Turning Archive 2005
>Somehow the link I posted that listed the toxicity of different woods got eaten by Microsoft. I found a different source and copied the section on horses and black walnut. Here it is:
SIGNS: Horses are most often affected. When horses are bedded on wood shavings containing more than about 20% of black walnut shavings (which tend to be dark in color), clinical signs of laminitis (inflammation of the laminae in the hoof) can occur within 12 to 18 hours of contact, but 24 hours may elapse before signs manifest. Consumption of the shavings may cause signs of laminitis as well as mild colic. Affected horses become unwilling to move or have their feet picked up, are depressed, may exhibit limb edema and signs of laminitis. Difficulty in breathing (increased rate and depth) may be noted. Horses on pasture may show mild respiratory signs from pollen or fallen leaves.
Bottom line: Don't use black walnut for a horse's stall or bedding.