Cargill Investigates California Horse Deaths


By Pat Raia, The Horse

May 18, 2017


Horse feed manufacturer Cargill says an investigation has revealed that a minuscule amount of monensin was detected in a specific bag of its Nutrena SafeChoice Senior feed, but declined to speculate on what caused the deaths of two California horses.


Monensin is an ionophore antibiotic sometimes included in ruminant, swine, and poultry feed, but which is toxic to horses. Clinical signs of ionophore poisoning in horses include poor appetite, diarrhea, weakness, rapid heart rate, labored breathing, exercise intolerance, depression, wobbly gait, colic, sweating, recumbency, and sudden death.


In a written statement, Nutrena parent Cargill said two horses boarded at the La Tuna Stables in Sun Valley were found dead in their stalls in April, three days apart. Both the animals had consumed feed from the same bag of SafeChoice Senior.


“When the first horse died, there was speculation that it was a heart attack,” the statement said. “After the death of the second horse, there were questions about whether the two events were related.”


Samples of the feed, as well as ingesta from the second horse, were sent to the University of California, Davis, for testing. The statement said laboratory testing revealed...