Hello!
A suggestion about the type of muzzle to get if you decide you really need one for your yorkie. Since you are going to be using it while he's on walks and it will be on while he is active you may want to get a basket muzzle instead of the one previously posted. A basket muzzle will allow him to pant and breath comfortably. They come in plastic or wire and since they are "open" they also allow the dog to drink water.
Italian Basket Dog Muzzle Size 1 There is also a fabric type of "basket" muzzle that allows them to breath and pant, but not drink water.
ProGuard Tuffie Dog Muzzles