Hmmm, not sure, T. I would say contacting a power animal and contacting a spirit guide are the same thing except that a power animal is sure to be an animal. 
Oh, wow, forgot I hadn't replied to this. I always thought that spirit guides were external entities whereas power animals were metaphorical manifestation of your higher consciousness, i.e a part of you. Maybe I got that bit wrong?

An update on Dark Moon Mysteries, my copy came in a week back and so far it looks good. I had a question regarding the guided meditation exercises...the first exercise is about identifying a shadow mask; and what's got me confused is...am I supposed to be puppeting? That is to say, I have something of an idea of what my shadow mask
is...am I supposed to be thinking of it consciously while doing the meditation...or do I just lay back and let the images come?
For example, while trying to do a guided meditation years ago to find...kinda sorta a power animal...I kept seeing a sparrow when I just let the images come, even though I have no conscious attachment/attraction to sparrows; like I do with dogs (say). I could
visualise a dog quite clearly when I tried or wanted to, of course, but it kept turning to a sparrow when I wasn't paying attention- does that make sense?