@Izzie,
Izzele, I see no reason why a cat should feel guilty about catching a mouse. Just as a lion shouldn't feel guilty for catching a wildebeest. They are following their instincts. They're not plotting and planning evil and bad things.
I got my first cat for the express purpose of her following her instincts. I wanted her to catch mice. And she did. Thank you Miranda.
Terrific picture, BTW.