Unknown condition - Mare has red around right eye
I have a 13 yr old Thoroughbred mare that was given to me some months ago when I purchased her filly. She has an inflamed area around the right eye which she has had since at least the beginning of last year according to her medical records. She has been placed on antibiotics with no change in the condition.
The eye doesn't seem to bother her at all and her vision does not seem to be affected, however I am curious as to what could be causing this condition. It does not seem to be a growth of any kind but more like simple inflammation yet it does not go away. The eye itself is clear and healthy looking, it is only the tender skin around the eye which is red.
Your suggestions would be greatly appreciated.