Horses can get infections of the middle ear, inner ear or the outer ear flap, or pinna. Not only are ear infections painful, they also can greatly impair a horse's coordination and lead to deafness.
Causes of equine ear infections include parasites, illnesses such as vestibular disease, injuries that don't heal properly, and foreign objects or fungal spores that lodge in the ear and cause injury, which can lead to infection.
According to Kenton H. Arnold, DVM, symptoms of horse ear infections include frequent head shaking, not wanting the ear to be touched, swelling and more ear wax than usual.
Because the horse may be in pain, she needs to be sedated before a veterinarian can properly examine her ears and determine the cause of the ear infection.
Types of horse ear infections include fly-bite dermatitis, which is caused by any biting parasite; otitis externa, the infection of the pinna; otitis media, the infection of the middle ear; and otitis interna, the infection of the inner ear.
According to Horse Owner's Home Veterinary Handbook 2008, using soap, alcohol or oil inside the pinna to clean it can cause equine ear infections. Instead, clean the ear flap with a soft towel or sponge.