Why do cats eat mice and leave guts?

Cats eat mice primarily for their protein content, as their carnivorous diet requires nutrients found in animal flesh. They often leave the guts because they instinctively prefer the muscle tissue, which is more palatable and nutritious, while the organs may be less appealing. Additionally, leaving the guts can be a behavior inherited from their wild ancestors, who would consume only the most optimal parts of their prey. This behavior also helps them avoid potential toxins that can be present in some organs.