Bruce rescued the dog from Hugo Strange's lab but strangely enough the dog didn't have a scratch on him after all the treatment, it's collar remained but it's eyes glowed bright red.

It immediately grew fond of Bruce following and listening to him most likely mistaking him for his actual owner and displaying abilities that should've been impossible for human being let alone animal. 

Bruce spent days trying to figure out it's origin and how to translate the name on the collar.. By the next time you showed up at the manor he finally cracked cracked it.

When you looked down at the translation puzzled by the name he surprised and horrified you by showing the dogs invulnerability by using a weapon on it. The dog barely noticed like it was the light touch. " He's like a Canine of Steel!"