By Dr Tom Shurlock of The Golden Paste Company
How Skin Functions
The skin has been described as a layer of dead cells that are released from underlying layers that form an impenetrable layer over the whole body of an animal. Whilst being an oversimplification, and not entirely true, it does capture the role of the skin, and its function quite nicely!
The skin is the largest organ of the body and is a complex interdependency of various types and tissues.
The epidermis is the layer of dead skin, released from the dermis, and is the outer layer we associate with the term “skin”. The dermis itself is suffused with blood vessels, glands, hair erector muscles, nerve endings; the subcutaneous layer consists of adipose tissue with sweat glands and hair bulbs. These structures give clues of one of skins major functions – temperature control. Blood capillaries running close to the surface of the skin can regulate heat loss. Supported by muscular erection of individual hairs a layer of still air over the skin can help insulate. This is further supported by the layer of adipose tissue, acting not only as an insulant, but is also a storage organ for antioxidative components such as gamma tocopherol, a form of vitamin E.
The nerve endings show that the skin is also a massive sensory organ; heat/cold, irritation, pain are all stimulants that generates a response from the horse, whether physiological or behavioural, and these are all factors in addition to its barrier function.
So, the skin is a barrier to all manner of actions; these include environmental conditions, infective and toxic agents, biting insects and potential antigens. This makes the skin an extremely versatile and multifunctional barrier/defence/heat exchange mechanism.
However, the skin is not impermeable or impenetrable, but is protected by its own maintenance systems. These include specialist secretions from both the sebaceous and sweat glands – that cool and lubricate, help repel insects and infuse antimicrobial agents to protect against infection – to repair of damaged surfaces.
As with any system, the impermeability of the skin is not totally effective and there are daily invasive agents. Whether it is the allergens in the saliva of biting insects, a localised infected cut or a more damaging puncture wound, the skin is also a major immunological organ. Physical damage, infective agents and toxins will stimulate an immune or repair response, by releasing inflammatory cytokines and initiating the healing/repair cycle.
What is apparent about the skin is that is involved in sensory, regulatory, defence and repair systems and should be treated accordingly.
Supporting the Skin in Summer
Skin function, arguably, can be subjected to additional stress during the summer months. Not only is there likely to be increased activity – resulting in required rapid responses to heat loss and conservation, but the rise of potential antagonists such as biting insects, physical damage and allergens such as mycotoxins can impact on skin physiology and function.
Feeding can certainly affect those impacts. We are increasingly aware of “heart healthy” diets, supplements for muscle development, the importance of optimising the microbiome, mainly from human nutrition. But the same rules apply to horses, and there are steps we can take to maintain skin health, from macro- to micro- nutrition. General good nutrition, a forage based diet with quality protein and minerals will help support healthy skin, but there are other steps to be taken.
Feeding dietary sources of omega-3, 6 & 9 fatty acids support a range of processes. Physically, they are components of cell membranes, the vascular and neural systems, but also are the building blocks of prostaglandins that are integral to the inflammatory/repair cycles. Additionally, they are involved in the regulation of neurotransmission, which can support pain relief. Furthermore, omega-3 is involved in the production of sebum, the lubricant that protects the external face of the skin, and the hair follicles. Other components secreted in the sebum can include terpenoids. These are the essential oils of certain plants and they have been shown to discourage ectoparasites and biting insects. There is also some information that shows turmeric terpenoids can support the natural antifungal properties of sebum.
Supplying antioxidants is also beneficial for skin health. The subcutaneous adipose layer is rich in gamma tocopherol and supply of this version of vitamin E helps mop up free radicals, whose presence degrades cell structure. However, there are other oxidative mechanisms. Oxidative enzymes interact with inflammatory cues and can promote inflammation. Plant polyphenols are powerful antioxidants and can support the interplay with anti-inflammatory mechanisms. In situations where the skin is subjected to physical damage from, for example, of biting insects or where allergenic material penetrates, antioxidant support can benefit the natural cycle of inflammation and repair. Accompanying such irritation, there are behavioural responses such as itching the penetration site, leading to more inflammatory cues and possible infection. Some plant flavonoids have an effect at the neural level and this can help the sensation of itching, leading to less physical damage of the skin. This further supports the role of omega-3 generated prostaglandins, giving a two-pronged support.
The skin has many roles, and skin health has many requirements. Nutrition not only supplies the major nutrients, but selective use of plant bioactives can support the skins response to the challenges it receives – physical damage, invasive components whether insect, tick or microbe borne – whilst supporting its structural integrity. Supplementation with omega fatty acids, natural antioxidants, essential oils, flavonoids and other plant polyphenols can give a multifaceted support to skin health, all components that can be found in TurmerItch from The Golden Paste Company.
For further information please visit www.goldenpastecompany.com. You can also follow The Golden Paste Company on Facebook and Instagram (@thegoldenpastecompany).