Our 8 month old lab mix Tom gets really excited sometimes when he's running around outside and he'll jump up at us and bite at our shoes and ankles. We are working on the jumping, and so far it is going well, but we aren't sure what to do about the biting at the feet. We are using the turn around and ignore method, which makes him stop jumping right away, but then he comes over and knaws on our feet. Any suggestions as how to get him to stop? He has already ruined a pair of boots.