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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). References:Galey, F. D., Whiteley, H. E., Goetz, T. E., Kuenstler, A. R., Davis, C. A., Beasley, V. R. 1991. Black walnut (Juglans nigra) Toxicosis: a model for equine laminitis. J. Comp. Pathol., 104: 313-326. MacDaniels, L. H. 1983. Perspective on the black walnut toxicity problem - apparent allergies to man and horse. Cornell Vet., 73: 204-207. Minnick, P. D., Brown, C. M., Braselton, W. E., Meerdink, G. L., Slanker, M. R. 1987. The induction of equine laminitis with an aqueous extract of the heartwood of black walnut (Juglans nigra). Vet. Hum. Toxicol., 29: 230-233. True, R. G., Lowe, J. E. 1980. Induced juglone toxicosis in ponies and horses. Am. J. Vet. Res., 41: 944-945. Nomenclature:
Scientific Name: Juglans nigra L. Vernacular name(s): black walnut Scientific family name: Juglandaceae Vernacular family name: walnut References:Agriculture Quebec. 1975. Noms des maladies des plantes du Canada/ Names of plant diseases in Canada. , Quebec City, Que., Canada. 288 pp. Alex, J. F., Cayouette, R., Mulligan, G. A. 1980. Common and botanical names of weeds in Canada/Noms populaire et scientifiques des plantes nuisibles du Canada. Revised. Agric. Can. Publ., Ottawa, Ont., Canada. 132 pp. Bailey, L. H., Bailey, E. Z. 1976. Hortus third. Revised. MacMillan, New York, N.Y., USA. 1290 pp. Scoggan, H. J. 1978, 1979. The flora of Canada. Nat. Mus. Nat. Sci. (Ottawa) Publ. Bot. 7(1)-7(4). 1711 pp. Van Wijk, H. L. 1911. A dictionary of plant names. Martinus Nijhoff, The Hague, The Netherlands. 1444 pp. Victorin, M. 1964. Flore Laurentienne. 2nd ed. Univ. Montreal, Montreal, Que., Canada. 952 pp. Geographic Information
Ontario References:Bailey, L. H., Bailey, E. Z. 1976. Hortus third. Revised. MacMillan, New York, N.Y., USA. 1290 pp. Boivin, B. 1966, 1967. Énumération des plantes du Canada. Provencheria 6. Nat. Can. (Que.) 93: 253-274; 371-437; 583-646; 989-1063. 94: 131-157; 471-528; 625-655. 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 References:
Minnick, P. D., Brown, C. M., Braselton, W. E., Meerdink, G. L., Slanker, M. R. 1987. The induction of equine laminitis with an aqueous extract of the heartwood of black walnut (Juglans nigra). Vet. Hum. Toxicol., 29: 230-233. 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 References:Minnick, P. D., Brown, C. M., Braselton, W. E., Meerdink, G. L., Slanker, M. R. 1987. The induction of equine laminitis with an aqueous extract of the heartwood of black walnut (Juglans nigra). Vet. Hum. Toxicol., 29: 230-233. True, R. G., Lowe, J. E. 1980. Induced juglone toxicosis in ponies and horses. Am. J. Vet. Res., 41: 944-945. Animals/Human Poisoning:Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation. HorsesGeneral symptoms of poisoning:ataxia References:Galey, F. D., Whiteley, H. E., Goetz, T. E., Kuenstler, A. R., Davis, C. A., Beasley, V. R. 1991. Black walnut (Juglans nigra) Toxicosis: a model for equine laminitis. J. Comp. Pathol., 104: 313-326. MacDaniels, L. H. 1983. Perspective on the black walnut toxicity problem - apparent allergies to man and horse. Cornell Vet., 73: 204-207. Minnick, P. D., Brown, C. M., Braselton, W. E., Meerdink, G. L., Slanker, M. R. 1987. The induction of equine laminitis with an aqueous extract of the heartwood of black walnut (Juglans nigra). Vet. Hum. Toxicol., 29: 230-233. True, R. G., Lowe, J. E. 1980. Induced juglone toxicosis in ponies and horses. Am. J. Vet. Res., 41: 944-945.
Information Source: ©Canadian Poisonous Plants Information System, Canadian Biodiversity Information Facility. Go to Harmful Chemicals Page
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