Hi. I'm just reading this thread for the first time now. I'm so sorry that you lost her but thanks for sharing the necropsy result.
What occurs to me is that you keep a duck and drake with the chickens. I would be surprised if one female will satisfy the urges of a drake, particularly at this time of year and more so if he is young and it may be that he has also been mating the hens. This can easily be the cause of her infection because chickens are not biologically compatible to be mated by drakes but sadly it happens more often than it should. You might want to consider penning the ducks separately and getting him more females to ease the strain on the one he has. It may be that this is not the cause of her infection but it is certainly very possible and worth preventing in the future.
What occurs to me is that you keep a duck and drake with the chickens. I would be surprised if one female will satisfy the urges of a drake, particularly at this time of year and more so if he is young and it may be that he has also been mating the hens. This can easily be the cause of her infection because chickens are not biologically compatible to be mated by drakes but sadly it happens more often than it should. You might want to consider penning the ducks separately and getting him more females to ease the strain on the one he has. It may be that this is not the cause of her infection but it is certainly very possible and worth preventing in the future.
