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Friend or foe? Plants & Foliage That Are Poisonous To Horses *Sponsored*


Country and Stable are leading suppliers of equestrian wear and country clothing, as well as horse equipment, boots and tack. Here they share insight into the flowers, weeds and trees that can either be a friend or a foe to horses.

No matter how long you have been a horse owner, the threat of your horse being poisoned by toxic foliage and plants remains a real danger, and, sadly, as reports are emerging all the time, it’s clear that many horse owners don’t realise what their horse has eaten and whether it’s harmful or not.

Increases in equine deaths from plants also depends on what time of year it is, so with that in mind…

Do you know in which seasons poisonous plants and trees are most likely to harm your horse?

Whether you keep your horse out to pasture in a field, or head out on regular hacks, you are bound to stumble across a number of unknown plants in the countryside. It is therefore incredibly important to be able to instantly recognise which areas of nature are poisonous and potentially fatal to your horse, as well as the common places where such plants and trees are likely to grow.

FOE: Common plants and trees that are poisonous to horses in the UK…

Ragwort It may be synonymous with a sunny, early spring day, with its bold yellow rosettes – but it is deadly to horses.

What is it?…



Particularly prevalent in early spring, ragwort contains toxins called pyrrolizidine alkaloids that when ingested result in liver failure and even death, even when eaten in such a low quantity as 1-5kg over the horse’s entire lifetime!

Thriving on low-quality grazing land, ragwort produces millions of seeds which are carried by the wind, so even if you think your land is clear of ragwort, it could appear at any time! Ragwort has become such an issue in recent years that local councils have legal authority to order land owners to dispose of the weed.

How does it affect horses?…

The digestion of ragwort can have both terrifying immediate and long term effects. An immediate, acute reaction occurs when ragwort is eaten in large quantities and sudden death is guaranteed. The effects of chronic poisoning is not always observed until months have passed where small doses of poison accumulate in the horse’s liver, causing irreparable damage to the cells. Signs of a poisoning include loss of appetite, diarrhoea, weight loss, sensitivity to sunlight and jaundice, as well as neurological symptoms such as head pressing and circling.

How to avoid it…

To eradicate ragwort, it needs to be sprayed with herbicides when the plant is at the rosette stage. Trying to cut away ragwort will become a headache as it makes it grow back even more quickly! Ensure that ragwort also does not come into contact with hay as the toxins can contaminate it.


Tree poisoning – How otherwise inconspicuous and common trees can be fatal to horses…

How do trees affect horses?…

Yew trees are in general poisonous to horses, and when the leaves are dried, are also toxic. A few mouthfuls (just 0.5kg) can cause death – it is most common for horses to come into contact with yew when leaves and cuttings are ingested by the horse. This is something to be particularly mindful of in autumn when out hacking in the countryside and leaves have fallen from the trees.

Oak poisoning can come from fallen acorns, which in general are not harmful to horses when only a few are ingested. A serious problem does however arise when large quantities are eaten, which can cause kidney damage or colic.

How to avoid it…

Ensure that your horses are not kept in a field where oak trees are surrounding the area dropping acorns that are accessible to horses. If oak trees are present, ensure to regularly cultivate as many acorns as possible. When you’re out hacking, discourage your horse from interacting with acorns at all.


Atypical myopathy – Sycamore poisoning


Sycamore Seeds

Helicopter seeds in the autumn and new-season spring saplings from sycamore trees contain the chemical Hypoglycin-A, which causes atypical myopathy – a serious muscle disease often found in grazing horses where seeds are prevalent on the ground.

How does it affect horses?…

The fatality rate of atypical myopathy is around 70% and the onset of the poisoning is rapid, causing muscles to become stiff, as well as muscle tremors and colic symptoms. Sometimes the horse’s urine is dark and is an early warning symptom.

How to avoid atypical myopathy…

When pasture is poor, supply extra hay and ensure that you pick up and remove sycamore seeds. It is also important to inspect that seeds haven’t blown over from nearby fields. If keeping your horses around sycamore seeds is unavoidable, ensure that you only turn your horse out for short periods.


Monkshood – The most poisonous plant in the UK

This rare flower is also incredibly poisonous to humans, and so it is wise to be well aware of this flower in case it starts growing in your field. The violet blue flowers do not look dissimilar to a foxglove (also poisonous to horses) with their monk’s hood shaped bloom.



How to avoid them…

Luckily they are rare in the UK. However, if you do find some be very careful removing these deadly flowers as their roots contain the alkaloid ‘Aconitine’ which paralyses the nerves of pain, touch and temperature.


Other poisonous plants to be aware of…

Box privet: A very common style of hedge seen in most gardens. If you are out on your horse and it comes into contact with this particular foliage, be aware that even small quantities can kill a horse.

Buttercups: These small, dainty flowers are poisonous to horses when eaten fresh, but due to their size, a large quantity would need to be eaten to cause death.

Deadly Nightshade: Surprisingly, deadly nightshade is not directly fatal to horses, though if eaten it can cause unconsciousness and convulsions which could exacerbate other underlying complications.

Rhododendron: When eaten in even the smallest quantities, rhododendron are highly poisonous to horses, causing respiratory system failure.


FRIEND: Interesting flowers and plants that horses eat

Horses are natural forages and can often be found munching on various kinds of plants and flowers. The following cause no direct fatality to horses, if eaten in low quantities.

  • Dandelions
  • Thistles
  • Sunflower seeds and plants
  • Peanut plants
  • Raspberry/blackberry bushes
  • The wood and bark from most trees

Did you know that horses have also been known to enjoy eating tobacco, licorice, and cinnamon and chilli flavoured snacks… all without problem! Though it is widely known that greedy horses will stick their nose into anything that looks or smells tasty.

What is the strangest thing you’ve known your horse to eat?

(*)  We always recommend seeking professional help from a vet if you are concerned about your horse and any poisonous plants it may come into contact with.



Last Updated on 30/09/2020

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