i dont see any harm in it, but idealy for training you want somethig small and sof that they dont have to chew, like chicken, chees hotdogs liver/livercake cut into bits about the size of you pinky nail. you dont want them spending to much time chewing or crunching
I agree with Adrienne, and our training class trainer mentioned the same. With Rufus, a great way for us to train him was with his "lunch" when he had one. So, we would feed him breakfast in his bowl as usual... but then over the course of the day, dump his cup of "lunch" portion of dry food into a little bag so we knew how much he was going to get anyway, and then give him little bits while we were making him do sits, downs, stands, etc. That way he is getting the food but it's doing double duty and training as well.