Integumentary System of a Horse

The integumentary system of a horse consists mainly of the outer covering of skin. Other structures of the integument include the hair, glands and hooves. The skin is a sensory organ that also protects, excretes, absorbs, aids in the regulation of body temperature and helps with the synthesis of vitamin D. The skin, the largest organ in mammals, helps store nutrients.

  1. Skin

    • A horse's skin is composed of three layers: epidermis, dermis and hypodermis. The epidermis is made of keratinized, stratified, squamous epithelial cells; the outer keratinized cells are dead. The epidermis is composed of five layers: basal, spiny, granular, clear and horny. Just under the epidermis is the dermis. The dermis is tissue made of irregular connective fibers and cells. It contains hair follicles, nerve endings, glands, smooth muscle, blood vessels and lymphatics. This is the layer that makes up the horse's hide. Under the dermis, the hypodermis is a subcutaneous layer that allows the skin to move freely. The horse's pigment or color is due to melatonin.

    Hair

    • The primary function of the hair is the regulation of temperature. The three parts of a horse's hair include the shaft, the root and the follicle. Horse hair undergoes three phases during its life cycle: the growth phase, the transition phase and the quiescent phase, which ends with the loss of hair. Horses also have three types of hair, including guard hair and wool-type hair covering most of the body and some tactile hair or whiskers.

    Glands

    • The horse's sebaceous glands are located in the dermis and are responsible for moisturizing and waterproofing the skin and hair. The sweat glands guard against heat loss and are responsible for animal odor.

    Digits

    • A horse's hoof is a mass of horny keratin. The inner part is attached to the bone and the outer part is epidermis. The third digit of a horse (the hoof) is the only weight-bearing digit. The other digits are the chestnuts and ergots. Chestnuts are the horn-like medial growths on the horse's leg. Ergots are small projections of epithelium in the center of the caudal (tail) part of the fetlock, which is located immediately behind and above the hoof.

    Uses

    • Horse hair has been used as a textile to make rope, rugs, brushes and upholstery. Horse hide is prized among some collectors for gun holsters because of it's soft, buttery feel.