Wormwood
Artemisia absinthium
Horse
Moderate
Any suspected ingestion is an immediate veterinary emergency. Approximately 500 grams to 1 kilogram consumed over a short period.
Equio informs, it does not diagnose. When in doubt, call your vet.
What to do now
- Antidote
- No specific antidote. Symptomatic and supportive treatment by veterinarian.
- Time to signs
- A few hours to 24 hours
- Prognosis
- Good for the horse's life (lethal doses are rarely reached by grazing), but dramatic for gestation.
- Remove the animal from the contaminated area.
- Keep the animal calm.
- Close veterinary monitoring.
- Contact a veterinarian if nervous symptoms or suspected abortion occur.
Its ID card
- Height
- 30 cm – 1.2 m
- Flowering
- July to September
- Toxic parts
- Entire plant, especially leaves and flowering tops.
- Toxin
- Ketones (Thuyone) and bitter principles (Absinthin)
- Habitat
- Embankments, dry wastelands, roadsides, rockeries, calcareous and uncultivated soils.
- Soil indicator
- Calcareous, arid, sunny, and poor soils.
- Regions
- Europe, Asia, North Africa, America (introduced)
- In hay
- Yes — stays toxic once dried
- Palatability
- Extremely bitter, it is normally ignored when growing. The risk is greater in very dry hay where the bitterness is somewhat masked.
When the risk rises
July to September (flowering) and in hay.
Spotting it in the field
Mugwort (Artemisia vulgaris, also toxic but with dark green foliage on top and white underneath), Tansy. — smell : strong, aromatic, and acrid smell, particularly pronounced when the plant is crushed.
- Bushy plant reaching up to 1 meter.
- Highly dissected foliage, grey-green/silvery, covered with fine silky down.
- Small yellow flowers in capitula resembling small round buds.
- Very strong and characteristic aromatic odor.
Signs to watch for
Both acute and chronic toxicity (from repeated ingestion of small quantities).
Dose : Difficult to establish precisely by grazing, but significant ingestion (several hundred grams) can be dangerous, especially for pregnant mares.
- Nervous disorders (excitement, tics, muscle spasms)
- Convulsions (absinthian epilepsy) at high doses
- Mild colic
- Spontaneous abortion
- Strong smell on the breath
Who is affected
Other species : Neurotoxic for humans (historical absinthism syndrome), abortifacient for ewes and cows.
In pregnant mares : highly abortifacient (causes violent uterine contractions).
Getting rid of it
Method : Pull the plant before flowering, wearing gloves. Avoid letting it go to seed. Destruction by fire may be considered for waste.
- Inspect pastures and remove the plant if present.
- Avoid mowing and distributing hay from areas where wormwood is abundant.
- Be particularly vigilant with pregnant mares.
Frequently asked questions
Can Equio identify Wormwood from a photo?
It can help organize visual clues, but plant identification must remain cautious when horse health is at stake.
Is Wormwood 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.