Is your senior horse losing his eyesight? Unlike elderly people and dogs, who suffer age-related vision changes that can lead to blindness, it's rare for a senior horse's aging eyes to go blind. In fact, since significant vision loss is rare in horse eyes, many veterinarians don't consider horse vision exams a must for a senior horse except as part of a general 'physical.' But there are good reasons to specifically request a horse vision exam, including the following age-related changes that can spark problems in horse eyes:
Weakening Immune System: As your horse ages, his immune system weakens. This can increase his susceptibility to horse eye maladies, such as corneal ulcers and moon blindness. Cataracts, common in other species, do occur in horses but less often. Observed as an opacity of the eye?s lens, they will impair the horse's ability to see straight ahead, while his peripheral vision may remain relatively unaffected.
Ability to mask vision loss:Horses with compromised vision can conceal their condition in familiar environments by adhering to familiar routes and routines. In fact, they?ll attempt to conceal the problem in unfamiliar surroundings, too. Horses are prey animals. In the wild, predators are likely to single out the herd member that looks most ?impaired.? A sight-challenged wild horse has the best survival chance if he keeps his secret to himself. Your domestic horse instinctively knows this.
So, your senior's ability to navigate with his peripheral vision--and adhere to his normal routine--can make detection of a vision problem difficult. However, if he begins spooking, tripping, having trouble negotiating different elevations, or knocking into objects, his vision could be the culprit. Perform the "Quick Vision Test," then report your results to your veterinarian. (Be sure to test both horse eyes.)
Quick Vision Test
What you'll need:
• Halter and lead rope
• A disposable diaper or clean dish towel
• Tape, such as duct or electrical
• A handful of cotton balls
• Hay or straw bale
Halter your horse. Blindfold one eye by laying a lightweight, thick pad, such as a disposable diaper folded in half, or a dish towel folded in thirds, across the eye. (If using a diaper, place the absorbent side against his skin.) Tape it to your horse's halter.
Wear clothing that doesn't ?swish.? In a well-lit area with minimal distractions, have a helper loosely hold your horse. Stand 3 feet away, to the side of the uncovered eye, where the opposite eye is completely concealed. Lob 3 cotton balls toward him, one after the other, so they bounce gently off the side of his face between his eye and muzzle.
Observe his reactions. Did he flinch when the first one approached, before it touched him? Did he try to avoid the second? Did he watch the third one? If your answers are no, no, and no, he probably can't see out of that eye. Repeat with the other eye.
If you're still unsure, move him to a well-lit area.With one of his eyes covered, lead your horse on a loose lead rope toward a bale of hay set 15 feet ahead. Walk purposefully?don't go so slowly that he has time to lower his head and smell it.
Observe his reactions. Does he try to avoid hitting the bale? If not, he probably can't see it. Cover the other eye, and repeat.
From Hands-On Senior Horse Care by Karen E.N. Hayes, DVM, MS, & Sue M. Copeland