There are no known treatments for horses once the symptoms appear. References:
Cheeke, P. R., Shull, L. R. 1985. Natural toxicants in feeds and poisonous plants. AVI Publishing Company, Inc., Westport, Conn., USA. 492 pp.
Cordy, D. R. 1978. Centaurea species and equine nigropallidal encephalomalacia. Pages 327-336 in Keeler, R. F., Van Kampen, K. R., James, L. F., eds. Effects of poisonous plants on livestock. Academic Press, New York, N.Y., USA. 600 pp.
Panter, K. E. 1990. Toxicity of knapweed in horses. Wash. State Univ. Knapweed, 4(3): 2.
Nomenclature:
Scientific Name: Centaurea repens L.
Vernacular name(s): Russian knapweed
Scientific family name: Compositae
Vernacular family name: composite
Go to ITIS*ca for more taxonomic information on: Centaurea repens
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
Alberta
British Columbia
Manitoba
Ontario
Saskatchewan
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.
Image or illustration
Russian knapweed: Images: images.google.com
Notes on Poisonous plant parts:
Horses must ingest fresh aboveground plant material for prolonged periods to reach a threshold level of unknown toxicity and then the symptoms appear abruptly. Chewing disease in horses has occurred in parts of the western United States. In California the peak times of disease onset are June-July and October-November (Cordy 1978).
Toxic parts:
leaves
mature fruit
stems
References:
Cheeke, P. R., Shull, L. R. 1985. Natural toxicants in feeds and poisonous plants. AVI Publishing Company, Inc., Westport, Conn., USA. 492 pp.
Cordy, D. R. 1978. Centaurea species and equine nigropallidal encephalomalacia. Pages 327-336 in Keeler, R. F., Van Kampen, K. R., James, L. F., eds. Effects of poisonous plants on livestock. Academic Press, New York, N.Y., USA. 600 pp.
Mettler, F. A., Stern, G. M. 1963. Observations on the toxic effects of yellow star thistle. J. Neuropathol. & Exp. Neurol., 22: 164-169.
Toxic plant chemicals:
unknown chemical
References:
Cheeke, P. R., Shull, L. R. 1985. Natural toxicants in feeds and poisonous plants. AVI Publishing Company, Inc., Westport, Conn., USA. 492 pp.
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:
drowsiness
gait, unsteady
incoordination
restlessness
References:
Cheeke, P. R., Shull, L. R. 1985. Natural toxicants in feeds and poisonous plants. AVI Publishing Company, Inc., Westport, Conn., USA. 492 pp.