Earlier this year I was honoured to be asked to write an editorial for British Dressage magazine, which was featuring allergic reactions and the relatively new and exciting development of allergy testing and desensitisation.
The horse’s skin is perhaps the most forgotten organ of the body. It provides a first line physical barrier against infection protects the underlying structures and plays a role in heat regulation and electrolyte balance. When hot the blood circulation to the skin increases -think of a thoroughbred after running a race- nearly all its surface veins are visible. The skin then produces sweat which evaporates to cool the underlying blood vessels. In the cold the coat will fluff up by a process known as pilo-erection- the hairs stand on end and create an insulating layer suited to the ambient conditions. When the surrounding air warms up, the hairs lie down again, thus allowing the horse to maintain the same body temperature, Moreover, the coat is changed twice a year to fit in with weather conditions. I once wintered a thoroughbred foal outside with a field shelter. In the coldest mornings, she would actually have frost on her back but a hand placed through her winter woollies revealed a warm skin. All this and waterproof too! In my opinion native types which are not being worked in the winter are better off without any type of rug. We have all seen native ponies which look drenched but the oil in the coat serves to repel the water. Thick manes, tails and feathers grow out of specialised areas of skin to provide protection not only from the elements but from insects too.
In addition to all this, the skin has the ability to self-repair when damaged on a much quicker timescale than most other parts of the body, small surface wounds are plugged quickly by a blood clot which helps prevent infection setting in. When unfortunately proud flesh appears on a horse’s leg (never ponies as they are literally made of different stuff), this too prevents a barrier, being rich in local antibodies.
So, horse skin evolved perfectly over the last 3000 years or so to cope with all nature had to offer. Then we started to ride them and perhaps that is where the problems started to occur! Our horses no longer roam free, browsing for food, eating a variety of sparse grasses, supplemented by herbs and the odd tree leaf that might seem tasty, but also have natural anti –inflammatory and anti -toxic properties, nor are they left to maintain their coats naturally by rolling in the mud and dust. (Most do, however, exhibit this natural behaviour, usually before an important competition) Our horses are kept on limited acreages, usually on pasture that is not as diverse as ideal- most grassland having been put down for farm animals. We want to ride or drive our horses- no-one wants to place their very expensive tack onto a filthy dirty animal and working animals with thick coats causes sweating and loss of condition, therefore we groom, clip and rug them up. Grooming will remove the natural oil content of the hairs and clipping more drastically removes them completely so they no longer provided a protective layer.