Common Name
Laurel , mountain laurel, calico bush
Botanic Name
Kalmia L.
Plant Family
Ericaceae (Heath Family)
Acidic soils, high rainfall areas
Eastern, northwestern States
Animals Affected
Cattle, sheep, goats, horses, camelids, humans
Kalmia latifolia (Laurel)
Toxic Principle
Diterpene compounds called Grayanotoxins are present in all parts of the plant including the nectar. Grayanotoxins bind to sodium channels in heart, nerve and muscle maintaining cells in a state of depolarization. Ingestion of 0.2-0.6% of the animals body weight of green laurel leaves will cause poisoning.
Indigenous to North America, Kalmia's 6 species are perennial,evergreen, spring flowering shrubs. The leathery green, lanceolate, leaves are poisonous
Excessive salivation, regurgitation of rumen contents, vomiting, abdominal pain, anorexia. Diarrhea is uncommon.
Muscle tremors, weakness, ataxia and recumbency
Activated charcoal via stomach tube, saline, cathartics are helpful in clearing the plant from the digestive tract. Atropine may be necessary if bradycardia is severe.
Cardiovascular system
Increased heart rate, heart irregularity. In severe cases of poisoning the heart may be abnormally slow.
Respiratory System
Increased respiratory rate. Death often results from inhalation pneumonia.
Nervous System
Muscle tremors, recumbency, seizures, convulsions
Reproductive System
Fetal mummification may occur
Autopsy findings are generally nonspecific and include hemorrhagic enteritis, and aspiration pneumonia. Kalmia leaf parts may be found in the stomach.
Special Notes
"Mad honey" disease occurs in people who eat quantities of honey made from bees feeding on laurels and rhododendrons. Affected people develop excessive salivation, bradycardia, severe hypotension, muscle weakness, convulsions and coma in severe cases.
Kalmia latifolia hybrid.(Laurel)