Will Falconer, DVM Moderator
Hey Rachelle,
I'd give both of your dogs the preventative remedy if only one will be potentially exposed, but come back home to the older guy.
The Chicago round lasted from about March till mid-summer of 2015, if my memory serves me. The hysteria? Ha! Anybody's guess.
You should be fine as long as you bring your remedies and avoid the fear mongers.