We’re veering back into more familiar territory with this month’s nutrition topic. Most farriers have at least a passing familiarity with the role of vitamins in hoof health — and indeed, several play a vital part in the growth of healthy horn and soft tissues.

But what exactly are vitamins?

Strictly speaking, they’re tiny organic compounds, with a disproportionately large impact on the health and well being of the horse. Sometimes gleaned from the diet and sometimes manufactured within the animal’s digestive tract, vitamins have the power to promote and regulate virtually all of the horse’s normal functions.

Researchers have classified vitamins into two categories, which describe how the vitamins are absorbed, stored and excreted by the body: fat-soluble and water-soluble.

Vitamins A, D, E and K are the fat-soluble vitamins, which tend to be stored in the body (and thus can build up toxicities if there is an excess). The B vitamins and vitamin C are water-soluble, meaning that any excess tends to be excreted rather than stored.

Vitamins can also be classified according to their source. Under normal conditions, the horse quite efficiently produces vitamins C, D and niacin (one of the B-complex vitamins) from other organic molecules that he ingests. The beneficial microbes living in the cecum and large intestine, as part of their symbiotic bargain, produce all of the other B vitamins, as well as vitamin K. Only vitamins A and E are not produced within the horse’s body and must be obtained from vegetable matter…