I hate to burst anyone's bubble, but the chances of somebody having an unspayed/unneutered pair of those dogs and not taking care of the puppies themselves is REALLY small. Chinooks are so rare that most people have never even heard of them--I live in NH and have never seen one in real life; there's not a large population period, much less a large population of carelessly bred ones. And Malinois are the same--when your dog was born, there were maybe a thousand? Maybe two thousand? Malinois registered across the entire US. These are breeds that just don't contribute to the homeless dog population with any regularity.
Shepherds, labs, border collies, poodles, of course pit bulls by the thousands, hounds, the more common terriers, and the failed sales of the purebred and designer dogs bred by bad breeders--these are what end up breeding together to create the dogs found in shelters.
He's a very, very handsome shepherd mix, maybe shepherd/lab or similar. The masking gene is dominant, so a shepherd/yellow lab mix gets a mask.
There are lots of shepherds and Labs that are tall and skinny like that: I grew up with no-brand Shepherds and Labs and plenty were very narrow in the head and body. Like this guy:http://upload.wikimedia.org/wikipedi..._Dog_Casey.jpg
and this guy:http://www.southlandkennel.com/images/joejanuary.jpg