Probiotics are very helpful for pets. They are various healthy beneficial bacteria such as Lactobacillus bulgaricus, Bifidobacterium bifidum, Bifidobacterium longum, Streptococcus thermophilus that normally live in the intestines and promote normal bowel health.
I give my pets probiotics whenever there is possibility of upsetting the normal intestinal flora - surgery, while taking antibiotics or chemotherapy and if suffering from illness or stress. Probiotics can supply nutrients, aid in digestion, reduce pathogenic bacteria and yeasts and allow for better conversion of food into nutrients.
Probiotics improve the health of the gastrointestinal system in pets as well as in people. They produce chemicals that decrease the amount of harmful bacteria. They decrease toxins produced by this bacteria. They block adhesion of harmful bacteria to the intestinal cells and compete for nutrients needed for growth by pathogenic organisms. Overall probiotics stimulate the immune systems of the intestines.
Since probiotics are live organisms it is important that you buy quality products. They come in dosages of several million to several billion live organisms. Some pet brands add strains that are acid and bile resistant to give them with food. This makes them more apt to get digested and into the intestines rather than be destroyed in the stomach via digestive juices.
I suggest to give cats and dogs 1/8 to 1/4 of the human dose of supplements. Larger animals should take more.