Ionophore poisoning in cattle
Most outbreaks involve mixing errors in commercial and home-mixed concentrate rations, although maduramycin poisoning has been documented with the feeding of chicken litter to cattle and sheep.
In cattle pathology is characterized by cardiac and skeletal muscle damage of equal severity, skeletal muscle pathology with myoglobinuria predominates in sheep and swine, while in horses myocardial damage predominates. Hindlimb muscles may be the site of severe degenerative changes. Grossly these degenerative changes are characterized by white streaking and pale foci in skeletal and cardiac muscle with haemorrhage. Terminal cardiac cases reveal myocardial necrosis (arrow + note streaking of diaphragm), fluid accumulation in body cavities (stars), pulmonary congestion and oedema and hepatic congestion. Histopathology is characterized by multifocal degeneration and necrosis with lesions of similar duration (monophasic)
Ionophore toxicity in cattle may be potentiated by concurrent vitamin E selenium deficiency, clinical or subclinical acidosis, gossypol contamination (on whole cotton seed), exposure to other cardiotoxic plants or concurrent use of certain antibiotics (doxycycline, tiamulin, erythromycin, chloramphenicol, tylosin, tilmicosin)