In nature most animals do not die of old age or sickness. In fact, dying of old age or sickness is the most horrifying and prolonged death possible for any life form. It's torture. Being hunted and dead in the span of hours, or even minutes is far more "humane" (I hate the etymology of this word).
Preserving an animal's life artificially until it's so old it dies from its age is what is actually unnatural (also see the original point 3). So the focus should not be on extending an animal's life length, but improving those animals' life quality.
And actually if you would replace "animal" with "human" in anything I say, it still applies. This is how you know I'm not discriminating against an animal's life. Which would be pure ignorance.
Preserving an animal's life artificially until it's so old it dies from its age is what is actually unnatural (also see the original point 3). So the focus should not be on extending an animal's life length, but improving those animals' life quality.
And actually if you would replace "animal" with "human" in anything I say, it still applies. This is how you know I'm not discriminating against an animal's life. Which would be pure ignorance.