The black walnut tree and its nut are considered toxic to horses and other animals because they contain a chemical called juglone, writes Emily Fought. She continues to warn horse owners about leaves and nuts contaminating grass, hay and water sources. Just 20 percent black walnut in horse bedding, sawdust or shavings can cause toxicity.
Source: Cowgirl, November 8, 2025. Link.
Carefully check pastures for black walnut trees . . . fence them off or have them removed. Remember, the area may remain contaminated for many months afterwards.”
Image: Link.