Functions of the Skin

Skin is the largest body organ and covers the entire outer surface of the body. It is the only visable organ and its efficient functioning is essential for health. It is a complex structure composed of; the Epidermis, Dermis, Hypodermis, Subcutis and fascia and is richly supplied with an abundance of blood vessels and nerve endings. The thickness of equine skin varies from 1 – 5 mm, the thickest areas are found on the dorsal aspect of the tail and over the dorsal trunk. The thinnest areas found on the ventral abdomen, lower neck and face. The main functions of skin can be divided into the following categories:

1 ~ Support Skin is designed to provide support to the body as a whole; cells are laid down in a fashion that enables flexible support. This arrangement of cells produces “Tension Lines”; the direction of support can be clearly seen by the direction of the hair lie and whorls of the coat. It is a tough and elastic structure that is designed to prevent tearing. Healthy skin should feel elastic and supple, and the coat should display a glossy and healthy appearance.

2 ~ Barrier Skin acts as a barrier to chemical, living and physical external agents; protecting the body from ultra-violet light, physical injury, mechanical, thermal and chemical attack from poisonous substances and harmful micro-organisms. Ultra-violet rays are absorbed by the pigment in the skin, resulting in protection of the cells from damage. The subcutaneous fat within the skin helps protect the body from minor knocks and the elasticity prevents tearing. The skin is an incredibly tough structure, this is important to the barrier characteristic function of skin.

3 ~ Transmits Sensory Information Skin is rich with nerve endings that transmit sensory information to the Thalamus in the brain, resulting in constant communication with both the external environment and all body systems. Physical sensations of touch and pressure are detected by mechano-receptors, heat and cold are detected by thermo-receptors. When there is excessive stimulation of these receptors, pain is experienced by the animal. Pain is one of the most important sensations, it plays a vital role in the survival of the animal. Some areas of the skin are more sensitive to others; this is due to a) the number of sensory receptors servicing the area (dermatome) and b) the varying thickness and make up of the skin.

4 ~Control Of Body Temperature And Fluid Loss Skin plays a vital role in stabilization of body temperature through sweating, vasodilation and muscular activity. In the cold weather, erector muscles of each hair contract, causing them to stand up. Air is trapped between these hairs, helping to provide insulation to the horse. The sebaceous glands become more active, providing more sebum for the coat for further insulation. In addition to this, blood vessels within the skin constrict reducing the amount of heat loss, the horses metabolic rate alters, muscles contract involuntary causing “shivering” and as a by-product heat is produced. In warm weather or after exercise when the horse is hot, superficial muscles dilate to dissipate heat; sweat glands are stimulated and become active and metabolic rate decreases. Sweat evaporates off the skin, resulting in reduced body temperature. The skin is water proofed by sebum, which in addition to repelling water also keeps water in. Acting to prevent dehydration, by controlling body fluid loss. Sweating can lead to electrolyte depletion and dehydration, it is important that body salts lost in sweat are replaced in the form of electrolyte supplementation to ensure normal functioning of body cells.

5 ~ Excretion Skin is an excretory organ. Waste products are excreted in the form of sweat. Glands associated with hair follicles are used to excrete waste products. To enable efficient excretion of waste products in this fashion, it is important that the pores of the equine skin are kept clean and clear.

6 ~ Regulation Of Blood Pressure

7 ~ Camouflage

8 ~ Provides A Source Of Antigen Presentation to T-Lymphocytes

9 ~ Immunological Responses

10 ~ Produces Vitamin D Following Synthesis Of Sunlight