Arabinogalactan Powder, from Larch Tree, is water-soluble polysaccharides and fiber that support proper immune system function in dogs and cats. It also supports the growth of probiotic bacteria such as lactobacilli and bifidobacteria in the intestines, which are important for GI tract health. The Larch Tree extract powder in this product is Immun Enhancer™ AG from Larex, Inc.