What do you need to know to properly care for and feed your horse in the cold winter months? Horses are very adaptable to a wide range of temperatures and are well-suited to living in cold climates.

However, you may need to adjust your feeding and management practices when the weather turns cold to keep up with your horse’s higher calorie demands.

Horses that are overwintered outdoors will need to consume more feed so they can maintain their core temperature without losing body condition.

Generally, the digestible energy requirement for a 500 kg (1100 lb) horse increases by 2.5% of every degree below -15oC (5oF). [1]

Increasing access to forage, feeding gut-friendly calorie sources and providing access to adequate shelter and warm water are key aspects of feeding and managing horses in winter.

Here we will review how to feed horses in winter, taking into consideration their body condition, age, and management practices. For help with optimizing your horse’s winter feeding program, submit your horse’s diet for evaluation by our equine nutritionists.

Thermoregulation in Horses

Like all mammals, horses are homeotherms (warm-blooded) meaning they maintain their core body temperature within a narrow limit independent of changes in the ambient temperature.

When temperatures in the environment fall below a lower critical temperature (LCT) the horse will need to expend more calories to keep warm.

A wide range of LCTs have been reported in horses, but young animals always have a higher LCT.

For a 500 kg mature horse that are adapted to the cold, the LCT is approximately -15oC or 5oF.

Note that each individual horse’s LCT will vary depending on several animal and environmental factors including:

  • Body condition and size – especially the amount of insulating fat
  • Age
  • Health status
  • Reproductive status
  • Coat condition
  • Genetics
  • Shelter availability
  • Blanketing

Below the LCT, they will need to alter their metabolism. It has been found that Shetland ponies actually slow down their metabolism to preserve precious calories in the cold. [19]

In addition to seeking shelter and huddling together, horses will also burn more calories to maintain their body temperature. This is another way of saying they have an increased metabolic rate.

Certain hormones, such as catecholamine and active thyroid hormones, increase in order to make energy metabolism less efficient meaning more is “lost” as heat rather than being used to make ATP for cellular energy. This is known as non-shivering thermogenesis. [21]

How Horses Maintain Body Temperature

There are many physiological mechanisms that horses use to maintain temperature homeostasis, or a stable core body temperature.

For example, horses sweat to dissipate excess heat when it is hot. When it is cold, the following mechanisms can help to preserve or generate heat:

  • Digestion and fermentation in the digestive tract
  • Shivering
  • Altered metabolism
  • Changing behaviour
  • Growing a thicker winter coat

If your horse’s core body temperature drops below 33 – 34oC, mental and physiological functions will be affected.

In extreme cases, poor adaptation to prolonged cold weather exposure can cause severe hypothermia which could result in heart failure. Fortunately, these extremes are unlikely to happen in typical climates and modern management situations. [2]

Cold Weather Adaptations

Horses, like all mammals, have special receptors in their skin and core that sense temperature called thermoreceptors.

During acute, short-term exposure to cold there are several mechanisms that horses can use to maintain body temperature, including:

  • Vasoconstriction: reduced blood flow to the skin and extremities reduces heat loss
  • Piloerection: raising hairs to trap air close to the skin to provide insulation
  • Shivering: involuntary muscle contraction for the sole purpose of generating heat

There may also be changes in behaviour as horses sense the colder temperature including huddling with others, finding shelter, standing downwind, and reducing spontaneous activity.

If exposure to colder temperatures persists, further adaptations come into play to help the horse stay warm, including:

  • Increased appetite and food intake
  • Growth of a dense hair coat for insulation

How effectively horses adapt to prolonged exposure to colder temperatures can be influenced by the management of horses, including their feeding program and proper provision of shelter.

Inadequate management of horses in wintertime can lead to excessive loss of body condition, causing your horse to become underweight. This can put them at risk of health concerns or impact performance in the following season.

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How to Feed your Horse in Winter

The changing seasons give horse owners an excellent opportunity to evaluate how well their feeding programs are meeting the needs of their horses.

Most horses naturally follow a different diet in the winter from the warm summer months, with less pasture access in the winter months.

Activity levels, environment, housing situations, and common health concerns can also vary in winter compared to spring, summer and fall.

Below are seven key considerations for establishing an appropriate feeding program for your horse through the winter.

1) Assess Your Horse’s Body Condition

Your horse’s body condition score is a key metric for assessing how the energy supply of the diet is matching his or her calorie requirement.

The BCS scale provides a way to objectively estimate the amount of body fat that your horse has. Body condition assessments should be conducted year-round but especially in the fall and winter.

The ideal body condition is 5 on a 9-point scale. When body condition scoring a horse in winter, be sure to feel your horse’s ribs, neck, and rump. A thick winter coat can hide weight loss.

Overweight or over-conditioned horses have better adipose tissue insulation for cold weather, as well as greater energy reserves to generate heat. These horses likely have a lower LCT and are less likely to require additional calories in their feed to help them maintain their body temperature.

While providing a benefit for cold tolerance, being overweight can have detrimental health effects, including a higher risk of painful and debilitating conditions such as laminitis and osteoarthritis.

Underconditioned horses have less insulation and will be more susceptible to excess heat loss during cold weather. These horses have a higher LCT, meaning they need extra calories to maintain a stable body temperature.

Blanketing underweight horses is useful to help minimize heat loss and keep them comfortable.

2) Identify health concerns

Regular veterinary checkups can help you identify potential health issues before they become bigger concerns. In particular, if you notice a decrease in body condition, look out for possible contributing factors including:

  • Dental health issues such as EOTRH
  • Metabolic disorders such as Cushing’s / PPID
  • Gastrointestinal disorders
  • Endoparasitism
  • Social and behavioural issues

Senior horses are particularly susceptible to being under-conditioned during the winter months. Ageing affects metabolic processes and gut microbial diversity, which can contribute to decreased body condition. [3]

Dental issues and metabolic disorders are also more prevalent in older horses and may impair their ability to maintain adequate body condition.

3) Estimate Lower Critical Temperature

It is important to be aware of your horse’s Lower Critical Temperature (LCT) and to increase the calories supplied by the diet when temperatures fall below this number.

On average, healthy adult horses of normal body condition that have been acclimatized gradually to winter temperatures have an LCT of around -15oC / 5oF.

Young, growing horses are more sensitive to cold temperatures and have a higher LCT. [1] The following LCTs are estimated for newborn foals and yearlings:

  • Yearling fed free-choice: LCT of -11oC / 12oF
  • Yearling that is limit fed: LCT of 0oC / 3