Black walnut-Juglans nigra L.-Poisonous plant

Black walnut

General poisoning notes:

Black walnut (Juglans nigra) is native to southwestern Ontario and has been planted as a cultivated tree. The shavings of wood from this tree have caused laminitis in horses in the United States. Black walnut shavings are less likely to be used as bedding in Canada because the tree is not common here. However, if bedding is obtained from a hardwood mill or furniture manufacturing plant, sufficient black black walnut shavings may be present to cause problems. Reforestation of black walnut has been attempted in southern Ontario by leaving nuts for squirrels to gather in the autumn. The squirrel bury them for the winter, allowing many black walnut trees to germinate by this method. Pollen of black walnut has been implicated in causing laminitis in horses (MacDaniels 1983, Minnick et al. 1987).

Nomenclature:

Scientific Name: Juglans nigra L.

Vernacular name(s): black walnut

Scientific family name: Juglandaceae

Vernacular family name: walnut

Geographic Information

Ontario

Notes on Poisonous plant parts:

Wood shavings of black walnut have caused symptoms in horses. The chemical juglone has not been found in appreciable amounts in the wood. Other chemicals are probably involved in causing symptoms in horses from wood shavings (Minnick et al. 1987).

Toxic parts:

Bark, mature fruit, wood

Notes on Toxic plant chemicals:

Juglone, a naphthoquinone, has been found in the bark, nuts, and roots of black walnut. Pure juglone is less potent than a crude extract of the plant in inducing toxic effects. Additional compounds seem to be involved in causing more severe cases. Two ponies given 1 g of pure juglone orally developed mild laminitis that disappeared within 24 h (Minnick et al. 1987).

Toxic plant chemicals:

Juglone

Animals/Human Poisoning:

Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.

Horses

General symptoms of poisoning:

Ataxia, breathing, rapid, depression, laminitis, lethargy, recumbency.