Sick drake duck

[Quacking ducks]

Hi, my Silver Appleyard drake duck is not doing very well. in the last couple months, I have already lost two female duck that had some of the same symptoms as what my drake duck “Ducky” has… his symptoms are runny nose and eyes ( his eyes watered enough yesterday that his face was all crusty last night) and very thirsty. By the time my other ducks were showing symptoms one died within a couple hours the other one died within a week of showing. He is still eating and drinking fine right now. Any ideas what wrong with him and what I could do to help him?

Thank you
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[Wyorp Rock]

https://www.backyardchickens.com/threads/sick-duck.1605165/