Yay or neigh? Horses vote on wearing rugs.

Yay or neigh? Horses vote on wearing rugs.
05 Jan 2020

By Jessica Morton

Surely every horse owner has wondered at one point or another what their horse would say to them if they could talk.

One of the questions many of us would ask our horses, is: would they prefer to be rugged or not?

That’s precisely what a group of scientists in Sweden and Norway and their team of 23 horses set out to find out. 10 horses usually wearing blankets and 13 horses usually not wearing blankets were tested for their preferences. 

And it is now believed that horses are intelligent enough to tell their owners whether or not they want to wear a rug under different weather conditions. 

Straight from the horse’s mouth

Over 14 days, professional trainers from Norway taught the horses how to communicate when they were hot or too cold using a training method used in a previous study (2).

Using positive reinforcement, the horses were trained to choose between three symbols that signified “blanket on”, “blanket off, or a “no change” symbol.

To check whether the horses had come to understand the meaning of the symbols, they were turned out for two hours in different weather conditions and then tested to obtain their preferences. Although it took time for some of the horses to understand what was expected of them, within two weeks all the horses were able to communicate whether they wanted a blanket or not when they went outside.

The horses ‘asked’ for a blanket when the weather was cold, windy or raining and did not want a blanket when the weather was warm and sunny. This was a key indicator that the horses understood the consequences of their decisions, which were chosen based on their own motivations, not that of the trainer.

When to rug your horse

By air temperature

When the results measured only air temperature and not the influence of other weather factors, the horses preferred to have a blanket on in 80% and 90% of tests taken in temperatures under -10°C degrees. As air temperature increased, the horse’s preferences for keeping the blanket on decreased. At 20 °C, all of the horses tested preferred to have no blanket.

In windy weather 

100% of the horses tested chose to keep their rugs in windy conditions.

Strong winds substantially increase thermal discomfort in horses kept outside by taking away body heat faster than any other weather condition, and past studies have indicated that horses are more likely to utilize a shelter under strong wind (3, 4). It is therefore not surprising that the 23 horses tested showed a clear preference of wearing a blanket in windy weather.

In snow

Interestingly, on days with snow or sleet, only 59% of the horses tested wished to wear their rugs. Snowfall is not particularly chilling to horses already adapted to colder weather, as the snow gathers on their winter coats without drawing away body heat (4).

Many a confused horse owner has wondered why their horses stand outside rather than taking shelter, and this may be the reason.

When overcast or raining

On cloudy days with low temperatures, 59% of horses wished to wear their rug. When there was rain, 100% of the horses wanted to wear a rug. It should be noted that the horses were tested with rugs that their owners deemed appropriate for the climate. 

During heavy rain, the horses were turned out wearing waterproof blankets. From a welfare point of view, a non-waterproof blanket is worse than wearing no blanket as it will increase the heat loss from the body (via contact with a cold wet layer) and prevent the horses’ normal systems working properly (e.g. the hairs cannot raise themselves to trap heat) (5).

20°C and above.

When the temperature was higher than 20 degrees, 100% of the horses tested preferred not to wear a blanket.

In warm weather, horses will sweat, and their surface blood vessels will dilate to encourage heat dissipation. Where possible, they will move to a shady area where they have access to water. All these mechanisms help the horse to lose excess heat. By adding a blanket, the horse’s health and wellbeing can be severely affected. The only mechanism that will work for them is to sweat under the rug. 

Heat stress can cause electrolyte imbalances and in extreme cases is fatal (6). A horse that is not wearing a blanket in the cold can run and move to warm himself up – but an over-rugged horse in warm temperatures has no escape.

Dangers of wearing rugs

The debate of whether to rug a horse or not is always a lively one amongst owners and industry professionals. Some believe in meticulously rugging their horses in all seasons, while others believe that horses are resilient enough to withstand even the harshest conditions without any help. Of course the workload of the horse, whether the horse is clipped or not and the owner’s chosen discipline also come into play. 

The study consisted of a mixture of horses that normally wore blankets (10 total) including horses that were clipped (n=4) and horses that were not clipped(n=6) and horses that did not normally wear blankets (13 total).

Of the four unclipped horses, two preferred to have the rug left on 100% of the time, suggesting that clipped horses who are deprived of the insulating properties of an intact hair coat do prefer a rug. Since there were only four clipped horses in the study group, further research will be needed to confirm this theory. 

Critics of blankets note how poor fit can cause the horses to suffer from pressure sores (particularly around the shoulders and withers) and that proper adjustment of the fasteners is critical to blanket safety since fittings can easily break, which may cause injury (7).

Bacterial infections thrive under blankets that are not cleaned or aired frequently and by not allowing a horse time in the open air (8).

Vitamin D intake does not appear to be affected by rugging although more research is needed in this area (9).

Horses, when given the chance to answer themselves, seem to unanimously prefer a blanket when conditions include strong winds, rain and low temperatures. but all the tested horses preferred to be left un-blanketed when temperatures increased above 20 degrees.  

Recent studies have shown that blankets are no substitute for shelter in the heat (10) or cold (11).

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References: 

  1. Mejdell, Cecilie M., et al. “The effect of weather conditions on the preference in horses for wearing blankets.” Applied Animal Behaviour Science 212 (2019): 52-57.
  2. Mejdell, Cecilie M., et al. “Horses can learn to use symbols to communicate their preferences.” Applied Animal Behaviour Science 184 (2016): 66-73.
  3. Jørgensen, G. H. M., et al. “Preference for shelter and additional heat in horses exposed to Nordic winter conditions.” Equine veterinary journal 48.6 (2016): 720-726.
  4. Mejdell, Cecilie M., and Knut E. Bøe. “Responses to climatic variables of horses housed outdoors under Nordic winter conditions.” Canadian journal of animal science 85.3 (2005): 307-308.
  5. Bass, L “To blanket or not to blanket? That’s a good cold-weather question.Coldorado State University Veterinary Teaching Hospital (2013).
  6. Hodgson, D. R., R. E. Davis, and F. F. McConaghy. “Thermoregulation in the horse in response to exercise.” British Veterinary Journal 150.3 (1994): 219-235.
  7. Steinhoff-Wagner, J. “Coat Clipping of Horses: A Survey.” Journal of Applied Animal Welfare Science 22.2 (2019): 171-187.
  8. Kentucky Equine Research, “Rain rot in horses.” (2011).
  9. Azarpeykan, S., et al. “Influence of blanketing and season on vitamin D and parathyroid hormone, calcium, phosphorus, and magnesium concentrations in horses in New Zealand.” Domestic animal endocrinology 56 (2016): 75-84.
  10. Padalino, Barbara, et al. “Effects of a light-colored cotton rug use on horse thermoregulation and behavior indicators of stress.” Journal of veterinary behavior 29 (2019): 134-139.
  11. Jørgensen, Grete Helen Meisfjord, Cecilie Marie Mejdell, and Knut Egil Bøe. “The effect of blankets on horse behaviour and preference for shelter in Nordic winter conditions.” Applied Animal Behaviour Science (2019).


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