Horses are usually pretty clever about knowing what’s good to eat, and what’s not. And usually poisonous plants protect themselves from being eaten through their bitter tastes and smells.
But when grazing is restricted, horses may, out of hunger, try plants that they would normally avoid. Spring shoots seem quite tasty to horses who bored after a winter of hay and muddy grazing, and as young plants are less bitter than older ones, they are more appealing to a hungry horse.
And in dry summers, when the grass is burned off and scarce, tender shoots of poisonous plants will be more tempting too – so will succulent plants over the fence, when everything inside the paddock has been munched.
And, to make matters even worse, some plants lose their bitter taste when dried in hay, when unsuspecting ponies can eat them.
And finally, the reason horses and ponies are especially susceptible to poisoning is that unlike us, they cannot vomit (in fact, did you know that horses, rats, guinea pigs and rabbits are the only animals that can’t throw up?). If they eat a toxic substance, it has to go right through their system unless vets can intervene by putting in a stomach tube to help remove the poisons – this is both a horrible experience for a horse, and very expensive.
Please note that there are many more plants which are poisonous to horses and ponies – these are just some of the more common.
Nightshade
Deadly nightshade, black nightshade and woolly nightshade are three varieties of this poisonous plant, which is related to the potato. Luckily, horses don’t eat them very often, but it’s still best to remove them if they pop up in your paddocks. Deadly nightshade is the most dangerous but it’s also very rare in NZ. Its flowers are quite big and purply green – and this is how you can tell it apart from black nightshade, which is a very common weed with white flowers and green berries that soon turn black. Woolly nightshade is much bigger (almost a tree), and has purple flowers and large pale green leaves with distinctive ‘woolly’ white undersides. It’s very smelly to touch and nothing will grow underneath it, as rainwater dripping off the leaves is poisonous!
Yew
Yew trees are quite common in gardens, parks and hedges. They have small, stiff needle-like leaves and red berries – the berries aren’t harmful but the rest of the plant is highly toxic. Unfortunately, the leaves are quite tasty to horses and other livestock, such as cattle, which is dangerous because they show very few signs before dying.
It’s quite common in New Zealand for stock to die after eating yew tree cuttings dumped in their paddocks – farmers have lost their whole herds this way. Never NEVER let anyone dump tree cuttings in your horse’s paddock. There is no treatment for yew poisoning, so the best way to deal with yews is to fence them right off and keep your animals right away from any cuttings.
Ragwort
It’s a nightmare! This quite pretty yellow plant spreads quickly and can take over paddocks in just a few years. Although horses don’t normally eat it when it’s growing, it becomes more palatable when it’s cut down or broken, and may find its way into bales of hay. Ragwort damages the horse’s liver and its effects can cause illness and death a long time after the horse has eaten it.
Pull any ragwort you find up by the roots (wear gloves though, as it will irritate your skin), and all parts of the plant must then be removed from the paddock, and burned.
Hemlock
The trouble with hemlock is that it looks a lot like wild carrot (aka carrot weed), but it is deadly poisonous both to people and to horses. Luckily, it’s not very common, and horses don’t usually want to eat it. You can tell it apart from wild carrot by looking at the stem – hemlock has a purplish tinge, while wild carrot has a hairy stalk.
Bracken
This fern plant is very common right throughout New Zealand, and watch that your horse doesn’t snatch a mouthful while hacking. Never use bracken for bedding, as it’s more toxic when it’s dried.
Acorns
The seeds from the oak tree are a tasty treat for pigs, deer, mice and even birds, but along with oak leaves and branches, they are toxic to horses and cattle, especially when eaten in large amounts. In small amounts, eating acorns is harmless, but it’s been reported that some horses develop a passion for acorns almost like an addiction, and will overindulge to the point where they get severely ill. This is because of certain acids in the plant that cause damage to the kidneys and digestive system. We think it’s best to keep your horses away from oak trees when there are lots of acorns on the ground.
Buttercup
The pretty little yellow flowers look harmless, and aren’t toxic to humans or sheep, who like to eat them. They love damp areas and are often found in poorly drained parts of the paddock. They don’t taste great to ponies, but when there are heaps of them – and not much grass – they will sometimes be eaten. Buttercups irritate the mouths of horses (and cattle), and can cause colic, diarrhoea and abdominal pain. In severe cases, the animals can have breathing difficulties and convulsions, and buttercup poisoning in cows can give milk a bitter taste.
Foxgloves
Everyone knows the gorgeous foxglove, as it’s a common garden flower with towering white, pink or purple ‘trumpets’, and it can also be found growing wild. But all parts of the plant are toxic to pretty much everyone – humans, horses and other stock, cats and dogs – even chickens! It’s most likely to be eaten by ponies when it’s dried in hay.
