Musher's Secret is one of the best ones. It's also good to coat their noses with it--especially if they like "bulldozing" in snow.
Even still, if you are getting out near areas that have been salted, you need to wash their pads, nose, and mouth off when you get inside.
We're lucky in the fact that I don't have to get them near salted areas. We've got "pet safe melt" for the patio if it gets REALLY bad.