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Notes on poisoning: Conium maculatum


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).

References:

Anon. 1951. Unusual case of hemlock poisoning in swine. Calif. Vet., 5(2): 26.

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.

Edmonds, L. D., Selby, L. A., Case, A. A. 1972. Poisoning and congenital malformations associated with consumption of poison hemlock by sows. J. Am. Vet. Med. Assoc., 160: 1319-1324.

Frank, A. A., Reed, W. M. 1987. Conium maculatum (poison hemlock) toxicosis in a flock of range turkeys. Avian Dis., 31: 386-388.

Hannam, D. A. 1985. Hemlock (Conium maculatum) poisoning in the pig. Vet. Rec., 116: 322.

Keeler, R. F., Balls, L. D., Shupe, J. L., Crowe, M. W. 1980. Teratogenicity and toxicity of coniine in cows, ewes and mares. Cornell Vet., 70: 19-26.

Keeler, R. F. 1974. Coniine, a teratogenic principle from Conium maculatum producing congenital malformations in calves. Clin. Toxicol., 7: 195-206.

Lampe, K. F., McCann, M. A. 1985. AMA Handbook of poisonous and injurious plants. American Medical Assoc. Chicago, Ill., USA. 432 pp.

MacDonald, H. 1937. Hemlock poisoning in horses. Vet. Rec., 49: 1211-1212.

Panter, K. E., Bunch, T. D., Keeler, R. F. 1988. Maternal and fetal toxicity of poison hemlock (Conium maculatum) in sheep. Am. J. Vet. Res., 49: 281-283.

Panter, K. E., Keeler, R. F., Baker, D. C. 1988. Toxicoses in livestock from the hemlocks (Conium and Cicuta spp.). J. Anim. Sci., 66: 2407-2413.

Panter, K. E., Keeler, R. F., Buck, W. B. 1985. Congenital skeletal malformations induced by maternal ingestion of Conium maculatum (poison hemlock) in newborn pigs. Am. J. Vet. Res., 46: 2064-2066.

Panter, K. E., Keeler, R. F. 1989. Piperidine alkaloids of poison hemlock (Conium maculatum). Pages 109-132 in Cheeke, P. R., ed. Toxicants of plant origin. Vol. I. Alkaloids. CRC Press, Inc., Boca Raton, Fla., USA. 335 pp.

Penny, R. H. 1953. Hemlock poisoning in cattle. Vet. Rec., 42: 669-670.

Short, S. B., Edwards, W. C. 1989. Accidental Conium maculata poisoning in the rabbit. Vet. Hum. Toxicol., 31(1): 54-57.

Widmer, W. R. 1984. Poison hemlock toxicosis in swine. Vet. Med. Small Anim. Clin., 79: 405-408.

Nomenclature:

Scientific Name: Conium maculatum L.

Vernacular name(s): poison-hemlock

Scientific family name: Umbelliferae

Vernacular family name: parsley

Go to ITIS*ca for more taxonomic information on: Conium maculatum

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

British Columbia
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

Conium maculatum:

Images: images.google.com

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

References:

Anon. 1951. Unusual case of hemlock poisoning in swine. Calif. Vet., 5(2): 26.

Cromwell, B. T. 1956. The separation, micro-estimation and distribution of the alkaloids of hemlock (Conium maculatum L.). Biochem. J., 64: 259-266.

Edmonds, L. D., Selby, L. A., Case, A. A. 1972. Poisoning and congenital malformations associated with consumption of poison hemlock by sows. J. Am. Vet. Med. Assoc., 160: 1319-1324.

Fairbairn, J. W., Suwal, P. N. 1961. The alkaloids of hemlock (Conium maculatum L.) - II. Phytochemistry (Oxf.), 1: 38-46.

Frank, A. A., Reed, W. M. 1987. Conium maculatum (poison hemlock) toxicosis in a flock of range turkeys. Avian Dis., 31: 386-388.

Hannam, D. A. 1985. Hemlock (Conium maculatum) poisoning in the pig. Vet. Rec., 116: 322.

MacDonald, H. 1937. Hemlock poisoning in horses. Vet. Rec., 49: 1211-1212.

Panter, K. E., Keeler, R. F. 1989. Piperidine alkaloids of poison hemlock (Conium maculatum). Pages 109-132 in Cheeke, P. R., ed. Toxicants of plant origin. Vol. I. Alkaloids. CRC Press, Inc., Boca Raton, Fla., USA. 335 pp.

Penny, R. H. 1953. Hemlock poisoning in cattle. Vet. Rec., 42: 669-670.

Widmer, W. R. 1984. Poison hemlock toxicosis in swine. Vet. Med. Small Anim. Clin., 79: 405-408.

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

References:

Bowman, W. C., Snaghvi, I. S. 1963. Pharmacological actions of hemlock (Conium maculatum) alkaloids. J. Pharm. Pharmocol., 15: 1.

Cromwell, B. T. 1956. The separation, micro-estimation and distribution of the alkaloids of hemlock (Conium maculatum L.). Biochem. J., 64: 259-266.

Fairbairn, J. W., Suwal, P. N. 1961. The alkaloids of hemlock (Conium maculatum L.) - II. Phytochemistry (Oxf.), 1: 38-46.

Keeler, R. F., Balls, L. D., Shupe, J. L., Crowe, M. W. 1980. Teratogenicity and toxicity of coniine in cows, ewes and mares. Cornell Vet., 70: 19-26.

Keeler, R. F. 1974. Coniine, a teratogenic principle from Conium maculatum producing congenital malformations in calves. Clin. Toxicol., 7: 195-206.

Panter, K. E., Bunch, T. D., Keeler, R. F. 1988. Maternal and fetal toxicity of poison hemlock (Conium maculatum) in sheep. Am. J. Vet. Res., 49: 281-283.

Panter, K. E., Keeler, R. F., Baker, D. C. 1988. Toxicoses in livestock from the hemlocks (Conium and Cicuta spp.). J. Anim. Sci., 66: 2407-2413.

Panter, K. E., Keeler, R. F., Buck, W. B. 1985. Congenital skeletal malformations induced by maternal ingestion of Conium maculatum (poison hemlock) in newborn pigs. Am. J. Vet. Res., 46: 2064-2066.

Panter, K. E., Keeler, R. F. 1989. Piperidine alkaloids of poison hemlock (Conium maculatum). Pages 109-132 in Cheeke, P. R., ed. Toxicants of plant origin. Vol. I. Alkaloids. CRC Press, Inc., Boca Raton, Fla., USA. 335 pp.

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).

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.

Keeler, R. F. 1974. Coniine, a teratogenic principle from Conium maculatum producing congenital malformations in calves. Clin. Toxicol., 7: 195-206.

Panter, K. E., Keeler, R. F., Baker, D. C. 1988. Toxicoses in livestock from the hemlocks (Conium and Cicuta spp.). J. Anim. Sci., 66: 2407-2413.

Penny, R. H. 1953. Hemlock poisoning in cattle. Vet. Rec., 42: 669-670.

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.

References:

MacDonald, H. 1937. Hemlock poisoning in horses. Vet. Rec., 49: 1211-1212.

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).

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.

Lampe, K. F., McCann, M. A. 1985. AMA Handbook of poisonous and injurious plants. American Medical Assoc. Chicago, Ill., USA. 432 pp.

Rabbits

General symptoms of poisoning:

ataxia
breathing, shallow
death
trembling
weakness

References:

Short, S. B., Edwards, W. C. 1989. Accidental Conium maculata poisoning in the rabbit. Vet. Hum. Toxicol., 31(1): 54-57.

Sheep

General symptoms of poisoning:

ataxia
carpal joint, flexure
death
defecation, frequent
salivation
tail, kinked
trembling
urination, frequent
weakness

References:

Panter, K. E., Bunch, T. D., Keeler, R. F. 1988. Maternal and fetal toxicity of poison hemlock (Conium maculatum) in sheep. Am. J. Vet. Res., 49: 281-283.

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

References:

Anon. 1951. Unusual case of hemlock poisoning in swine. Calif. Vet., 5(2): 26.

Edmonds, L. D., Selby, L. A., Case, A. A. 1972. Poisoning and congenital malformations associated with consumption of poison hemlock by sows. J. Am. Vet. Med. Assoc., 160: 1319-1324.

Hannam, D. A. 1985. Hemlock (Conium maculatum) poisoning in the pig. Vet. Rec., 116: 322.

Panter, K. E., Keeler, R. F., Buck, W. B. 1985. Congenital skeletal malformations induced by maternal ingestion of Conium maculatum (poison hemlock) in newborn pigs. Am. J. Vet. Res., 46: 2064-2066.

Widmer, W. R. 1984. Poison hemlock toxicosis in swine. Vet. Med. Small Anim. Clin., 79: 405-408.

Turkeys

General symptoms of poisoning:

death
diarrhea
enteritis
kidney, congestion of
liver, congestion of
lungs, congestion of
paralysis
salivation
weakness

References:

Frank, A. A., Reed, W. M. 1987. Conium maculatum (poison hemlock) toxicosis in a flock of range turkeys. Avian Dis., 31: 386-388.

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Date modified: 2009-09-01