This was my virgin year, so I'm not sure what the norm is out there, but I saw a lot of pets that people snuck in. A lady camping across the street from me had a cat walking around camp all week, out on the open playa I ran into a guy with a little yorkie in his bike basket, and I repeatedly saw a man riding his bike with a dog (on leash) running along side him. Oh and I saw another cat when I was out riding around the city (can't remember where I was though)
I guess if someone really feels they can take proper care of a pet out there then okay, but I couldn't help wondering how the poor animals felt with all the loud noises, heat, dust, etc. Also, there aren't any veterinary services out there so if your pet gets into trouble (dehydration, etc) then what are you going to do?
I don't know, just seemed like a bad idea to me.