all the research I can find indicates there is not sufficient evidence to conclude that non-human animals understand personal mortality, so given the choice, the pig would even understand.
I would think the cases of non-human animals committing suicide (mostly cetaceans) would be indicative that at least some of them can comprehend personal mortality on some level. It’s a bit different if an animal doesn’t eat due to stress or whatever and starves to death, I wouldn’t call that suicide. But whales occasionally just drown themselves, that’s pretty hard to rationalize any other way
Nothing concrete of course, because it’s very difficult to study at a stage where we cannot communicate or directly observe the emotional states of animals, nor ethically design a study where one attempts to cause animals enough distress to engage in self harm or bring about their deaths (and simultaneously prove that was their intent).
It’s in no way a concluded topic, but it doesn’t make sense to reject outright either - and I definitely think there is enough evidence around for animals understanding of their peers mortality, why start with the assumption that they have an inability to recognize their own mortality in the first place? It’s good to be skeptical, but unproven anthropomorphism is just as illogical as the opposite assumption.
i am open to evidence, but I do not have enough evidence now to support the belief that nonhuman animals understand personal mortality, so I do not believe that they do.