I have a couple of Louis Dog dresses, one worn once, one never. The sizing didn't work for Lady. Lady has a 14.5" chest and is 10.5" long. I got a medium, but they run small IMO. They are a bit too short and snug for my taste. A friend with a Yorkie slightly larger than Lady tried a couple Louis Dog in a large and said they were just
huge.
I don't know if it was just these two dresses, but these are the ones that I have that run small. I love, love the mint one and she's never worn it.
I got them from Ritzy Rover and didn't send them back because they charge a restocking fee plus I'd lose the shipping costs. It wasn't worth it.
Maybe someday I'll have a dog they fit.