It depends on if it is croup caused by a virus or allergies. I think I would keep them home, though. Beyond not wanting to spread it, I think they probably would feel better at home in their jammies, with mommy there, and able to just lay on the couch and stuff.
If the temp is gone and overall feeling better other than the cough than send him because the cough lingers for a few weeks. My dd gets it and was hospitalized for it last September. It is nothing to mess with.
Re: ? about Croup