Poison-hemlock
General poisoning notes:
Poison-hemlock (Conium maculatum) is a naturalized herb found in parts of southern Canada. The plant grows on dry to moist soils. Cattle, goats, horses, swine, and sheep as well as rabbits, poultry, deer, and humans have been poisoned after ingesting poison-hemlock. Animal species vary in their susceptibility to acute toxicity (Keeler et al. 1980):
cows | 3.3 mg/kg body weight | 1.5-2 h |
ewes | 44 mg/kg body weight | 1.5-2 h |
mares | 15.5 mg/kg body weight | 30-40 min |
Poison-hemlock causes toxicity and death in animals after it is ingested. It also causes teratogenic effects called crooked calf disease in young pigs and cattle, caused by the chemical coniine (Keeler 1974, Panter et al. 1985).
Nomenclature:
Scientific Name: Conium maculatum L.
Vernacular name(s): poison-hemlock
Scientific family name: Apiaceae
Vernacular family name: parsley
Conium maculatum L.
Geographic Information
British Columbia, Nova Scotia, Ontario, Quebec, Saskatchewan.
Notes on Poisonous plant parts:
All parts of poison-hemlock contain some level of the alkaloids, except for the sap in young plants. The most toxic chemical, gamma-coniceine is abundant in leaves flowers and less common in the fruits, where it is quickly converted to coniine and N-methylconiine (Cromwell 1956).
Toxic parts:
Flowers, leaves, mature fruit, roots, seeds, stems, young shoots.
Notes on Toxic plant chemicals:
gamma-Coniceine is the precursor of the other alkaloids in poison- hemlock. This chemical is a partly unsaturated piperidine alkaloid. The other chemicals, including coniine and N-methylconiine, are saturated. During the first year of growth, gamma-coniceine is the predominant chemical. During the second year of growth, the content of both coniine and N-methyconiine increase, especially in the leaves and fruits, with a decrease in the first chemical. gamma-Coniceine is considered seven or eight times more toxic than coniine, with N-methyconiine even less toxic (Cromwell 1956, Fairbairn and Suwal 1961, Panter and Keeler 1989).
The following LD50 toxicities in mice have been reported (Bowman and Snaghvi 1963):
gamma-coniceine | death time |
2.6 mg/kg (intravenous) | 30 sec |
12.0 mg/kg (subcutaneous) | 12 min |
12.0 mg/kg (oral) | 8 min |
coniine | death time | ||
19.0 mg/kg (intravenous) | 30 sec | ||
80 mg/kg (subcutaneous) | 15 min | ||
100 mg/kg (oral) | 10 min | ||
N-methylconiine | death time | ||
27.5 mg/kg (intravenous) | 30 sec | ||
150.5 mg/kg (subcutaneous) | 16 min | ||
204.5 mg/kg (oral) | 12 min | ||
Toxic plant chemicals:
Coniine, gamma-coniceine, N-methylconiine.
Coniine
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:
arthrogryposis
breathing, rapid
carpal joint, flexure
depression
diarrhea
elbow joint, flexure
gait, unsteady
incoordination
limbs,lateral rotation
muscle spasms
salivation
scoliosis
teeth grinding
torticollis
trembling
urine, coffee-colored
vomiting
Notes on poisoning:
General signs of poisoning in all types of livestock include apathy, salivation, frequent regurgitation, teeth grinding, and reduced milk production. For a lethal dose, cattle require coniine at a rate of about 16 mg/kg of body weight (Keeler et al. 1980).
Horses
General symptoms of poisoning:
collapse
trembling
unconsciousness
Notes on poisoning:
Horses exhibit symptoms similar to other types of livestock that have ingested poison-hemlock. Trembling and paralysis are common symptoms.
Humans
General symptoms of poisoning:
coma
convulsions
death by asphyxiation
dizziness
headache
incoordination
pupil dilation
thirsty
vomiting
Notes on poisoning:
Poison-hemlock has been ingested on purpose and accidentally. Socrates was executed in 399 B.C. by an extract of this plant. Humans have accidentally ingested it, mistaking it for carrot or parsnip. The symptoms are similar to those in other animals. Coldness is often felt in the extremities. There is rapid onset of irritation of mucous membranes of the mouth and throat, accompanied by salivation and nausea. Severe poisoning may cause coma and death by respiratory failure. Treatment includes administering activated charcoal after emesis ceases. Treatment is otherwise symptomatic. Despite the severity of poisoning mortality is low (Cooper and Johnson 1984, Lampe and McCann 1985).
Rabbits
General symptoms of poisoning:
ataxia
breathing, shallow
death
trembling
weakness
Sheep
General symptoms of poisoning:
ataxia
carpal joint, flexure
death
defecation, frequent
salivation
tail, kinked
trembling
urination, frequent
weakness
Swine
General symptoms of poisoning:
arthrogryposis
articular rigidity
ataxia
blindness
blindness, temporary
breathing, labored
breathing, rapid
carpal joint, flexure
collapse
death
death by asphyxiation
fetlock joint, flexure
gait, staggering
gait, unsteady
heart rate, elevated
lacrimation, severe
palatoschisis
paralysis
prostration
pupil dilation
scoliosis
syndactylism
temperature, elevated
trembling
urination, frequent
vision, impaired
weakness
Turkeys
General symptoms of poisoning:
death
diarrhea
enteritis
kidney, congestion of
liver, congestion of
lungs, congestion of
paralysis
salivation
weakness
