Aural plaque, or aural papilloma, is commonly but incorrectly referred to as ear fungus. White, thick, crusty, flaky patches inside the horse’s inner ear cause the underlying skin to change pigment and become thicker. Small, hard bumps may form in the aural plaque. The horse’s ears can become sensitive, making the horse difficult to handle when haltering or bridling.
Aural plaque can be caused by papillomavirus, which causes warts. Fluids leak from the bites of small gnats, causing a crusty layer to form over the skin of the inner ear. That crusty layer can lead to aural plaque.
The inside of the horse’s ear will be covered with white, crusty patches, possibly with small, hard bumps. The aural plaque will be flaky to the touch. Lesions may form as well. The skin under the aural plaque will be thicker, and the underlying pigmentation will change to pink. The horse may shake or toss his head and resist when you try to handle his ears.
Because aural plaque is not actually a fungus, antifungals and antibiotics will not work. Oil-based ointment will clean away the plaque. Baby oil can also be used. Once the plaque is removed, the skin underneath can be treated with soothing lotion or ointment. If warts are involved, antiviral ointment may be helpful.
Any changes to skin pigment are permanent, but the hair should grow back. The lesions will heal once the plaque is removed. If the plaque is difficult to remove entirely, ear covers can be worn by the horse to prevent insect bites inside the ear. Fly masks with ear covers are available.
Avoiding fly bites on the inside of the horse’s ear is the best way to prevent aural plaque. Individual sensitivities to flies can make aural plaque more of a problem for some horses. Repeated clipping of the ear hair allows easier access for gnats and flies, increasing the chances that your horse will develop aural plaque. If you have to clip your horse’s ear hair for show purposes, ear covers will help with prevention.