Felisyl Immune System Support Granules - Support Healthy Tissues, Respiratory and Vision for Cats - 3.5 oz Felisyl is a supplement for cats and kittens for conditions responsive to L-Lysine. SUPPORTS THE IMMUNE SYSTEM: L-Lysine is an essential amino acid that helps support the immune system so it can function normally and produce antibodies. It also helps maintain healthy tissue, supports respiratory health, and may even help with your cats vision. Recommended as an aid in the treatment of the feline herpes virus and its associated respiratory and ocular symptoms. DELICIOUS POULTRY AND FISH FLAVOR: Palatable flavor will make these granules easy to give to your cat or kitten, just sprinkle over or mix in their food. INGREDIENTS: L-Lysine, Proprietary Blend of Poultry and Fish Flavoring, and Beet Sugar Made in the U.S.A.