Our little Jack is a rescue mutt, got him last November and just love the little bugger. He's some kind of terrier mix. He actually looks like a Scotty/ Schnauzer mix. Tho he acts a lot like a jack russell.
All I know is that he's one fab little dude. He was a stray, and I can't imagine how anyone would either dump him (happens alot here in Phoenix) or not come looking for him once he went missing.
He has his faults, like systematically eating our family room sofa, and eating the chamois out of expensive bike shorts, but we love him nonetheless.
In fact he loves other dogs, so we are considering taking him down to the shelter to pick up a brother or sister.