Wild Mustard
Sinapis arvensis
Horse
Moderate
Get veterinary advice the same day and remove access. Significant and repeated ingestion over several days, especially when the plant is going to seed.
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 2 days.
- Prognosis
- Generally good if consumption is stopped in time. Fatal cases are very rare in horses.
- Remove contaminated feed.
- Contact a veterinarian.
- Treat intestinal inflammation.
- Administer gastric protectants.
- Use mild laxatives if necessary.
Its ID card
- Height
- 30 cm – 1.2 m
- Flowering
- April to September.
- Toxic parts
- The entire plant, with the seeds being the most dangerous part, concentrated in irritating oil.
- Toxin
- Glucosinolates (which release isothiocyanates, mustard oil) and goitrogens.
- Habitat
- Cereal fields, fallows, embankments, roadsides, pastures.
- Soil indicator
- Rich agricultural soils, calcareous soils, disturbed land.
- Regions
- Entire Europe
- In hay
- Yes — stays toxic once dried
- Palatability
- Moderate (pungent taste). Grazed when young with grass, or accidentally ingested in hay.
When the risk rises
May to July (flowering and seeding).
Spotting it in the field
Rapeseed (identical flowers but smooth, bluish leaves), Wild Radish (often white/purple veined flowers). — smell : characteristic pungent and acrid smell when crushed or cut.
- Plant covered in stiff hairs.
- Leaves deeply lobed at the base, simpler towards the top.
- Cross-shaped flowers with 4 bright yellow petals.
- Fruits are long siliques (thin pods) containing round seeds.
Signs to watch for
Both acute and chronic (cumulative) toxicity.
Dose : Difficult to quantify precisely, depends on horse size and toxin concentration. Significant and repeated ingestion is required.
- Severe gastroenteritis (colic, profuse diarrhea)
- Hypersalivation
- Difficult and accelerated breathing
- General weakness and sometimes incoordination
- Goiter (swelling of the thyroid in the neck) in case of chronic consumption
Who is affected
Other species : Toxic to ruminants (also causes goiters and imparts a bad taste to cow's milk).
In pregnant mares : goitrogenic compounds cross the placental barrier and can cause thyroid malformations in foals.
Getting rid of it
Method : Pull the plant before seed formation, ideally by hand with gloves. Burning may be considered for large infestations.
- Inspect pastures and hay for the presence of wild mustard.
- Avoid grazing infested areas, especially in late spring and summer.
- Manage weeds in paddocks and pastures.
- Ensure a balanced diet to reduce the temptation to graze undesirable plants.
Frequently asked questions
Can Equio identify Wild Mustard from a photo?
It can help organize visual clues, but plant identification must remain cautious when horse health is at stake.
Is Wild Mustard 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.