“Sit. Spin to the left. Spin to the right. Take steps in reverse. Put your head on my knee.” 8-pound Coby responds to each command, each trick reinforced with a training treat. A lot of practice goes into the training of the Yorkie-- lots of treats are awarded. And dog mom Mary Wu makes sure none of those bites are the canine equivalent of gummy bears or potato chips. She wants her good little boy to be a healthy boy, too. That is why she’s in the kitchen on the day we meet.