Gosh he is cute!! It looks like he has grown into his ears! He still looks very beagle to me. If I were to guess another breed I'd say whippet (can also be brindle) over boston terrier since he has a thinner build than either a beagle or a boston...but I don't really see whippet either....except I just found this one who is that mix that looks a lot like him http://dogfriendly.com/server/genera...ages/00174.jpg Whatever he is he is one adorable pup!