Eupatorium cannabinum
Eupatorium cannabinum
Horse
Moderate
Any suspected ingestion is an immediate veterinary emergency. Chronic intoxication: repeated grazing or heavily contaminated hay over several weeks.
Equio informs, it does not diagnose. When in doubt, call your vet.
What to do now
- Antidote
- No specific antidote. Intensive supportive treatment focused on liver function.
- Time to signs
- Several weeks to several months (chronic)
- Prognosis
- Grave if hepatic signs (jaundice, neurological disorders) are already visible, as liver destruction is irreversible.
- Immediate removal of suspect feed.
- Emergency liver function tests.
- Liver support (vitamins, hepatoprotective agents).
Its ID card
- Height
- 1 – 1.5 m
- Flowering
- July to September
- Toxic parts
- Entire plant (flowers, leaves, stems). Totally toxic in hay.
- Toxin
- Pyrrolizidine alkaloids (Eupatorine, tremetone)
- Habitat
- Riverbanks, damp ditches, forest clearings, marshes, woodland edges.
- Soil indicator
- Cool, peaty, very damp soils, often in shaded edges.
- Regions
- Entire Europe
- In hay
- Yes — stays toxic once dried
- Palatability
- Low (very bitter taste), but grazed in clearings when grass is scarce, or ingested indiscriminately in hay.
When the risk rises
All year round in hay, July to September when fresh.
Spotting it in the field
Hemp (for the leaves, but hemp flowers are not pink pom-poms), Valerian (non-toxic). — smell : slightly aromatic but not strong odor when crushed.
- Tall erect plant (1 to 1.5m).
- Stem often hairy and reddish.
- Opposite leaves, deeply divided into 3 or 5 long, toothed leaflets.
- Inflorescences in large, fluffy corymbs, dirty pink to purplish.
Signs to watch for
Primarily chronic and cumulative toxicity.
Dose : Chronic ingestion of small quantities over several weeks. Difficult to quantify precisely, but contaminated hay is the main risk.
- Chronic and delayed symptoms (sometimes months after ingestion)
- Massive weight loss (muscle wasting)
- Yellow eye mucous membranes (jaundice)
- Photosensitization of light skin
- Behavioral disorders (head pressing, encephalopathy)
Who is affected
Other species : Toxic to all herbivores. Ruminants are slightly more resistant but are affected in the long term.
In pregnant mares : abortion and hepatic malformations of the fetus (alkaloids cross the placenta).
Getting rid of it
Method : Uproot the entire plant before flowering, wearing gloves to avoid contact with alkaloids. Destroy the uprooted plant by burning or deep burial to prevent its spread.
- Inspect pastures and hay fields for the presence of the plant and remove it.
- Avoid mowing or grazing horses in areas known to harbor Eupatorium cannabinum, especially when the plant is in bloom.
- Provide a varied and high-quality diet to reduce the risk of horses grazing on undesirable plants due to lack of forage.
- If the plant is present, ensure hay is free from contamination.
Frequently asked questions
Can Equio identify Eupatorium cannabinum from a photo?
It can help organize visual clues, but plant identification must remain cautious when horse health is at stake.
Is Eupatorium cannabinum 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.