The Eyes of a Horse

eyes of a horse

The eyes of a horse can tell you quite a lot. They can show fear or excitement, as well as a horse being happy and relaxed. They can also tell you if a horse has a problem that needs attention. Injuries and disease involving the eye should always be considered as a veterinary emergency. It is very important to recognize the early signs of an ocular problem before it becomes severe, as this could potentially result in permanent loss of vision or even the eyeball itself.

The equine eye is the largest of any land mammal. It is active day and night and has excellent night vision due to the structure of its retina (called the tapetum lucidum). The eyes are protected by not only the upper and lower eyelids but also a nictitating membrane, often called the third eyelid. The nictitating membrane, which is a whitish color and located under the other eyelids in the inside corner of the eyes, is designed to protect the eye from scratches and objects that could cause irritation. The nictitating membrane also spreads tears over the surface of the cornea, which keeps it moist and clears away small particles that might scratch the eyeball or irritate it.

Horses have a very wide range of visual abilities and they are able to detect a variety of colors. The eyes are also very responsive to motion and a horse can easily see its way around obstacles when it is gallopping in the dark.

One of the most common problems affecting horses is a corneal ulcer. This is a painful condition that can be difficult to diagnose because the horse might be so uncomfortable it won’t open its eye. In these situations, veterinarians use a fluorescent dye to stain the cornea and make the ulcer more visible on examination.

Another common ocular problem is inflammation of the choroid or the retina. This can be caused by foreign bodies such as grit or grass seeds embedded in the eye, infection and even certain parasites such as a serious worm called Equine Progestin Reproductive Toxoplasmosis. The inflammation can lead to a condition called recurrent uveitis. This is a recurring inflammation of the inside of the eye that can eventually cause cataracts, scarring of the cornea and damage to the optic nerve and retina.

The best way to avoid these ocular conditions is to perform regular, routine equine health exams. Exams should include a thorough examination of the entire body and a close inspection of the eyes including the surrounding area. Be sure to look for asymmetry (one eye might be more affected than the other), tearing or squinting, a change in the color of the eye and the presence of any discharge. It is never a good idea to apply ointments to the eye without consulting your veterinarian first. For example, using a steroid ointment on a corneal ulcer will worsen the condition and may result in permanent damage.