The Astro’s oil Nitrogen-Creatinine Scrub works extremely well on its own. However, if you wish to enhance its efficacy, you can introduce a good quality probiotic (1 cap/day) or use 1 tablespoon of either kefir or probiotic yogurt as a treat. For pets that do not eat kefir or yogurt, you can mix Astro’s Oil Nitrogen-Creatinine Scrub into any wet food and administer 1 probiotic cap/day.