Verbum Ipsum has a post about the theological basis for the humane treatment of animals. He says that nature exists only as part of God's plan--to further His Kingdom. He says that the animal-human kingdom in Genesis is essentially a peaceable one in which mankind's role mirrors that of the Creator as beneficent caretaker of animals. There are those Christians, he says, that even go so far as vegetarianism as part of this ideal, although the blog author says the most important reaction to this theology is the humane treatment of animals while they are alive.
I think this Christian view of the man-animal relationship is one that is very needed in our world today. The Conservative Blog for Peace calls this article's point of view "crunchy granola conservatism". It *does* exist! One doesn't have to be a political liberal or non-Christian to care about animals. Look at the beautiful example we Catholics have in St. Francis of Assisi who called the animals and natural elements his brothers and sisters.