I know a little about it although I have never seen it personally. It is one of several contagious respiratory viruses and can cause gasping, “pump handle” respirations, and bloody mucus from the beak. Chickens with it can shake bloody mucus around the walls of their coop. There is no treatment since antibiotics do not treat it. It also is a reportable disease in many states. There may be less severe cases. Here is some reading about it: https://www.merckvetmanual.com/poultry/infectious-laryngotracheitis/infectious-laryngotracheitis