Our drake lost his quack (voice) right before Christmas. (Just so you know, I know there is a difference between a duck and drake noise and yes he has had a normal raspy, quiet quack drakes have.) He has been eating ok and drinking fine. He walks fine and active, with no drainage to the eyes and nostrils. He grooms himself and otherwise acts normal. He will make a "cough" sound every now and then, not frequently though. He opens his mouth like normal to make his quack but nothing comes out We live in Nebraska and the weather has been quite cold, especially last week with temps in the single digits at night. It has warmed a bit, not much. I put them inside a small duckhouse at night with hay, no heat lamp. They are protected and have ventilation and fresh water and fresh feed every day and are free ranging during the day. He is a Khaki Campbell and was born this past spring. I also have a Welsh Harlequin duck and she has NO symptoms and is completely healthy. Has anyone ever heard of this?