Its animal cruelty. I took my 3 INDOOR cats to a free spay/nuter with a donation a humane society was hosting and they cut my cats ears. Just because the animal is asleep and can't feel it at that point in time does NOT make it ok. "Ear tipping identifies free-roaming cats that have been sterilized. Ear tipping is completely safe and it is performed under general anesthetic. Ear tipping provides immediate visual identification, which alerts animal control that a cat is part of a colony"  It sure didnt look to safe when my male kittens ear was all bloody. Even if the cat is a feral cat it is still not ok. This is animal cruelty as far as I'm concerned!