Released November 12, 2008
COLLEGE PARK, Md. – The short answer may very well be “Yes,” however many horses blanketed during cooler months provides more comfort to their caregivers rather than to the animals themselves. Horses have evolved to have an excellent built-in temperature control: a very thick winter haircoat. Horses require between 10 and 21 days to acclimatize to colder temperatures. For instance, on the first day of 35° F weather, the horse may feel cold, but over 10-21 days of similar cold weather, s/he will “get used to it” and be more comfortable.
If temperatures drop and the horse is not used to the colder temperature, you will notice behavior changes including increased use of shelters if available, huddling together in groups with other horses, and lowering their heads and turning their hindquarters into the prevailing wind. These are all activities that help conserve heat. The shivering response will also occur in very cold horses, which generates a pretty substantial amount of body heat, helping to warm their critical internal organs.
Studies in Canada found that for adult horses in cold climates, the lower critical temperature, or the lowest temperature they can tolerate prior to a drop in body temperature, is approximately 5 degrees F, provided they are well-nourished. Given time, any horse, even in Maryland, can adapt to this low temperature. For temperatures lower than that, they will quickly lose body heat and need our help in order to deal with the cold. We can help either by providing shelter, extra forage, blankets or a combination of all of the above. Shelter alone can reduce heat loss by up to 20% through protection from wind and rain!
During cold weather, the horse’s hair stands on end, which creates an airspace around the horse where it can trap heat, enabling it to stay warm. This insulation will break down when the weather takes a nasty turn such as rain or wind – the former causing the hair to lie flat and the latter blowing away the warm air trapped in the upstanding hair. This phenomenon can also happen when a horse is inappropriately blanketed. In other words, when a blanket with inadequate insulation is put on a horse during milder weather, it forces the hairs to lie flat, taking away the horse’s natural insulation.
Here are some simple guidelines that you may find helpful in determining whether or not your horse needs the protection of a blanket:
- Horses that are clipped or kept in barns under light to discourage winter coat production should be blanketed when temperatures drop below 60 degrees F or when it is windy or rainy.
- Horses with a moderate haircoat can tolerate temperatures as low as 40 degrees F and if they have a heavy coat, they can tolerate temperatures down to about 30 degrees F. Wet conditions increase these temperature limits, so keep that in mind when blanketing!
- A horse that has recently moved from a warmer climate may benefit from some external help. Once they’ve spent the 10-21 days being exposed to the colder weather, they will adapt and need less help, but you may find it beneficial to blanket them until the next winter.
- Older horses that move around less benefit from blanketing in colder weather. Moving generates body heat which is why we often see horses’ levels of exuberance rise with cold weather!
- Remove the blanket on a regular basis – check to make sure your horse is not losing body condition, doesn’t have blanket rubs or injuries, and is not developing a skin problem such as rain rot under the blanket.
- When the weather is rainy, check to make sure the blanket is waterproof – you will be fighting a losing battle trying to keep a wet horse warm with a wet blanket! Place your hand under the blanket around the neck – your horse should feel nice and toasty warm and not sweaty under there!
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http://www.agnr.umd.edu/news/article.cfm?id=91f914170a5a5a8f00108c7de5576c4d
Contact: Erin Pittman, pittmane@umd.edu
