The whole issue of animals killing for sport (or fun) has been studied extensively, especially in apex predators such as wolves. The general consensus of research is that surplus killing is rare and the result of an opportunity that presented itself at that specific time. Research has also shown that surplus killing led to higher numbers of prey being cached.
Domesticated prey may present easier pickings than wild prey, especially if confined, as in a chicken coop.
Well, my wife’s fat cat regularly tortures squirrels, birds, and even a tortoise one time. Takes a half day to finish off whatever it chose to “play” with that day.
He’s a killer and just enjoys the “sport” of it.