Also a Chow can take down a Rottie or a Dobie in no time. (The Chow I had was small for male and he could scale a 6' fence in the blink of an eye, he could also get out a full harness in the blink of an eye, even after he was shaved so that we could get the harness on him tight without the bulky fur getting the way.)
They will be able to tell how old this mystery animal was by inspecting the teeth of it. It looks young to me.