hello, I have been battling some sort of infection with one of my ducks since August. She has an eye infection (her one eye has been very weepy and stained down) which I believe may be linked to a respiratory infection which her body has been fighting off. I was recommended Tylan 50, however tractor supply only had Tylan 200. Would anyone be able to provide me with information as far as dosage? The employee at tsc said I could use it and just quarter the dose. Has anyone else had experience with this? This is the injectable kind.