What is Frostbite?
Horses are better equipped to handle cold weather than humans and frostbite is rarely a problem for most equines. When frostbite does present a problem, it often causes loss of tissue and physical disfiguration and can become infected if it is not properly addressed. Newborns who are born outside when it is cold out are at particular risk of severe frostbite as they are generally wet when born and stay lying on the ground longer. Certain toxins found in molds and mildews can increase the chance that frostbite develops.
Frostbite, although not common in equines, can still cause loss of tissue and dangerous infections when it does occur, and should be addressed quickly.
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Symptoms of Frostbite in Horses
The symptoms of frostbite are difficult to see with horses as they are often obscured by hair. The area that is frostbitten initially loses both flexibility and sensation. Due to the lack of blood to the area, the tissues die and turn black, although this may not be as visible on dark skin. If left untreated, the skin becomes hard and leathery then falls off. The skin that grows over an area of frostbite often loses pigmentation. Severe cases of frostbite may have additional symptoms like depression, unwillingness or inability to stand, body temperature under 97 degrees, and a weak and rapid pulse.
- Leathery skin
- Blackened areas of skin
- Loss of flexibility of frostbitten area
There are a few areas on the equine body that are more susceptible to frostbite than others.
- Ears - The tips of the horse’s ears are more likely to be affected by frostbite than any other area of the body; frostbite on the tips of the horse’s ears frequently causes the tips to fall off
- Lower extremities - The lower legs have very little fat or musculature, making them somewhat more prone to developing frostbite than the more fleshy portions of the body
- Tail - In cold weather, most horses will turn their backs to the wind allowing their hindquarters and tail to absorb most of the cold. As the tail itself has very little fat, it can become a target for frostbite as well
Causes of Frostbite in Horses
- Age - Both young foals and senior horses are more susceptible to frostbite; foals that are born outside in cold weather are particularly at risk as they are wet when they are first born
- Illness - Illness can also make horses more prone to frostbite by encouraging the animal to spend more time on the ground or less mobile; some illnesses also contribute by reducing blood circulation and overall body temperature
- Improper housing - Poorly designed shelters, although intended to protect horses, may actually cause more harm than help; inadequate ventilation can cause too much moisture to collect, or cause the horse to sweat, increasing the likelihood of frostbite or even hypothermia, and dirty or moist bedding in the winter can lead to frostbite
- Toxins - Certain toxins, like some mycotoxins, can cause the blood vessels to contract; this reduced blood flow can make frostbite more likely
Diagnosis of Frostbite in Horses
As frostbite is rare in horses, the veterinarian will also want to evaluate the overall health status of the patient to determine if there is an underlying condition exacerbating the situation. The veterinarian will address the area of frostbite first, checking to see if there is any blood supply or sensation to the area. A Doppler ultrasonography may also be used to determine the amount of vascular flow to the area. After evaluating the damaged area, the examiner will perform a full physical inspection, paying close attention to the horse’s horse’s temperature and heart rate.
This will include standard blood tests like a biochemical profile and complete blood count. This will help confirm if any toxins or diseases are present that may be contributing the problem as well as ensuring that no chemical imbalances are occurring. This combined with a urinalysis will also be able to help the veterinarian assess the functioning of the kidneys and the liver. The dysfunction of these organs may cause loss of weight that can predispose the horse to develop frostbite.
Treatment of Frostbite in Horses
Anti-inflammatory medications will be recommended in almost all cases of frostbite, to mitigate the pain and inflammation. Frostbite that goes unnoticed until after it has warmed usually requires surgical removal to ensure that all of the dead tissue is removed and the wound is adequately addressed. With frostbite that has occurred recently, when the tissues are still frozen, the primary goal of treatment is to warm the area safely. It is essential that the area is warmed without rubbing the damaged tissues at all. A blow dryer is also a poor choice to warm the area as it tends to create inconsistent heat.
The most commonly used method to warm the tissues is to surround the area in warm, but not hot, water; using either a bucket or warm wet towel. This causes rapid warming of the tissues and may be quite painful for the patient. Many veterinary professionals prefer to sedate the horse during the procedures, for the safety and comfort of both the patient and doctor. Once the area has been thawed any dead tissue that remains will need to be removed surgically. Topical treatments such as anti-inflammatories, aloe vera gel, and even nitroglycerin (to increase blood circulation to the area) may be recommended during healing of the wounds.
Recovery of Frostbite in Horses
The prognosis of frostbite depends somewhat on where it is, how extensive the damage is, and how long the frostbite damage has gone untreated. Newborns who develop frostbite usually have large areas that are affected and typically require extensive treatment in order to recover. In the majority of adult cases, the final damage is mostly cosmetic, with missing ear tips and large scars being common.
In more severe instances the frostbite may cause damage to deeper tissues and muscle weakness can be the result. Infections in the damaged tissue can become lethal if sepsis develops. Frostbite is often prevented by providing windbreaks and open sheds for horses that are kept outside, ensuring proper ventilation in any stabling, and make sure that newborn foals are kept warm and attended to promptly.