My experience with the use of Probiotics is generally favorable, when high quality and appropriate species are used. However, forti-flora & other brands that are sold through Veterinarians for small animals are not adequate to the task. Most Veterinary probiotics are adopted from mixtures developed for calves, sheep, foals and pigs where they work well. If a probiotic developed for large animals has been repackaged to use in small animals you will see "E.coli" as one of the organisms. I do not recommend probiotics that contain E.coli for small animals. One month ago I searched the science/agriculture/medical literature looking for any data to support the use of E. coli in probiotics. I found none that showed a benefit and in some experiments infections resulted. I also evaluated the science papers available from the development companies. All studies I was given by these companies were inconclusive or so poorly done no effect would be measurable. Yet these companies claim their studies prove the benefit of their product. Lower price is the reason for this widespread practice. I recommend probiotics available for people and reduce the dose to 1/5th -1/10th of recommended on the label, based on body size. Look for products that: 1. Are kept in a cooler and have a use by date. 2. Have a minimum of 1 billion organisms on back side of label. 3. use at least 3 different organisms , ideally some lactobacillus species and bacillus species. 4. Cats, dogs or people may be allergic to the base ingredients. Most probiotics are grown in naturals oils or dairy products. With cats I avoid dairy as the base because so many cats are lactose intolerant once they are adults. 5. Better results occur if probiotics are mixed into warm (not hot) food and allowed to sit for 15 minutes. Between temperature of 85-100 degrees. Same as baby bottle temperatures. This allows the dried organisms to reactivate and multiple before entering the harsh stomach pH. 6. Do not give within 2 hours of giving an oral antibiotic. Probiotics are most useful for diarrhea that happens during or following antibiotic treatment. Begin probiotics the same day as the antibiotics and continue once a day for a full 30 days after the end of last antibiotic. Probiotics can be helpful for skin allergies after 1 to 3 months but only as part of a complete allergy treatment protocol. Used alone probiotics do not cure allergies. Long term probiotics assist the immune system to regulate itself as part of an anti-allergy diet. As far as allergies to food are concerned, probiotics are a helpful part of later in a treatment process when they do most benefit. Early in treatment, the Gut can be so irritated that it reacts to every new product. See a holistic Veterinarian who can determine the cause of feline diarrhea then a treatment approach can be determined.