You stand in the pasture and call your horse's name, but he doesn't raise his head and trot over as quickly as he used to. Is he just tuning you out or is his hearing starting to go?
Age-related hearing loss in horses is similar to what happens in people---tiny hairlike structures (cilia) within the inner ear become damaged, which interferes with their ability to convert sounds into electrical signals that the brain can interpret.
Detecting hearing loss in horses can be difficult because they are so responsive to body language, and they readily adapt to their circumstances. And, for the same reasons, deafness in a horse isn't a serious concern—most get along just fine. Nonetheless, it is important to identify deafness so you can make allowances in how you handle and manage your horse.
Here are some ways to determine whether your horse's hearing is impaired:
- Observe him with his herd for 30 minutes or longer. Horses rely on their hearing to track the movements of herdmates. Does he seem unaware of other horses as they move around the pasture? Is he startled when a frisky horse gallops by?
- Staying out of range of kicks, stand behind your horse while he is dozing and clap your hands sharply. A horse with normal hearing will react to the sound.
- Stand out of sight, shake a bucket of grain and watch for his reaction. Most horses will perk up at the noise.
If you need a more definitive diagnosis, contact your veterinarian. She may refer you for a brain-stem auditory evoked response (BAER) test, in which foam earpieces are placed in the horse's ears and small electrodes are inserted just under the skin at specific points around the head.
When a series of clicks are played through the foam, the electrodes record the signals carried along the auditory nerves. The BAER test can't determine how well a horse can hear, but it can detect total deafness.