80: The Concept of "Minimum Effective Dose" Applied to Therapeutic Nutrition for Horses

This week, we are focusing on dosing.

In this episode, I explain the concept of the minimum effective dose, which is the smallest dosage required for the body to respond to or benefit from. The same principle applies to horses when adjusting their nutrition or adding supplements. The aim is to provide just enough to see a positive response, without going so far that it causes unwanted or harmful effects.

Dosing Principles

In pharmacology, the ideal dosing range lies between the minimum effective dose and the maximum tolerated dose. That principle also applies to nutritional supplementation in horses, where exceeding the minimum effective dose could lead to side effects or adverse reactions. The goal is always to use the smallest amount that elicits a benefit, minimizing waste and risk.

Why Less Is More

Once a supplement starts to work, increasing it will not necessarily improve the results. It will likely reduce the effectiveness and strain the body. So, always start with just enough to be effective.

Individual Tolerance and Sensitivity

Every horse responds differently to supplements. Factors like breed, health history, and immune strength all play a role. One horse may tolerate pasture or a supplement easily, while another may react badly to the same thing. Sensitivity varies widely, so dosing should be based on the individual horse rather than generalized standards.

Understanding the Modern Horse

Today, horses are often nutrient-deficient due to poor food quality, high toxicity levels, and chronic stress. Those factors increase sensitivity and reduce nutrient absorption, leading to horses with leaky gut, immune disorders, or genetic diseases that require a more individualized approach to their supplementation.

Start Low

Many people tend to overdo supplementation, thinking more is better. That mindset could be harmful for sensitive animals like horses. When starting with a low dosage, you allow room to adjust upward if necessary and can avoid overloading the body. High doses can cause intolerance and side effects that could be mistaken for a problem with the supplement itself.

Special Considerations

The form and bioavailability of nutrients are the keys to determining whether or not a horse can absorb and benefit from them. For horses with inflammation, metabolic issues, or digestive stress, gentle and minimal intervention is always better. By avoiding multivitamins and using single, targeted nutrients instead, horse owners can support more precise and effective recovery.

Form Matters

Nutrient forms differ in their bioavailability. For example, magnesium oxide is less bioavailable than magnesium citrate or magnesium glycinate. When absorption is poor, you may need higher doses to see results, which can push the dose closer to the maximum tolerated limit without any real benefit. Choosing well-absorbed, high-quality forms helps ensure the horse benefits without adding stress to the body.

Watch for Absorption Issues

Stress and chronic health conditions can impair nutrient absorption. Even the best supplement will not help if the horse cannot digest or utilize it. Bloodwork is helpful, but if levels do not improve with supplementation, the issue may be poor absorption rather than insufficient dosing.

Over-Supplementing and Nutrient Competition

Supplements with too many ingredients can cause nutrients to compete for absorption, reducing their effectiveness. For example, copper and zinc interfere with each other when given together. Complex formulas can overwhelm the body, adding to its load. In many cases, simplifying the diet is more effective than increasing supplementation.

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