Let’s be honest – winter really sucks doesn’t it? It doesn’t get light till almost lunchtime and by supper it’s dark again. And while we grope around for a light switch our fingers are practically dropping off from being frozen. And seriously, and who can honestly say they’ve never uttered foul words when struggling to push a wheelbarrow through 3 feet of snow and then all the hay falls out? When it comes to our horses, I’m sure they feel the same. I mean, don’t we bundle them up in multiple heavy blankets complete with hoods, and lock them in cozy stalls for 18 hours a day? Of course, we do this because we love them and because it’s good for them, right? Well, before we start tucking our beloved ponies up in their winter woolies, let’s take a look at some of the science about horses in winter.
Let’s start with how the horse adapts to climate change from summer to winter. Most horses experience a decrease in the concentration and volume of sweat, and the skin becomes much thicker in winter.1 The horse also begins to change his/her breathing patterns at the ambient temperature and day-length changes, in an effort to protect against heat lost through respiration.4 In addition, heat production from eating (called ‘heat increment’) increases during cold weather. In effect this “turns up the furnace” and helps the horse keep warm from the inside.5 This furnace is particularly effective when lots of fibre (ie. hay) is fed, as hay has a much higher heat increment than grain. These changes occur in order to protect against heat loss, and they are remarkably effective. Weanling horses housed in northern climates don’t start having measurable heat-loss until a lower critical temperature between -9°C and -16°C. What is perhaps even more surprising is that heat loss is even less at temperatures around -23°C than at -9°C.2 Other things that horses do to protect against heat loss in winter is to grow a rather impressive winter coat which stands perpendicular to the skin creating a band of trapped warm air to keep heat against the horse’s skin. This phenomenon is called ‘loft’, and it is completely disabled when we drop a blanket on it. Which is perhaps fine if it’s a thick, warm blanket, but if we are simply putting a thin sheet to keep the rain off, this will actually prevent the horse from naturally reducing heat loss. And in any case, the horse is pretty good about keeping himself dry in wet weather – shorter day length (among other things) causes the horse to produce high amounts of ‘sebum’, a waxy material that coats the skin and haircoat, acting as an extra water-proofing against wet weather.
So these sciency facts about horses in winter show us that, in most cases, horses are pretty good at keeping themselves warm and dry in winter. As long as we provide adequate shelter from the wind, nature has adapted them incredibly well for the nasty Canadian winter. An exception to this rule might be horses that are expected to exercise intensely during the winter months. Not surprisingly, athletic horses with a full winter coat in the winter experience more heat stress and recover from exercise slower than horses with a clipped haircoat, in addition to performing worse than their clipped counterparts.3 For these horses, it might be preferable to clip the haircoat and blanket the horse. But before you shroud your equine pasture ornament in his man-made parka, consider the common sense of Mother Nature first. There are precious few of Her ideas that we’ve been able to improve upon, and certainly not the perfection of the horse.
In the event that Mother Nature needs a little help, there are some dietary strategies that can help protect your pony from the winter chills. Feeds that help increase core body temperature include those with high dietary fibre such as wheat bran, which is one of the more thermogenic forms of fibre.6 Some herbs are also known to increase core body temperature including capsaicin7 and green tea.8 You can also increase your horse’s dietary fat intake, preferably through use of omega-3 fatty acids from flaxseed or microalgae. Dietary fats can accumulate under the skin and act as an insulating layer against the cold, thus improving cold tolerance.9 Fat is also the preferred metabolic substrate for energy when an animal shivers in an effort to increase core body temperature.10
So remember, when ‘flurries’ becomes a 4-letter F-word don’t be too quick to turn your horse into an enshrouded cave-dweller. Some simple changes in diet can really help your horse build up natural protection against the cold and weather. And then we can take the money we would have spent on winter coats for our horses, and spend it on a nice warm tropical vacation!