The present invention encompasses pet food compositions that include one or more probiotic microorganisms, which are useful to improve the health of companion animals. For example, the invention encompasses pet food compositions including a probiotic, for example, Lactobacillus, Bifidobacterium and Streptococcus (Enterococcus). The present invention also encompasses the preparation of pet food compositions including one or more probiotic microorganisms intended for methods of maintaining or improving pet health through feeding a pet a pet food composition including the probiotic microorganism.