DC Comics Pet Costume, Small, Supergirl

I have a chi mix & weighs about 10lbs & i measured her chest and it was 15 and neck to tail was 13..should i get the small one? i usually buy medium

What size would best fit a 45 lb dog?

I ordered the costume but it was too big, I just reordered it and neede to make sure the correct size was sent. I need it in a medium not x-large

What size would be the best fit for a Mini Doberman Pinscher?