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Appropriate Supplements


Good nutrition is the foundation for good health, and for equine athletes, it is critical to top performance. It is not only natural but prudent to pay close attention to performance horses’ diet and to supplement regular feed to optimize their nutrition. But when it comes to supplementation, more is not necessarily better. If you are supplementing without a clear understanding of your horses’ nutritional needs, you could be wasting your money at best, and risking your horses’ health at worst.

Goals of Supplementation
Most owners overestimate the energy output of their horses and it is easy to assume with supplements that more is better. While supplements are generally recognized as being safe, the FDA does not oversee these products. This means that supplements can have widely varying amounts of active ingredients, fillers that can be potentially dangerous to horses, and very little quality control as most companies are not fiscally large enough to carry out safety testing.

When to Supplement

So when should we supplement?
Supplementation should be instituted with specific goals. Athletic horses have different energy and nutrient requirements than what a backyard horse will have and often need more energy supplied than what forage alone can provide. Supplements can also be used therapeutically by targeting specific disease processes or in helping with the prevention of disease (such as preventing gastrointestinal disorders and promoting joint and hoof health). Supplements can also be beneficial at different life stages to help provide appropriate nutritional needs for growing horses, more easily digestible rations for the geriatric horse, or in the case of illnesses.

For “normal” horses (i.e. those free of disease and without specific age-related issues), supplements are appropriate when feed is lacking. A high quality forage is sufficient as a stand-alone feed for most horses. However, even high quality forage may not provide 100% of a horse’s nutritional needs. In many parts of the United States, soils are lacking in selenium and vitamin E. Deficiencies can cause white muscle disease in young animals and can result in death. In older animals, muscle atrophy, decreased performance, and lethargy can be seen. This does not mean that all horses should be blindly supplemented, however, as selenium toxicity can cause death and high doses of vitamin E can inhibit absorption of other vitamins.
The best way to decide if your horse needs supplementation is to submit hay for analysis so that supplements can be targeted to each specific herd based on what the forage is lacking. If your horse is having performance issues, lab work can help determine what their specific supplementation needs are. Most horses who are on a forage only diet do well with a ration balancer to help cover nutrient deficiencies.

Risks of Supplementation
When it comes to nutrition, there can be too much of a good thing. For example, phosphorus is an essential nutrient for horses. But horses require an overall ratio of 1:1 to 2:1 parts calcium to phosphorus. If regular feed provides that balance, a phosphorus supplement could result in metabolic bone disorders like “big head.” Excess phosphorus can also pass through the horse’s digestive system to become an environmental pollutant in nearby bodies of water.

Drugs that are administered in the feed as supplements, such as progestins used to suppress estrus in mares, can present health risks to the humans administering them, and certain supplements can have drug interactions that can decrease efficacy of medications.

Even when a supplement is harmless, if a horse is getting enough of a particular substance, giving the horse more will not improve performance. Studies have shown that horses in heavy work who are being fed forage and grain have higher than necessary levels of magnesium, phosphorus, potassium and calcium.

In most cases, the biggest risk of using a supplement is that it’s useless. The supplement industry is not regulated, and many claims have not been tested. In some cases, useful ingredients like glucosamine are not provided in sufficient quantity to have any effect. Proprietary blends are combinations of ingredients that do not have to be listed in specific quantities. Without a list of ingredients, it is impossible to investigate the validity of such blends.

When it comes to supplementation, it’s buyer beware. Do your research and talk to your veterinarian, and then read labels carefully before spending your money.

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Pilchuck Veterinary Hospital


11308 92nd St SE Snohomish, WA 98290


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