I have a couple cornish pullets that I introduced to the flock that make a gurgling sound or maybe a purring sound, cant quite put my finger on what to describe it as.They are healthy as a horse apperarnce wise and actions. I hadnt heard any of my other heavy breeds doing that until today, and heard a few of the older 2.5yr old red stars doing it. kinda does sound like someone has a cold and is gurgling when they breathe, but no coughing or sneezing. Is this just a sound they make or do I need to medicate for something? if so what steps do I need to do? thank you.