I am medicating my chickens for a cold that two out of five have. I was told to put the tetracyclin in the water for the chickens untill it turns yellow. My ducks are in the same coop but they are seperated. They don't have the same water or food. They are in close contact with each other and my concern is do I medicate the duck water too???? They are laying eggs and I am worried they will get the same cold the chickens have.