Equine Winter Wellness Tips

Understanding the Thermoneutral Zone

The thermoneutral zone (TNZ) is the range of outside temperatures at which the horse can maintain its internal body temperature without changes in metabolic heat production or evaporative heat loss. In other words, extra energy is not needed by the body to maintain body temperature in a normal range. The upper critical temperature (UCT) is the highest ambient temperature a horse can withstand before processes in the body start to cool itself down, like sweating. The range for UCT can vary depending on each specific horse and can range from 68℉ in horses adapted to colder temperatures up to 86℉ for horses acclimated to warmer temperatures. The lower critical temperature (LCT) is the opposite, and it is the lowest ambient temperature the horse can withstand before it needs to generate heat to maintain its body temperature. These numbers vary depending on climate, age, body condition, hair coat, shelter, blankets, and health status. The LCT has been found to range anywhere from when acclimated to cold weather up to 40. Knowing your horse’s LCT is helpful when caring for a horse in the cooler months. When you see a horse shiver, it is a good indication that the LCT has been reached.

Shelter

Horses can comfortably withstand a wide range of temperatures, depending on the weather the horse is acclimated to. According to Pennsylvania’s animal welfare laws, an equine owner or facility must provide "access to clean and sanitary shelter which will protect the animal against inclement weather and preserve the animal’s body heat and keep it dry" (§ 5532. Neglect of animal). This type of shelter can be a 3-sided run-in shelter, a barn or other fully enclosed area, or even a tree line that provides a dense canopy and a break from the weather. Indoor stalls need to be cleaned daily and have adequate ventilation to reduce dust, moisture, stale air, and mold that can harm your horse. It is also essential to be mindful when feeding high protein feeds and hay, like alfalfa, because higher levels of urea will be excreted, creating a harsher smell in the barn that can damage the horse. Heated barns still require adequate ventilation to alleviate the amount of condensation that can build up causing mold and reduced air quality and provide fresh air to the horses. Outdoor run-in sheds may not need to be cleaned as frequently as indoor stalls, but it is a good idea to check weekly or monthly and remove manure if needed.

Blanketing

A big question for many horse owners is whether to blanket or not, and the answer is dependent on the situation. Before a blanket is put on, ask yourself a series of questions: what will the weather be? Will there be any precipitation? What is the haircoat like? What is the body condition? What is the size, fit, and thickness of the blanket? These questions will help when deciding if a blanket is appropriate.

Blanketing Considerations

The TNZ for a horse and a human are different, with the human LCT around 70℉ and the horses’ LCT ranging from 5℉-40℉. Horses can generally comfortably withstand colder temperatures than people. The horse has multiple physiological responses to keep themselves warm. One such response is piloerection. If you have ever looked out at your horse and their hair coat is fluffed up, you are watching a physiological response called piloerection. This is when the hair stands up and traps air against the body, creating a layer of insulation around the horse, like when a human gets goosebumps. Piloerection can be affected by moisture, mud, or ice; if the hair is wet, it cannot stand up, and the insulation layer is not created. Strong wind can also negate the insulating effect of piloerection. Trace clipping is very popular in the cooler months to make the cool-down process after exercise easier. However, this hinders the warming benefits of piloerection, and a blanket becomes necessary depending on the type of clip.

Fat can be used as a source of heat for the horse. In lower body conditions, when horses have minimal fat (Henneke body condition score of less than 3, potentially 4), a blanket should be provided because the fat reserves are not available to generate heat. Age and health status can be another reason to provide a blanket. Senior, young, or sick equids may not be able to maintain body temperature as well as a healthy adult. Horses can tolerate a wide range of temperatures, but it typically takes around three weeks to adapt to a new environment when relocating. If your equid is from a warmer climate and recently relocated, their haircoat will not be thick enough to provide adequate warmth, and a blanket will be needed.

Blanketing Tips

There are several different options for blankets available. When choosing the thickness of the blanket, the most important thing to consider is the outdoor temperature, wind, and precipitation for the period the blanket will be on. A sheet with no fill will lay down the haircoat of an unclipped horse and prevent piloerection without providing any insulation. As temperatures approach the horse’s LCT, then blankets with some degree of fill should be chosen. Be careful not to over-blanket; if the horse becomes too warm, it will sweat and may develop skin problems like rain rot. Make sure to check under the horse’s blanket daily. A horse may need different blanket weights throughout the day and night as temperatures fluctuate. If the blanket is worn in wet weather, make sure it is waterproof. Repeated laundering may destroy the waterproofing on blankets. Be aware of the fit of the blanket, as well. A blanket should not rub or leave marks while it is on and should not fit too big or too small. An improper fit can cause more harm than good. A blanket should also be fully dry and put on a dry horse. If not, the moisture is trapped under the blanket, not warming the horse. When used correctly, a blanket is a great tool that can be used to ensure the well-being of your horse.

Water

Colder temperatures can make managing horse water consumption difficult. Typically, the average, idle horse at maintenance will consume a minimum of 6 gallons of water daily and more depending on the weather and amount of work. In the warmer months, horses on fresh pasture may get some of their water needs from forage, but it is still necessary to provide fresh water. In the winter, dried forage (hay) provides much less water, so monitoring water intake is important.  Impaction colic caused by a reduction in water consumption becomes a major concern. Decreased water consumption can happen because of frozen buckets, cold water temperature, or horses not drinking.

Water Temperature

It is important to frequently check water heaters to ensure they are working correctly and that no stray electricity is on the surface, preventing drinking. It has been found that horses prefer warmer water, in the ranges of 45℉-65℉, over colder temperatures, even after exercise. An electric tea kettle can warm a bucket of cold water quickly but test the temperature to ensure the water is not too hot. When a power source is unavailable, breaking and removing the ice from the buckets at least twice daily is essential. You can provide some insulation to water troughs by wrapping them with blankets or straw to try and reduce freezing. Depending on the location, the amount of snowfall will vary. Some horses will consume snow, but it has not been found that enough is consumed to meet the daily water requirement. Fresh, clean, unfrozen water must always be available to meet hydration needs. 

Salt and Electrolytes

Water consumption can be encouraged by increasing salt intake. One way is to add a plain salt block to their stalls or close to their water source. However, only some horses will use a salt block. To ensure that salt is consumed, 1-2 tablespoons can be supplemented to the daily feed ration to promote drinking.  An electrolyte supplement can be provided for horses still in work throughout the winter and sweating regularly. However, it is more economical to add plain salt to the diet. Lastly, it is not recommended to add salt to the water. A fresh, clean source of water should always be available.

Nutritional Management 

A horse’s daily diet typically should contain 1.5-2% of their body weight in forage. Horses are hind gut fermenters, meaning that the microbes in the large intestine and the cecum work to break down the fiber portion of the ration into usable nutrients via fermentation. The process of fermentation generates heat as a byproduct. The average 1,000-pound horse requires 15 to 20 pounds of high-quality forage per day, but that can be increased by more than 25% in the colder months for horses living exclusively outside. A good rule of thumb is to increase the forage by 1% for every degree below their LCT. To break down the increase, that same 1,000-pound horse living outside with an LCT of 18℉ would need an extra 4-6 pounds of hay if temperatures were 15℉.

Forage Tips

Feeding for warmth is not necessarily about adding extra calories, but providing more fiber so the horse can generate more heat. However, feeding extra when the horse is still in the TNZ can cause weight gain from the additional calories that are not being utilized. Since fermentation creates heat as a byproduct, long stem, chopped, cubed, or pelleted forages are more fermentable than a basic concentrated feed. The added calories can be difficult when managing horses on strict diets or those with metabolic conditions. Hay can be soaked to reduce the overall nonstructural carbohydrate levels, or lower quality hay with lower digestible energy or higher acid detergent fiber can be supplemented to reduce overall calorie intake but still gain the benefits of the fermentation process. The energy expended to stay warm in the winter months can also jumpstart weight loss in obese horses.

Conclusion

Horses are adaptable animals and generally handle the colder months well. A few considerations, like shelter, blanketing, water monitoring, and additional forage by the owners, can help keep them happy, healthy, and warm during the winter.

References

Rutgers University. "Winter Care for Horses"

University of Minnesota Extension. "Caring for Your Horse in the Winter"

Kristula, Michaela A., Sue M. McDonnell. "Drinking water temperature affects consumption of water during cold weather in ponies". Applied Animal Behaviour Science, 41,3–4.