Thermoregulation and Rugging of Horses
To rug or not to rug – this can be a controversial issue and the answer and decisions on this question are often more led by personal ideas and interests of us humans than what the horse actually needs.
The reason I feel I like to address this topic is that I came across a rescue organisation’s advice on caring for horses in winter which suggested to put a rug on horses and ponies in general. While this advice is surely well intended I feel it does not keep the horses’ best interests in mind.
And to make things worse, this was here in Ireland where I am based. A country where we do not have much of a ‘real’ winter. The sun is shining today with outside temperatures of about 8 degrees Celsius. We rarely see any temperatures below zero and it makes me wonder how horses of mine survived in my native Germany where they had to put up with snow and minus 15 degrees Celsius WITHOUT a rug while living out for weeks. It also makes me wonder how horses and other animals could have survived for so long without any rugs and our human care under tremendous conditions in the wild.
All irony and sarcasm aside, let me be clear, I am not against the use of rugs in general and I also do rug my horses if I feel it is required. However, I will assess this on an individual basis considering several factors which I will address below. And it makes me feel very uncomfortable when I read something that suggests that even heavier coated equines need a rain proof rug during a mild winter and advocating the rugging of horses per se. I feel a statement like this shows disregard of the horse’s natural thermoregulatory system and its capacbilities and that by rugging we deprive the horse of the opportunity to make full use of them.
And before deciding about putting a rug on a horse, two other essential elements in horse-keeping should be provided and ensured which are the provision of (1) adequate and appropriate shelter accessible for the horses, and (2) sufficient amounts of forage. Not only compensates the food intake for weather related energy usage; the process of digesting long fibers produces heat as a by-product. Increasing feed intake increases heat production in the horse’s body.
In fact, horses are much better equipped to deal with cold weather than we are and the skin and coat act as insulators preventing heat loss. These insulators are supported by muscles producing heat through their movement. (For a more detailed overview on this and further extensive references please see: Natalija Aleksandrova, Thermoregulation in horses in a cold time of year; http://www.wolnekonie.org/science_en_thermo.html)
- Skin – The skin works as an insulating layer through its relative thickness which is supported by body fat. Horses may naturally add as much as 20 percent body weight in fat when cold weather approaches. This is an important aspect as fat is three times more insulating than other tissues.
- Coat – Horses naturally grow a thick winter coat depending on species and environment. On top of that they increase the insulating abilities by as much as 30 percent through piloerection, i.e. the raising or lowering of the coat via hair-erector muscles which when raised keeps warm air between the hair shafts. When we put rugs on horses, piloerection is not possible. Horses’ hair naturally has a greasy coating which provides a water-repelling effect and therefore protection from rain and snow which should not be taken away by excessive grooming.
- Arteries in the skin – Arteries can be narrowed or enlarged through muscle actions regulating blood flow to the skin. When constricting internal heat loss is prevented by reducing the amount of warm blood brought to the cooler body surface.
- Behaviour – We may see reduced activity of feral horses and horses kept in natural conditions during winter as it helps them cope with the increased energetic demands. At the same time, short sessions of activity and movement during sudden acute cold periods and adverse weather have been observed which may serve as a bridge for the thermoregulatory system adjustment to the new temperature conditions. Horses may stand very close next to each other and thereby block each other from the exposure to wind and weather.
Natalija Aleksandrova concludes:
Kept in stables or/and blanketed, horses lack stimuli (temperature fluctuations) triggering the activity of thermoregulatory mechanisms. They don’t need to exercise hair erector muscles, nor to dilate or constrict arteries, nor to activate the sweat glands, nor to prepare or deplete healthy fat reserves. All muscles atrophy without exercising for a period of time. If an animal in this state is suddenly exposed to the cold, they will not be able to activate necessary thermoregulatory mechanisms.
Keeping all the aforementioned aspects in mind, we hopefully can make a more educated decision whether it is our best choice that a horse needs a blanket to come through the winter. Generally, most horses living out in a group with access to adequate shelter to protect them from wet and wind and plenty of roughage do not need any rugs. Also, any older, sick or more sensitive horses may have to be assessed differently.
I will not address and discuss the rugging and potentially clipping of horses in more extensive work and respective requirements and implications. Also, I am aware that we have to make compromises at times and that we may be in situations where we cannot do or provide certain things as ideally as we liked to.
But when giving advice, I would like it to be based on expertise, skill, knowledge and experience in the very best interest of the horse, modelling best practices and standards that are available.
Reference: Natalija Aleksandrova, Thermoregulation in horses in a cold time of year
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