CHAPTER 83 – Ionophores

Ionophores are compounds that form lipid soluble, dynamically reversible complexes with cations, and by this means facilitate specific ionic transport across biological membranes. The ionophoric activity may alter normal concentration gradients resulting in cellular ion imbalance, pH change, calcium overload, lipid peroxidation, and disruption of plasma membranes. The alteration in the membrane transport of ions is the basis for the metabolic, organic, and functional effects of this class of compounds. This chapter provides an overview of ionophores as they relate to veterinary medicine, with emphasis on ionophore-induced toxicity. Large numbers of ionophore safety and toxicity studies are conducted in support of marketing approval, but results of many studies are unpublished. Confirmatory diagnosis requires efficient laboratory assays to determine the identity and amounts of the ionophore involved and a thorough consideration of differential diagnosis. These cannot be overemphasized. There is no known antidote or specific treatment for ionophore toxicoses, and treatment is largely supportive. Judicious use, avoidance of overdosing, and adherence to species recommendation may enhance livestock production and help prevent the occurrence of adverse effects associated with this class of compounds.