I follow the Celtic Shamanic Wicca path and I'm in a coven for a decade. Mi-Shell is right when she says solely the Native Americans have totem animals. Everyone else have power animals and/or animal guides but NO totem animals. The word "shaman" though is not Native American, it's from Siberia in Russia.
A power animal is an animal guide and protector that comes to you. It is necessary to have one power animal to do shamanic work since they can protect you while you do shamanic work. Power animals are there to teach you something, and they will leave once you've learned their lessons, to be replaced by another power animal, so they never stay for a long period of time. A person can get more than one power animal. In my case my power animal is the frog.
An animal guide is an animal guide that develops a fondness about you, and that will appear in your dreams and give you other signs. They can stay with all your life.
I say that because some are persuaded that the animals that they like are their power animal or animal guide, when it's those power animal or animal guide that choose you and not you that choose them. You have to be open to be surprised in a good way when you're looking for a power animal or animal guide.
In my case I love wolves, foxes, cats, black birds in general, and it's the frog that I got as power animal. And after working with it I don't regret it at all getting the frog. Frogs are shapeshifters and tricksters and since I do a lot of shapeshifting (in dreams and shamanic work), we often shapeshift together to get the job done, or just for the pleasure of it. He has a good sense of humor and we have a wonderful relationship. He likes to have a cute crown on top of his frog's head because he thinks he's the best, and I agree with him, he is. I've decided to call him Rupert because I think it sounds high class and he likes it.