What could be causing my son's coughs to always sound croupy?

Laryngotracheomalaci. Wow - there's a big word! Laryngotracheomalacia, or ltm, is a condition where the upper windpipe area is more floppy than usual. Thus, when the child breathes or coughs, it sounds croupy. This is a condition they will eventually outgrow when the cartilage rings that strengthen the trachea develop more. There are also a few rare things that cause croupy breathing - ask your pediatrician.