Growing up a child of the South, I never expected to live far beyond Atlanta’s warm glow. However, fate dictated otherwise, and I have had to learn to cope with nothern winter weather. During my first winter in New York, I learned just how cold it could get. Although I was lucky since most of my time was spent inside the warm large animal clinic at Cornell University, if I ventured outdoors for more than a few minutes, I had a rude and often painful awakening. The burning, aching, and tingling of feet and ears that were dangerously cold became common companions. I was told often that this feeling was the early stages of frostbite, and I wondered how my equine friends could last all day and night outside and I could only last 10 minutes. Why did unprotected hooves that lived in snowbanks for five months of the year not freeze and slough right off?
Although frozen water buckets are often the biggest concern for horse owners in Northern climates, frostbite is also a potential threat. How do you protect your horse from frostbite? Which horses are most at risk? How can you tell if you horse has frostbite, and what should you do if you think your horse or foal has frostbite? Just how serious is it anyway? In this article we’ll cover all these questions and more.
What Is Frostbite?
Frostbite can be defined simply as the freezing of the skin and/or the tissues underneath the skin, such as tendons, fascia (sheets of connective tissue covering or binding together body structures), or even muscle. Obviously, the deeper tissues are frozen, the more severe the frostbite. What I and most other people experience when their skin or extremities become very cold is frostnip. Frostnip is when the skin turns white and tingles. As the skin is warmed, it becomes red.
Because horse skin is often pigmented and covered with hair, it can be difficult to see the skin turning white (blanching) as the tissues become too cold. Frostbite occurs when those cold tissues are not warmed and the cells freeze. The frostbitten skin will then turn an “ugly” white or bluish color and begin to swell within several hours to a day. A line of demarcation — a line separating normal and frostbitten skin — will also become obvious. The abnormal skin might have blisters.
As the damaged skin dies, it will turn dark and eventually slough. The frostbitten skin will not have any feeling. There is no saving skin that is frostbitten; it must slough on its own or be surgically removed (debrided). Fortunately, most cases of frostbite are very superficial and little skin is lost.
Although frostbitten hooves are very serious, this doesn’t occur often. We do not understand the phenomenon completely, but the horse’s hoof seems to play a protective role against the cold. It can tolerate very cold temperatures without developing frostbite.
What Horses Are At Risk for Frostbite?
The risk of frostbite is determined by several factors, such as:
- Length of time the area (skin) is exposed to the cold;
- Temperature, including the wind-chill factor;
- Moisture — if the exposed skin is wet, the chances of frostbite are greatly increased;
- Age and illness.
In people, the elderly and very young (infants) are particularly at risk for frostbite. This is true of horses as well. Neonates (horses less than one month of age) are most susceptible, as they have don’t have many fat stores to keep them warm in the bitter cold. Like older people, older horses (over 20 years old) might have health issues that create poor circulation, or poor body fat stores that don’t allow them to stay warm.
Healthy, well-fed horses are not likely to develop frostbite. This is because horses, like cattle, create a large amount of internal heat or body heat from the normal way they digest their food. The fermentation process of breaking down roughage into energy can be likened to an internal furnace.
Contrary to popular belief, by digesting hay horses can produce 10 times the amount of body heat they produce when digesting grain. That is not to say horses don’t need grain during the winter, just that they can much more effectively produce body heat when digesting hay. Therefore, horses which have a constant supply of good-quality hay and adequate protection from the wind and weather during the winter are unlikely to develop frostbite. However, when it does happen, it most commonly develops in the extremities (lower parts of the legs, ears, or even the tail).
A Serious Medical Condition
Frostbite is very serious, as it can permanently damage and/or deform affected areas. In people, it can require amputation of a limb. In horses, it can cause sloughing of the hoof wall and warrant euthanasia.
The reason frostbite is so serious is the way the tissues are damaged by freezing. As the cells of the skin, underlying tissues, and even red blood cells are frozen, the fluids inside and between the cells crystallize. These ice crystals cause the cells to rupture or burst. Small blood vessels can become blocked and thus do not supply the tissues with oxygen. Even when the area is warmed again, the ruptured cells can’t repair themselves, so these areas of the skin, and possibly deeper structures, will die. As a result, frostbite often results in a large amount of skin cells dying and skin or even hoof sloughing. Sloughing of hooves is most often a fatal event, and large amounts of skin loss can be life-threatening due to secondary infections.
Luckily, the most common location that frostbite occurs is on the tips of a horse’s ears. Most people don’t realize that a horse has been frostbitten until the tip of the ear falls off, often several days to a week after the actual frostbite. Frostbite in this location is obviously not life-threatening, but is cosmetically unappealing.
The severe forms of frostbite I have seen occurred in newborn foals which arrived unexpectedly. These foals were born wet in very cold temperatures and did not have the energy to warm themselves so soon after being born, much less stand and nurse. These foals often have large areas of skin affected. In addition, they often have some degree of failure of passive transfer of antibodies (they did not get enough colostrum), so they rapidly become ill as the large areas of skin loss allow bacteria access to the foal’s body. Depending on the severity of the frostbite, some of these foals require very intensive care in order to survive.
Treatment of frostbite can’t begin unless someone notices that frostbite has occurred. However, identification of the frostbitten area can be difficult for the reasons stated earlier. The subtle change to a lighter shade of pale, which signifies the earliest stages of frostbite, can be difficult to see. However, as the tissue begins to die, the affected area will begin to swell and turn dark and very hard, similar to leather. Large areas that are frostbitten and thawing are quite painful, so the horse might paw, shake its head, or bite at the area. Eventually, the leathery tissue will slough off, and the horse is left with exposed, bleeding tissue.
If you do identify a frostbitten area, the tissue must be handled ever so gently; rubbing the area to warm it will only cause more damage! Your veterinarian should assist in treatment, and he/she can administer medication to help the process. Rapid thawing, although more painful than slow thawing, has been shown to be the most effective method. So, water that’s warm to the touch, not hot water, should be used. Apply warm water via a wet towel, or if possible you can submerge the area in a bucket of warm water.
Hair dryers are typically not recommended, as it’s tough to control the amount of heat they create. Most importantly, the frostbitten areas must be prevented from re-freezing. Subsequent freezing of these damaged tissues leads to even more dramatic damage to the horse’s skin. So, thawing frostbitten skin should not begin until the horse is in an area where he will not be subjected to freezing temperatures again.
Under the direction of your veterinarian, horses with frostbite will immediately receive some form of an anti-inflammatory such as phenylbutazone (Bute) or flunixin meglumine (Banamine) to help control the pain and inflammation involved with frostbite. As stated earlier, thawing of the frozen tissues is quite painful, and some horses might need to be sedated. Horses that are not current on their vaccinations might also need a tetanus booster.
In addition, some horses will have to be muzzled and bandaged to prevent them from damaging the area further. The tingling sensation of thawing damaged tissues can cause some horses to bite at their wounds. Because the lower legs of horses do not have much extra skin, frostbite in these areas often leaves ugly scars. However, horses which just lose an ear tip can have the ear cosmetically repaired via surgery.
As the adage goes, an ounce of prevention is worth a pound of cure — frostbite is much easier to prevent than it is to treat. As stated earlier, healthy horses which are provided with good-quality food and adequate shelter that allows them to stay out of the wind and avoid getting wet or overly cold are not likely to develop frostbite.
This does not mean that horses must be stabled all winter and never allowed to set a hoof in the snow. For most horses, a suitable run-in shed or wind break is all that is needed to prevent them from getting too cold. Horses with long winter coats usually do not need heavy blankets that compress the hair and decrease their ability to keep themselves warm. Horses are more comfortable in cold weather than humans, and they do very well in ambient temperatures just below and above freezing.
Horse left outside all winter should be monitored several times during the day to ensure that they are not in trouble, especially those horses left in temperatures well below zero degrees Fahrenheit (don’t forget about the wind chill). It goes without saying that mares which are nearing foaling should be brought inside at night so they can deliver in a warm, clean stall and be monitored closely.
If these simple precautions are followed for your horses, then you can prevent winter’s cold bite.
Provost, PJ. “Frostbite.” Equine Surgery. Eds. Jörge Auer and John A. Stick. WB Saunders, 186, 1999.
King, Marcia. “Frostbite: Is Your Horse at Risk?” The Horse, February 1998, 49-51. Article #440 at www.thehorse.com.