Supplements for the Endurance Horse

As we learn more about the requirements of athletic horses we find that, in general, forage is good at providing the majority of nutrients and energy. There is, however, a lot of variation between forages as to how much and which nutrients are supplied.

Supplements may help to fill in the gaps by providing certain nutrients required by the endurance horse. Energy is usually the first thing noted as inadequate if the horse cannot maintain its weight on the forage. Additional energy is supplied by the starch, sugars, and fats. Some supplements may have an influence on the way the energy is used or aid in the utilization of energy.

More subtly, the differences between certain nutrients found in varying quantities in the forage may have an effect on the horse’s ability to finish races, be competitive, fare well during competitions, and stay focused and sound. If the appropriate good-quality commercial concentrate or supplement is fed in recommended amounts to the horse, many of these nutrients will be supplied on a daily basis. Still, there may also be certain nutrients not found in the right quantities in forage or in commercial concentrates that may be beneficial to the successful endeavors of the competition horse.

It is important to point out that not every horse will respond dramatically to any specific supplement and that there may be variation in which supplements work best for each individual. Before deciding whether to use a supplement, it is always a good idea to check the list of acceptable substances from the governing organization.

With most organizations, the use of any drugs or performance-enhancing supplements is not acceptable because endurance horses are expected to compete using their own natural abilities. If it is a substance that is naturally occurring in the body or in the feed, or if it is a nutrient required by the body, it most likely will be acceptable. Several supplements commonly given to endurance horses are listed below, and the rationale behind how they might be beneficial to endurance horses is provided.

Probiotics and yeast. Beneficial bacteria and yeasts that occur naturally in the digestive tract of the horse live in delicate balance. Stress and any factor that affects feed intake can upset that balance.

Giving supplemental beneficial bacteria (probiotics) and/or yeast mixes can aid in rebalancing the microbial population and maintaining gut health. Further, they may help with fiber digestion. Probiotics and yeasts can be used daily or just around the time of the competition.

Antacids and buffers. Endurance horses may benefit from the use of stomach antacids because of the abuse the stomach must endure from the high salt content of electrolytes, erratic intakes caused by the stress of traveling, and the possibility of the presence of ulcers. Products for stomach buffering can contain minerals that have a coating action and other minerals that buffer the acid content of the stomach.

Mineral-containing antacids are acceptable substances, while drugs affecting acid production are not. Some riders mix antacids into the electrolyte mixture that is being syringed into the horse. Antacids can be used on a daily basis for horses prone to ulcers or solely at the competition.

Antioxidants like vitamin E, vitamin C, selenium, and lipoic acid. All of these antioxidants are present in the horse’s diet in varying amounts, though vitamin C can be made by the liver from glucose. Each antioxidant works in a different way, but as a whole they may have a beneficial effect on scavenging free radicals and preventing cellular damage. Supplementation should be on a daily basis but some acute supplementation can also be done at the competition, especially with vitamins E and C.

B-vitamins. These are important components in enzymes in almost every step of cellular energy generation. B-vitamins are normally supplied by the diet or from microbial fermentation byproducts, but supply may be inadequate in stressful situations like competition, decreased appetite, digestive problems, or periods of fasting—all of which can occur during an endurance competition. B-vitamins are not stored in the body and need to be fed at the time of need.

Generally, B-vitamins do not need to be supplemented on a daily basis and would be most useful as a supplement during travel and at the competition.

Branch chain amino acids (leucine, isoleucine, and valine). These are important muscle amino acids and supplementation with additional branch chain amino acids may reduce muscle breakdown and muscle wasting that occurs during competition and possibly prevent muscle soreness after the race.

They should be given before and during the race. Further benefit might occur after the race to help restore damaged muscle tissue. Research on the effectiveness of branch chained amino acids in endurance horses has been ambivalent.

Joint supplements. Chondroitin sulfate, glucosamine, and hyularonic acid are compounds commonly found in joints and function as building blocks in cartilage and joint fluid to keep joints performing optimally. Oral supplementation of additional amounts of the compounds aims to supply more of the building blocks and minimize inflammation and discomfort. Joint supplements should be fed on a daily basis to have an effect. The American Endurance Ride Conference (AERC) has these three substances listed as allowed substances but disallows some other common ingredients in joint supplements like MSM and yucca.

Electrolytes. These are needed for replacing sodium, chloride, potassium, calcium, and magnesium lost in sweat to help maintain fluid balance. Significant amounts of electrolytes are found in the normal feed of the horse (hay and concentrate) but should be supplemented if the horse is sweating heavily, as is common during an endurance ride, particularly in the warmer months of the year. Only oral supplementation is permitted by the AERC at an endurance competition by dosing syringe or mixed into the feed or water.

Carnitine. Carnitine is a naturally-occurring vitamin synthesized from the amino acids lysine and methionine in the body of the horse. It shuttles free fatty acids into the mitochondria for energy. In the exercising horse, supplementation would theoretically facilitate the use of fatty acids as a muscle fuel, sparing glycogen. Supplementation is still more conjecture than fact when it comes to its effectiveness. If there is a protein (lysine) deficiency, it would affect synthesis of carnitine and affect fat utilization. For supplementation to be effective, carnitine should be fed daily, not just during the race. This nutrient is in the grey zone of prohibitive substances because it is a naturally-occurring substance but may be perceived to have a performance-enhancing effect.

Energy supplements like corn syrup, honey, commercial carbohydrate loaders. Used to keep a steady supply of glucose going to the muscle cells for energy, these substances can be mixed in feed or dosed by syringe. Timing is crucial for effectiveness of this type of supplementation because of the dangers associated with insulin spikes and subsequent glucose crash.

Whether any of these supplements may be of any assistance to a horse will depend on the individual and/or the existing supply in the diet. Care should be taken in not overdosing the supplements because some of them are toxic in high amounts. Some may need to be fed on a daily basis to have an effect while others may be most suitable when fed during a competition.

When it comes to supplements, it is important to have realistic expectations of what supplements can actually do and not to expect miracles.

Read more from Feeding and Veterinary Management of the Sport Horse.