You’ve seen the white stuff on the inside of horses’ ears. Maybe you’ve even tried to get rid of it. In many cases, however, this substance—aural plaque—is challenging to eliminate. But researchers recently tested a cream that could prove useful for treating aural plaques: imiquimod, an immune-boosting paste sometimes used to treat sarcoids.

Aural plaques resemble warts and are caused by the Equus caballus papillomavirus (EcPV), probably spread by flies and biting insects. Not only are the warts unsightly, but they can also reduce a horse’s sale value and cause ear sensitivity of varying degrees. Treatment with a 5% imiquimod cream can be effective, but can result in inflammatory reactions in some cases. This could cause horse owners to stop treatment to before the veterinarian instructs them to do so.

“This is a big problem,” said José Paes de Oliveira Filho, DCV, FMVZ, at the Universidade Estadual Paulista (Unesp) in Brazil.

But, despite the side effects and based on the results of a recent study, Oliveira Filho asserts that the 5% imiquimod cream is effective for treating aural plaques in horses. “This treatment promoted clinical resolution in 93% of the treated ears and, moreover, the EcPVs was not observed in 71.4% of the treated ears after the treatment,” he explained