We use them for Romi with the corns. Measure very carefully, so you get the right size. It's also a good idea to keep her nails on the short side.
Practice inside with them before you have her wear them outside - they take some getting used to.
They are pretty much the best boot I've come across, however if corns aren't your issue, there are some others that are pretty impressive, I'll go see if I can find the link for them.
Ha, found it. One of the dogs in our playgroup has these, and they make a lot of sense to me, especially if you aren't dealing with corns:
Blizzard boots