Help with respiratory problem!

[BrickCoop15]

I need treatment advice for a respiratory problem in my flock of chickens. I have a flock of 22 hens and 4 are sick with some type of respiratory issue. It started with one hen back in July and I just recently noticed similar symptoms in three others. The main symptom they have is a congested sound in their breathing. I can hear it when I hold them to my ear. One sneezes ocassionally without any nasal discharge. I don't know what I am dealing with or how to best treat it. If it is a respiratory disease would it take months for it to go through the flock? Could it be a fungal infection? Any advice on what I am dealing with or treatments would be appreciated. Thanks!

 

[ChickenCanoe]

It could be bacterial, viral, fungal, protozoal, environmental or nutritional. So without a real diagnosis, there's no way to tell how to treat. Some can take a long time to move through a flock. Many people jump the gun and use antibiotics. I don't recommend that.
What state are you in?
The most definitive option is to sacrifice a bird, sending it to the state poultry lab.
https://www.aphis.usda.gov/animal_health/nahln/downloads/all_nahln_lab_list.pdf

In the meantime, the best you can do is clean the coop and improve ventilation.