Piperidine alkaloids are identified by their saturated heterocyclic
ring, i.e., piperidine nucleus. The best
known piperidine alkaloid poisons are those of poison hemlock, Conium
maculatum. Socrates is reputed to have been killed with a poison hemlock
extract. There are at least 5 naturally occuring
conium alkaloids. .
Fresh plant is enthusiastically consumed by pigs in feed trials. Third
eyelid expands over entire eye about 15 minutes after poisoning causing
temporary blindness. Weakness, trembling, and lethargy are observed. Both
seeds and foliage are teratogenic in swine causing cleft palates in piglets
exposed at 30 to 45 days gestation, and arthroryposis, scoliosis, hydrocephalus,
and severe contraction of fetlock joints in piglets exposed at 43 to 61
days gestation.
Cattle are about ten times more vulnerable than sheep apparantly because
of differences in liver metabolism. An injectable dose of 16 mg coiinine/kg
live weight is lethal in cows. Field trials have induced crooked calf disease
in the offspring of cows fed poison hemlock or dosed with conium alkaloids,
implicating poison hemlock as a likely cause of deformed calves on ranges
with no lupine herbage present.
Although horses are readily poisoned by poison hemlock, field trials
thus far have not been able to induce teratogenic responses in pregnant
mares poisoned with conium alkaloids, indicating that the horse fetus may
be resistant to these toxins.
Signs of poisoning in sheep are restlessness, followed by tremors and
ataxia. The lethal dose for sheep is @ 240 mg coiinine/kg live weight.
Their resistance to poisoning when compared to cattle is attributed to
species differences in liver metabolism. Research indicates that poison
hemlock is not teratogenic in sheep.
Swine paddocks should be monitored for poison hemlock because swine
will readily eat it. Poison hemlock is not highly palatable to cattle,
horses, and sheep and rarely will they eat a toxic amount of it if more
palatable vegetation is available on the range. Because conium alkaloids
are teratogenic to cattle, care should be taken that cows in the first
3 mo of pregnancy not be grazed on sparse pastures with an appreciable
population of poison hemlock. The seeds contain the highest concentration
of toxicants. Therefore, feed grain can potentially be contaminated with
poison hemlock. Although, herbicides and routine cultivation severely reduce
the amount of poison hemlock in grain fields, seed contamination is still
a potential danger in unsprayed or newly established grain fields.
[Index] [Introduction]
[Poison Hemlock][Distribution]
[Description][How
to distinguish from other plants] [Symptoms of poisoning]
[Swine] [Cattle][Horses][Sheep][Prevention
of poisoning] [References] [return
to list of toxicants]
This series of web pages was created by an undergraduate student at Cornell University for the AS625 class. All comments and suggestions are welcome.
WARNING: These web pages are only meant to be informative. Neither Cornell University nor the author of this site endorse or recommend the use of these plants.
