I just had Nilla and Sasha spayed at a low-cost spay/neuter clinic, and they tattooed rather large "S" on their chest. I wasn't crazy about that, but I guess the hair will grow over it. I'll have to post a pic. when I can get one. My husband has a number of tattoos and several ear piercings, but we would both be vehemently opposed to tatooing or piercing pets unless it is for safety or health reasons. It's just unnecessary to cosmetically alter your animals like that, and unnatural, too.