You can do like R2L has suggested if you are able to do so. I've thought about having pen filled with some rock just for that reason. After the dog living in the pen for about a month, and walking on the stone all the time, their paws toughen up to where they can withstand whatever type of work you're doing.

You can use Jack's product. I use Happy Jack Pad Kote as it's just easier for me to get, and it works great.