Equine Eye Care
A horse's eyes are an important key to its well-being and should be checked at least annually by a veterinarian. It is usually recommended that geriatric horses be checked twice a year. Horses depend on their keen vision to keep them safe. Their eyes work independently of one another (monocular vision), each enabling the horse to visualize a full 350 degree field. Handlers should check their horse's eyes daily to note any changes or abnormalities that may require veterinary attention since eye problems in horses can worsen rapidly. The eyes of a healthy horse should be bright and clear with the inside of the lid pink and moist.
Equine Eye Examinations
Equine eye examinations begin with an overall evaluation not only of the horse's eyes, but of its general posture and attitude. Sometimes there is obvious damage to the eye evidenced by a cut on the eyelid, a lash turned inward, redness or swelling in the region. Pain is always an important clue to eye disease, so the doctor looks for any sign of eye discomfort, including squinting or small pupil size. Other signs of possible eye disease include:
- Excessive tearing
- Ocular discharge
- Abnormal angle of drainage
- Cloudiness of aqueous humor, lens or cornea
- Bloodshot eyes
- Tumor on the eyelids
In order to examine the horse's eyes, the veterinarian normally works in a darkened area, using a transilluminator, or slit lamp. While a horse cannot be tested for visual acuity, it is possible to evaluate the functionality of the retina, either using the dazzle response of the indirect pupillary light reflex (PLR). The "dazzle" response is a simple sudden squint of the eye in response to bright light. The PLR is appropriate pupil constriction as a reaction to bright light. Both tests are positive indicators of vision.
Equine Eye Disease
Equine eye disease, like human eye disease cover a wide range of problems. Some are mild and easily treated with medication. Some are severe and may result in blindness. In all cases, equine eye disease should be diagnosed and treated promptly by an equine veterinarian or veterinary ophthalmologist to ensure the horse's comfort and protect its vision.
- Blood in the eye hyphema)
- Conjunctivitis, bacterial or viral
- Corneal abscess, necrosis, edema, or ulcers
- Dry eyes
- Retinal or optic nerve disease
- Viral keratitis
For some of these conditions, there are simple remedies. For others, the solution is more complex or there is no cure, but only containment of symptoms.
Diagnosis of Equine Eye Disease
Apart from the straightforward eye examination with the transilluminator, veterinarians have several other diagnostic tests available if eye disease is suspected. These include the following:
- Flourescein dye to detect epithelial defects or corneal problems
- Rose Bengal stain to evaluate tear film stability
- Corneal scrapings to check for corneal ulcers
- Cellular examination for presence of bacteria or fungus
- Intraocular pressure tests for glaucoma
- Ocular ultrasound
In order to keep the horse from blinking during some diagnostic tests, temporary nerve blocks may be administered.
Treatment of Equine Eye Disease
First aid for a horse with an eye problem is to carefully clean any injury with sterile eye solution, to keep the horse in quiet, dim surroundings, and to get the animal examined as quickly as possible. Many mild infections and serious disorders may present with the same symptoms, so it is important not to dismiss any eye abnormalities without medical evaluation. In some cases, topical antibacterial or antifungal drops or ointments may be all that is necessary. In others, systemic medication may be required. If anatomical abnormalities or tumors are present, surgery may be recommended.