Equine supplements for the off-season

Here’s why giving your horse supplements can be just as important during the winter as during show season.

The leaves are changing and falling, crunching under your horse’s hooves. There’s a slight chill in the air that wasn’t there before. As fall and winter approach, you make preparations for colder temperatures and potentially less time in the saddle. This is your horse’s “off-season” — and it can be just as important to give him supplements then as it is during his “peak season”.

With a change in season comes a change in your horse’s nutritional needs. In addition to the right supplies and equipment for off-season care, the right building blocks for his diet are equally important.

Preparing for health challenges

During this time, it’s possible for your horse to face several health challenges.

Joint issues

An arthritic horse may experience more stiffness during the cold months, due both to chilly temperatures and the lack of movement that comes from less riding and less turnout.

Dehydration and colic

When the mercury drops, some horses do not drink as much. This can leave them dehydrated and prone to impaction colic, caused by a blockage when feed material obstructs the large colon. A horse that isn’t adequately hydrated may have dryer colonic contents and decreased gastrointestinal (GI) motility, creating greater potential for an impaction. An increase in stall time during the off-season can also increase a horse’s risk for colic – light physical activity (e.g. walking) stimulates normal GI motility. So if your horse goes from long periods of summer turnout to spending more more time in the barn, his GI motility can suffer.

Weight concerns

Winter in some regions means lack of access to pasture. Without grass in his diet, your horse relies more on good quality hay and grain to fulfill nutritional needs and maintain body weight. If he is a hard keeper or senior, he may have more trouble holding his weight through harsh winters. The greater caloric demand caused by keeping warm, combined with less pasture, can necessitate a different diet to prevent weight loss.

Weakened immunity

The off-season can also be an ideal time to bolster your horse’s immune system – changes in daylight, temperature and routine all stress him to some degree, compromising his immune system and making him more prone to disease.

With the right nutrients, you can support your horse through these challenges, giving him what he needs to thrive in the months ahead.

I recommend providing your horse with five categories of supplements for the best off-season care:

  1. Immunity
  2. Weight gain/maintenance
  3. Prebiotics and probiotics
  4. Electrolytes
  5. Joint supplements

1. Immunity supplements

Look for supplements containing Echinacea, mushroom blends, Omega 3 fatty acids, vitamins E and C. Echinacea has been shown to effectively stimulate equine immuno-competence. Vitamin E is a powerful antioxidant that protects against disease by neutralizing damaging free radicals. Vitamin C also neutralizes free radicals, protecting the body from their harmful effects.

Omega 3 fatty acids have been shown to reduce inflammation as well as the allergic inflammatory response. One of the best sources of Omega 3 fatty acids for horses is flaxseed oil, fed as a standalone supplement or incorporated with other ingredients.

Mushrooms have been used for thousands of years to nourish the human body, and are recently being included in more horse supplements. Many mushrooms are adaptogens, meaning they help your horse manage stress by supporting efficient communication between the immune, endocrine and nervous systems. Mushrooms also contain several antioxidants, and the polysaccharide known as beta-D glucan, which has been studied for its ability to modulate the immune system as well as its anti-tumor effects. In particular, reishi, cordyceps, turkey tail and shiitake mushrooms are especially supportive of the immune system.

2. Weight gain/maintenance supplements

Adding fat to your horse’s diet is a smart way to include more calories without increasing sugars or starches. Flaxseed oil is a rich source of Omega 3 fatty acids for horses while remaining low in non-structural carbohydrates (sugars and starches); and as mentioned above, it helps with immunity. Another good source of Omega 3 fatty acids is soy oil.

When adding oil to a horse’s diet, I recommend starting with ¼ cup mixed into a meal, increasing by another ¼ cup every week or so until the horse is receiving one to two cups a day (the total amount will depend on the horse’s needs and weight). This slow transition gives his GI tract time to adjust to the added fat, reducing the likelihood of soft manure (a common but temporary side effect of feeding oil).

3. Pre- and probiotics

Prebiotics are food for good bacteria living within the GI tract – they provide support and energy so good bacteria can convert feed into nutrients more effectively, thus making more nutrients available for absorption in the GI tract.

Probiotics, on the other hand, are the actual good bacteria and are added to boost the existing microflora of the GI tract. Additionally, they contribute to disease prevention by limiting bad bacteria from colonizing the gut.

Supplement labels typically list prebiotics as mannanoligosacharides (MOS) or fructooligosacharides (FOS). Both are carbohydrates that provide nutrients for the good bacteria in your horse’s gut. Strains of Lactobacillus and Saccharomyces (especially Saccharomyces cerevisiae, a yeast) are two common microorganisms found in probiotics that you should also check for.

A caveat with probiotics – research has shown that the beneficial effects of probiotics do not last beyond the period of administration. Your horse needs to be kept on them long-term or else repeat/pulse them as needed.

4. Electrolytes

Electrolytes in the winter? Yes, you read that right. Even when your horse doesn’t work up as much of a sweat as normal, he can still benefit from electrolytes.

If he tends to drink less in the winter, add electrolytes to his diet to encourage more water consumption. More water leads to appropriate hydration status and improves GI motility. Provide electrolytes in the form of a free-choice salt or mineral block, or an actual electrolyte supplement. When choosing an electrolyte supplement, avoid those with sucrose or dextrose (sugars) listed among the main ingredients; look instead for products containing predominantly salt or other minerals.

Ensure your horse has access to clean, fresh and unfrozen water at all times. If you are adding electrolytes to his water, provide a separate bucket of plain water too.

5. Joint supplements

You’ve heard about the familiar ingredients in many joint supplements, namely g0lucosamine, chondroitin and MSM. But as research in this area continues to advance, many new ingredients are being incorporated into equine joint supplements – and with promising results.

One of the newest ingredients is resveratrol, a compound found in many plants, including grape skin. In a 2016 study, 45 horses exhibiting hind end lameness were treated with a steroid injection in the lower hock joints; owners then received unmarked containers filled with either a supplement containing resveratrol or a placebo, along with instructions to feed the supplement for four months. The research team found that at the end of four months, the horses consuming a resveratrol supplement following joint injections were significantly less lame than horses consuming a placebo. Several additional studies have also shown resveratrol to support healthy free radical levels in horses, as well as a healthy inflammatory response.

Avocado/soybean unsaponifiables (ASU) complement the effects of glucosamine and chondroitin, working synergistically to prevent cartilage breakdown and support joint function.

Turmeric, a plant in the ginger family, has been used by humans for thousands of years to flavor food, add color, and provide many health benefits. The main active substance, curcumin, has been found to have beneficial effects on many areas of the body, joints included. Turmeric acts as an antioxidant and promotes a normal response to inflammation.

The off-season is the perfect time to rest, recharge, and set new goals for the upcoming riding season. If your horse has any special needs or considerations, contact your veterinarian to discuss them further.

Wishing you and your horse a healthy and happy off-season!


Dr. Justine Griesenauer is an equine veterinarian at Cedarbrook Veterinary Care, a mobile equine practice in Washington that takes a holistic approach to caring for horses. As a lifelong rider and horsewoman, she knows how important your horse is and this is reflected in her treatment. She is a graduate of the University of Tennessee College of Veterinary Medicine.