Seresto collars remain in spotlight after hearing

Elanco Animal Health defended its Seresto flea and tick collar as safe and effective before a congressional subcommittee’s June 15 hearing. In May 2021, the Pet Poison Hotline expressed its support for the collar’s safety after a review by its boarded veterinary toxicology experts, adding that the collar’s benefits outweigh the “the extremely rare risk of a serious adverse event.”

Flea and tick control is an important preventive measure pet owners can take to protect animals and humans from diseases and conditions—some deadly—related to these parasites, says Dr. Gail Golab, the AVMA’s chief veterinary officer.

“The risk associated with the use of medical products is never zero,” Dr. Golab said, “so it is necessary to balance possible risks against anticipated benefits—in this case, protection against parasites that can seriously harm animal and human health.”

Dog being fitted with a flea collar

The U.S. House of Representatives’ Committee on Oversight and Reform’s Subcommittee on Economic and Consumer Policy has been looking into the collars since March 2021 after USA Today and the Midwest Center for Investigative Reporting revealed the Environmental Protection Agency had received more than 75,000 incident reports involving Seresto collars since they were first introduced in 2012. Those reports allege the collars were responsible for 1,700 deaths of pets and about 1,000 incidents of harm to humans. Since then, the number of reports has increased to more than 98,000 and the number of alleged associated pet deaths to 2,500. More than 33 million collars have been sold over this same time period, according to Elanco. The subcommittee’s staff released a report requesting a voluntary recall, for the EPA to begin proceedings to cancel the Seresto collar’s registration, to improve the required companion animal safety studies, and improve the collection of incident data involving pets.

At the time of publication, review of the product by the EPA is ongoing. The agency’s review will assess whether there is a causal connection between reported events and the product, as well as their severity and frequency.

Seresto collars, developed by Bayer and now manufactured and sold by Elanco Animal Health, contain two pesticides: imidacloprid, which is a neonicotinoid, and flumethrin, which is a pyrethroid. The EPA regulates most flea and tick products applied topically and without a systemic mode of action, such as these collars and spot-on products.

Seresto was approved by the EPA on the basis of positive results from more than 80 safety, toxicity, and efficacy studies, said Jeffrey Simmons, president and CEO of Elanco Animal Health, in a written statement for the congressional subcommittee.

He also noted that a report of an adverse incident does not mean that the adverse incident was caused by a product—and that the company’s pharmacovigilance team has not identified any deaths caused by Seresto’s active ingredients.

The Pet Poison Helpline said in its May 2021 statement that, since 2013, it has managed approximately 400 cases involving Seresto, the majority of which involved dogs ingesting all or a portion of the collar. There were no deaths, and most of the adverse events were mild.

“In the medical opinion of our boarded veterinary toxicology experts these collars are a safe and important treatment for the vast majority of cats and dogs. The health protections these collars provide far outweigh the extremely rare risk of a serious adverse event,” according to the Pet Poison Helpline. “People who avoid using these products out of concern for a negative reaction may be putting their pets at greater risk of harm by leaving them susceptible to diseases caused by fleas and ticks such as Lyme disease, Ehrlichiosis, Anaplasmosis and Rocky Mountain Spotted Fever. These diseases pose a far greater health risk to a pet than Seresto collars.”

The AVMA seeks to support and protect the integrity of the medical and scientific analysis of adverse events and whether reported adverse events are causally related to a product. Accordingly, it has urged the EPA to not cancel Seresto’s EPA registration prior to completing its evaluation of the updated data. The hope is that evaluating that data will provide a clearer picture of the safety of these collars and help determine their continued availability and appropriate use, including any changes needed to their labeling.