Pink Eye in Horses

Vladimir Negron
Nov 02, 2011
4 min read
Image: Photo Grapher / via Image Bank

Conjunctivitis in Horses

Much like humans, horses can contract conjunctivitis (inflammation of the conjunctiva which is a part of the eye), also known as pink eye. It may be due to several factors such as a dusty environment, an illness, or a viral or bacterial organism infecting the eye. Depending on the cause, it can be also highly infectious.

Conjunctivitis is normally associated with a clear or yellow/white discharge in the eye. It may or may not contain mucus. At the same time, itching and irritation are also clear signs of the beginnings of conjunctivitis and these symptoms may appear before others symptoms arrive.

Symptoms

  • Redness of the eye
  • Discharge (clear, yellow, or with mucus)
  • Irritated eyelids
  • Swollen eyelids
  • Closed eyelids or squinting
  • Adverse reaction to bright light
  • Adverse reaction to dust
  • Rubbing the eyes or shaking the head

Causes

  • Infection of the conjunctiva
  • Inflammation of the uvea (uveitis)
  • Numerous organisms responsible for infection – may be of viral (herpesvirus) or bacterial origin
  • Secondary infection to an underlying illness
  • Result of damage or trauma to eye
  • Lack of or insufficient tear production
  • Abnormally shaped eyelid
  • Face flies (bacterial transmitters)
  • Environmental irritants (i.e., dust, heat, dryness, pollen, other allergies)

Diagnosis

A simple examination of the eye is often enough for a veterinarian to make an initial diagnosis of pink eye in the horse, since the symptoms are outwardly obvious. Following that, your doctor will perform a thorough physical and ophthalmological exam on your horse, taking into account the background history of symptoms and possible incidents that might have led to this condition.

Some of the tests that may be used in the diagnostic process are cultures of the discharge that is seeping from the eye, tissue scrapings, and fluorescein stain, a technique that uses a non-invasive dye, which illuminates portions of the surface of the eyeball that have been injured due to abrasions or the presence of foreign objects.

Treatment

To protect the eye from further infection, your veterinarian will probably prescribe an antibiotic ointment or drops that can be applied to the eye and surrounding lids. Most topical medications such as these must be applied to the infected eye 2-3 times a day.

Specific care will depend on the results of the laboratory tests. If a foreign material is found to be the cause, the eye will be cleansed thoroughly and ointments and drops applied to encourage healing and prevent infection. An anti-inflammatory medication may also be given to decrease swelling and inflamed tissue, as well as to treat discomfort.

Your veterinarian will advise you in cleaning techniques for your horse's eye(s). A gentle saline solution is usually mixed and used one or more times daily throughout the length of treatment, and the eyes protected from dust, harsh light, and flies. Your horse's sleeping space should be kept especially clean, and flies kept to a minimum — as much as that is possible.

To protect your horse's eyes further from irritating flies (which can also conduct bacteria into the eyes), use a fly mask to prevent the flies from gaining access to any part of your horse's face. Placing a fan in the stall can also help discourage the accumulation of flies.

After a period of time, the symptoms for pink eye should clear up and vision should return to normal.

Living and Management

It is important to keep in mind that symptoms of pink eye will often become less apparent, with the horse showing all indication of being healed of the infection before the infection has been fully eradicated from the body. It is therefore important that any antibiotics that have been prescribed are used in their entirety for the length of time that they have been prescribed. Often, when a medication is not used in its entirety, the infection will recur, sometimes more severely than before.

Usually, an uncomplicated case of conjunctivitis will not affect the horse’s vision but will make it sensitive to light. If possible, keeping your horse away from brightly lit areas during convalescence will help reduce squinting and tearing of the affected eye. It is important to monitor the eye very closely during its time of healing. If the horse accidentally bumps or scratches the diseased eye, it can make the irritation worse and even introduce more infection. Complications of conjunctivitis include corneal ulceration and even a corneal abscess. However, most cases of conjunctivitis heal quickly with minimal complications.

Some horses seem prone to pink eye and it may be a seasonal problem for some horses, especially those with other allergy problems or sensitivities. If this is the case with your horse, keeping an extra tube of antibiotic ophthalmic ointment on hand is a good idea.

Prevention

Keeping your horse in a clean, well-ventilated area is the best prevention against pink eye and many other conditions. Additionally, since some causes of this eye disease are infectious, if your horse is boarded at a barn with many other horses, it is always a good practice to not share items such as grooming equipment and feeding buckets, especially if other horses have just returned from a show or other social outing.

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