We figured it out!

Well, we've been trying to figure out what Lucas is mixed with and finally figured it out. The receptionist at the Vet thought maybe a pointer or hound. We looked up pointer/lab mix and the pictures that came up were Lucas. It explains some of the things I've noticed like his front leg lifting up and his whole body "pointing" when he is checking something out in the yard. It's still a guess, but we think it's pretty close.