Equine recurrent uveitis, sometimes known as moon blindness, is a disease of the horse's eye that can be caused by many different things -- bacteria, virus, parasites, or trauma.
Signs that an eye is in distress include redness, swelling, pus, pupil constriction in the dark, cloudiness, squinting, and photophobia. Uveitis is often diagnosed as something far less serious and valuable treatment time is lost. If not treated aggressively from the onset, there is less chance of saving sight in one or both eyes. Unfortunately, even with very aggressive treatment, some eyes cannot be saved, but in other cases the disease can be halted or at least slowed down.
When the uveitis first starts, if the original cause can be determined then additional treatment may be used depending on the cause. The usual short term treatment includes atropine to dilate the eye, followed by either a steroid or antibiotic. Treatment must be prescribed by a veterinarian because if a steroid is used when the eye is ulcerated, blindness can result. Bute, banamine or aspirin are used as anti-inflammatory agents along with the other medications.
After the original episode has been successfully treated, the inflammation and signs will disappear and the eye may appear to be normal or almost normal. At sometime in the future, if it is recurrent uveitis, a set of circumstances will cause the eye to have another episode. The circumstances can be internal; external such as wind, dust, pollen; stress of any kind; or due to stopping the anti-inflammatory medicine prematurely. With recurrent uveitis, the episodes continue to occur. Each one lasts a little
longer and each time the eye loses a little more sight.
Long term maintenance treatment will often include aspirin, bute or banamine on a regular basis in an attempt to keep the inflammation from starting. Many horses wear fly masks to cut down on thy light and owners are also using dietary supplements to help build up the horse.
Signs
Signs that an episode is beginning can be varied. Uveitis unfortunately is often misdiagnosed as something less severe or in some cases it is totally ignored. It is important that uveitis be diagnosed correctly because lack of or incorrect treatment can have serious consequences.
Equine recurrent uveitis is very painful to the horse. The most common signs are puffy, watering eyes, squinting, and red blood vessels at the sides of the eye and in the lids. Horses will often be photophobic (very sensitive to the sun and often to any light) In some eyes you can notice a white cloudiness or a blue or green tint. Another major sign to look for is a pupil that is constricted when the horse is in the barn or a darkened stall. A constricted pupil indicates that it is in spasm, and is very painful. Immediate treatment is needed to alleviate the spasm.
Other signs may include head shaking, a runny nose, white spots or bleeding in the eye, matter or pus collecting, loss of balance, tripping, running into things or rubbing the eye. In some cases if you look across the surface of the eye you may even see ulcers. They look like little declivities, but usually you will need to stain the eye to see them and the untrained eye can still miss them.
If signs persist even with treatment, you or your veterinarian may want to consult a veterinary ophthalmologist since this disease can lead to blindness in one or both eyes if not treated aggressively.
Author: ©1996 Mary G. Nelson
Click here for her complete article on ERU