Keeping Pastured Horses Safe During Drought

Drought-related toxicity in horses is rare but typically has serious consequences if it occurs.

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Keeping Pastured Horses Safe During Drought
During periods of low moisture, certain grass species can produce toxic products such as nitrates. | Photo:
Some parts of the country are experiencing drier than normal conditions and, thus, some horses living on pasture might soon have limited forage choices. Owners must take care to ensure pastures do not contain certain plant and weed species capable of producing toxins during stress conditions such as drought.

Horses aren’t as susceptible to nitrate toxicity or prussic acid poisoning from plants as are ruminant species, such as cattle and sheep. A rumen’s microorganisms facilitate toxin release from the plants into the animal’s digestive tract. Horses, however, are monogastric (one- stomached) animals and are more capable of breaking down prussic acid in the stomach, and convert very little nitrate to nitrite (wherein lies the problem in cows) in the large intestine.

Nitrate and prussic acid toxicity in horses are rare, but when they do occur, they typically have serious consequences.

During periods of low moisture, certain grass species can produce toxic products such as nitrates. Nitrates accumulate in plants–such as pigweed, smartweed, ragweed, nightshade, and goldenrod–that are heavily fertilized with nitrogen, or during certain weather conditions and after frost

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Written by:

Kristen M. Janicki, a lifelong horsewoman, was born and raised in the suburbs of Chicago. She received her Bachelor of Science degree in Animal Sciences from the University of Illinois at Urbana-Champaign and later attended graduate school at the University of Kentucky, studying under Dr. Laurie Lawrence in the area of Equine Nutrition. Kristen has been a performance horse nutritionist for an industry feed manufacturer for more than a decade. Her job entails evaluating and improving the performance of the sport horse through proper nutrition.

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