Hound's tongue
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).
Nomenclature:
Scientific Name: Cynoglossum officinale L.
Vernacular name(s): hound's tongue
Scientific family name: Boraginaceae
Vernacular family name: borage
Cynoglossum officinale L.
Geographic Information
Alberta, British Columbia, Manitoba, New Brunswick, Nova Scotia, Ontario, Quebec, Saskatchewan.
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
Notes on Toxic plant chemicals:
The following LD50toxicities 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.
Echinatine
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:
death
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).
Horses
General symptoms of poisoning:
Ataxia, breathing, rapid, coma, convulsions, death, depression, diarrhea, hemoglobinuria, icterus, liver, cirrhosis of, lungs, congestion of
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).
