Horses love nothing more than a good graze in the field – but sometimes, those natural food sources can spell danger.

Some common plants are poisonous to horses, causing gastrointestinal damage or worse. That’s why it always pays to have good horse insurance in place in case your equine needs expensive emergency treatment.

Read on for our guide to six of the most frequently found toxic plants, and find out the best ways to keep your horses safe.


  1. Ragwort

The most common cause of equine poisoning by plants is ragwort. This common yellow flower brightens up the countryside, but can be fatal to horses.

Its bitter taste means that your horse is unlikely to graze on it when it’s growing in the wild. Dried and hidden in hay, however, it’s more palatable – but still poisonous.

The effects can accumulate over time. You’re likely to notice your horse losing weight, then potentially losing its sight.

If spotted early, the condition can be treated with steroids, but otherwise could eventually cause your horse to collapse and die.

So if you spot any of the warning signs, don’t hesitate to contact your vet before it’s too late. Good horse insurance will help cover vets’ fees.

Ragwort takes two years to mature, so look out for a rosette of frilly leaves in its first year. In its second year, you’ll see daisy-like bright yellow flowers from late June to August.

Landowners can be penalised for allowing ragwort to spread on grazing land, so dig it up and burn it as soon as you spot it.

A yellow flowered plant in a field

  1. Yew

Yew trees are another potentially deadly plant for horses. Traditionally planted in churchyards to prevent animals from grazing among the gravestones, they’re common in gardens, too.

While you’re unlikely to have a yew tree growing on your land, the fallen leaves and bright red berries can be carried by the wind onto your grazing pasture.

The poison is fast acting, and just a relatively small amount can cause your horse to start trembling, convulsing, having difficulties breathing, and then suffering a cardiac arrest.

While the yew’s bitter taste does put horses off eating it, you don’t want to take the risk – there’s no cure once it’s been eaten.

So keep an eye out for yew trees, and make sure no berries or cuttings make their way into your horse’s paddock.


  1. Sycamore, maples and other acers

It’s only recently that the effects of these common trees on equines has been understood.

It’s now believed that their saplings and helicopter seeds contain Hypoglycin-A, which causes the potentially fatal equine condition atypical myopathy, also known as seasonal pasture myopathy or sycamore poisoning.

If your horse eats such saplings or seeds, it can suffer symptoms including muscle stiffness and tremors, sweating, a high heart rate, and dark reddish urine.

It may appear weak, depressed, and reluctant to walk, but still want to eat.

If you spot these symptoms, call your vet as an emergency as the condition is thought to have a 70% fatality rate. Horse insurance will help you cover the cost.

It’s thought that some horses have a genetic predisposition to the disease, and that younger horses are more susceptible – but it is a risk for all equines.

The fruit from a sycamore tree hanging amongst its leaves

  1. Oak

While many poisonous plants taste so bad to horses that they avoid eating them, the oak presents the opposite problem.

Many horses just love acorns – and some owners even suspect their animals of becoming addicted to them.

In fact, all parts of the oak tree are poisonous to horses: they contain tannic and gallic acids that can badly damage your horse’s digestive system and kidneys.

Signs to watch out for are constipation, weight loss, bad colic, blood in the urine, and fluid accumulation causing swelling in the legs.

Your vet can advise, and may suggest you give your horse activated charcoal so it will excrete out the toxins harmlessly.

Better still, avoid the problem in the first place by moving your horse away from oak trees when they’re shedding acorns in the autumn.


  1. Privet

The ornamental plant privet is used to hedge off gardens up and down the UK. It’s not planted as a field hedge for good reason: the leaves and especially the berries are poisonous to animals. 

Your horse is unlikely to chew down a mouthful of privet as it tastes pretty nasty. But it might ingest a small amount, particularly if it’s mixed in with a tastier hedge.

The most common effect is gastrointestinal distress, but privet can also affect the nervous system, causing paralysis, convulsions and even death.

Act fast – although very rare, fatalities can occur within a few hours. Call your vet and tell them your horse has eaten privet.

Although there’s no specific treatment, your vet can give your horse activated charcoal to reduce the effects of the toxins, and also stabilise your horse through fluid or electrolyte therapy.

Such intensive treatment doesn’t come cheap, so make sure you’re covered with horse insurance.

Small black Privet berries dangling in a tree on a sunny day

  1. Rhododendron

Thanks to their dark glossy leaves and beautiful jewel-coloured flowers, you’re likely to know if you’ve got rhododendrons on or near your land.

But did you realise that they can be fatal to horses even in small amounts? They can cause the respiratory system to fail.

The fruits, flowers and young leaves are particularly toxic, though even dried leaves can cause problems.

Fortunately, horses will choose to leave rhododendrons well alone – unless they don’t have an alternative.

In fact, the very best way to keep your horse away from all poisonous plants is to provide plenty of healthy, tasty pasture for it to graze.

Make sure hay is free from any nasties, as horses may be less able to detect toxic plants once they’re dried. Buy hay from a reputable source, or make your own with care.


Get a quote from Equesure today

While prevention is better than cure when it comes to plant poisoning in horses, vets provide an essential back-up. That’s why you need to make sure your beloved equine is covered with suitable horse insurance.

At Equesure, we’re specialists in arranging cover to suit most animals, requirements and budgets. Get a quote today to keep your horse covered.

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