Older horses or animals that are sick or injured are more prone to frostbite and need additional care. Photo: Christina Weese.

Preventing frostbite in horses

Frostbite isn’t a common medical issue in horses, but under extreme temperatures, a horse’s body decreases the blood supply to its extremities — such as ears, genitals and feet.

By Dr. Valentina Ragno
Frostbite and hypothermia are often reported in donkeys and miniature horses whose smaller size makes them more vulnerable to cold. Photo: Christina Weese.

As a result, fluid in the cells of these body parts forms ice crystals that break or harm cell membranes and cause permanent damage.

The risk is always greater in extreme cold, especially if a horse has no shelter from the wind. Wet conditions are the worst. There’s a higher risk of frostbite if a horse gets wet from rain or from sweating and is then exposed to low temperatures. Standing in mud is also conducive to frostbite, even though horses can stand in snow without any ill effects.

What areas of the body are commonly affected?
The most typically affected areas are the tips of a horse’s ears. In males, the penis can be affected if it’s dropped for an extended time. The feet may also be affected, particularly around the coronary band where the hoof meets the skin.

What are some of the risk factors for frostbite?
Older animals are more susceptible to frostbite, possibly because of other issues such as arthritis that prevent them from moving around. Although newborn foals are also vulnerable, they’re not generally born in the winter. Horses that are sick with other conditions – for example, if they are lying down due to colic or an injury – can be very prone to frostbite and hypothermia, a potentially fatal condition in which the whole body is below the ideal temperature range.

A horse that is thin or in poor physical condition is predisposed to frostbite. Having a healthy layer of fat as well as good nutrition during the cold winter months is essential for prevention.

Size can also be a factor. Miniature horses and donkeys tend to have more frostbite and hypothermia problems, partly because they’re closer to the ground and because their ratio of body surface to body weight is greater. Moreover, donkeys did not evolve to live in very cold climates. Endocrine dysfunction has also been hypothesized to underlie miniature donkey hypothermia.

Certain medications, particularly tranquilizers and sedatives, cause a horse’s penis to drop for an extended time so that it’s unprotected by the sheath and more vulnerable to frostbite.

Mouldy feed or hay can produce certain mycotoxins that constrict the peripheral blood vessels, impairing circulation and increasing the risk of frostbite to extremities.

How can a horse owner check for signs of frostbite?
Do a daily inspection, especially during extreme temperatures or during weather where there’s a combination of wind, precipitation and cold temperatures. Look for an obvious distinction between normal and frostbitten tissue as well as pale areas indicating a lack of blood supply. If you suspect a problem, gently feel the area. At a later stage, clinical signs of frostbite include inflammation or swelling, followed by patches of red or black, scaly skin.

How should frostbite be treated?
If possible, bring the animal into a warm shelter. Soak a towel in warm water that’s slightly above body temperature (around 40° Celsius) and apply to the affected area. Do not rub or use a hair dryer.

Call a veterinarian to determine the extent of the damage and prescribe any necessary medications. The clinician may conduct a physical examination and take blood tests to determine any underlying conditions that have increased the animal’s vulnerability to frostbite.

Prescribed medications may include a non-steroidal anti-inflammatory drug (NSAID) to reduce pain and inflammation and an antibiotic ointment to prevent infection of a relatively small area. In more severe cases, the horse may need a systemic antibiotic to control infection. The veterinarian may also prescribe a medication to prevent blood clotting. Surgery is needed to remove any dead tissue that does not slough away.

What steps can be taken to avoid frostbite?
Horses need more TLC during cold weather. If possible, keep them in the barn on extremely cold, windy days. Ensure your barn is well ventilated to prevent the animals from sweating and to avoid airway irritation from an ammonia buildup in the air. Being outside and free to move is equally good for horses that are used to it, but be sure to have a shelter available.

If a barn isn’t available, provide shelter so your horses can protect themselves from the cold, wind and any precipitation. Three-walled shelters that break the wind provide adequate protection.

Provide special accommodations such as blankets for older horses or those with underlying conditions. Always use blankets for horses that have moved from a warmer area and haven’t had time to acclimate to the cold. It is important to check under the blanket every day to detect any sweat or skin lesions.

Ensure your horses get adequate nutrition, and increase their rations during cold spells. High fat supplements or vegetable oil can be offered to increase caloric intake. Increasing forage is also important since the act of digesting hay itself produces an important amount of heat. Do not feed hay or feed that looks or smells mouldy. You can submit your feed for nutritional analysis to ensure that it’s adequate and does not contain mycotoxins.

Provide your horses with constant access to a heated source of water during cold months. Drinking less can predispose them to impaction colic, and dehydration affects the movement of blood through the peripheral tissue, increasing the risk of frostbite.

Be aware of any medications that cause a stallion or gelding to drop its penis for an extended time. Ensure that the animal is kept warm until the penis retracts.

While frostbite isn’t commonly seen in horses, it can be extremely painful and can cause permanent, extensive damage as well as infection. By taking extra care and being more vigilant of your horses during cold weather, you can protect them from the painful complications of frostbite.

Dr. Valentina Ragno is a clinical associate and member of the Equine Field Service team at the WCVM Veterinary Medical Centre. Click here for more information. Reprinted with permission from Horse Canada.