When the eyes turn red, it is most likely that they have an inflammation ongoing. The term we would use is a "conjunctivitis," meaning simply that some irritant is present. The discharge is the horse's attempt to cleanse this irritation away and heal the eye. This type of problem may indicate an allergic reaction, or it may be infectious, caused by a virus or bacteria. The danger in these situations comes from continued irritation that may lead to corneal damage and an ulcer. Eye problems in a state like Florida are considered an emergency. Any discharge from the eye that is accompanied by pain causing the horse to keep the eye closed should be examined by a veterinarian.
