Aural Plaques in Horses

What is it?

Aural plaques in a horse's ear

Aural plaques in a horse’s ear

Aural plaques are white or light yellow growths on the inside of a horse’s ear.  These lesions have a flaky appearance and may resemble “warts”.  Aural plaques are believed to be a result of chronic inflammation caused by a papilloma virus spread by flies and biting insects.  While similar to warts, the lesions in the ear do not spontaneously resolve like the common warts found on younger horses.  Aural plaques tend to affect a single animal in a herd. While the virus is contagious, many animals are immune to it and do not develop aural plaques.

For a small number of horses, aural plaques are just a cosmetic issue that can be ignored.  However, in most cases, aural plaques are a constant source of irritation and pain, particularly when bridling or haltering the horse.   Many owners report that their horse is “head-shy” when attempting to groom around the ears. A horse should be examined by a veterinarian to diagnose aural plaques and rule out other types of tumors or growths that can affect a horse’s ears.

How is it treated?

There have been few successful treatments available for aural plaques until recent years.  We have had great success using a prescription drug called imiquimod 5% (generic for Aldara™), although it does not resolve all cases.  Research has shown that the product provides a long-term resolution in 87.5% of horses treated.  This drug works by stimulating a local inflammatory response, encouraging the horse’s immune system to heal the plaque on its own.

Aural plaques during 2nd treatment week (4th application) with imiquimod 5%

Aural plaques during 2nd treatment week (4th application) with imiquimod 5%

First, the animal is sedated by the veterinarian so that the hair within the ears can be shaved, and all crusts are removed.  Wearing gloves, the ears are treated with imiquimod 5% ointment.  The owner can repeat treatment as directed by the veterinarian. The ears are treated 2-3 times per week and repeated every other week for 2 months.  The ointment causes redness, swelling, and oozing within the ears during treatment. Horses may be restrained using a nose twitch to facilitate treatment.  In some cases, horses may require sedation for each treatment.

As the skin heals in the weeks following the last treatment, the skin surface will resemble that of a normal horse and the hair will regrow.

 

Photos from University of Minnesota Equine aural plaques at diagnosis, mid-treatment, and after treatment.

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