Common Tansy
Tanacetum vulgare
Horse
Moderate
Any suspected ingestion is an immediate veterinary emergency. From 500 grams of fresh plant consumed in 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 (fluid therapy, sedatives if necessary).
- Time to signs
- A few hours to 24 hours
- Prognosis
- Good for the horse's survival, but very detrimental to gestation.
- Keep the horse calm
- Ensure rider safety
- Call a veterinarian
- Administer gastric protectants
Its ID card
- Height
- 30 cm – 1.5 m
- Flowering
- July to September
- Toxic parts
- Entire plant, especially flowers and upper leaves.
- Toxin
- Terpene ketone (Thujone)
- Habitat
- Roadsides, riverbanks, wastelands, embankments, debris.
- Soil indicator
- Nitrogen-rich soils, cool to moist, often disturbed.
- Regions
- Entire Europe
- In hay
- Yes — stays toxic once dried
- Palatability
- Very strong odor generally repulsive, but some horses seem to develop a taste for it, or consume it dried in hay.
When the risk rises
July to September (flowering).
Spotting it in the field
Ragwort (which has outer petals, unlike tansy). — smell : strong, camphoraceous, and aromatic smell, particularly pronounced when the plant is crushed.
- Stiff, reddish stem
- Highly dissected leaves, resembling fern fronds
- Yellow flowers resembling tight small buds (capitula without outer petals) clustered at the top
- Strong camphor/resin smell when crushed
Signs to watch for
Acute and chronic toxicity (abortifacient potential more pronounced with repeated or prolonged exposure).
Dose : Approximately 500 g of fresh plant per 500 kg horse can cause severe symptoms; the risk of abortion is higher.
- Behavioral changes, nervousness, sudden bouts of meanness/aggression
- Tremors and muscle spasms
- Colic and diarrhea
- Abortion in pregnant mares
- Rapid pulse and breathing
Who is affected
Other species : Toxic and abortifacient for ruminants, dogs, and humans.
In pregnant mares : major risk of very rapid abortion.
Getting rid of it
Method : Mow the plant before flowering to prevent seed production. Pull plants wearing gloves to avoid skin contact. Dispose of waste safely (controlled burning).
- Inspect pastures and borders to identify and remove tansy before it is consumed.
- Avoid mowing tansy and leaving it to dry in hay, as it can become more palatable when dried.
- Restrict access for pregnant mares to areas where tansy is present.
Frequently asked questions
Can Equio identify Common Tansy from a photo?
It can help organize visual clues, but plant identification must remain cautious when horse health is at stake.
Is Common Tansy 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.