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Black walnut: a toxic horse bedding

Quick facts

  • Don’t use black walnut shavings for horse bedding.

  • Toxicity signs include stocking up, warm hooves, founder and colic.

  • If your horse starts showing these signs, remove them from the contaminated bedding.


  • Large tree with big, round and symmetrical canopy appearance

  • Leaves consist of 11 to 13 leaflets that are long and toothed

  • Dark brown to nearly black, deeply furrowed bark

  • Flowers appear in April through June

  • Dark shavings

Black walnut shavings
Dark black walnut shavings surrounded by lighter-colored pine shavings
Black walnut leaves
Black walnut leaves Photo credit: Paul Wray, Iowa State University


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.



Don’t use black walnut shavings for horse bedding. Black walnut shavings are common from furniture manufacturers.

Krishona Martinson, equine Extension specialist; Lynn Hovda, DVM, adjunct assistant professor, College of Veterinary Medicine; Mike Murphy, DVM, former professor, College of Veterinary Medicine; and Patrick Weicherding, former Extension educator

Reviewed in 2018

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