Immune System Support Veterinarian Recommended Non-GMO Quality Seal NASC Perfect for Multi-Cat Households and Boarding Gluten Free Now® Pets L-Lysine Powder helps support a healthy immune system, normal respiratory health, and also helps to maintain ocular health. Now® Pets L-Lysine Powder is recommended by renowned veterinarian Dr. Barbara Royal, DVM, CVA, founder of The Royal Treatment Veterinary Center. Suitable for use in cats only. NOW Foods Pets L-Lysine For Cats 226g