Unlike the other dwellers of the Junk Yard, the guard dog was actually built not from scrap but was a highly sophisticated security model once. Trouble is like everything else on the scrap heap, he was forgotten and left to rust. His asymmetrical appearance is actually decades of weathering.
It isn't just his outer shell which is damaged, years of neglect have led to his programming becoming corrupted. Now he is a vicious half wild creature who will allow nothing to leave the junk yard. Touch even one piece of wire and he'll attack - and trust me, his bite is much worse than his bark.
I've had this idea for a dog-bot for years and when I started brainstorming my Junk Yard theme I just thought it would make a great addition. The rusting neglected security drone back story was more to explain his uniform build but patchwork colour scheme. Unlike the rest of the designs which are all different parts for different limbs etc.
I have an idea to reverse build these into what could have been the original robot that became junk in the first place. I'll post pics if the results are decent.