Common Wormwood
Artemisia vulgaris
Horse
Low
Remove access and monitor the horse; call at the first sign. A very large quantity (several kilos) consumed over a few days. Fatal poisoning is almost impossible.
Equio informs, it does not diagnose. When in doubt, call your vet.
What to do now
- Antidote
- No specific antidote. Symptomatic and supportive treatment.
- Time to signs
- A few hours to a few days.
- Prognosis
- Excellent. Severe neurological cases are only observed with absinthe or tansy.
- Remove the horse from the pasture.
- Keep the horse calm (especially if showing signs of excitement).
- Monitor for neurological signs.
Its ID card
- Height
- 1 – 2 m
- Flowering
- July to October.
- Toxic parts
- Entire plant, especially the upper leaves and flowering tops.
- Toxin
- Ketones (low dose thujone) and bitter principles.
- Habitat
- Wastelands, embankments, edges of agricultural paths, construction sites, recently disturbed soils.
- Soil indicator
- Heavy soils, very rich in nitrogen, and recently disturbed (earthworks).
- Regions
- Entire Europe
- In hay
- Yes — stays toxic once dried
- Palatability
- Very low (extremely bitter and very fibrous/tough), horses almost always avoid it unless forced by hunger in a dry wasteland.
When the risk rises
August to October.
Spotting it in the field
Absinthe (which is entirely silvery/grey), Ragweed (allergenic but leaves are green on both sides). — smell : strong, bitter smell when crushed.
- Erect plant (1 to 2m), very robust and fibrous.
- Stiff stem, often grooved and reddish.
- Leaves are deeply lobed, smooth dark green on top, covered with very white cottony down underneath.
- Small greenish flowers in inconspicuous clusters.
- Strong, bitter smell when crushed.
Signs to watch for
Both acute and chronic toxicity possible (neurological and abortifacient effects).
Dose : Not applicable, fatal poisoning almost impossible. Risk of abortion in pregnant mares.
- Mild hyperexcitability, tics or muscle spasms
- Sweating and accelerated pulse
- Mild to moderate colic
- Possible abortions
- Strong aromatic smell of feces/breath
Who is affected
Other species : Abortifacient and imparts a very bitter taste to the milk of cows (and goats).
In pregnant mares : abortifacient (thujone causes uterine contractions), absolutely to be avoided for pregnant mares.
Getting rid of it
Method : Repeated mowing before flowering, manual pulling if possible (with gloves). Avoid reseeding.
- Avoid overgrazing, which favors the establishment of this plant.
- Mow areas where the plant is present before it goes to seed.
- Maintain good vegetative cover in pastures.
Frequently asked questions
Can Equio identify Common Wormwood from a photo?
It can help organize visual clues, but plant identification must remain cautious when horse health is at stake.
Is Common 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.