It’s so cold your nostrils stick together every time you breathe in. You’re bundled up to the point you look and feel like blob with a riding helmet on top and your fingers are so stiff and achy they can barely hold onto the reins. Welcome to a Canadian winter cold snap. While “normal” people tend to opt for indoor activities during wickedly freezing temperatures, many equestrians are compelled to keep riding no matter what the forecast says. But, is there a point at which working in extreme cold could cause our horses physical harm?

It’s commonly known human athletes can suffer cold-induced airway inflammation (sometimes called ski asthma), whether or not they experience difficulties in fairer temperatures. Even typical asthma sufferers will also find their lungs more reactive in the winter. U.K.-based physiologist and biochemist, Dr. David Marlin, who has done work in academia, industry and consulting in a number of areas, most notably equestrian sport says, “We know that exercising in cold air has the same effect in horses as it has in people. Many horse owners don’t appreciate the fact that the horse’s lungs are affected by the cold.”

As it happens, the temperature threshold for lung damage might be higher than you think, says Dr. Marlin. He first began studying thermoregulation (how a living being maintains its core body temperature) in horses around 1993 on the lead-up to the 1996 Atlanta summer Games. Much research was being done at the time over concerns that horses might struggle with the location’s heat and humidity. He is currently the main advisor on climate management to the Fédération équestre internationale (FEI) as the organization prepares for the Tokyo Games in 2020.

“I really started with at looking at the hot end of how horses cope, but you can’t help but get involved in the lower end,” he said. “I’ve done some studies in cold climates as well. For example, in Northern Europe, Scandinavia, Finland, Sweden, you get some pretty cold temperatures.”

Well, That Doesn’t Seem Cold for a Horse

Normally, cold air shouldn’t be a problem for a heathy horse, at rest, walk or even trot to some extent. Evolution has ensured that when horses breathe in through their nose, even cold air, which has a low moisture content, is warmed and humidified by the upper respiratory tract before it reaches the lungs.

However, when a horse is forced to exert himself, he inhales quickly and deeply, and the body doesn’t have time to warm the cold air. The thin layer of fluid that lines the airways evaporates faster than it can be replaced, effectively drying them out, causing inflammation and constriction. An increase in mucous production and thickness further compounds airway restriction. All this potentially damages lung tissues or creates more problems in already compromised respiratory tracts. The impairment may lead to chronic breathing issues.

“And when I’m talking cold, I’m, talking -5° to -10° [Celsius],” said Dr. Marlin. “People will say, ‘But wild horses live out in -30°C.’ Well, they do, but they don’t go cantering around a lot. They don’t do anything like the type of exercise that domesticated horses do. A wild horse will do pretty much 99% walk and a tiny bit of trot and canter. Their lungs aren’t getting that same exposure. Domesticated horses will do a little bit of walk and usually a lot of trot and canter. We’re making them breathe much harder than they would want to.”

An Oklahoma State University College of Veterinary Medicine study, in which Dr. Marlin was involved, suggested the lungs of fit horses under controlled exercise on a treadmill, breathing air from a special delivery system could sustain damage at what many Canadians would consider a fairly decent plus 4°C and 5°C. “We were able to find increased numbers of inflammatory cells in the airways even at those temperatures.” And, still another Oklahoma State study showed horses still had evidence of airway construction two days after exercise at -5°C.

Exercise intolerance and increased nasal discharge following moderate to hard work are likely indications of airway inflammation, as is cough, said Dr. Marlin.

“The way most horse people tend to view cough is that when you take your horse out from the stable and you start riding, most horses cough. And this gets ignored because of the idea that it’s just the horse just clearing its throat or its chest. That’s not normal. Healthy horses don’t cough,” said Dr. Marlin. “If you look at these horses that give one or two coughs when they start exercising, when you scope them, you’ll pretty much always find that they have airway inflammation that needs to be treated. Cough should never be ignored in horses.”

Practical Cold Weather Tips for Horse Care

So, what does this mean for you and your horse? If Canadian equestrians avoided riding in temperatures below 4°C and 5°C, we would barely spend time in the saddle. While riders can wear scarves or masks over their mouths and noses to warm and moisten inhaled air, horses don’t have that option. So, we have to do some risk assessment on their behalf.

Bearing in mind the lower the temperature, the less moisture in the air and, therefore, the greater drying effect on the airways, Dr. Marlin suggests backing off training during truly cold spells. At the very least, keep workouts low-key – perhaps practice groundwork or skills that don’t require a great deal of physical exertion.

Winnipeg, Manitoba bears the (dubious) distinction of having the coldest winter weather of any major Canadian city. Not only does it experience the lowest average temperatures, it also drops to -30°C or below most frequently. Tara Reimer and her family own Cloud 9 Ranch, in Steinbach, about 60 kilometres southeast of Winnipeg, where they offer western and English riding lessons and vaulting. “Lessons continue regardless of temperature,” Reimer said, “However, they are moved into a heated barn and become ground lessons when the temperature is below -30°C.”

The Reimers themselves ride all gaits up to -25°C and walk/trot up to -32°C. But she said, it’s “walk only beyond that. The cold air takes the breath away.”

Dr. Marlin also suggests riding at warmer times of the day and watching certain horses carefully for signs of respiratory distress, especially:

  • Animals with respiratory problems such as equine asthma – also known as chronic obstructive pulmonary disease (COPD), recurrent airway obstruction (RAO) and, more commonly, heaves.
  • Those with a history of moderate to severe exercise-induced pulmonary hemorrhage (bleeding).
  • Aged, unfit and young animals.

Dr. Marlin noted many horses can have even moderate to severe respiratory disease without showing symptoms. Just because a horse is worked hard at canter or gallop and doesn’t cough or show nasal discharge, doesn’t mean it it’s unaffected. “It’s the same as with people. There will be horses that are pretty tolerant of the cold and there will be horses that are sensitive to it.”

Other Equine Cold Considerations

Beyond respiratory concerns, there are other important factors to consider when cold-weather riding. Riders need to increase their horse’s warm up time, as muscles, ligaments and tendons take longer to loosen and limber. “What that means, essentially, is spending more time in walk,” said Dr. Marlin. If you normally do 10 minutes of walk, and five minutes of trot, and then go into the canter, you probably want to be looking at doubling that – 15 to 20 minutes walking, five to 10 minutes trotting. That’s going to help you reduce the risk of soft tissue injury.”

He also advised using a quarter-sheet over your horse’s back end to help him warm up more quickly. Likewise, a slow progressive cool down is recommended, especially for unclipped, shaggy horses. In fact, Reimer said one of the biggest problems they face in winter is drying off sweaty, long-coated horses to avoid chill setting in. “All our horses are kept outdoors, but after evening riding in winter, they often have to be kept indoors just to dry off.”

Another soft tissue consideration, particularly for horses with arthritis and existing soft tissue issues, said Dr. Marlin, is the ground condition. Deep snow may provide great resistance training, but can also put a horse at risk of injury as can hard, frozen ground, which increases the chance of concussive damage. Ice, of course, should be a total no-go zone. And while studs or caulks on horseshoes can increase grip in slippery conditions, there might be a trade-off.

“If we look at horses cantering or galloping on grass or soft surfaces, we see that there is a tendency for the foot to slide. If you stop that, you’re increasing the concussing, jarring type forces. So again, if you’ve got a horse that’s arthritic, or has a tendency to bruise soles or for filled legs, then potentially that’s not going to be helped.”

As with so many things in life and equines, venturing out with your horse in frigid conditions boils down to common sense. If you’re frosty all over and the air is making your own lungs ache, dial back your workout significantly or skip it altogether. Chances are your horse isn’t going to begrudge some extra downtime.

Can Horses Get Frostbite?

Another cold weather concern for some horse owners is frostbite. Click here to learn how to prevent it.