Probiotics are these “friendly” microbes, like yeasts and bacteria, that live in your and your dog’s gastrointestinal tract. They help with the food digestion, provide some vitamins and nutrients, aid against the potential pathogens and overall do good to the immune system.
Yeast is a single-celled fungus that is found on and in all animal species, including your dog. They are an important part of gut flora, the complex mix of microorganisms that live in the digestive tract and have a considerable effect on health. When the gut flora are well-balanced, they are beneficial, but when they fall out of balance, they can cause serious problems. If yeast reproduces too rapidly, the body's defences will try to act to dispose of it, unless the immune system is compromised. Excessive yeast can cause immune system disorders because of the toxins that they produce.