Harmful Plants That Your Horse Should Avoid
Horses need time to spend on the pasture so they won’t go stir-crazy cooped up in stalls or stables, but turnout time can come with risks depending on the plant life that may be growing in the area. Vines, broadleaf weeds and other undesired plants may spring up where horses graze, and while some may be nothing more than an eyesore, there are other plants that can be poisonous to horses if they happen to nibble on them.
Some toxic plants may go unnoticed at first, falling under the radar of land managers, but other plants can become prevalent and prolific on pasture land and horses may be tempted to check the plants out and have a taste.
The severity level of toxic plants can vary and in some cases, certain toxic plants won’t appeal to horses anyway due to being unpalatable. Also, given the fact that horses weigh half a ton, some toxic plants will have little effect on a horse as opposed to a much smaller animal. Also if your horse is healthy and in good shape, their health can overcome toxic plants.
However, there are some toxic plants that can inflict a lot of damage even from a small curious taste. Your horse can nibble a plant and come down with a serious illness that can even possibly lead to death if nothing is done or help doesn’t arrive in a timely manner.
Below we will share the top harmful toxic plants to be wary of so you can detect them on your lands, where you ride your horse or wherever your horse is active and remove them to protect the health of your precious equine friends.
Also known as Poison Hemlock, hemlock is a weed that likes to grow along fence borders in area that has lots of shade or moisture. The plant is native to Europe and was introduced to North America as an ornamental plant. It is characterized by its erect, hairless stems that have purple blotches and it’s white flowers that open up like an umbrella.
It is a very toxic plant and extremely poisonous to horses and humans. Hemlock’s leaves, stems and seeds contain several neurotoxins that detrimentally affect the nervous system with symptoms being nervousness, tremors and lack of coordination with an hour or so of consumption. The one positive of this plant is that it is not palatable to horses and has a very strong foul odor, so horses may not want to go near it. Even so, if you see these plants, you should take care to remove it immediately.
Red Maple Trees
Red Maple Trees are native to North America and can be found all over the country. Known for their green leaves in the spring and summer, the Red MAle Trees leaves turn bright red in the Fall. Generally, this tree is not threatening to horses until the leaves become wilted. The toxins in wilted leaves cause red blood cells to break down, preventing the blood from carrying oxygen.
So for example, in the fall or after a tree has fallen (from a storm, harsh winds etc.) the leaves can become wilted and put horses at risk if they ingest them. Some symptoms that horses exhibit when ingested are loss of appetite, dark-colored urine, dehydration, and rapid heart rate.
When the leaves of Red Maple Trees start to fall, care should be taken to remove the leaves.
Distinguished by its triangular leaves and curled fiddleheads, bracken fern is a plant found all over the world in nearly every climate. These plants grow in clumps around woody areas and areas of moisture meaning your horse may come across this plant on a trek but it can also invade hayfields under the right conditions.
The problem with bracken fern is that when consumed, it inhibits the absorption of essential vitamin thiamin or vitamin B1. This vitamin helps with nerve function and can lead to neurological impairment. As concerning as this sounds, a horse would have to eat a significant amount of Bracken Fern—such as several pounds a day for at least 30 days—before it can begin really causing problems.
The worrisome thing is that if horses have been consuming bracken fern, they can develop a preference for it and that’s when you will have to intervene before your horse begins to show symptoms of overeating this plant (depressions, lack of coordination and even blindness).
While horses can safely eat many different fruits and vegetables, avocados are ones that they should steer clear of because of the toxic reaction they may endure from ingesting either the avocado fruit itself or the leaves of an avocado tree.
Avocado trees are usually grown in areas with tropical climates which may be near where horses graze or on a pasture. Why is avocado so harmful to a horse? It is the result of Persin, a derivative of the fatty acids found in avocados which can be toxic when ingested by horses, causing symptoms like colic, respiratory problems, neurological issues and other feelings of being ill.
If you graze horses near an avocado orchard, you should make sure they don’t feed on avocados or play it safe and not allow them in areas where they have access to avocado as they may be tempted to eat them, especially if there are no other good choices to eat on a land.
Also known as crazy weed, Locoweed is a wildflower that has 200 different varieties with only a few of them being considered poisonous. Because all these species look very similar, it can be hard to tell them apart unless you are experienced with the plant.
The locoweed has small stems or stemless and the seeds are the shape of an ankle bone. It’s name is very fitting because when horses ingest the plant they consume swainsonine which disrupts the function of brain cells and causes the horses to bob their head, stagger, fall over or display an awkward, high-stepping gait. All of these “loco” symptoms can immediately give off that something isn’t right.
Yellow Star Thistle/Russian Knapweed
Both of these plants are grouped together because of the toxic effect it has on horses, an agent that affects the brain and compromises the nerves and the act of chewing. Yellow Star Thistle is an annual weed that grows from a single base stem, can grow up to 3 feet tall and has round yellow flowers surrounded by spiky spines that stick out. Russian Knapweed is similar looking but has purplish flowers and no prickly spines.
Both plants commonly grow across the country along roadsides, in fields and in pastures so a horse may likely encounter them. While it is toxic, the poisoning is chronic and effects are only shown when horses consume a large amount of the plant during a short 1 to 3 month span of time.
A variant of poison hemlock, water hemlock is regarded as one of the deadliest plants in the US and looks similar to regular poison hemlock with its group of umbrella-shaped white flowers, hairless stems, and toothed leaves. The difference is that water hemlock grows in wet areas such as around marshes, irrigation ditches and along streams.
Most of the toxicity is found in the roots but all parts of the plant contain a toxin known as cicutoxin alkaloid that affects the central nervous system. Less than a pound of leaves ingested by a horse can be fatal, with death being a result of violent convulsions.
If you see this plant growing on a pasture or along where you travel with your horse, it would be best to remove the plant or take a different route as to not risk the horse going near it.
Oleander trees are a beautiful sight to see where they grow but this bright-colored shrub is highly toxic. This tree gives off a lot of leaf litter that falls off the tree and can get blown around and if it falls into the water it can make the water toxic.
All parts of the plant contains toxins known as oleandrin and nerlin which result in symptoms such as irregular heart rate, trouble breathing and a compromised pulse.
A mere 30 or 40 leaves ingested by a horse can be deadly to a horse and put your horse at risk.
Yew trees are a common ornamental plant that grows around the nation and stand out with their needle-like leaves and red berry seeds. All parts of the plant, aside from the berries contain the toxic alkaloid known as taxine, which, when ingested, can cause respiratory issues and cardiac collapse.
The horse usually comes across yews when wandering around a house or barn that has yews planted on the land. A small mouthful of these yew needles can be fatal to a 1,000 pound horse, with sudden death occurring within 2 to 3 hours of ingestion.
Johnsongrass is a weed that is edible to livestock but offers little to no nutritional value and is very hard to get rid of where established. Both grass types are coarse and have broad leaves and can grow up to six feet tall and have multibranched seed heads. Often times, these grasses are used as a forage crop or as part of haystacks for horses to eat, which is not a good idea.
If a horse eats the leaves and stems of either Johnsongrass or Sudan Grass, their health could be at risk because the grass contain a cyanide compound which is harmless when the plant is healthy but can be harmful when the grass has been wilted or damaged via trampling or frost.
Cyanide poisoning can occur if your horse eats too much of this plant where the symptoms are rapid breathing, tremors, the constant need to urinate or defecate, gasping and at worst, convulsions.
Tansy Ragwort is a noxious weed that came from Europe and has many different species but is most commonly identified by its tallness and clusters of daisy-looking yellow flowers. This weed can grow along roadsides or in pastures but mostly becomes a problem when mixed with horse hay.
Tansy Ragwort contains a toxic alkaloid that interferes with cell division, particularly in a horse’s liver. The damage to the liver is irreversible and there really is no signs that show that a horse has been consuming this plant until you see photosensitization (sensitivity to light) or a loss of appetite, depression, weight loss or jaundice.
If this weed is growing on the pasture, do your best to take it down with a herbicide and eradicate the weed so horses do not eat it and make sure the plant is not mixed in with hay.
These are just a few of the common plants that can grow around pastures that as a horse owner you need to keep an eye on and address for the sake of your horse’s health and safety. Whether through mechanical means, herbicidal means or modifying your horse’s routine, avoid these plants so they will not threaten your horse and put them at risk for medical complications.