My cat, like many others, is a highly efficient mouse hunter and killer. He can consume a mouse in 60 seconds. He always, or nearly always, leaves the gallbladder and the photograph shows you what it looks like: scrubbed and cleaned, licked and left behind.
The only thing that is left behind after my cat has consumed the mouse. There is no blood. The only thing that really hurts me is the sound of the mouse screaming at the moment she has been killed and the crunching of the mouse’s skull when my cat begins to eat it. It is entirely natural and it must be accepted but it is difficult and you wonder whether the human-to-cat relationship actually works sometimes.