Q: My 8-year-old mare’s body condition score (BCS) tends to fluctuate depending on the season. She often stays around a 5 or 6 BCS during the warmer months but drops to a 4 as the weather gets colder. She is fed a balanced diet and is turned out overnight year-round. Her workload decreases during the coldest months of the year. Is it concerning or indicative of a problem that her BCS fluctuates like this? What can I do to combat it?

A: Weight loss in the colder months commonly occurs because horses need more calories to stay warm. They can use up to 25% more energy to maintain adequate body temperature. Several other factors can influence your horse’s energy requirements, such as housing, age, and environment.

Track Your Horse’s Body Condition

The Henneke body-condition-scoring system involves palpating six body areas—neck, withers, shoulder, ribs, back, and tailhead. I recommend performing this on your horse every two weeks to track her body condition and make sure you are not misled by her winter coat, which can make her appear fatter than she is.

Some weight fluctuation in the colder months is normal, and occasionally encouraged with easy keepers that tend to become overweight in the spring and summer. However, if your horse maintains a healthy condition through the summer but drops to a BCS of 4 in the winter, she likely needs supplemental calories to support a BCS of 4.5-5.

If you notice unexplained weight loss in your horse, first consult your veterinarian to rule out any health or dentition issues. From that point an equine nutritionist can help you make diet changes to combat the weight loss.

Use Forage to Help Your Horse Maintain Body Condition

The best way to keep a horse warm in the winter months is with high-quality forage. If your horse begins losing weight, first increase her hay. Free choice access to high-quality forage can help promote weight gain, especially in cold weather. The fermentation process that occurs in your horse’s hindgut when she consumes forage produces heat, which can help fuel her internal furnace and support thermoregulation.

Water for Horses During Winter

Many horse owners overlook water as an important nutrient during the winter. If horses drink less water, they don’t eat as much. Water offered to horses must be fresh, clean, and free from ice. If you live in a very cold climate, add a trough heater or other mechanism to keep the water from freezing and ensure your horse has continual access.

Supplemental Energy for Horses in the Winter

If your horse does not maintain her weight with an increase in forage intake and a balanced diet, you might need to consider adding a fat source. Horses do not have a gallbladder, but they can digest fat well if you introduce it slowly to their diet. Fat is more calorically dense than carbohydrates, which meaning it contains more than twice the amount of calories per pound. You can find numerous fat supplements to top dress your horse’s already balanced diet.

With this approach it will be easy to add and remove the fat product when the horse does not need additional calories.

Take-Home Message

In the winter you might notice your horse’s weight fluctuates slightly because she requires more energy to stay warm. However, you should not notice significant changes in her BCS. Horses always need access to fresh water and a high-quality hay source. If they still lose weight on a balanced diet with free-choice access to high-quality forage, consider adding a fat source for additional calories.

Do you have an equine nutrition question?