There is discussion on holisticat.com regarding Fortiflora that I want to share here. I used to use Fortiflora as a probiotic but have since switched to another brand. On a minor note, there's no way to know from where the "animal digest" in FF comes from. But for your larger consideration:
*FF contains only 1 type of bacteria -- Enterococcus faecium use of which is controversial because "enterococci, because can be opportunistic pathogens and probiotic strains of enterococci are able to transfer the vanA gene; the gene responsible for vancomycin resistance."
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC340078/
http://www.carnivoreconservation.org/files/thesis/koeppel_2004_dvm.pdf
Other brands that are better: Mega Flora (from iherb.com)
Garden of Life Primal Defense (from Amazon)
*FF contains only 1 type of bacteria -- Enterococcus faecium use of which is controversial because "enterococci, because can be opportunistic pathogens and probiotic strains of enterococci are able to transfer the vanA gene; the gene responsible for vancomycin resistance."
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC340078/
http://www.carnivoreconservation.org/files/thesis/koeppel_2004_dvm.pdf
Other brands that are better: Mega Flora (from iherb.com)
Garden of Life Primal Defense (from Amazon)