Looks like 100% ALL AMERICAN BEAGLE to me too. Our boy is a tad over 18 although we got him through the county humane society. The previous owners supposedly paid 2 grand for him and he was bred down in the south (we are in Washington state, 2000 miles away..). He has long legs just like your Bella. I wish he was as skinny though ;-) I'm very familiar with big beagles since we have one AND there are several close contenders at our local dog park, two or three of them that must be about 17 and just as long legged. Together with your Bella we just about have a Beagle Basketball team!