In California it is illegal to use "pet" animals as food for humans or other animals. It probably has been done (like pretty much every deplorable act people can imagine), but it's a crime.
In regards to the feral cat discussion, we had a longstanding battle with mice until we started feeding a random feral cat. She popped out two kittens, we trapped and spayed/neutered the whole family, released, and for the last 4 years not a single hint of rodents. They live in the back yard, where we built a small shelter for them to use in bad weather. The cat family shares the shelter and the evening cat food with a family of wild possums and the occasional raccoon.
The cats eat mice to this day. but ignore even the baby possums.