The ear is an organ of hearing and an organ of balance. It consists of the outer, middle, and inner ear.
The outer ear includes the pinna (the part you see that is made of cartilage and covered by skin, fur, or hair) and the ear canal. The pinna is shaped to capture sound waves and funnel them through the ear canal to the eardrum. The pinnae are mobile and can move independently of each other, allowing horses to locate multiple sounds at the same time. In general, horses hear slightly better than people and are able to hear sounds at both higher and lower frequencies. Horses are good at hearing the high-pitched squeaks or cracks associated with the stealthy approach of a predator.
Inside a horse's ear
The middle ear includes the eardrum and a small, air-filled chamber that contains 3 tiny bones: the hammer, anvil, and stirrup. It also includes 2 muscles, the oval window, and the eustachian tube (a small tube that connects the middle ear with the back of the nose, allowing air to enter the middle ear).
The inner ear is a complex structure that includes the cochlea (the organ of hearing) and the vestibular system (the organ of balance).
Physical Examination of a Horse's Ear
Infections of the ear and other ear disorders are less common in horses than in dogs or cats; wounds, flystrike, and skin masses are more common ear problems in horses. Although the external ear can be examined, the anatomy of the equine ear makes it difficult for veterinarians to evaluate the ear canal. This procedure usually requires a short-acting anesthetic.
If an infection is suspected, tests will be performed on samples of fluid or secretions from the ear to determine the organisms involved and the proper treatment. Infections are most commonly caused by bacteria or parasites.
A biopsy may be necessary to diagnose some types of ear disease in horses. Further tests, including x-rays, computed tomography (CT scan), magnetic resonance imaging (MRI), neurologic tests, or electronic tests, may be needed to confirm certain conditions.
