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Ask the Veterinarian
with Dr. Brent Pugh
How often should I blanket my horse and should I clip his hair coat during the winter?
With cooler temperatures on the way, this fall/winter season, many owners become concerned about their horse’s ability to stay warm. There are several factors to consider when asking yourself “To Blanket or Not to Blanket?” such as health status, intended discipline, and natural hair coat.
Ever wonder why horses tend to buck and play, run and snort more when temperatures are lower? They love the cooler temps and their metabolism is under less stress, as well. Horses, as well as other livestock, have what is called a “thermoneutral zone.” The thermoneutral zone can be defined as: The range of ambient temperature (surrounding environmental temperature) in which a horse is able to produce enough body heat to maintain constant body temperature under normal metabolic demand. This is a characteristic of homoeothermic (warm blooded) animals. This zone is not constant and it can depend on age, sex, and breed, level of acclimatization, weather and feeding practices, even if it is day or night.
A study performed in the 1980’s (McBride et al, 1985) determined this zone for acclimated, mature Quarter Horse geldings to be between 5⁰F to 50⁰F.[i] This means that in this temperature range these horses were expected to produce enough body heat to equal the amount of heat loss without placing additional demand on metabolism. Adult healthy livestock and horses, when adapted and allowed to grow sufficient hair coat, are “metabolically” comfortable in colder temps.
I hope you would agree that horses love colder weather. There are fewer flies, less sweating, and horses do not seem as irritated as they do during the dog days of summer. There is, however, a lowest critical temperature for horses. This is defined as that temperature in which the body cannot generate enough heat to maintain normal temperature. It must then increase metabolism to generate the lost body heat. This concept does not mean your horse will become hypothermic. It means that the body will need to increase metabolic output in order to maintain normal body temperature. For example, shivering generates body heat as well as walking and moving around. I do not intend to mean that just because your horse shivers that it needs a blanket. It’s just the body’s normal response to stay warm.
Nutritional demand will also increase as ambient temperatures come closer to a given horse’s lowest critical temperature. The feeding of hay and higher fiber feeds (complete pelleted feeds, whole oats, and alfalfa/timothy pellets) produces body heat through a process called heat of fermentation. Fermentation is the process of hindgut bacteria breaking down the fiber in hay and feed stuffs during digestion. This produces the beneficial by-product of heat and nutrients for the horse. High starch feeds do not generate this fermentative heat. Therefore, corn, molasses, and sweet feeds do not make your horse “hot.” It may increase their energy and excitability, but does not generate significant core body heat. If you pay close attention to your horses’ hay intake, they will increase hay consumption when the weather is colder, because this helps them to generate body heat through the metabolic digestive process. I will actually save my bales of hay that seem to have more coarse hay for the coldest days. There is a higher fiber content and more heat will be generated during the chewing and digesting process.
A lot of fine stemmed Bermuda grass hay can sometimes cause intestinal impactions in horses during winter. So make sure you don’t suddenly lock your horse in the stall and feed three times the amount of hay normally fed, along with a frozen bucket of water. Remember: gradual sensible changes for your horses.
All this information is relevant to blanketing because hopefully it will help you understand there are other ways to keep your horse warm than with a blanket. But, with all that said we must then enter horse owners into the equation.
As owners we can enjoy a lot of different events with our horses during the colder months such as: trail rides, fox hunting, winter series barrel racing and ropings, and a few rodeos. Many horses are intended to rest and recover over the winter. I cannot provide a scenario for every equine discipline within this article, but I will go back to my basic horse care advice, “keep it simple.” My goal of this article is to help you determine when to blanket your horse and when to remove it. I personally do not even own a horse blanket and cannot remember if or when I have ever blanketed my horses. But, I will be buying one very soon because my geriatric horse just cannot seem to handle cold, wet weather like he used to.
Remember, horses are creatures of habit and do well with what they are used to. In normal situations horses can insulate themselves very well with their natural hair coat if it is allowed to grow. I know there are exceptions to every rule. I have seen many horses that do not put on a thick hair coat and start shivering when the temperatures get cooler. But, in general, most horses cope very well with the coat they have.
As I said in previous articles, remember to provide the option for horses to seek shelter if they so desire and provide plenty of good quality, clean hay and water. Many times I have seen this scenario with my horses: it will be raining and 50 degrees with 15-20 mph winds and they are standing in the pasture with their rumps to the wind, just relaxing. Trust me; they have the choice to get out of the weather. So, I figure they are happy.
There are other factors of “cold weather” to consider when deciding to blanket your horse. Simple examples include the wind, rain, humidity, sun exposure, herd numbers, and hay/water availability. Please take into consideration that your horse is likely warmer outside on a sunny winter day at 20 degrees, than locked in a stall. Just like with the summer heat, if you are more comfortable outside than in your horse’s stall, I’m certain he will be also. I feel that in the Mid-South we do not often reach the lowest critical temperature for most of our normal, healthy horses. For the cases I see and with my horses personally, the coldest days in the Mid-South winter are those days with prolonged rain and wind, giving them no real break. The toughest, in my observation, is about 35 – 40 degrees with rain and a strong, constant north wind. Now that they are older, I will then consider blanketing my horses in that type of weather if they appear to be having a hard time.
A horse’s hair coat is like insulation in your house. It has a great ability to hold heat if not compressed tightly. Blanketing a horse can actually decrease the hair coat’s natural insulation properties. I feel that a horse with an adequate hair coat and shelter is better without a blanket. Imagine wearing a large heavy fleece that is soaking wet when it is cold outside; your horse is cold and you would be as well!
In the normal horse, the hair coat will respond to its demands. If a horse is consistently blanketed early in the cool season, that horse may not grow a full hair coat and more blanket time is warranted. A horse that is body clipped for show or performance purposes will definitely need some blanket and/or stall time to keep the animal warmer. So the answer to when to blanket your horse depends heavily on the horse, its discipline, and the owner’s perception of their horse’s comfort. I strongly believe if you plan to blanket your horse, just look at the weather and plan accordingly. If it is going to be 30 degrees at night and 65 degrees during the day, please take the blanket off that morning so the horse can comfortably enjoy the warm day. If horse owners want to provide the whole natural concept to their horses, then I believe unnecessarily clipping their winter coat and/or constantly wearing a blanket is about as unnatural as it gets.
So to briefly summarize, God made horses to live outside all year long. It is our responsibility as their owners to provide a common sense approach to help our horses adapt to the changes we place on them. Your horse is probably fine without a blanket, in most cases, as long as they have a good healthy winter hair coat, shelter, plenty of good quality hay, access to water that is not frozen (please consider a water tank de-icer), sun exposure, and access to physical activity. If your horse is geriatric, very thin, grows a poor hair coat, or their job requires them to be body clipped, then wise use of a blanket is necessary. Most horses do enjoy cold weather- allow them to do so sensibly.
If you have any specific equine health related questions you would like me to address just email them to email@example.com. Mention if you wish to remain anonymous, otherwise I look forward to helping you understand any health questions you may have concerning our wonderful equine companions. Thank you. Dr. Brent Pugh
concentrations of mature horses in response to changes in ambient temperature. Can. J. Anim. 65: 375-382 (June 1985)
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