MiL used to wring the necks of chickens on the family farm when she was young. It was a functional chore to get food in a poor country. The chickens has a good life, a quick end and served a practical function. They were respected as living creatures and there was no gratutious pleasure in causing them harm.
I once aquired a brace of pheasants. The deed was done anyway so I accepted the offer and the chance of free, good quality food. I filleted them and thanked them for their life. Not that the thanks made a difference to them, but it was a mark of respect to them as creatures. They were bred and raised in the local woods for the hunting. Not my scene, but I put the situation to practical use.
When I ended the life of a wounded pigeon in the garden, I felt pretty rotten about it. It had broken a wing after flying into a window, it was stuck on the ground for days, showing distressed behaviour, and being attacked by other pigeons. It was not having a happy, healthy life and would inevitably be a victim to a cat or fox at some point in the future. It was a deed I did out of respect to the creature's life and future suffering, but an act that I derived no pleasure from doing, but did because I felt that there was some moral value to it.
The issue with the hamster thread was that the boy's actions and emotional response to the situation didn't seem to consider the hamster as a living creature, nor the relationship of the hamster as a loved pet. He also had history of aggression.
There is variation in people's moral values towards animals, but generally in British society it's accepted to some extent that some species are farmed for food (although some don't partake), some are raised as pets and you don't hurt animals without a practical benefit (e.g. food, easing suffering)