Even in the wild, there seems to be a mutual respect among predator and prey. Animals tend to only kill what they need and do so a quickly and “humanely” as possible. But the Hyena does not play by this rule.
Hyenas are extremely dangerous wild animals. They aren’t afraid of anything, hunt in gangs, and do what they need to survive.
They also sometimes eat their prey alive…
Hyenas are not built to kill with a bite to the throat like a lion, for example. They hunt by chasing their prey until it is exhausted, then pulling it down and disembowelling it. They need to eat as much as they can while they can – if one hesitates, its companions may eat its share, or other predators, like lions, may steal the kill. They therefore begin to eat as soon as they catch their victim.
It also decreases the chances of more powerful predators such as lions forcing them to abandon the kill before they have taken what they need. Also, they lack the power big cats do to throttle their prey in the same way, so it is more beneficial for them to use their powerful jaws to disembowel their prey instead. It’s all to do with efficiency.
It’s worth noting that the prey will rapidly go into shock, which prevents it feeling the worst of the pain, and also that disembowelling can actually lead to a quicker death than the suffocation method employed by big cats. You also cannot judge animals by human standards of morality. Hyenas do what they do because they are trying to survive, not because they are trying to be cruel. Only humans are deliberately cruel for no reason.