Environmental Triggers – Part 3: Mold & Mycotoxins

When we think of environmental stressors for horses, mold and mycotoxins are often overlooked. Yet these hidden threats—present in hay, grain, bedding, water, and even pasture—can quietly erode health long before obvious symptoms appear. Unlike acute illness, mycotoxin exposure is typically chronic and insidious, leaving horses in a state of suboptimal health that owners may mistake for “just how they are.”

What Are Mold & Mycotoxins?

• Mold is a type of fungus that thrives in warm, damp, or poorly ventilated environments. It grows readily on hay, grains, bedding, or stored feed.

• Mycotoxins are toxic secondary metabolites produced by molds. These compounds are invisible, tasteless, and not destroyed by processing or pelleting. Even when mold is not visibly apparent, mycotoxins may still be present.

Horses are particularly sensitive because they consume large volumes of forage, making even small amounts of contamination impactful over time.

Common Sources of Exposure

• Hay & Forage: Damp or improperly cured hay is the most frequent source of mold spores and mycotoxins.

• Grain & Pelleted Feed: Commercial feeds often carry hidden mold spores or mycotoxins that survive storage and processing.

• Pastures: Fescue and other grasses under stress can harbor endophyte fungi that produce toxins.

• Bedding: Straw or shavings stored without airflow can grow mold, releasing spores into the air.

• Water Sources: Stagnant troughs or contaminated wells may support fungal growth.

Signs Owners Might Notice

• Chronic cough or nasal discharge despite no infection

• Recurrent mild colic or digestive upset

• Lethargy or poor performance

• Weight loss or poor topline despite adequate feed

• Persistent skin or hoof issues

• “Mystery” symptoms that don’t fully resolve with veterinary treatment

Management & Prevention Strategies

• Forage First: Prioritize clean, well-cured hay. Avoid round bales left in wet conditions.

• Storage Matters: Store hay, grain, and bedding in dry, well-ventilated spaces. Use pallets to keep hay off the ground.

• Test Feed & Water: When in doubt, send samples for mycotoxin testing.

• Improve Ventilation: Keep barns well-aired to minimize inhalation of spores.

• Rotate Pastures: Prevent fungal overgrowth by maintaining healthy, diverse pastures.

Natural & Herbal Support

While management is key, natural approaches help horses recover from exposure:

• Binders: Bentonite clay and zeolite can adsorb certain mycotoxins in the gut, reducing absorption.

• Liver Support Herbs: Milk thistle, dandelion root, and burdock root aid detoxification and liver regeneration. Check out our Equine Liver/Kidney Support

• Immune Support: Echinacea and astragalus strengthen immune resilience. Check out our Equine Detox/Immune Support

• Respiratory Relief: Mullein, elecampane, and thyme help clear lungs irritated by spores. Check out our Equine Lung Support

• Nutritional Balance: Sea kelp and bentonite clay, forage-based diets restore minerals depleted by toxin load.

Closing Thoughts

Mold and mycotoxins are silent saboteurs in the horse’s environment. Because their effects mimic so many other conditions, they’re often dismissed or misdiagnosed. But by recognizing the role these toxins play, supporting horses with clean forage, proper management, and targeted herbal support, we give them the chance not just to survive—but to thrive.

🌿 Prevention is always the best medicine, but when exposure happens, nature provides tools to restore balance.

With Love, Herbs & Harmony

~Debbi, Whilehearted Harmony

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