know if it was a factor in the pet’s death, but it gets included as an “adverse event” anyway.

There have been a LOT of counterfeit collars being sold from online pharmacies (did you know that most of the big pharmacies can’t tell you where their supply came from… but your full service veterinarian can). We see a much higher rate of reactions from these fake collars than from real ones. Unfortunately the counterfeiters are so skilled at reproducing fakes that they’ll include serial numbers to try and fool the big buyers (which is how they end up being sold to owners online). It’s a sad reality that when something works well others want to get a cut of the profits, but at your (and your pets’) expense.

What about if my pet’s wearing a Seresto collar?

  • First, if your pet has had no reactions, there’s nothing you need to do! Woohoo!
  • If you notice any redness or irritation around the collar site, remove the collar and give your dog a bath. Dawn dish soap works great here since it removes the oils from the skin (remember, the oil glands are where the medication from the collar are stored – it’s NOT absorbed into the blood). These reactions are typically noticed within a few hours to days of wearing the collar, and are a good indication we need to consider a different class of preventatives.
  • If your pet has a reduced appetite after applying the collar, remove it and wait 24 hours before reapplying. In young puppies it may be the newness of the collar. In other dogs it may be the odor (just like a new car has a distinct smell, so do collars and other topical drops). If any other stomach issues (vomiting or diarrhea) develop, remove the collar and see if the symptoms resolve over the next few days. They may be in that small subset with a sensitivity to the medication (and it’s best to avoid other topical drops for this reason).

So what will I be doing, going forward, as your veterinarian?

At this time I am still confident in the safety and efficacy of Seresto collars, and will continue to include them in my discussions with all owners regarding flea and tick preventatives.

I recommend that any owner who has a concern about a potential adverse effect reach out directly to Elanco using their veterinary hotline at 800-255-6826. Each company has their own specialists to answer your questions, and Elanco is no exception. When you purchase your products directly from your veterinarian you get the full support of the companies as well.

I will continue to focus on education so that all owners will have the best information they can regarding the options available. You can read about ticks in our area and available preventatives

Finally I just want to say that I have unfortunately watched more pets get sick from Lyme disease than any preventatives in the last decade. I’ve seen more pets with intestinal illness secondary to Anaplasmosis than I have from Seresto collars. I have treated more cases of Idiopathic (unknown causes for seizures) than I have from Seresto collars or the oral flea and tick tablets. So please discuss all options with us and no matter which you choose, continue to use it all year long.

Have questions?


Please do not hesitate to contact us today! Our team is here to help.