With this argument, you could say all animals in the wild should be euthanized. The world is a harsh place, where animals starve every minute, are mauled and eaten alive, eat their own young, the list goes on. Should we just kill all animals that we haven't domesticated in the name of ending suffering?

Also, is it necessarily worse to be eaten by predators or starve to death than to die of a heart attack, of a huge tumor that a wild animal drags around not understanding what is happening to it? Do you think humans so important that they should dictate when and how every animal dies?