Vitamin B12 (cobalamin) is an important nutrient for animal health because of its role in metabolizing nucleic acids (e.g., DNA) and forming proteins from amino acids.  It also helps the body process fats and carbohydrates, and is used by the liver to make glucose.

Cobalamin interacts with folic acid in several interesting ways:

• Vitamin B12 modifies folic acid so that the cells can use it.
• The two vitamins work together to produce certain essential amino acids.
• Both vitamins play a role in manufacturing red blood cells.

Vitamin B12 is necessary for the growth and reproduction of many cells, which is especially critical for DNA repair and fetal development.  Other useful functions include maintaining the nervous system and aiding sheep in the production of wool.

Since the signs of cobalamin deficiency are so nondescript, some producers consider supplementation a good idea in any situation where an animal is "just not itself."  This can include assisting baby animals that have gotten off to a bad start for no obvious reason.

Vitamin B12 may be used successfully to treat some cases of anemia.  It can also help repair the digestive system after a worm infestation or a round of antibiotics, and is helpful for short-term stabilizing of pets diagnosed with diabetes, pancreatic insufficiency, or kidney disease.

In otherwise healthy animals, vitamin B12 can be used as a preventative measure to counteract the effects of stress.  For example, this vitamin is sometimes given to performance horses to help them fight fatigue and keep up a healthy appetite.