[FistfulOAwesome]

Alright. I'm just going to try to write down why people care about dogs.

Dogs have throughout history and many cultures have served as protectors and friends to people. From early on, people trained dogs to be alarm systems, fellow hunters, and even let the kids play with them. Few other animal (types) have served as useful and diverse a purpose to humans than dogs (except livestock, but it's hard to prescribe a unique importance to something we know we're going to eat (thus my earlier comment about not caring about chickens)). Of course, in the modern world, dogs have lost their importance. We no longer need them to serve as an alarm or to join in the daily hunt, thus their only left over purpose is as friends (usually to kids, though there are certainly plenty of adults with pet dogs). In some areas this has left dogs to be seen as rats (is Dimnos right about the "dogs are rats in Mexico" thing? (also, certain East Asian countries (I won't name names) famously eat them))), simply because they don't hold the same purpose they used to. Still, the amount of care they still receive in many countries (in America, it's a sort-of cliche to mention that you would garner more sympathy from a movie audience if you showed a dog limping across a battlefield over a human doing so) certainly speaks to how ingrained their prior importance still is.

What does this have to do with Fry's dog? To imply that one of the reasons people care so much about that episode (or at least find it sad) is because (in America at least) how much dogs still matter (again, try to remember that Futurama is an American show, and thus primarily made for an American audience). People cared about that little dog because people (Americans anyway (and generally)) care about dogs (also all the other reasons I outlined in my third post).

I don't really have much more to add than that.