Thanks for all the replies. We are still up in the air. I could never have imagined that we would have such problems leaving.

We have driven from Wiesbaden (Frankfurt area) to Carlazzo and area (Lake Como / Lake Lugarno) and back some years ago now. It is not a difficult drive (4 - 5 hrs?), although you may be stopped at the border if you go via Switzerland or have to drive through slowly. We were stopped once on the way. We didn't find it anything to be worried about, it's just pro forma. However, you may be asked questions about your dog, although I can't speak to this as I've never done it myself. I did find this, though:

http://www.pettravel.com/immigration/Switzerland.cfm

I don't know how much of this will be important for you. Perhaps you could contact them and ask further.

We stopped in Luzern on the way down and on the way back we drove through Switzerland and Liechtenstein, where we had lunch, and then via Bregenz and Lake Constance. Neither route made much difference to the time. You can certainly do it in a day from northern Italy, not sure how much your area adds on to the trip. You could go via Austria if you are a bit nervous about getting stopped in Switzerland. However, I heard they are now deploying soldiers at the border between Austria and Italy as of July to stop the immigrants (Brenner Pass / Brennero), so there may be some controls still. I doubt they are worried about dogs, they wouldn't be looking for you and I think you would be quite OK there.

http://www.pettravel.com/immigration/austria.cfm

It would be a nice drive, either way. If you go via Austria you have the Dolomites in Italy (beautiful). If you go via Switzerland of course you have all the mountain views, and you could stop for the night in the Black Forest. Good luck and I hope you have found a solution!

Lavandula

A reasonably easy way would be as follows:
1. Train from Florence to Verona. For example, Italo has a train leaving at 20.54 arriving at 22.23
2. Night train from Verona to Munich - leaves 22.52 and arrives 8.19. You can book a 2 bedded cabin. There are showers at Munich station.
3. Direct train from Munich to Frankfurt airport. First connection leaves Munich at 8.52 arriving at Frankfurt airport at 12.22

Thank you so much for the train info. Everything we found on line contained bus transfers. Not logistically feasible, nor physically pleasant. I will look into this further.