DO HORSES HAVE ALLERGIES? MARE HAS HAD GREEN GOO IN HER EYES FOR THE PAST TWO MORNINGS. WE BUSHHOGGED THE PASTURE JUST RECENTLY. COULD IT BE FROM THIS? NO OTHER PROBLEMS WE HAVE NOTICED.WOULD YOU CALL VET OR TRY PENICILLIN FIRST? AND IF SO, HOW LONG TO GIVE THE MEDS?