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Key takeaways

Aural plaques in horses are white, round, raised lesions on the inside of the ear caused by a papillomavirus (warts) infection.

  • Horses become infected with the virus by the bite of a black fly
  • Aural plaques can cause irritation to the surrounding area, but are most often benign and cause no symptoms other than the plaque itself
  • Diagnostics include a physical examination and biopsy of the lesion
  • Treatment is most often not necessary, and only recommended if it is causing discomfort
  • When warranted, treatment includes topical application of an antiviral or steroid cream
  • Prevention can include utilizing fly masks to cover the ears and limiting outdoor activity during times when biting flies are more active
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A closer look: Aural Plaques in Horses

Aural plaques are common in horses. These lesions are benign and unless they are causing distress or pain, treatment is generally not recommended.

Risk factors

Occasionally, aural plaques can be accompanied by inflammation or irritation of the surrounding area. Irritation is especially common with repeated handling of the affected ear. In some horses, this irritation can cause discomfort.

Any horse is at risk of aural plaques. They are more common in older horses. Since the virus is spread by biting flies, horses in areas with high populations of biting flies are at highest risk of developing aural plaques, especially during times of year when there is peak insect activity.

Possible causes

Aural plaques are caused by a papillomavirus infection caused by the bite of black flies. Wounds or injuries within the ear may also lead to aural plaque development.

Main symptoms

These lumps are usually raised, white, rounded lesions on the interior surface of the ear. These plaques can vary in size and number.

Testing and diagnosis

Most aural plaques are diagnosed based on physical examination. In some cases, a biopsy of the plaque is taken to confirm the diagnosis and rule out other similar-appearing conditions.

Steps to Recovery

Treatment is generally not required unless the plaques are causing distress or irritation to the horse. Treatment can involve topical applications of a steroid or specialized antiviral cream several times a week. These treatments can increase inflammation and irritation, and many horses resent application of the cream. These horses may require sedation for application.

Aural plaques do not often spontaneously resolve on their own. With treatment, they can be reduced, but this is often not necessary. Most cases of aural plaques are not treated unless they are bothering the horse.


Prevention involves reducing exposure to insects, particularly black flies. Strategies include using fly masks with ear netting, stabling during times of high fly activity, and avoiding unnecessary contact with the ears.

Aural plaques are not directly contagious between horses.

Are Aural Plaques in Horses common?

Aural plaques are common in horses.

Typical Treatment

No treatment is typically required but can involve topical creams if necessary.


Sandra Diaz , DVM, MS, DACVD - Writing for Merck Veterinary Manual
Dr. Lydia Gray - Writing for SmartPak
No Author - Writing for HorseDVM

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