Some of the formulations contain such ingredients as glucose-amine. Thought to help maintain cartilage for lealthy joints; fatty acids such as docosahexaenoic acid for proper brain development and healthy skin and hair; and antioxi-dants to strengthen the immune system. Other products are vegetarian or are formulated for pets that suffer from intolerances to certain food ingredients. Still other are said to contain a balance of certain ingredirnts to help maintain a healthy urinary system or prevent hairballs in cats.