What is he mixed with?

This is Eddie, my ten month old wild child. The humane society said he was a rat terrier mix but I’m so curious as to what he could be mixed with. I see some blue heeler in his spots and his stance, and maybe even some hound in his body shape. He’s literally all legs, weighs about 27 pounds. He is the smartest dog I have ever owned, and his energy level is off the charts. Does anyone else have a pup that looks similar?