Clear runny nose, no other symptoms

[Seiryu]

I have 3 blue wheaten ameraucana's that have constant runny noses. I took them to the vet and had them treated for respiratory infections. They're happy chickens, pecking and eating and active. They just have clear runny noses. The vet doesn't know and I'm hoping someone here will have some idea. They have spread the runny nose to other chickens but it's just that. A runny nose.

 

[Eggcessive]

Infectious bronchitis is the most common respiratory disease in chickens. It is caused by a virus, and symptoms are clear nasal drainage and sneezing. It tends to spread rapidly throughout the flock over weeks or months. All chickens in the flock remain carriers for up to a year after the last chicken reccovers, so it is best to not hatch or add birds to your flock for at least that long. As with all respiratory diseases, IB can be complicated by secondary infections making a milder disease much worse. You may be able to get testing done on a few birds locally by your county extension agent. Here is a link about common diseases, and IB is described there:
http://edis.ifas.ufl.edu/ps044

 

[Seiryu]

How contagious is IB? I have 10 other chickens that are seperate from these chickens but they can see them through fencing. Recently thesw seperate chickens have gotten upper respiratory infections. But their symptoms are different from the blue wheatens. They gurgle and have runny noses and sneeze. The vet had me treat them the same as the others with oxytetracyline. Could these blue wheatens have spread this?