The skin is the largest organ of the horse's body, it protects against injury and harmful organisms and serves as a sense organ. Besides looking beautiful the hair protects and insulates the skin.
The skin consists of an outer layer from which the hair grows and a thicker inner layer, which contains the support system for the hair. The skin's health depends on good nutrition and exercise, which produces good circulation and delivers the necessary proteins, oils and vitamins to grow a healthy, functioning skin and a shiny coat.
The skin oiled called sebum is secreted by the sebaceous glands. Sebum is the source of moisture for the skin and hair and helps to keep the skin and hair smooth and pliable. Exercise and sweet help in this process- exercise and skin movement stimulate the sebaceous glands, and sweat rinses the coat and helps to distribute the skin oil over the hairs. Vigorous grooming also helps this process.
A fit, well-groomed horse sweats a thin, watery sweat that evaporates easily. The sweat contains salt and other minerals, but it is mostly water. An unfit horse's sweat is less watery, containing more salts and waste products, and it mixes with sebum, dandruff and dirt to form a thick, scummy lather that evaporates slowly. This makes the skin less efficient at cooling the body, and the unfit horse gets hotter and cools more slowly, with a greater risk of heat exhaustion. It is known that horses who are over weight and are unfit, tend to suffer with summer seasonal recurrent dermatitis. The British Horse Society are reporting a specific vaccine to help alleviate sweet itch is currently in development and researchers hope it will be available by 2021. If successful, the vaccine will drastically improve the welfare and quality of life of those affected horses.
To condition the skin and hair, the extra scurf and dirt must first be removed from the skin. This is best done by regular good grooming, using a rubber currycomb to loosen the scurf and massage the skin and the dandy and body brushes to sweep the skin clean. Bathing especially with detergent shampoos, temporarily removes some of the skin's natural oils and so may decrease the shine of the coat for a short while. This is one reason why bathing cannot substituted for good daily grooming.
Grooming stimulates the production of sebum or skin oil and distributes it evenly over the surface of the hairs. It also removes debris and loose hairs. Grooming is most effective when done right after exercise, when the skin is warm.
There is no current cure for Sweet Itch but you can help by protecting him with a fly sheet during the day and a light cotton sheet at night. A silicone dressing can be applied to clean hair - the silicone coats the cuticle, making it harder for the biting midges to get to the skin.