Of equine coats

ANATOMY OF A HAIR

Your horse’s coat is made up of millions of hairs, each consisting of distinct layers. If you were to look at a cross section of an equine hair shaft under a microscope, you’d see a tiny core, called the medulla. The medulla is filled with loosely packed cells that shrink when dehydrated, leaving air spaces. In general, the diameter of the medulla determines the diameter of the hair--thicker mane and tail hairs have larger medullas than thinner body hairs. In gray or white human hairs, the medulla is more prominent, but it is missing altogether in very fine hair.

The next layer is the cortex, which provides the bulk of the shaft. This layer is 85 percent keratin, a fibrous protein that also makes up hoof walls and your own fingernails. These protein fibers are long and parallel, cross-linked for strength. In addition to keratin, the cortex contains water, fats, melanin (the black or brown pigment that provides coloration) and minerals.

The outermost layer of the hair shaft is the cuticle, which is made up of overlapping cells that give it a rough, almost scaly surface. The cuticle anchors the hair shaft in the follicle and plays an important role in how we