
17/09/2025
Lets talk about Poisonous Plants 🍂🌳
As autumn arrives in the UK, certain trees drop seeds, leaves, or berries that are toxic to horses - even in small amounts. Recognising the risks can help keep your horses safe.
Here are 5 autumn culprits:
🌰 Acorns (Oak trees)
* Appearance: Shiny brown nuts falling from oak trees in autumn
* Toxin: Gallotannins
* Signs: Colic, constipation or bloody diarrhoea, dark urine, kidney damage, weakness.
🍁 Sycamore (Maple seeds)
* Appearance: Winged “helicopter” seeds scattered under sycamore trees in autumn
* Toxin: Hypoglycin A
* Signs: Atypical Myopathy - muscle weakness, stiffness, sweating, difficulty moving, dark brown urine, sudden death.
🌼 Ragwort
* Appearance: In autumn, plants often look dried and brown with fluffy white seed heads or low green rosettes at ground level. Still toxic even when dead or dried in hay.
* Toxin: Pyrrolizidine alkaloids
* Signs: Chronic liver disease - weight loss, poor coat, behaviour changes, photosensitivity, incoordination.
🌲 Yew
* Appearance: Evergreen tree with dark green needles and red berries
* Toxin: Taxine alkaloids
* Signs: Often sudden death from cardiac failure. Tiny amounts can be fatal.
🌿 Privet (Garden hedge)
* Appearance: Dense hedge with small green leaves and clusters of white flowers or black berries
* Toxin: Glycosides
* Signs: Colic, salivation, weakness, tremors, collapse. Often from garden clippings thrown into fields.
Top Tips:
✔️ Fence off oak and sycamore trees during autumn seed/fruit drop.
✔️ Never dump garden clippings in horse fields.
✔️ Check hay and haylage for toxic weeds.
✔️ Provide extra forage to reduce risk of horses grazing harmful plants.
✔️ Unsure about a plant? Take a photo and ask your vet!