Case report: outbreak of sodium monensin intoxication in feedlot cattle from Mexico

Abstract

In July 2010,89 out of 800 calves (8-18 months old) from a feedlot located in the state of Tamaulipas, Mexico, exhibited severe oedema in inclined areas followed by sudden death. Hydrothorax, hydropericardium, pulmonary oedema, and enlargement of the heart and dilated ventricles with fatty degeneration were seen at necropsied. The liver showed severe diffuse congestion coupled to several necrotic foci and gallbladder distension. Histologically, severe diffuse fatty degeneration with vacuolisation and dissociation of the hepatic cords, multifocal necrosis and tissue infiltration with neutrophil and eosinophil granulocytes, cholestasis and fibrosis were observed in the liver parenchyma. Because of recycling of the concentrate containing sodium monensin from the past day to the next one, monensin intoxication was suspected. After complete concentrate removal from diet, no other case has occurred in this feedlot. These results showed that the improper use of adequate amount of monensin as a food additive can lead to a severe intoxication leading to acute cardiac failure in calves.