I guess it's a question of whether you believe that certain forms of life are more valuable than others. Is a cat or dog any different than a rat or mouse? Some may not see the difference. Is a mealworm any less alive than any of those? What about an ant or a germ or bacteria for that matter? It's all life right? Well yeah, it is but I think that most of us would have a harder time hitting a cat or dog with a hammer than we would have bonking a mouse and it would be easier still to step on an ant. We don't have the least bit of sympathy for the bacteria we kill with cleansers in our homes. It's all life but we instinctively place different values on different forms of life. It's not a difficult question for most of us whether we should kill a cancer to save a person. Some people would have a hard time killing mice so that their snake can live, others won't. Some of us can whack bunnies all day and may even be able to switch to kittens if we have to. I think most of us would rather kill a "lower" form of life where possible meaning we would rather kill the rat than the kitten. I think that's where people get upset, when they see a more valuable animal being used as feed it seems cruel. Of course if the things are dead in the first place...?
I feel a little light headed... maybe you should drive...