Nitrate Poisoning in HorsesBy Kentucky Equine Research Staff · February 8, 2010
According to information published by the Livestock Disease Diagnostic Center at the University of Kentucky, nitrate poisoning in horses is fairly uncommon unless a horse has consumed fertilizer, forage or hay grown in an area where fertilizer was spilled, or water contaminated with nitrates.
A few cases have been reported after horses ate high-nitrate hay that was baled wet or became wet after baling. In these cases, nitrate was converted to harmful nitrite by microorganisms in the hay. While horses are not as efficient as ruminants in converting ingested nitrates to nitrites, equines are quite sensitive to the effects of nitrite absorption. Nitrites cause injury to red blood cells, and signs of poisoning range from difficulty breathing to sudden death.