What Breed Is My Dog?

I got Zorro from a rescue. They said he was probably a German Shepherd/Husky mix.
He is about 18 months old and weighs 33lbs. The vet doesn't expect him to get any bigger. He howls very much like a Beagle and I know the black and tan coloring very often makes people think Shepherd. Any thoughts as to what mix he may be?