Animal characters are welcome within limits, and the limits exist to keep scenes fair and the worlds running smoothly. Non-human avatars are restricted to domestic animals, cats, dogs, and by tradition goats, and they can be killed in combat like anyone else. The rules below cover the rest.
What you can play, and the risks
Stick to domestic animals. A dangerous dog, especially a stray, runs a real risk of being killed, so play one knowing that. Animal characters are part of the world’s danger, not exempt from it, and a beast that threatens people should expect people to respond in kind.
Animesh pets have hard limits
A pet that is an animesh attachment cannot fight at all, and cannot carry a death limit. If your animal is an attachment rather than a played avatar, it is a companion and a presence, not a combatant. To keep the worlds running smoothly for everyone, attach animesh pets only for the scenes that need them, and detach them when a region is full or lagging.
No double-logging as handler and beast
You cannot control both a handler or owner and a potentially dangerous animal at the same time. Running two avatars in a combat scene is unfair to everyone else in it, giving one player two bodies where everyone else has one. If your animal might enter a fight, it is the only character you play in that scene.
Play the animal as a real presence with real vulnerability and the worlds are richer for it. The last of these rules covers technology.