Don't take the pup to the store - until his immune system is fully developed, he could pick up anything in there!! If you want to wait to buy the collar, measure his neck after you get him home so that you get the right size. I've never owned a dog that small, so I couldn't begin to guess what size collar he would need. I would also buy a bag of some small training treats so that you can start training. For a shih tzu, I would also buy a good brush and a detangling comb. Don't forget shampoo unless you plan on taking him to a groomer. That's all I can think of right now. Hope that helps!
