Marans getting sick

[FarmalI]

Are some bird breeds more susceptible to having respiratory issues?

 

[micstrachan]

Not that I am aware of, but others here will know more about that.
If you have a problem with some of your birds, there’s a great questionaire called something like “Please Read First” up above. Answering as many questions as you can will give us a lot of information to help you. Good luck.