Eye problems are common in horses because of the structure of their eyes. Most eye conditions are considered serious by veterinarians and should not go untreated. Even minor eye problems can quickly progress, become serious, and threaten a horse's sight. Knowing the symptoms of common eye conditions can help you quickly recognize potential problems.
If caught early and treated, a corneal ulcer will heal in about 7 to 10 days. But left untreated, an ulcer can cause serious problems, including a rupture of the eye. These ulcers are caused by a scratch on the cornea, or surface, of the eye. Many things can cause scratches, such as tree branches and debris. Signs of a corneal ulcer include a white, cloudy spot on the eye, squinting, or abnormal tearing.
Equine Recurrent Uveitis
This eye disorder is the leading cause of blindness in horses. Equine recurrent uveitis, also known as moon blindness, is caused by inflammation in the middle layer of the eye, or the uveal tract. One case of uveal tract inflammation doesn't mean your horse has equine recurrent uveitis. The disorder is diagnosed only after several infections. Eye injuries or bacteria can cause uveal tract infections. Signs of this condition include redness, swelling, light sensitivity, squinting, tearing, and cloudy spots in the eye. Topical medications can be used to treat flare-ups.
Conjunctivitis happens when a horse's conjunctiva—the lining of the inside of the eyelid—becomes inflamed or infected. Conjunctivitis can be caused by bacteria, parasites, fungi, or viruses. People sometimes get bacterial conjunctivitis, which is known as pink eye. Your horse could have conjunctivitis if he has a thick discharge from one or both eyes, if his eyes are swollen or red, or if he rubs his face.
Obstructed Tear Duct
A horse's nasolacrimal, or tear, duct extends from the corner of the eye to an opening near the nostril. If it becomes blocked, due to infection or inflammation, for example, a thick discharge will collect in the corner of the eye. Tear ducts can also be obstructed due to a genetic abnormality. Your veterinarian can insert a tube into the duct and flush it with saline solution. Your horse may need to have her tear ducts flushed periodically.
Squamous Cell Carcinoma
Squamous cell carcinoma is the most common form of eye cancer in horses. This cancer most often forms in horses older than 11 years old and is usually caused by exposure to the sun. Squamous cell carcinoma looks like a growth on or around the eye. Treatment depends on the size and location of the tumor and may include surgery to remove the tumor and chemotherapy.