Adjusting To the Seasons:
Can Horses Read A Calendar?

By Lori Hall-McNary

In the summertime, a horse’s coat is sleek and shiny. Your hand will slide over the hair of a well-groomed horse just like smoothing a velvet bedspread.

Northern winds puff frozen droplets of winter air. You can stay warm indoors sipping hot chocolate while gazing out at the icy landscape. Take a closer look at those horses playing in the snow covered field. Why aren’t they freezing? 

Like dogs and goats, horses grow hair and shed it as the season changes. How can they do this without reading a calendar?

Horses start early getting their bodies ready for the winter cold. After the longest day of the year, which is summer solstice, June 21, receptors (which are receivers of information) in the horse’s eyes detect the shortening  daylight hours. This information is sent to the brain. The shorter days and cold weather tells the horse’s body to release special hormones. These hormones inform the haircoat to stop sleeping, wake-up, and grow. 

How thick and long a horse’s hair will grow depends on the temperature. Some people keep horses in a stable with the lights on 24/7 to stop the winter hair growth. If a horse does not have their winter coat they must depend on humans to blanket them and keep them warm in a barn when the mercury drops. 

Many horses that have a full winter coat look like giant teddy bears. By the shortest day of the year—winter solstice December 21 the horse has stopped growing his winter coat.

The longer daylight triggers his summer coat to start growing in. The thick teddy bear, lighter colored hair, will begin to shed. By summer you’ll see the handsome, sleek, darker colored coat again.

Horses can’t read a calendar. Nature provided an internal clock to keep these beautiful animals warm or cool no matter what the season.