We got a size S for Luna (6.8 lbs Chihuahua mix terrier) and we tried dressing her up like Bao hahahahaha!!! Luna has a baby face and shorter front legs - I think she can't carry this jacket just like Bao did LOL. She looks like a baby girl stealing her mom's clothes hahaha but we still love it a lot. It's very chic and thick, very good quality and perfect for winter!