A spiritual werewolf
is a person who believes that his or her spirit
is truly of lupine
nature, not necessarily human
or only human
How can animals have souls? Well, let me answer a question with another question: How can humans have souls? Occam's Razor suggests that one should posit as few jumps in logic as possible, in attempting to develop a hypothesis to explain an observed phenomenon. It is a jump in logic to assume that there is any difference between humans and animals in the soul department, and thus it is undesirable to continue to make that jump.
Plus, there is also the recent article in US News and World Report asking "do animals have feelings?", and presenting evidence to suggest that they do experience emotions. If animals do feel emotion, then it is even more of a stretch to believe that there is no soul in an animal, while there is a soul in a human.
(Not to mention that humans are animals too.)