Any of you ever use Tuf Foot? Just had a neighbor ask what she should do about her dog that injured her paws when walking on her sundeck today. The skin has peeled off on one of the dogs's pads, and the other pads are a little damaged as well. Dog is limping a little. I said I had a bottle of Tuf-Foot that I could let her borrow. But she's worried about the "potency." I looked at my bottle and there is no expiration date. I bought it about four years ago.