It seems Gus' regression is being examinated carefuly by doctors, which seems to have a bunch of experience on it. Judging by Gussy's daily regression, they told him that soon he'll be at the size of an infant... or just a real infant, who knows?
Harsh news for the little skunk, but there's nothing he can do, other than get a nice bath and get ready for his family visit. Maybe it's time for them to prepare the supplies for when Gus go back with them in a few weeks.