Bifidobacterium animalis is a Gram-positive anaerobic rod-shaped bacterium, which can be found in the large intestines of most mammals, including humans. Bifidobacterium animalis and Bifidobacterium lactis were previously described as two distinct species. Presently, both are considered B. animalis with the subspecies Bifidobacterium animalis subsp animalis and Bifidobacterium animalis subsp lactis. Both old names B. animalis and B. lactis are still used on product labels, as this species is frequently used as a probiotic. In most cases it is not clear which subspecies is used in the product.