Rx B12 is a nutritional supplement for dogs and cats containing pure cyanocobalamin, a man-made form of vitamin B12. It is not produced by the body but is an important part of cell reproduction, blood formation, and protein synthesis. It may be given to animals with a deficiency due to illness or disease, or to replace missing nutrients from their daily diet. Consult with your veterinarian before using this product, and follow their guidelines for use. Rx B12 flavored, palatable liquid available in a 4oz dropper bottle.