The first pic makes him look like a coyote in the face.

Border Collie/Collie/Shepherd?

The coloring is what is so distracting. There's so many breeds that can have brindle coloring. We have a couple of ACD mixes in our program that are brindle, but I've never seen a brindle Heeler and it's hard to say what they are mixed with that could have caused the brindle coat.

Check out Mahon and Brenah:

www.hppl.org

Mahon probably has Chow in him, but his mom is a Heeler mix and they look just alike, except both of mom's ears stand up and her tail doesn't curl over her back.