• The Village Vet

Seresto Collars (Spoiler: They're Safe!)

Recently an article came out that raised concerns from several clients about the safety of Seresto collars. I'd like to take a few minutes to discuss the article and it's implications for your pet.

First, I want to say that you do NOT need to immediately remove and destroy the Seresto collar your pet is wearing if they have no problems with it. In the vast majority of households, we see NO adverse reactions (either in pets or their 2-legged family members).


What we want to discuss here are the few pets that 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 the vaccination. We don't know that your cat will have flea allergies until they meet a flea. We don't know that your dog has an allergy to bee stings until they try to play with the bee. The same goes for people - you had no way to know your child was allergic to peanut butter until they took that first bite. So what do we do? We prepare ourselves with the knowledge needed to recognize adverse reactions and understand the steps needed to treat them.


I have been recommending Seresto Collars almost since they came on the market (yes, I've been practicing that long!). In fact, I remember the first patient I ever recommended it for - a cat that had epilepsy (a seizure disorder) and flea allergies who needed topical drops every 2 weeks. We elected to switch to the Seresto collar due to the prolonged duration of protection and... no additional seizures (or fleas)!! I usually see a reaction to the collar about every 2-3 years, and it's typically localized inflammation (redness) and less often alopecia (hair loss) around where the collar sits. Unfortunately, the pets that react to the Seresto collar also typically react to every other topical product applied. Why? Well, they're all very similar classes of parasiticides. It would be like a person being allergic to walnuts and their doctor advising them to avoid all other tree nuts due to the high likelihood of similar reactions.


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

  1. 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.

  2. 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, and often times 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.

  3. 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.


And what about my pet that is 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?

  1. 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 spend a LOT of time outside my normal appointment hours researching vaccinations, medications, preventatives and treatments, and I am always working toward providing the BEST care possible. Rest assured that if evidence arises at any time that brings into question the safety of these collars I will let you know.

  2. 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.

  3. 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 here.

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


:-) Dr. Johnson

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