Eye injuries and infections are common in horses given the large size and prominence of their eyes. This is just one of the reasons you should check your horses —and not just from over the pasture fence — at least twice daily.
With prompt treatment, many eye problems can be brought under control within a few days. In most cases, a veterinarian should check the eye, but most management can be done by you, at home.
What Are Eye Infections in Horses?
The most common eye issues in horses include bacterial infections and traumatic wounds.
Untreated eye problems can become nasty very quickly. Minor problems can even result in blindness if left untreated. If the eye becomes badly infected, the structures of the eye can be eroded until the entire eye collapses. Eye problems are also extremely painful and for animal welfare, should be treated as soon as possible.
Symptoms of Eye Infections in Horses
Your horse's eyes should be clear, bright, and the lids tight, with the inside of the lid pale pink and moist. Tearing should be minimal with perhaps only a droplet at the corner of the eye. Sometimes, if there is dusty, dry wind, a horse’s eyes might run a bit, just as yours would.
Symptoms that require treatment include:
- Cut or torn eyelids
- Swollen eyelids
- Obvious damage to the eye itself
- White film either over the whole eye or in spots
- Red or inflamed eye or of any surrounding tissue, including the white sclera and lids
- Tears running down the horse's face, which may indicate a blocked tear duct
- Copious discharge other than a thin tear-like stream
- Tumors growing on or around the lid
- In foals, turned under eyelids that cause the eyelashes to rub against the eye
Causes of Eye Infections
Horses can develop an eye infection after having a foreign object lodged in there. If the surface of the eye was scratched, environmental bacteria can be quick to set up infection. This will make the horse's eye appear cloudy and red. The horse will likely squint and tear profusely and may be reluctant to let you take a close look. These types of infections should be seen by a veterinarian who will prescribe antibiotic ointment and perhaps other therapies to treat the infection and help heal the eye.
Recurring uveitis is another, much more serious eye infection in horses that can lead to blindness if left untreated. Also known as "moon blindness," this condition may have multiple causes. Research has indicated that a bacterial disease called Leptospirosis can be the cause, although it is suspected there are other causes as well.
The signs of uveitis include squinting and hypersensitivity to light, a cloudy eye, and eye pain. Symptoms may flare up and then decrease, only to flare repeatedly again.
Infection with the parasite Thelazia, also known as the eyeworm, is also a cause of ocular equine disease. Horses are infected with this parasite via flies. Thin worms can be visualized within the eye. A veterinarian will have to remove the worms from the horse's eye with surgical instruments (usually a forceps) while the animal is under sedation. Fortunately in the United States, these parasitic infections are rare in horses.
If your horse has an eye injury or infection, call your veterinarian as soon as you can. Prompt treatment is key to a successful outcome for any eye issue. While waiting for your vet, here are some things you can do to help your horse:
- Put a fly mask on the horse to keep flies away.
- If possible, keep your horse in subdued light such as its stall until the veterinarian arrives.
Your veterinarian will likely sedate your horse for a thorough eye inspection. Don't try to force a horse's eye open as a horse can be extremely head shy if the eye is painful. Rips and tears in the horse's eyelids should be attended to by a veterinarian so the lid can be stitched if necessary. The vet will also check for damage to the cornea and anything that may be lodged in the eye (splinters, awns from grasses, or grit). A vet can assess the overall health of the eye and may be able to see problems that aren't apparent to the untrained eye.
If an infection is diagnosed, your veterinarian will likely give you an ointment or gel to apply to the eye multiple times a day. In some cases, she may draw a vial of the horse's blood and make a solution from it that you will irrigate the eye with; the serum in a horse's own blood acts as a healing agent for eye tissue. With all medications, make sure that you follow the veterinarian's instructions to the letter and be scrupulously clean as you apply any dressings or ointments.
Just because you see marked improvement within a few days, don't stop the medication until the full course is up. Stopping treatment before the infection or injury is completely healed can result in the infection flaring up again and possibly causing more damage.
When working with a horse with an eye problem be aware that it may have obscured vision and be a little more jumpy than usual. Talk gently so you don't surprise your horse if you walk up on a "blind side."
How to Prevent Eye Infections and Injuries
Your horse's environment should be as dust free as possible. If hay is dusty, or bedding is very dry and dusty, dampen it or use other fodder or bedding. Make sure that sharp edges on water troughs, metal buildings, fences, or other obstacles are covered or inaccessible. Pound in or pull any old nails that may be protruding from fences or other structures.
Taking care to make your horse's home as safe as possible will help prevent accidental eye injury.