A couple of days I got in an argument with my girlfriend while watching TV. There was an episode of Bones on where they go to investigate a dog fighting ring. I don't really find that all that sad. Here's why.
With dog fighting specifically, dogs are being made to kill each other for the entertainment of humans. When you ask people why that's wrong ... well, most of the time, people will just tell you that it's wrong, and evil, and cruel. The thinking goes that dogs are capable of cognition, and therefor causing them pain is evil. I can accept that people believe this argument, and if you do believe it then I can understand the outrage.
The problem is that most people don't that dog-fighting is wrong on any rational basis, but for two other, less defensible reasons. First, they believe it because it's a fairly common belief - you aren't supposed to question taboos. Second, they believe it because dogs are fairly easy to anthropomorphize. Dogs are sympathetic.
So here's the second part of my argument; why is it okay to kill pigs, chickens, and cows, but not dogs and cats? Here the argument about intelligence doesn't work, because there are numerous studies that show that the dumbest species of pig is smarter than the smartest species of dog. Now you might take that information and say "Well, then I'll stop eating pigs, and it will be okay," but that seems to me to be fairly arbitrary. Making random judgments about which animals are dumb enough to warrant consumption isn't really all that much better than deciding on what to eat based on how cute it is, or what other people are doing.
Now here some might protest that my argument basically boils down to "if bacon then dog-fighting", and remind me that the dogs are being killed for the entertainment of humans, rather than for food, and that a death by fighting another dog is cruel, whereas a death in the slaughterhouse is not. In the first case: we do not need to eat meat, eggs, or any other animal derived product to survive. It's actually pretty inefficient in terms of using arable land. We like to eat meat, because it tastes good. In the second case: slaughterhouses are cruel, if we're still working off the theory that animals can feel. Watch any of the million videos that PETA puts out showing slaughterhouse conditions. The difference is that the cruelty takes place on an industrial scale, and is less personal, which I don't think you can really argue is much better.
So if you've come to the conclusion that you shouldn't eat meat, or drink milk, so as not to support these horrible things, I would fully agree that that's one way to see it. I can understand and even empathize with those people who get really mad about it; it's not how I feel, but it's logical.
I believe that animals can feel things; I also believe that it doesn't matter, because they're not human. To me, nothing is more important than the human life except for other human lives. The lives of animals are meaningful only in that they further human goals, or give humans satisfaction and happiness. They can do this by being our companions, our workers, or our food.
Now I'm not saying that dog-fighting is right, I'm just saying that I view it in the same way as I would view a little kid torturing a doll. I wouldn't worry about the doll so much as the mental stability of the kid.