Rooster inflated with air like a balloon

[Kaisahr]

I saw him grow huge over the last few days and since he's only a few months old but i thought nothing of the fast growth as they are all growing quickly now. But i picked him up and felt the underside of his belly was filled with air, you can poke his skin and it would take quite the distance to actually touch his meat that's how much his skin was separated from his meat with all the air. Imagine poking a hole in a chicken and filling it with an air compressor, that's how much air was in there. This was one that was already marked for culling so i won't be doing anything to remedy this but what is this? After culling him i poked a hole on his skin and air just came blowing out.

Also noticed he would open his mouth randomly as if he was suffocating, do i need to worry about other chickens?

 

[Wyorp Rock]

Sounds like a ruptured air sac/subcutaneous emphysema.

Often releasing the air by sterilizing the skin, then inserting a sterile needle or syringe into the skin will resolve the problem.