Could a Cream Eliminate Equine Aural Plaques?

Could a Cream Eliminate Equine Aural Plaques?

Aural plaques resemble warts and are caused by the Equus caballus papillomavirus.

Photo: The Horse Staff

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.

The rate of clearance observed in horses is similar to or higher than that observed in human studies using imiquimod. “We think the high rate of clearance of EcPv observed in the present study, after treatment, can result in a reduced risk of virus spread,” he added.

The treatment might not prevent future infection, but it appears capable of reducing the spread of the virus and providing comfort to horses with aural plaques.

Oliveira Filho cautioned, however, that “veterinarians need to be aware of the side effects and should clarify the owner about that.” Further, he said, the veterinarian should take steps to ensure the horse receives the entire treatment—no stopping imiquimod application early; this could be as simple as stressing the importance to an easy-to-educate horse owner or as intensive as making arrangements to have treatment applied if the owner isn’t likely to carry through.

Further research is needed to determine if lower concentrations of imiquimod can still be effective while reducing the adverse effects, Oliveira Filho said.

The study, “Imiquimod treatment for Equus caballus papillomavirus infection in equine aural plaques,” which was supported by São Paulo Research Foundation–FAPESP, was published in Veterinary Dermatology

About the Author

Katie Navarra

Katie Navarra has worked as a freelance writer since 2001. A lifelong horse lover, she owns and enjoys competing a dun Quarter Horse mare.

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