Shine on

Dr. Rebecca Hamilton Fletcher MRCVS investigates the science behind horses’ coats

- Dr. Rebecca Hamilton Fletcher

AN equine coat is socially significant, with a lustrous, glossy appearance indicating the health, virility and genetic fitness necessary for herd dominance. The coat also has other physiological roles that are important for a horse’s survival and can be manipulated through adaptation and management.

Hair is classified in three types: permanent, such as the mane, tail and feathers; tactile, such as the hairs on the muzzle and inside the ears; and temporary, referring to everything else. Each hair originates from a follicle under the skin’s surface, which is supported by a sweat-producing sebaceous gland plus a vascular, sensory and muscular system.

A horse’s coat colour is determined by the amount of black, brown or yellow melanin pigment in each hair, and is genetically determined. Other hereditary characteristics include coat length and texture.

These features are unique to each individual and may also be breed-specific. The Akhal-Teke, for example, has a cream gene that produces a metallic sheen. The Bashkir Curly, as its name suggests, has an unusual curly coat and furry ear lobes.

Regardless of colour or type, the equine coat has a remarkable ability to perform an array of useful functions.

LET IT GROW

HAIR growth is not continuous but occurs in cycles, controlled by pre-determined physiological responses to environmental factors. The term anagen describes the active growth phase. Next comes the resting stage, or telogen, when the hair is technically dead. The transition period between the two is called the catagen.

This ability of the hair to grow to different lengths, in cycles — and to stand up or lie flat —means that it is well adapted for various roles:

• thermoregulation

Hair grows in response to daylight hours, rather than ambient temperature.