"Very few people question that it is an act of kindness to put an animal painlessly to death if it is injured beyond possibility of a pain-free future; or that it is better to neuter pets than to allow thousands of unwanted litters to be born. But mention it might be better for a breeding sow in a farrowing crate if she had never been born, and you will be met with chants of "Any life is better than no life". Humans have an odd way of finding pleasure in activities that bring them pleasure, or profit, or both." Bronwen Humphries
A Slow Loris
Animal Rights FAQ
The End of Suffering?
The Post-Darwinian Transition
Reasons to be Vegetarian (video)