I would only give a prescribed amount of
antibiotics. So, I would not recommend that, in the event that you do find
antibiotics, give it to them randomly. Just keep cleaning their little noses to make it easier for them to breathe. Provide warm places and clean the area where they roam as frequently as you can. I am always spraying disinfectants in the house, opening windows and doors, and keeping the house clean to try to minimize the effects. But yours are barn kitties.