Hound's Tongue (Common name)

General poisoning notes:

Hound's-tongue (Cynoglossum officinale) is a naturalized biennial plant found across southern Canada. The plant contains pyrrolizidine alkaloids, which have caused poisoning and death in horses and cattle. The plant causes disorders of the central nervous system and can cause hepatic failure in horses (Knight et al. 1984).

References:

  • Cooper, M. R., Johnson, A. W. 1984. Poisonous plants in Britain and their effects on animals and man. Her Majesty's Stationery Office, London, England. 305 pp.
  • Knight, A. P., Kimberling, C. V., Stermitz, F. R., Roby, M. R. 1984. Cynoglossum officinale (hound's-tongue) - a cause of pyrrolizidine alkaloid poisoning in horses. J. Am. Vet. Med. Assoc., 185: 647-650.

Nomenclature:

Scientific Name:
Cynoglossum officinale L.
Vernacular name(s):
hound's tongue
Scientific family name:
Boraginaceae
Vernacular family name:
borage

Go to ITIS*ca for more taxonomic information on: Cynoglossum officinale

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
  • New Brunswick
  • Nova Scotia
  • Ontario
  • Quebec
  • 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

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Notes on Poisonous plant parts:

The concentration of the various alkaloids is highest in the rosette stage, i.e., when the leaves are all attached to the root crown and a stem has not grown yet (Knight et al. 1984).

Toxic parts:

  • leaves

References:

  • Knight, A. P., Kimberling, C. V., Stermitz, F. R., Roby, M. R. 1984. Cynoglossum officinale (hound's-tongue) - a cause of pyrrolizidine alkaloid poisoning in horses. J. Am. Vet. Med. Assoc., 185: 647-650.

Notes on Toxic plant chemicals:

The following LD-50 toxicities have been determined in male rats:

heliosupine
60 mg/kg
echinatine
350 mg/kg

The amount of pyrrolizidine alkaloid content in the plant has been reported to be 0.6-2.1% of dry matter (Cheeke and Schull 1985).

Toxic plant chemicals:

  • echinatine
  • heliosupine

References:

  • Cheeke, P. R., Shull, L. R. 1985. Natural toxicants in feeds and poisonous plants. AVI Publishing Company, Inc., Westport, Conn., USA. 492 pp.
  • Knight, A. P., Kimberling, C. V., Stermitz, F. R., Roby, M. R. 1984. Cynoglossum officinale (hound's-tongue) - a cause of pyrrolizidine alkaloid poisoning in horses. J. Am. Vet. Med. Assoc., 185: 647-650.

Animals/Human Poisoning:

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

Cattle

General symptoms of poisoning:

Notes on poisoning:

Cattle have also been poisoned after ingesting hound's-tongue. The animals often have staring expressions and diarrhea. They experience increased thirst, nervousness, and a drop in milk yield. Necropsy shows an inflamed stomach as well as swollen, edematous mesenteric lymph nodes. Death occurred within 24 h of plant ingestion (Cooper and Johnson 1984, Knight et al. 1984).

References:

  • Cooper, M. R., Johnson, A. W. 1984. Poisonous plants in Britain and their effects on animals and man. Her Majesty's Stationery Office, London, England. 305 pp.

Horses

General symptoms of poisoning:

Notes on poisoning:

Actual and experimental cases of hound's-tongue ingestion by horses have resulted in sickness and death. Postmortem examinations show severe icterus and hepatic cirrhosis with diffuse, severe megalocytosis, biliary hyperplasia, and fibrosis (Knight 1984).

References:

  • Knight, A. P., Kimberling, C. V., Stermitz, F. R., Roby, M. R. 1984. Cynoglossum officinale (hound's-tongue) - a cause of pyrrolizidine alkaloid poisoning in horses. J. Am. Vet. Med. Assoc., 185: 647-650.

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