I ordered this vest for our newly adopted 65lb Weimaraner. She has been somewhat tough to fit in Ruffwear, sometimes a medium, sometimes a large. She is very petite, but has a very deep chest, 31”. I ordered the vest in large, but it was too big. I’m exchanging for medium - it is typical exceptional Ruffwear quality and super cute. Can’t wait to get the medium so she can wear this winter as solo piece or layer under the puffer vest.