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Hidden Dangers of Fall Foliage: Poisonous Fall Plants to Horses

Fall is many equestrians' favorite time of the year. Cooler temperatures mean spicy horses, long rides, and plentiful pleasant days spent at the barn. However, you may also notice your horse sampling plants and fallen leaves around their pasture, especially if heavy summer grazing has left their field depleted and barren of fresh grass.

Collage of fall weeds and trees

Autumn weeds and falling foliage can contain many hidden dangers for our equine companions. Horse owners should be aware of the poisonous plants and trees that can tempt our horses in the fall.


Poisonous Weeds

Spring and summer are defined by the rampant growth of flowers, grass, and weeds. Many horse owners know to keep an eye out for signs of health complications as they wean their horses onto lush summer pastures. However, autumn brings about a second flush of growth and vigor that creates another round of headaches for horse owners. Several poisonous weeds make their appearance in the waning days of summer and first weeks of autumn. This means owners need to be vigilant in monitoring their fall pastures for signs of nasty weeds that pop up in autumn and can cause dire health complications to their horses.


Ragwort

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Ragwort

Ragwort is a prolific weed that encompasses over 70 species, including Saint John’s Wort and Tansy.


Fresh ragwort has a bitter taste and is rarely eaten by horses unless they are left without access to proper forage. However, when dried, ragwort loses its bitter properties and becomes more palatable, making it a late summer danger in hayfields. Because horses are more likely to nibble on wilted ragwort, it is important to not leave clippings in the horse paddock.


Ragwort is best removed when it is at the rosette stage and should be pulled out of the ground by its roots instead of mowed, which could lead to more widespread growth. After pulling ragwort, be sure to remove all remnants of the plant from the field.

Ragwort plants

Appearance

Ragwort is a tall, erect plant that stands about 3 feet tall. It bears large clusters of tiny flat-topped yellow flowers that have a daisy-like appearance when viewed up close. Ragwort leaves are generally long and thin with a toothed edge. These yellow flowers bloom from July to October and can be prolific in unimproved grasslands. They create a large number of seeds that are then dispersed to the surrounding landscape on the wind.


Ragwort Toxicity

Even though it is rarely consumed, ragwort is highly toxic. Just 2 pounds can be enough to kill a full-sized horse. However, horses can still show signs of toxicity if they consume a small amount over a couple of days.

Close up of ragwort

Ragwort toxicity compromises a horse's liver function and can cause liver failure if eaten in great quantities or over an extended period of time.


Horses suffering from ragwort toxicity can appear weak and dizzy, displaying a characteristic lack of coordination. Sometimes horses will lose their sight, leading to more imbalance and trouble getting around. Diarrhea, constipation, and colic are other symptoms of ragwort toxicity. In severe cases, paralysis can result.


Goldenrod

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Goldenrod is another yellow-flowered plant that tends to grow alongside ragwort in late summer and autumn. This prolific plant can often be seen adding a splash of yellow color to horse pastures and undeveloped land. Another weed that is generally unpalatable to horses, goldenrod is rarely consumed unless horses are kept in heavily overgrazed pastures and without access to adequate forage. However, it should still be removed from horse's reach to prevent curious equines from sampling the plant.

Yellow- flowered goldenrod

Appearance

At a quick glance, goldenrod can look very similar to ragwort, however, they tend to have smaller flowers clustered along long stems.

Up close shot of goldenrod flowers

These tiny yellow flowers have a disc-like appearance when viewed up close and often grow in lines of 8-21 along the top of separate stems. Goldenrod can have several stems containing flowers interspersed at regular intervals towards the top of the main stem. Leaves are long and narrow with smooth edges.


Goldenrod Toxicity

If goldenrod is consumed, horses can quickly succumb to its toxicity.

Goldenrod contains the toxic trematone and only 1-1.5% of a horse's body weight is necessary for health complications to appear. Goldenrod poisoning can cause a multitude of ailments, including paralysis, muscle tremors, and coma.


Horses suffering from goldenrod toxicity often appear weak, especially in their hindlimbs, and go into respiratory distress, characterized by heavy breathing and flared nostrils. A distinct acetone odor on the breath can be a telltale sign of goldenrod poisoning.


Pokeweed

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Pokeweed

Across much of the United States, pokeweed is a weed that makes itself at home along fence lines and pasture edges. The plant is most easily identifiable by its dark purple berries in September and October. These unique berries are highly toxic, however for horses the entirety of the pokeweed plant, including the roots and stem, and poisonous. Even though commonly found around farms, pokeweed is rarely eaten. It contains phytolaccatoxin which leaves a burning sensation in the mouth when consumed. However, curious horses or those left without adequate access to forage may nibble on the plant, leading to a host of medical complications.

Pokeweed plant with berris

Appearance

While the dates vary across the country, pokeweed often bears fruit in late summer (around August to October).

Dark purple pokeweed berries

Pokeweed is easily distinguishable by its black-purple berries that grow in racemes (linear clusters with each berry or flower on a short stem). Pokeweed grows on long, flexible stems that can become quite large, sometimes there is a purple or red tinge to the stem. Fully grown, pokeweed often looks like a bush, with many small stems reaching up and out from the base. Leaves are rather large and are usually about 7-14 inches long by 4-7 inches wide.


Pokeweed Toxicity

For horses, the roots of the pokeweed plant are the most toxic, however, they can be poisoned by any part of the plant. Severe diarrhea and colic are the most common symptoms of pokeweed ingestion. The best way to prevent pokeweed poisoning is to provide adequate feed and forage and keep fence lines, where they grow up vigorously, mowed.


Dangerous Fall Foliage

In many parts of the United States, autumn brings about a stunning display of color as the trees begin to change. When these beautiful leaves begin to fall in our horse paddocks and pastures, they can become a tasty buffet for bored or hungry equines. While some fall leaves are harmless, others contain toxins that can quickly become deadly. As a horse owner, it is important to be able to identify and remove poisonous fall foliage from horses' reach before they can be consumed to a toxic level.


Wild Cherry

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Wild cherry tree with cherries

Wild cherry is just one fruit tree that is toxic to horses. In fact, all members of the prunus family are poisonous, including plums, pears, and peaches. These popular farmland crops look beautiful and provide plentiful delicious fruits, but pose a danger to our horses, who may wander over for a snack.


All parts of these trees are toxic, including the seeds, leaves, and bark which contain cyanide. Horse owners should be vigilant year-round to ensure their horses aren't sampling the leaves and bark. However, these trees can become more dangerous in the fall when they begin to drop their leaves. Cyanide is more concentrated in wilted leaves, making them likely culprits for toxicity if ingested.

Wild cherry tree with cherries

Appearance

Wild cherry trees are most recognizable by their unique smooth, reddish-brown bark and their clusters of cherries that appear in July. The leaves of a wild cherry tree are about 2 to 5 inches long and have a serrated edge and pointed tip. However, the wild cherry tree is just one prunus you have to look out for. Take note of which trees in your pastures bear fruit and be on the lookout for all types of cherries, pears, peaches, and plums.

Pear orchard


Prunus Toxicity

The cyanide in prunus trees is what makes them lethal. A full-sized horse only needs to consume 2.5 pounds of leaves from one of these trees to experience the negative symptoms of toxicity.


Cyanide in large doses prevents cellular uptake of oxygen, causing cells to die off. Horses suffering from wild cherry poisoning often experience anxiety, weakness, and heavy breathing. In severe cases, convulsions and death can occur.


Red Maple

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Wilted red maple leaves in grass

Across much of the United States, red maples light up the landscape in autumn. These stunning trees are known for their vibrant red display and are a favorite among leaf peepers in the Northeast. However, in autumn these beautiful trees pose a huge threat to the health and safety of our horses.


Red maples are extremely poisonous to equines and, while rare, toxicity most often occurs in the late summer and early autumn. That's because red maple leaves become more dangerous as they wilt and fall off the tree.


These wilted leaves have a sweeter flavor than the fresh ones, making horses more likely to give them a try. Fresh, green maple leaves are not toxic, however, once they start to wilt, they become hazardous and can retain their toxicity for four weeks after coming off the tree.

Red maple in fall

Appearance

In the autumn, red maples can often be distinguished by their signature red color. However, because their danger lurks outside of the fall season, it is important to be able to identify them year-round.

Maple leaves have three distinct lobes and a toothed edge. The leaves are bright green with a red stem and a silver-white underside. They are easy to get mixed up with the sugar maple, which looks similar but has five lobes instead of three.


Red Maple Toxicity

It remains unclear which toxin is responsible for red maple's poisonous ways, however, its extreme toxicity is well known.


Horses only need to consume 1.5 pounds of red maple leaves to experience toxicity; 3 pounds is fatal. Red maple toxicity attacks the red blood cells, leading to severe anemia and death. Horses that are experiencing red maple toxicity often have an increased heart rate, difficulty breathing, and show signs of weakness. In severe cases, they can have dark brown urine and yellow mucus membranes.


Oak and Acorns

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In the summer, these large trees are a great addition to pasture and provide ample shade for the hottest days of the year, however, once autumn rolls around they become a huge headache.


While most horses will leave oak leaves and acorns alone, some develop a taste for these bitter snacks and seek them out. Young, fresh oak leaves and acorns are the most toxic, however, horses can also experience symptoms from eating wilting autumn leaves. Fall can be devastating for horses that take an interest in eating oak leaves and acorns.


Even though oak toxicity is rare, it is not unheard of, especially in the Northeastern United States. The best way to prevent the ingestion of oak leaves and acorns in the fall and spring is to fence off trees and clip branches that are within reach.

Oak branch with leaves and acorns

Appearance

There are several different species of oak trees, however, they all have long, symmetrical lobed leaves.

Some trees have pointed lobes while others are smooth and the number of lobes may vary. Mature oak trees often have rough bark with distinctive vertical grooves. In autumn, oak trees drop copious amounts of hard, oval-shaped nuts with a distinctive hat on top.


Oak and Acorn Toxicity

Even though toxicity is rare, it is not unheard of for horses to gorge themselves on oak leaves and acorns. Spring buds and green, unripe acorns are the most toxic, although horses can still experience symptoms after ingesting wilted leaves.

Oak leaves and acorns contain tannins, which when consumed in large quantities can cause kidney damage. Horses need to consume a substantial amount of acorns and leaves to experience severe oak toxicity, which is one of the reasons the condition is rare. However, be mindful of your horse's oak leaf and acorn consumption because the toxins can build up over a few days or weeks of consistent ingestion and cause problems later on.


Horses suffering from oak toxicity often experience kidney damage and gastroenteritis. Common symptoms of oak poisoning include general depression, lack of appetite, constipation, bloody diarrhea or urine, and colic.

 

Be vigilant throughout the fall. Keep an eye on your horse to ensure they aren't eating poisonous fall plants. Be on the lookout for signs of poisoning and your horse will make it through fall happy, healthy, and enjoying the cooler weather.


Toxic fall plants to horses


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