All the ingredients of PD are transient organisms. They are not normal inhabitants of the gut.
The claim that PD contains an animal based strain was made by Duncan Crow on the Yahoo groups Candida Forum . He made it on the basis of an article in the Journal of Gastroenterology (if I remember correctly).
I'm not interested in bashing PD. I've just given my experiences, and what I have heard elsewhere from reliable sources. That is in no way discounting other peoples positive experiences.