This condition is quite common in horses during the spring and summer months when flies are particularly bad.  The membranes that line the inside of the eyelids, the conjunctiva, become inflamed. This condition can also occur due to disease in other parts of the eye, corneal ulcers for example.




* The eyelids appear swollen.  In mild cases it will be noticeable on the inside of the lid.  In more severe cases the outside of the eyelid will appear swollen.
* The horse is reluctant to remain in bright light.
* Depending upon the severity, the discharge will range from mild and watery, to very thick and pus-like.  The discharge is a result of over-production of the tears, or the swelling has closed the tear duct and the tears are unable to drain away normally.  There is usually a degree of both present.
* The eyelids are reddened; the inside of the lid may become diffusely red or show an increased number of small blood vessels.  It may also affect the whites of the eye showing an increased number of small blood vessels.
* The horse may experience discomfort and mild eye pain, with the eye slightly closed. 

To check the tear duct is not blocked a fluorescent dye is placed in the eye.  If no blockage is present then the dye should appear at the bottom of the tear duct which lies just inside the nostril  - this should take approximately 20 minutes. If the vet suspects an infectious cause, or if the eye is not responding to treatment as expected, an eye swab may be taken to culture bacteria to determine the best course of treatment. It is usual for a topical treatment to be used in the first instance.  Antibiotics or steroids may be used; or a combination of the two.  Antibiotics deal with bacterial infection and the steroids are used to reduce inflammation.
A blocked tear duct will need to be flushed out with saline.  Eye drops are often used in the duct itself to help prevent it becoming inflamed and blocked again.
If possible, your horse will appreciate access to a cool, shaded stable to help ease discomfort and whilst waiting for the vet.

* Clean the eye area with a sponge twice a day.
* Take action immediately you see signs of infection, don't wait for it to develop.
* Rinse the sponge between applying it to each eye, to avoid cross infection.
* Fly masks are excellent as a preventative measure.
* Ensure shelter is available so your horse can get away from flies.
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