what size would best fit a 20lbs bosten terrier ?
SHERRY A I used the size chart and measured my standard poodle she weighs 50lb. I bought her the large and it fits her perfectly. Couldn't be happier with the jacket.
JOE F I would guess an "Extra Small? but all you really need to do is measure his/her girth at the chest. The Ruff Wear size guide is accurate and the clip fasteners on each side offer a wide range of adjustment.