Ask the Vet

Flea Collars and Pet Illnesses, Deaths

No flea and tick product is 100% safe, but fleas and ticks are 100% dangerous. (DTN/Progressive Farmer file photo by Dean Houghton)


I have seen reports in the newspaper and online about pet deaths and illnesses related to the use of Seresto collars. What can you tell me about this?


Many reports have been submitted to the EPA regarding pet illnesses owners felt were related to the use of Seresto flea collars. EPA is the federal agency that approves and oversees all topical insecticides.

In my practice, I have seen no proof of severe illness or death caused by Seresto. Elanco, the maker of Seresto, maintains the collar is safe based on internal studies. A company-financed analysis found that the two chemicals in Seresto, imidacloprid and flumethrin, have not been responsible for any pet deaths.

We have used this product since its release more than 10 years ago and have had very few issues and no deaths. We have had some pets with minor issues, including skin irrigation, lethargy, and loss of appetite, but those were resolved when the collar was removed.

There have been issues with fake Seresto collars purchased through online sellers. The only issue our clients reported regarding these collars has been a lack of efficacy. But, with counterfeit merchandise from China, you never know what could be in those collars.

I always advise that you read and follow label directions exactly. Proper placement of the collar is essential. Make sure two fingers can fit between the collar and the neck. Any excess collar length should be cut off. If your pet has any issues, immediately remove the collar and call you veterinarian. You can also report problems to the EPA.

Collars are not our primary recommendation for flea and tick control. We feel the isoxazoline class of flea and tick products are the best option for most pets. These include Bravecto, Bravecto Plus, NexGard, Simparica, Simparica Trio, Revolution Plus and Credelio.

No flea and tick product is 100% safe, but fleas and ticks are 100% dangerous. Please consult with your veterinarian to find the best parasite-control program and product(s) for your pets. If you feel there is an issue, talk to your veterinarian.


Editor's Note:

Please contact your veterinarian with questions pertaining to the health of your herd or other animals. Every operation is unique, and the information in this column does not pertain to all situations. This is not intended as medical advice but is purely for informational purposes.

Write Dr. Ken McMillan at Ask the Vet, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email