Plants in the horse pasture – what grasses and poisonous plants are there?

Summer pastures can serve as a complete feed supply for some horses, which is why different grass species should be found in a horse pasture. To create an optimal and versatile forage base, it is best for the stable manager to select a seed that is specifically designed for keeping horses. As a horse owner, it is also worth taking a close look „between the blades“ to have a certain basic knowledge of grasses, herbs and poisonous plants.

Important grasses for the horse pasture

A good horse pasture should be palatable, hard-wearing, capable of regenerating quickly and provide a sufficient forage yield. Some grasses like to grow in width, have short stems and provide a dense sward that protects the soil from tread damage by horses‘ hooves. Other grasses serve as fodder suppliers.

The following grasses are suitable for this purpose:

• Perennial ryegrass (dense sward, tread and bite resistant, very tasty)
• Meadowgrass (tread-resistant, very tasty)
• Red fescue (gap filler, thrives even under unfavourable conditions)
• Timothy grass (nutrient-rich, very tasty)
• Meadow fescue (hardy)
• Cocksfoot (low in fructan, drought resistant, tasty when young)
• < 20% white clover (gap filler, high-quality protein supplier)
• Native herbs (ribwort, nettle, milk thistle, dandelion, wild carrot)

Perennial Ryegrass: friend or foe of horses?

Although ryegrass is a very fructan-rich grass, it is often sown in horse pastures. The reason: ryegrass is extremely hard-wearing and stress-resistant. Deep grazing, hoof treads and drought cannot harm the hardy grass. This means that it can meet the high demands of a horse pasture.

But its resistance does not come by chance, because so-called endophytes help the grass to survive. These are fungi or bacteria that form a symbiosis with the grass and protect it from overgrazing, drought and parasites by producing toxins in stressful times. These toxins can be harmful to the horse’s health – especially for horses sensitive to metabolism. Endophytes, however, only become a danger for the horse when the host grass comes under stress. To avoid this, the following pasture care should be practised:

• Rotate horses early; do not allow them to graze down to the sward first
• Adjust the number of horses to the available pasture area
• Have stable managers fertilise the pasture in spring
• Avoid gaps and tread damage by not letting horses out when the ground is wet

It is therefore not advisable to put metabolism-sensitive horses or horses on a diet on overgrazed pastures, as toxins from endophytes can form and put additional strain on the metabolism.

Under good pasture care, ryegrass does not come under stress and does not secrete any toxins. Due to its palatability, but also its resistance to drought and its high tread resistance on horse pastures, ryegrass is often counted as horse seed.

With regard to its high fructan content, it may be advisable for pre-diseased and overweight horses with a sensitive metabolism, in addition to sufficient exercise, to put them on pastures without ryegrass. Seed mixtures without ryegrass are available for this purpose. Healthy horses should have no problem with ryegrass as long as their feed intake is adapted to their work.

Poisonous plants – Which plants are not allowed in the horse pasture under any circumstances?

Poisonous plants contain alkaloids and bitter substances, which on the one hand are supposed to deter the horse by their unpleasant taste. On the other hand, they can have a toxic to lethal effect above a certain amount. The toxicity of the plants varies due to the toxin content, which in turn depends on the vegetation period, sunlight, fertilisation, weather or soil consistency.

The myth that horses intuitively avoid poisonous plants is not entirely true. This is because poisonous plants do not exude enough bitter substances in all vegetation stages to be recognised by the horse. It becomes particularly critical when there is little other forage available and the horses are hungry or greedy. In such a case, an unhealthy plant is quickly eaten. Horses that could not learn from experienced horses, for example because they grew up in a pure herd of youngsters, cannot benefit from the experience of older horses.

Therefore, always keep a watchful eye on the pastures and while hacking and avoid the following poisonous plants:

Autumn crocus – highly toxic

The highly poisonous autumn crocus is lethal from a dose of 50g and is also highly poisonous when dried in hay. Autumn crocus appears in spring to midsummer without flowers, which is why it can easily be confused with non-toxic wild garlic (Caution: risk of confusion!). Pale purple funnel flowers appear in August to October. The only effective treatment is to prick out the plants at the beginning of May and destroy the bulb.

Ragwort – highly toxic

The highly poisonous ragwort is unfortunately present in many horse pastures. Ragwort is lethal from 40-80g per kilogram of body weight due to liver damage. When fresh, horses avoid the herb because of its unpleasant odour. In hay, however, it loses its bitter substances, but not its toxicity, which is why horses eat it unknowingly and it can lead to death! Ragwort spreads strongly and should be dug out before seeds form.

Buttercup – poisonous

The buttercup is a poisonous, yellow flowering plant. It is mainly found in wet areas and overgrazed paddocks. It is left standing by horses, which is why it spreads more and more when overgrazed until the horse can no longer select sufficiently. In hay, buttercup loses its toxicity.

Foxglove – highly toxic

Foxglove with its striking bell-shaped flowers is highly poisonous both fresh and dried. In hay, as little as 25g cause death, while 100g of fresh leaves are lethal. As foxglove is a protected species, it must not be removed. If you discover it in the horse pasture or nearby, it should be moved to a new meadow.

Deadly nightshade – poisonous

Oval, pointed, pale green leaves with purple-brown flowers that appear from June, are followed by green berries in August that turn to shiny black. All parts of the plant are dangerous if ingested.

Symptoms appear quickly and include blurred vision, dilated pupils, slurred speech, hallucinations, rash, headaches, unconsciousness and if left untreated, death.

Acorns – poisonous

Acorns can cause severe damage to the equine gastrointestinal system and kidneys. It doesn?t end there either ? all parts of the oak are toxic so, ensure there are no oaks in or near the fields horses are likely to graze in. Oak trees pose a particular threat to horses when they drop their acorns in the autumn – be sure to scoop up any acorns that may have found their way into the field before horses develop a taste for them. Signs of acorn poisoning include severe colic, weight loss, constipation, blood in the urine.

Sycamore – poisonous

In sycamore, especially the seeds and cotyledons are poisonous, which can lead to muscle diseases in horses (pasture myopathy) with often fatal consequences. In spring, when the grass growth is less than 10 cm, seedlings can be accidentally ingested by the horse. In autumn, wing crops are critical and horses resort to them when all pastures and paddocks have already been eaten. Be sure to feed hay in addition. Horses react differently to poisoning by sycamore maple. In this case, 32 to 9,000 eaten seeds are sufficient.

Yew – highly toxic

Yew is highly poisonous and deadly even in small quantities. The horse only needs to eat 100-150g of the coniferous tree with the red berries and black seeds and can die from it. Both needles, berries, seeds, bark and small twigs can cause death in minutes from heart failure. Yew trees are often found near pasture fences and forest paths.

Privet – poisonous

The leaves and especially the berries are poisonous to animals. A 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 is 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.

Rhododendron – poisonous

Can be fatal to horses even in small amounts. Rhododendron can cause the respiratory system to fail. The fruits, flowers and young leaves are particularly toxic, though even dried leaves can cause problems.

Boxwood – highly toxic

Boxwood is very popular as a decoration at tournaments and is artfully trimmed. Actually, this plant should grow as far away as possible from horses, as even 700 – 900g of leaves can have a lethal effect. In addition to cramps, boxwood also causes paralysis, which eventually leads to death through heart and respiratory paralysis.

Other poisonous plants are:

• Fern/Bracken
• Spotted hemlock
• Ground ivy
• Ivy
• Lily of the valley

How do you deal with poisonous plants in the horse pasture?

Only allow your horse to feed on pastures that are known to you and free of poisonous plants. You should never let your horse graze on foreign meadows and pastures. The same applies to breaks during long hacks.

The best protection for horses is to locate the poisonous plants and remove them immediately. Mowed pastures used for hay production must also be checked for poisonous plants. This is because many poisonous plants do not lose their toxins when dried, but they do lose their bitter substances. As a result, it is no longer possible for the horse to distinguish between edible and toxic.

Walk your horse’s paddocks regularly and at any time during the grazing season and remove unwanted plants. Especially before seeds form, poisonous plants should be removed to prevent them from spreading further.

The horse has eaten poisonous plants – what to do?

If your horse has ingested poisonous plant parts despite all precautions, act quickly:

• Remove the horse from the area where it ate the poisonous plant
• Provide the horse with sufficient water
• Contact the vet
• Collect all parts of the poisonous plant to show to the vet

In case of an emergency, have the following information ready for your veterinarian:

• Which plants did the horse eat and how much of it?
• What symptoms can you observe? Balance disorders, shortness of breath, increased pulse, muscle tremors, salivation, cramps, paralysis or colic.

When, how quickly and how acutely symptoms of poisoning appear depends strongly on the amount ingested and the type of poison. If the poison gradually accumulates in the body due to permanent ingestion, the effects of eaten poisonous plants may not become apparent until months later. Tracing back makes this all the more difficult. Regular control of the grazing areas is thus the safest precaution to protect the horse from poisoning.