EPA confirms registration, safety of Seresto collar

The Environmental Protection Agency (EPA) announced July 13 that the Seresto flea and tick collar will remain on the market after completing a multi-year review of the pet collar. Comprehensive data from the review showed that these collars continue to meet EPA's standards under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) while providing flea and tick prevention for dogs and cats, and lice control for dogs.

At the same time, the EPA is requiring Elanco Animal Health, maker of the Seresto collar, to implement additional measures that will alert veterinarians and consumers of potential risks and provide more information about how to prevent and report adverse reactions from Seresto collars. The new measures will also improve the quality of adverse incident data reported to EPA to aid in the continued review of this product, according to the agency.

Since its launch in 2013, more than 41 million Seresto collars have been sold in the U.S. In 2022, the estimated incidence of adverse events in the U.S. following exposure to the Seresto collar was approximately 0.116%, which equates to approximately one animal with a reported adverse event for every 1,000 collars distributed in the U.S.

The Seresto collar, first developed by Bayer and now sold by Elanco, faced increased scrutiny, including a Congressional inquiry and class action lawsuits, following a March story by the Midwest Center for Investigative Reporting and USA Today. The reporting alleged the collars were responsible for 1,700 deaths of pets and about 1,000 incidents of harm to humans since being introduced in 2012.

The EPA began an in-depth review in 2021 of the Seresto-related incidents reported to its Incident Data System.

The EPA analyzed all incidents that reported death for Seresto. This included 1,400 deaths reported to the EPA from 2016-20, which represent 2% of all Seresto incidents reported for these years. In many of the death-related incidents, critical details of the incident were often missing, preventing the Agency from determining the cause of the death, the agency says.

"The only reported deaths that were found to be 'probably' or 'definitely' related to Seresto product use were associated with mechanical strangulation or trauma caused by the collar, often associated with a failure of the release mechanism," according to the EPA.

For all other deaths, the EPA did not identify cases with a probable or definite association between collar use and death, often because of other factors, such as an existing medical condition.

The EPA also analyzed all nonlethal incidents, such as neurological symptoms.

"In some incidents with moderate or severe clinical signs, removal of the collar seemed to alleviate symptoms and/or reapplication of the collar coincided with a reoccurrence of symptoms," the agency says.

To help with the continued review of Seresto collars and raise awareness among veterinary professionals and the public about potential risks from pesticide products used on pets, Elanco has agreed to take the following actions:

• Include label warnings on Seresto collars that describe common adverse effects that have been reported, along with instructions to remove the collar if those effects occur and instructions on how to report the incident.
• Develop an outreach program to more effectively communicate with veterinarians and the public on the risks of using the product and other similar pesticides on pets.
• Pursue additional information to ensure that complete details of each adverse event are captured. The Seresto pet collar registration has also been split into two registrations, one for cats and one for dogs, to make comparison of incident data across products easier in the future.
• Report incident and sales data to EPA on an annual basis. Evaluate potential changes to the emergency release mechanism of Seresto pet collars to prevent death by strangulation or choking. The company must submit a report of this effort within one year.

The EPA has limited its current approval of Seresto collar registrations to five years. The company must implement the new registration requirements by the next printing of Seresto pet collar labels, which must happen by July 2024.

Pets should be monitored for side effects or signs of sensitivity after putting on the collar, according to the EPA. More commonly reported adverse events include itching for dogs and hair changes near the cat collar application site. Less common adverse events include neurological symptoms, such as convulsions or ataxia.

In case of an adverse event, owners should report the incident on EPA's website or contact the National Pesticide Information Center, which is staffed by individuals trained in responding to pesticide exposure incidents, including those involving pets.

A version of this story appears in the October 2023 print issue of JAVMA