Entire flock of 10 chickens sneezing and coughing

[rbcarroll]

I'm new to chicken keeping, I've had my birds for about 10 months. I have one black Australorp rooster and 9 barnyard mix hens. Everyone has been in perfect health all their lives.
Last night one hen sneezed a couple times but everyone was eating, pooping, laying eggs, so I was thinking maybe she had gotten into a patch of something that didn't agree with her (they alternate between being in their run/coop and free roaming my property, and yesterday they were out roaming) .
This morning every single one is sneezing. No puffy eyes no nasal discharge, they are running around and eating but they are all sneezing intermittently. Is there anything that can be done for them? I am so scared I'm about to lose my whole flock. I've just done nutridrench in their water. Thanks in advance.

 

[Eggcessive]

Welcome to BYC. Can you spend some more time with them today, and watch if the same chickens are sneezing every few minutes, and not eating feed at that time? How is your coop ventilation? There is a milder respiratory disease, infectious bronchitis virus, that can cause sneezing and mild congestion every few minutes. It lasts about a month, and most grown chickens recover, while being carriers for 5 months. It spreads through the whole flock over weeks to months. Antibiotics do not help. It does affect younger chickens more severely, and may cause reproductive or kidney issues later on in some chickens. If any do develop bubbles or foam in an eye or increased symptoms, that could be MG, and antibiotics then might be effective.

 

[rbcarroll]

I took out a plate of scrambled eggs and rice for them and verified they every single chicken ate some of it. There was a lot of random sneezing and coughing but it didn't seem to interfere with their eating.
The ventilation in their nighttime coop is probably not the best, it has hardware cloth windows on every side but they are small. I used to let them sleep in their "run" because they like to roost on some high spots in there but I got worried that it wasn't warm enough once our weather turned here and have been putting them into a smaller, house-like coop at night that's insulated. Then they come back out first thing in the morning. They've been spending nights in that smaller coop since December.

 

[dawg53]

Ammonia fumes from soiled bedding and improper ventilation will cause the symptoms you're seeing in your birds

 

[rbcarroll]

Ammonia fumes from soiled bedding and improper ventilation will cause the symptoms you're seeing in your birds

Hmm, i change it out pretty frequently but I guess it's possible! Is it likely that it would affect them all at the same time like that? I'm going to do some reconstructing of their space immediately.