Guide
Recognizing toxic plants on horse pasture: the most common in Switzerland
3 min read
A horse pasture isn't a neutral piece of meadow. Depending on region and season, it can contain toxic plants that harm or kill a horse. This guide presents the most common in Switzerland, their effect and what the sharer must observe during pasture checks.
Why toxic plants are an underestimated risk
Horses usually don't eat toxic plants spontaneously. Their natural taste warns them. But two situations override this.
- Insufficient feed. A hungry horse on short pasture eats what it normally avoids. Most important case.
- Processed plants in hay. Many toxic plants taste less bitter dried but keep toxins. Ragwort in hay is more dangerous than fresh.
- Young curious horses without experienced herd members.
SVPM and GST note that the majority of Swiss horse poisonings come from few known plants.
The five most common in Switzerland
Ragwort (Senecio jacobaea). Most dangerous on Swiss pastures. Yellow-flowering, at edges and waste ground. Contains pyrrolizidine alkaloids that slowly destroy the liver. Symptoms often weeks after ingestion. More dangerous in hay.
Sycamore samaras (Acer pseudoplatanus). Winged seeds cause atypical myopathy, often deadly muscle disease. Mainly autumn, in pastures with sycamore at edges. GST has issued repeated warnings.
Yew (Taxus baccata). All parts except the red aril are highly toxic. A handful of needles can kill. Often as garden hedge at pasture edge. Symptoms very fast.
Oaks, especially acorns (Quercus). Tannins in acorns and young oak leaves can cause colic and kidney/liver damage. In autumn, danger peaks. Young horses and ponies particularly sensitive.
Black locust and laburnum. Trees and shrubs with golden-yellow flowers, often ornamental. Both contain strong toxins. Risk also over the fence.
Other Swiss toxic plants: foxglove, autumn crocus, buttercup (more dangerous in hay), hemlock, water hemlock.
Poisoning symptoms
Variable but several patterns recur.
- Apathy and anorexia. Horse isolates, ignores food.
- Salivation and mucous changes. Increased saliva, red or pale mucous.
- Movement disorders. Stumbling, swaying, wobbling.
- Colic signs. Agitation, lying-standing, rolling, sweating.
- Breathing distress. Elevated frequency, labored breathing.
- Yellow mucous. Indicates liver damage (ragwort).
- Weak, fast pulse. Shock indication.
Multiple of these: call vet immediately, keep horse calm, photograph suspected plant. Tox Info Suisse has a vet emergency line.
Pasture check: what the sharer can do
Owner has main responsibility. Sharer adds valuable perspective from regular pasture view.
- Visual check at paddock changes. Notice unusual plants, yellow flowers, acorns on ground.
- Photos of suspect plants to owner. ID apps help, but final assessment by owner or vet.
- Seasonal attention. Spring and early summer for growing plants. Autumn for falling acorns and samaras.
- Pasture edges. Horses often eat over fences. Toxic hedge in neighbor garden equally dangerous.
Swiss practice
FSVO and Swiss equestrian practice have prevention standards.
- Hay from trusted supplier. Reduces ragwort-in-hay risk.
- Annual pasture walk with owner before season, remove toxic plants with root.
- Enough hay on thin pastures. Horses eat toxic plants mainly from lack of other feed.
- Young or sick horses on particularly checked pastures.
- Doubt: act. Better call vet once too often than too late.
Frequently asked questions
Most common in Switzerland? Ragwort, sycamore samaras, yew, oak acorns, black locust.
On discovery? Remove horse, inform owner and vet, identify, remove.
Symptoms? Apathy, anorexia, salivation, colic signs, movement disorders, trembling, yellow mucous, breathing distress.
Prevent ingestion? Regular checks, root removal, enough hay, vigilance near hedges.
Swiss law? OPAn requires compliant keeping. Holder responsible for pasture control.
Sources
Document pasture observations in HorseCompanion
Pasture checks documented per horse: last check, plants removed, observations. Start for free
Updated: June 2026