look like somebody just shot your dog. To appear to be devastated: shocked, stunned, angry and sad all at once.

So what exactly is being said here, how can we understand the precise meaning of the simile? The news would be stunning, but not (quite) in the same category that word that someone has murdered one of your children would be. I suppose that this might depend upon whether one has children or not. Regardless, it seems like distinctly more distrressing news than that of your car being stolen and totalled. Depending perhaps on whether you have children, own a dog, or not.

My observation is that the simile tends to be used a bit hyperbolically. For example when high-level negotiations broke down…yet again, “A Capitol Hill aide described Sen. Majority Leader Harry Reid's demeanor upon returning from the White House: ‘He looked like someone shot his dog.’” Actually, Harry Reid always has that look.