It doesn’t happen very often, but horses can freeze to death. Horses are well suited to keep themselves warm, but hypothermia can happen. Old horses, very young horses, and sick horses are most likely to become hypothermic, and when they do, hypothermia for horses is usually fatal.
What is Hypothermia for horses?
Hypothermia happens when the horse’s body can’t keep itself warm. Eventually, the core temperature drops. Usually, healthy horses don’t get hypothermic- they’re evolved to live in cold weather. Most horses love cold weather!
Instead, hypothermic horses usually have an underlying problem, like colic, tooth problems, or a hormone imbalance. Unsheltered newborn foals and neglected older horses make up a large percent of horses that freeze to death each winter.
When a horse’s electrolytes (salts like sodium, chloride, and potassium) or blood sugar are out of balance, they are more prone to hypothermia.
How Horses Stay Warm
Horses are really good at insulating themselves and generating heat. Still, horses lose a lot of body heat when the weather is bad- even more if it’s wet or windy.
five factors affect how cold a horse can tolerate before they freeze to death:
- temperature outside
- how moist the air is (humidity)
- if it’s raining, snowing, or sleeting (precipitation)
- wind speed
- and if the sun is out (solar radiation)
The temperature is the most important of the five factors that produce hypothermia, but all of them play a role.
Wind makes horses cold, which can stress their bodies. Rain makes it easier for the horse’s body to lose heat through evaporation and through convection (that’s when warmth from the body moves out and warms up the rain on the outside of the body- just like how horse coolers work to cool off sweaty horses).
Wet fur is less able to keep a horse warm because it can’t “puff” up and trap air to help keep the horse warm.
Snow vs Rain: Which is harder for Horses to Stay Warm?
You might be surprised to learn that for most horses, a cold rain “feels” colder than snow. This is because horses have a thick winter coat that keeps the horse’s body heat in and keeps horses from freezing to death. It works so well that often horses have a layer of snow on their back, unmelted! Seeing snow on a happy horse’s back is actually a sign that the horse’s fur is doing a good job insulating its body.
A horse’s coat is really good at trapping heat close to the body. The coat is made up of two types of hair- long, thick guard hairs and shorter, thinner undercoat hairs. The undercoat hairs are really good at trapping heat (and for getting stuck to everything during shedding season!)
When Horses become Hypothermic
Fatal hypothermia for horses, aka “freezing to death” is rare. If horses have access to a windbreak, drinkable unfrozen water troughs, and food to eat (digestion produces heat, for horses) a healthy horse will not become hypothermic even when it is very fold. However, when a horse is hypothermic, the outlook is usually bad.
Unfortunately, it is very hard to tell when a horse is beginning to freeze to death. But here are some signs a horse is dangerously cold:
Their Temperature is under 86 degrees: As soon as the animal’s body core temperature drops to 86 degrees Fahrenheit or less, it is considered to be hypothermic- but that’s not always a measure available when a horse owner does checks on a horse on a cold night.
They won’t shiver. Because a hypothermic horse will have lost the energy to shiver, it won’t appear to be shivering.
The horse may seem depressed or slow to respond. The horse may look depressed when it is in this state, with slow breathing, less muscular activity, and slow reflexes. Having less blood flow causes hypoxia (lack of oxygen) and the heart rate slows down.
Keeping Winter Foals Warm:
When foals are born, they are often low on glucose and potassium. They should be warmed by protecting them from wind and drafts, drying them, and making a small area in a barn with a bit warmer temperature. With or without extra heat, you should use thermal blankets to keep their body warm. You should put them in an insulated stall without direct heat. Direct heat can actually make hypothermia worse. Because it makes blood flow faster at the skin level, it draws bloodg from the core and can worsen cause hypothermia and cause heart failure.
How to Help a Horse that is Freezing to Death
To help horses that are hypothermic, call your veterinarian immediately. In the meantime, monitor their body temperature and heart rate until the vet arrives. Your vet can provide the best care, since preventing the death of a freezing horse can be done through skilled warming, heart monitoring, and keeping enough blood flowing in the horse’s body (IV fluids). Potassium problems are common, and they can happen quickly.
Some horses may get worse during the warming process, which is why it’s important to be in contact with your vet when caring for a horse you only suspect might be freezing. During the warming process, provide food and drink that have been heated to body temperature- no warmer or colder.
Avoid major temperature changes, like bringing a horse from sub-zero temps into a cozy heated room, since uneven warming can cause skin blood vessels to dilate and draw blood away from the struggling heart. Instead, your vet may provide gently warmed air via an oxygen mask, lavage, or other gentle warming.
How to Prevent Hypothermia in Horses
The best way to prevent hypothermia is to make sure your horse has a warm, dry shelter to stay in during cold weather, with water and forage. If you can’t provide a shelter, at least make sure your horse is wearing a blanket. Hay helps horses generate heat, and it’s especially important for horses that are unable to move around much to stay warm.
Finally, pay attention to your horse’s behavior. If they seem unusually cold, lethargic, or uninterested in food, it could be a sign of hypothermia. Contact your veterinarian right away if you think your horse may be hypothermic. Hypothermia, or “freezing to death” is a serious condition that can be fatal to horses, but fortunately, it is preventable. By providing your horse with a warm shelter, plenty of hay, and paying attention to their behavior, you can help keep them safe and warm all winter long.
References for this article include:
Cecilie M. Mejdell, Knut Egil Bøe, Grete H.M. Jørgensen, Caring for the horse in a cold climate—Reviewing principles for thermoregulation and horse preferences, Applied Animal Behaviour Science, Volume 231, 2020, 105071, ISSN 0168-1591.