Though rare, frostbite has potential implications in horses
- Last Updated on Saturday, 05 January 2013 00:00
Frostbite is not as common in horses as it is in humans, or even in cattle.
Horses have a tremendous cardiovascular system and also have some special adaptations that enable them to stand for hours in deep snow during cold weather, without freezing their feet.
Horses prevent frostbite
Frostbite in healthy horses is quite rare. They handle cold temperatures much better than humans do; the horse’s body is actually better at conserving heat in cold weather than dissipating it in hot weather.
As summer turns to fall, they start shedding his short summer hair and growing a longer, denser hair coat. As nights start getting cold, his metabolism begins to change also, enabling them to store more fat under the skin for insulation – making it more difficult for heat to escape from the body and providing insulation against the cold. The layer of fat requires very little energy to maintain and has few blood vessels. The surface vessels that radiate heat in summer draw back, deeper under the skin, in winter.
Humans tend to get frostbitten toes, fingers and noses in severely cold weather, but horses rarely suffer frostbite.
The horse’s muzzle is richly supplied with blood and can withstand extreme cold without freezing. Their feet and legs are designed in such a way that they can stand in deep snow during extreme cold without discomfort or damage. A horse’s slender legs are mainly bone and tendons below the knees and hocks, requiring less blood circulation than muscles and are thus less susceptible to frostbite.
Tissue cells in bones and tendons need less blood for maintenance and also lose less heat. The horse is able to shunt most of the blood away from his feet and still have a very functional foot. When their feet start to get cold, the shunts open up so the blood can flow from the smallest arteries directly into the veins without having to pass through the smaller capillaries.
Thick eyelashes protect horses’ eyes from winter wind and cold temperatures. The mane and tail also give protection. If the wind blows, they instinctively turns their back to it, protecting his thin-skinned face and neck, which have more surface blood vessels. The rump and back have thicker skin and hair, fewer surface blood vessels and can withstand the wind better.
The tail protects his more delicate underparts, and his mane and forelock give insulating (and waterproof) protection for his head and neck. Horses in groups stand close together to block the wind and also benefit from each other’s body warmth.
Rare frostbite occurances
Occasionally, however, extreme cold or an abnormal situation – such as a horse that’s very sick or in shock, or dehydrated, can lead to frostbite.
In adult horses usually the only sign of frostbite is loss of ear tips.
Foals born outside in cold weather may be more adversely affected, since they are wet at birth and have very little body fat for insulation.
Cid Hayden, DVM, an equine veterinarian in Salmon, Idaho, says that we see a lot more frozen ears, tails and feet in calves than in foals, mainly because horses are seasonal breeders and most foals aren’t born until milder weather of spring or summer.
“In order to have foals born in the middle of winter, you have to go to extreme lengths to manage those mares – with artificial lighting, etc. – to breed them that early. Anyone that goes to that effort will generally make sure those foals are born in a barn, with a 24 hour watch on them. Because of this, we rarely see a foal with frostbite,” he says.
“I have seen some horses, however, that may have suffered a little frostbite in their feet, when it was 30 below zero for a week or two and they were standing in six inches of snow. Those were horses that had no shelter. The way we dealt with those was to find a more sheltered area, such as in some trees, and scraped all the snow away, piling straw on the ground. If they can stand under trees and have some protection for their feet, they will do fine,” says Hayden.
In general, however, horses usually do fine outdoors even in severe weather. “Horses tend to move around more than cattle and also tend to seek shelter during a storm,” he says.
They also stay on their feet more than cattle do (they aren’t lying around most of the day, chewing the cud) and are less vulnerable to being chilled by lying on frozen ground.
“Signs of frostbite include tissue with no sensation, such that the animal wouldn’t be able to feel a pin prick, loss of flexibility of the skin, and then it turns black. Of course on a horse you can’t see the blackness unless it’s on an area of pink skin. It usually occurs on extremities, like ears, tail and feet. The skin then becomes hard and stiff, and eventually sloughs away,” says Hayden.
“If someone brings me a horse with signs of frostbite I would immediately start that animal on antibiotics and anti-inflammatory drugs,” he says.
Non-steroidal anti-inflammatory drugs can help reduce the pain and inflammation, and the antibiotics would help prevent infection. The horse would be at risk for infection in the dead and dying tissues.