Opthamology

By September 19, 2017

Equine Ophthalmology

by Shanna Nelson DVM

Horses have the largest eyes of any land mammal, and being prey animals, they make good use of their vision to detect potential threats and navigate through their environment. Horses’ large eyes and flighty nature, unfortunately, also mean these delicate organs are prone to injury. Ophthalmic (relating to the eye) issues are nearly always considered a veterinary emergency, so it is important to recognize the signs of ocular pain so that concerns can be addressed properly.

Often times, it is not subtle when a horse’s eye hurts. He may squint and have excessive tears, or the discharge coming from the eye may be more mucoid in appearance. The tissues around the eye may be swollen, and the conjunctiva (pink tissue) may look red and inflamed. The cornea (surface of the eye) may be cloudy, bluish, or pitted. The pupil may appear smaller than normal (reflex constriction due to pain). There may be cuts and blood around the eye. If the horse cannot see, he may hold his head tilted to the side, act very spooky, run into objects, or refuse to move entirely. Any time any of these signs are noted, it is worth an immediate call to your veterinarian. Your vet may advise you to give pain medications if you have any at home (Banamine is the most effective for treating ocular pain), but it is generally not recommended to put any ointments in the eye until after examination, as some medications can make certain conditions worse.

Some of the most common ophthalmic conditions we see include eyelid lacerations, corneal ulcers, and uveitis. Lacerations are obvious–there is a cut involving the eyelid. It is important to have these examined and sutured as soon as possible, because preserving the integrity of the eyelid is important to ensuring the health of the eye (the eyelid is needed to protect the eye from sunlight, dirt, and damage). The eye itself can also be examined at the same time to make sure it is not injured.

Corneal ulcers are very common in horses, and involve a defect in the surface of the eye, when the top layers of cells is damaged. Ulcers are very prone to infection with bacteria or fungi, so starting on appropriate topical treatment is very important. Otherwise, infection can quickly take over and potentially destroy the eye. Ulcers are also very painful, so your horse will appreciate prompt treatment. Depending on the severity of the ulcer, you may just need to treat the eye with antibiotics several times per day at home, or it may be recommended to place a lavage tube under the eyelid and hospitalize the horse for ’round-the-clock intensive treatment.

Uveitis is also a relatively common condition, especially in Appaloosas and Warmbloods. Uveitis means inflammation within the eye, which can have a number of causes, ranging from genetic predisposition and sun exposure to bacterial infection, systemic disease, and more. Like corneal ulcers, uveitis is very painful, and aggressive treatment is necessary to reduce inflammation and restore normal function to the eye. Without treatment, glaucoma, retinal detachment, and blindness can result.

Other ophthalmic issues range from parasitic infection and abscesses to cancer and cataracts. All require a thorough examination to properly diagnose and treat.

Diagnostic tools for ophthalmic examination include an ophthalmoscope (a specialize handheld microscope for viewing the eye), staining strips (to look for evidence of corneal defects), tear strips (to measure tear production), tonometry instruments (to measure the pressures within the eye), and local/topical anesthesia. We offer all of these tools at Fox Creek Veterinary Hospital, and we are experienced with the diagnosis and treatment of many eye conditions. We can also place subpalpebral lavage tubes for the management of severe ulcers, and we perform enucleation surgery (removal of damaged eyes) with either standing sedation or general anesthesia at our hospital. In the event of treatment-resistant or specialized cases, we can also offer referral to a board-certified ophthalmologist for further assessment.

To schedule an ophthalmic examination, please contact our office at 636-458-6569. In the event of an after-hours eye injury, please do not hesitate to contact the doctor on call so that your horse can be evaluated on an emergency basis.