Hemlock
Conium maculatum
Horse
Critical
Any suspected ingestion is an immediate veterinary emergency. Approximately 1 to 2 kilograms of fresh leaves for a horse (less sensitive than cattle, but still lethal).
Equio informs, it does not diagnose. When in doubt, call your vet.
What to do now
- Antidote
- No specific antidote. Intensive symptomatic and supportive treatment.
- Time to signs
- 15 minutes to a few hours
- Prognosis
- Very grim once paralysis begins. Death by asphyxiation while remaining conscious.
- No known antidote.
- Absolute veterinary emergency.
- Gastric lavage if possible and recent.
- Administration of activated charcoal.
- Intensive respiratory and cardiovascular support.
Its ID card
- Height
- Jusqu'à 2 m
- Flowering
- May to August
- Toxic parts
- The entire plant, but especially the seeds and roots.
- Toxin
- Piperidine alkaloids (Coniine)
- Habitat
- Damp places, hedgerows, ditches, wastelands, rubble, stream banks.
- Soil indicator
- Soils rich in nitrogen, often damp.
- Regions
- Europe, Asia, North America
- In hay
- Yes — stays toxic once dried
- Palatability
- Repulsive odor (mouse urine), generally avoided when growing, except in spring (young shoots are less odorous).
When the risk rises
May to August.
Spotting it in the field
Wild carrot, Wild chervil, Hogweed (very difficult to distinguish from other members of the Apiaceae family). — smell : strong, unpleasant odor reminiscent of mouse urine when crushed.
- Tall plant (up to 2m).
- Smooth, hollow stem, spotted with red/purple at the base.
- Highly dissected leaves (parsley-like).
- Small white flowers in umbels.
- Characteristic mouse urine odor when crushed.
Signs to watch for
Acute toxicity.
Dose : Approximately 1 to 2 kg of fresh leaves for an adult horse.
- Intense muscle tremors
- Pupil dilation
- Paralysis of hind limbs (horse sits down)
- Jerky breathing then respiratory arrest
- Cold extremities
Who is affected
Other species : Extremely toxic to cattle, sheep, pigs, and humans.
In pregnant mares : teratogenic (causes fetal malformations in many animals).
Getting rid of it
Method : Uproot the entire plant before seed formation, wearing impermeable gloves. Destroy the uprooted parts by burning or deep burial.
- Identify and remove the plant from pastures and surrounding areas.
- Avoid mowing the plant and leaving it to dry in pastures, as it remains toxic.
- Closely monitor young horses and curious animals.
Frequently asked questions
Can Equio identify Hemlock from a photo?
It can help organize visual clues, but plant identification must remain cautious when horse health is at stake.
Is Hemlock 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.