How To Prevent Winter Weight Loss in Horses

In the spring and summer, when the pastures are lush, your horse will pack on a little extra weight to prepare them for the winter. In the winter, they’ll burn off those extra fat reserves to stay warm. While it’s normal and even beneficial for horses to lose some weight in the winter, some do need help maintaining a healthy weight.

Healthy Seasonal Weight Fluctuations In Horses
A study on weight changes in Thoroughbred racehorses showed an average of 13-18 pounds of fluctuation throughout the year. For horses with a healthy body condition, small fluctuations are normal. Your horse’s wild ancestors experienced much greater fluctuations over the winter, but our domestic horses live in milder conditions and have access to food and shelter year-round.
Around 50% of horses are overweight, and about 10% are obese. Many horse keepers do not realize that their horse could benefit from losing weight in the winter. As long as your horse does not lose weight rapidly, and they maintain a body condition score of 5 or 6, you do not need to make any major changes to their diet in the winter.
Monitor your horse’s weight by taking photos at least every other week. Your horse should have slight fat cover over their ribs, but they should not be easily visible. Your veterinarian can help you determine your horse’s ideal weight if you’re unsure.

When Is Winter Weight Loss Unhealthy?
Weight loss in the winter can be concerning for foals, pregnant mares, hard keepers, and senior horses. Foals and senior horses may have more trouble maintaining their core body temperature. Horses that would normally have higher caloric needs may struggle to maintain their weight as their metabolism speeds up.

How To Maintain Weight in the Winter
If your horse is losing more weight than usual this winter, despite adequate nutrition, they may have an underlying health issue like internal parasites or dental pain. If your horse has a clean bill of health, they may simply need more calories in the winter.
Hay is the best fuel for your horse in cold weather. The high fiber content ferments in the gut, generating heat so your horse stays warm. Your horse should have constant access to hay in the winter. You can replace up to 25% of your horse’s forage with alfalfa hay, it’s more calorie-dense than grass hays. Alfalfa hay should make up no more than 50% of your horse’s diet.
If your horse struggles to keep weight on even with round-the-clock hay access, you may need to add a fat source to their diet. Vegetable oils are cheap, popular, and easily accessible, but they’re not the best option for all horses. Ground flaxseed, flaxseed oil, and soybean oil are good sources of omega-3 fatty acids and vitamin E, nutrients that support joint, immune system, and cognitive health.
Also, make sure your horse always has access to fresh, clean water. Horses can become dehydrated in the winter when their trough or bucket freezes over, and in turn they may not eat enough. You can use a heater water trough or place a floating object like a soccer ball in the trough to prevent ice from forming.
Any additions to your horse’s diet should be introduced gradually. Aim for steady progress, rather than quick gains. It’s generally better for a horse to be slightly lean than overweight. If you do not start to see progress in a few weeks, or their weight continues to drop, see your veterinarian for advice.