- Japanese pieris is a shrub or small tree with oval to lanceolate leaves with finely serrated margins. Small white flowers are borne on a terminal panicle.
- Geographic range
- Japanese pieris grows in a range and habitat similar to that of rhododendrons and azaleas, but it is less common.
- Toxic principle
- Andromedotoxins (grayanotoxins) are water-soluble diterpenoid compounds. Leaves and flower nectar (including honey made from plant nectar) are sources of the toxin.
- As little as 3 ml nectar/kg body weight or 0.2% of the body weight as leaves may be toxic or lethal.
- Mechanism of toxicologic damage
- Andromedotoxins bind to and modify the sodium channels of cell membranes, leading to prolonged depolarization and excitation. Modification of the sodium channels favors calcium movement into cells and results in a positive inotropic effect similar to that of digitalis.
- Clinical signs
- Salivation and a burning sensation in the mouth are followed by emesis, diarrhea, muscular weakness and impaired vision. Bradycardia, hypotension (caused by vasodilation) and atrioventricular block are serious cardiovascular effects that may be lethal. Dyspnea, depression, and prostration develop, and death may occur within 1-2 days. Ruminants often bloat. Aspiration pneumonia can develop secondary to emesis.
- Laboratory diagnosis
- Generally non-specific findings.
- Lesions are non-specific
- Detection of leaves in GI tract may assist in diagnosis.
- Detoxification. Emesis is used where appropriate. Activated charcoal should be administered repeatedly the first day.
- Supportive therapy. Fluid replacement therapy and respiratory support may be necessary. Atropine is recommended for severe bradycardia. Isoproterenol or sodium channel blockers (e.g., quinidine) may be used to treat heart block.
Honey made from the plants has been reported to cause cardiac arrhythmias, emesis, mild paralysis and convulsions in humans and is known as “mad honey”.