I have to say it is not first choice behavior with a sheltie, seems like they are much more food motivated from get go or at least that is what I have observed with mine. I have made all kinds of mistakes teaching my dogs to play and tug but we are slowly up and going in right direction, I have honest to goodness tugging sessions and chase games, they fast becoming our favorites. I also like it because I have struggled to keep my boys at healthy weight due to all that training we do. Che now at healthy weight but more struggles with Leo as he is small so there is only so much food that can be spared for training/ they practically get to lick their bowls as meals, everything else goes into training/ http://susangarrettdogagility.com/2012/04/improve-your-dog-training-by-playing-like-a-dog/ so do you tug? and why or why not? and if you do what toy you had best success with?