At the time Elanco defended the products as safe given that the volume of collars sold was more than 25 million units and the overall number of incidents was relatively minor compared to that volume. A 2021 article from the AVMA mostly agreed with Elanco's assessment, finding that most actual issues were minor and anecdotal.
This past week a congressional subcommittee investigating this issue came to a very different conclusion. A 22-page report released by the committee found that since the product's introduction in 2012, there have been more than 98,000 incidents with 2,500 pet deaths. The report also cited that Seresto had incidents of death five times greater than the next most popular competing product.
A June 2022 article from the Midwest Center for Investigative Reporting also showed that the Canadian equivalent of the EPA found hundreds of human incidents and pet deaths linked to the collars and denied the use of Seresto in Canada. Despite that evidence, the report finds that the EPA ignored the Canadian findings, was possibly negligent in using incident data to properly evaluate the risk of Seresto, and has been slow in re-evaluating its danger.
For its part, Elanco continues to state that they believe Seresto to be safe and it continues to be approved by the EPA and AVMA.