Black Henbane
Hyoscyamus niger
Horse
Critical
Any suspected ingestion is an immediate veterinary emergency. A few tens of grams of the plant, equivalent to approximately 15 to 30 seeds, can be toxic.
Equio informs, it does not diagnose. When in doubt, call your vet.
What to do now
- Antidote
- No specific antidote. Symptomatic and supportive treatment: physostigmine (if indicated by vet), sedation, fluid therapy, seizure management.
- Time to signs
- 15 minutes to 2 hours
- Prognosis
- Very poor in the absence of immediate veterinary care.
- Critical veterinary emergency.
- Maintain absolute calm.
- Administer parasympathomimetics as indicated by the veterinarian.
- Perform gastric lavage if possible and safe.
Its ID card
- Height
- 30 cm – 1.2 m
- Flowering
- June to September.
- Toxic parts
- The entire plant, with roots and seeds being particularly potent.
- Toxin
- Tropane alkaloids (Hyoscyamine, Scopolamine).
- Habitat
- Wastelands, ruins, roadsides, sandy areas, rubble (often near old dwellings).
- Soil indicator
- Dry, sandy soils, rich in lime and nitrogen (often found in rubble).
- Regions
- Entire Europe
- In hay
- Yes — stays toxic once dried
- Palatability
- Strong and very unpleasant odor (like rat/mouse), making it rarely consumed fresh. However, it poses a danger when dried in hay.
When the risk rises
June to September.
Spotting it in the field
Datura, but Henbane flowers are not large white funnels and are distinctly veined with black. — smell : strong, unpleasant, and acrid odor, often described as a rat or mouse smell, especially when the plant is crushed.
- Hairy, sticky, and foul-smelling plant.
- Toothed and soft leaves.
- Asymmetrical flowers, pale yellow/beige with a network of purple/black veins.
- Fruits aligned on the stem, resembling small bells crowned with points.
Signs to watch for
Acute toxicity.
Dose : Difficult to quantify precisely for horses due to variable alkaloid content and palatability. A few tens of grams of fresh plant or a significant amount of contaminated hay can be dangerous.
- Total drying of mucous membranes
- Pupillary dilation and temporary blindness
- Stubborn constipation (halted transit)
- Agitation, delirium (horse is restless for no reason, paws the ground frantically)
- Muscle paralysis then respiratory death
Who is affected
Other species : Lethal to humans (highly toxic), dogs, and pigs (though pigs are slightly more tolerant, hence the name 'jus-quiame' meaning 'pig bean').
In pregnant mares : lethal to both the mother and the fetus.
Getting rid of it
Method : Pull the entire plant, including roots, before flowering and seed formation. Wear impermeable gloves. Destroy uprooted plants by burning or deep burial to prevent dissemination.
- Inspect pastures and surrounding areas for the presence of Black Henbane.
- Avoid letting horses graze in known infested or high-risk areas (ruins, rubble).
- Ensure adequate and quality feed to reduce the risk of horses browsing toxic plants out of curiosity or necessity.
- Identify and pull the plant before seed formation, wearing gloves.
Frequently asked questions
Can Equio identify Black Henbane from a photo?
It can help organize visual clues, but plant identification must remain cautious when horse health is at stake.
Is Black Henbane dangerous in hay?
This entry flags hay vigilance. Isolate suspicious forage and ask for professional advice if exposure is possible.
This page is informational. If ingestion is likely, if signs appear, or if the horse is fragile, contact a veterinarian immediately.