My Jack can be very stubborn

. Thats just the way Yorkies are from what I've heard. Our lab/cow dog mix chases cows and Jack picked that up from her. We keep her on a zip line now, but Jack still chases the cows. I am so scared he's going to get hurt. When he did it last night I kept yelling his name for him to come back but he wouldn't come. He knows his name too, he's just very stubborn at times. He's still my baby though. Just normal behaviour I guess.