Fix Our Ferals offers the following information and photos to help identify a feral cat that has already been 'fixed'.
When a feral is spayed or neutered, its right ear is given a small notch or tip. It’s a very minor medical procedure and a proud badge, demonstrating to neighbors, animal control officers, and animal shelters that this cat has a home and a caretaker. As you can see from the photos below, the cat’s beauty and charm remain in full force!
The ear may be marked in one of three distinctive ways: Notch, Tip, or Top Notch.