Identifying and Mitigating Ionophore Poisoning

Ionophores (e.g. Monensin, Rumensin, etc.) are toxic and can be deadly in equids (horses, donkeys, mules). Livestock, goats, and poultry can get health benefits from ionophores in their feed since they promote growth and act as a natural antibiotic. However, 1/10th of a safe amount for livestock can cause heart damage and death in horses. The feed label will clearly say “medicated”, list the specific ionophore, and warn about toxicity for horses. That is why it is critical to keep feeds separate and clearly labeled in the feed area, and to make sure horses are not sharing pens/feed with livestock receiving the medicated feed. One Oklahoma Ranch lost almost 80 horses (August, 2024) due to human and possibly mechanical error at the feed mill. Learn more about risk mitigation for your horse/livestock operations.