Im thinking maybe some border collie? Shepherd seems to be a very dominant breed when mixed, kind of like a lab, it overtakes the others mixed in. But I see the narrower nose, and the ears are also a bit wide, making me believe he was mixed with a dog whose ears didnt stand up, at least not fully like a shapherds. Also some of the hair on the head looks a bit longer and silkier.

I dont know why, just see the border collie. Its a random guess.