I appreciate Tim's points, but lions don't always kill their prey quickly either. There are many documented cases (and web videos) showing them slowly eating warthogs, water buffalo, baby elephants, and other animals while still alive. For one graphic example see:
It's also disturbing (to me at least) to hear some of the people you can hear in the background who are laughing and cracking jokes during the gruesome episode. But Tim is right that hyenas and other animals routinely devour their prey while still alive. Sometimes they rip them apart without even eating them, like Killer Whales who toss seals around in their mouths, slap them with their tails, and then sometimes just abandon them. Some try to argue that there are adaptive reasons for these behaviors, since the unpleasant alternative is that animals sometimes just enjoy tormenting and killing other animals. But of course we know that that is the sad fact even with some humans.
The reason I bring all this up is that I think an effective but seldom used argument against the existence God, or at least an "all-loving" God, is animal suffering. By all evidence, if God exists, he doesn't give a damn about animals. The Bible itself is filled with examples of God having no apparent regard for them, or even ordering their suffering and death. These include Noah's Flood which drowned millions of animals, countless animal sacrifices, plagues that killed whole populations of animals and people, and God's ordering the ham-hocking (a form of torture) horses while the Israelites were slaughtering their neighbors (also on God's orders). Moreover, I don't think there is a single Bible verse that depicts God showing any sympathy for the suffering of animals. There is a passage that says God knows about every sparrow falling to the ground. But how is that any comfort, if he knows about it, but doesn't care? Some apologists try to excuse
God suffering by saying it will be made up for in heaven. But this doesn't apply to animals (since even most Christians don't think they have souls or go to heaven), and is lame even as applied to humans. It's like saying it's OK if a parent abuses a child for years, as long as the child has a good life from then on. Nor do any of the other arguments for human suffering (like free will, or the consequence of sin), make any sense as applied to animals.
Many YECs try to rationalize animal suffering by claiming the "original creation" had no suffering or death, since "death" came after "The Fall." (They seem unable to accept the term "death" as spiritual here, even tho it is often used that way in many parts of the Bible). But the idea that all animals were vegetarians and immortal is absurd from several standpoints. Many animals are clearly predators, while others clearly have adaptations to fend off or elude predators. Furthermore, without physical death, unchecked reproduction would soon create exponentially exploding populations, turning the "good" creation into a veritable Hell on earth. In my article at http://paleo.cc/c... (intended mainly for Christian and YEC readers) I explain still other reasons why the "no physical death before the Fall" claim makes no sense scientifically or theologically. But many YECs continue to make the claim, seemingly oblivious to the problems.
I recall C.S. Lewis writing in one of his books that while physical pain can be very unpleasant, it is a necessary part of life. After all, he wrote (I am paraphrasing, since I don't recall his exact words), God had to have an effective way to warm us of dangers, and if people and animals had say, flashing lights on their bodies when injured, that would look silly. To which one of his critics replied, "Yeah, and they look lovely now, wreathing in agony."
The following is a good article on this subject. At first I thought it would turn out to be another Christian article making excuses, but the author ends up concluding that animal suffering is indeed hard to reconcile with a merciful God.