Quick facts
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Don’t use black walnut shavings for horse bedding.
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Toxicity signs include stocking up, warm hooves, founder and colic.
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If your horse starts showing these signs, remove them from the contaminated bedding.
Identifying
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Large tree with big, round and symmetrical canopy appearance
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Leaves consist of 11 to 13 leaflets that are long and toothed
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Dark brown to nearly black, deeply furrowed bark
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Flowers appear in April through June
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Dark shavings
Black walnut grows on the eastern half of the U.S. except the northern border.
Black walnut prefers moist well-drained soils, especially along streams and rivers. These trees usually grow scattered in mixed deciduous forests.
Toxicity
Black walnut shavings are a toxic bedding for horses. The innermost wood of the black walnut causes toxicity after oral or skin contact. Bedding containing as little as 20 percent fresh black walnut shavings made from old or new wood can cause toxicity.
Within a few hours of toxicity, the following signs occur.
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Depression
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Stocking up
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Warm hooves
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Acute laminitis (founder)
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Stiff gait
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Reluctance to move
As toxicity progresses you see,
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Flared nostrils
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Colic
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Swelling in the neck and chest areas
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High heart and breath rates
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High body temperature
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Laminitis may result in coffin bone rotation in severe cases
Signs of toxicity often subside within hours of removing black walnut shavings. A mild sedative and mineral oil may be helpful in some cases. In addition, nonsteroidal antiinflammatory drugs are often used.
Control
Don’t use black walnut shavings for horse bedding. Black walnut shavings are common from furniture manufacturers.
Reviewed in 2021