As horse enthusiasts, we’re well aware that certain plants pose a significant threat to our equine companions’ health and wellbeing. The issue lies in the fact that horses often aren’t able to distinguish between harmless flora and those that are toxic to them. As such, it falls on us to take proactive measures in keeping them away from these potentially deadly plants. While some may be more hazardous than others, all of the following should be treated with caution and avoided whenever possible:
Horsetail (Equisetum spp.)
In ideal conditions, Horsetail plants flourish in sandy soil, often situated near creeks, riverbeds, and marshy wetland areas. However, what’s often overlooked is the presence of a toxic compound that poses a significant threat to equine health. This toxin has been known to target and even destroy vitamin B in horses, with dried Horsetail proving more hazardous than its fresh counterpart.
When ingested, the plant can trigger a range of symptoms in horses, including depression, blindness, hindquarter weakness, and liver failure. If left untreated, these adverse effects can ultimately prove fatal.
Poison Hemlock (Conium maculatum)
The toxicity of this plant is remarkable, as it can be deadly to nearly all species that consume it, including humans and horses. The danger lies in the potential for mistaken identity, as people and equines may mistakenly ingest it thinking it’s its lookalike cousin, Queen Anne’s lace. This hemlock thrives in lowland and swampy environments, which increases the likelihood of accidental harvest for silage purposes.
Alarmingly, as little as two pounds of poison hemlock can be fatal to a 1000lb horse. The rapid onset of Conium poisoning is particularly concerning, as death can occur within just a couple of hours. If you suspect your horse has ingested this plant, prompt veterinary attention is crucial. Initial symptoms include excessive drooling, dilated pupils, disorientation, and muscle tremors, which will quickly deteriorate into collapse, coma, and ultimately, death.
Water Hemlock (Cicuta spp.)
The symptoms of Cicuta spp. are more severe and accelerated compared to poison hemlock. While the latter can be fatal within hours, Cicuta spp. can cause death in as little as 20 minutes. The onset of symptoms is swift, with horses exhibiting twitching and frothing at the mouth shortly after ingestion. This is accompanied by teeth grinding, head throwing back, and dilation of the pupils. As the condition progresses, limbs stiffen, pulse rate increases, and breathing becomes labored.
Seizures are a common next step, ultimately leading to sudden death.
Oleander (Nerium oleander)
Oleander bushes boast stunning beauty and widespread presence in the southern United States. They’re particularly abundant in South Carolina and Georgia, where they often flourish in coastal regions. Notably, these ornamental plants pose a significant threat to equine health, as they are equally toxic to horses as they are to humans – whether consumed fresh or dried.
In the event of poisoning, affected animals may exhibit symptoms such as stumbling, muscle tremors, labored breathing, and gastrointestinal issues like colic and diarrhea. Unfortunately, fatalities can occur within 8-10 hours without prompt treatment. As a result, prevention is crucial; ensure that oleander plants are absent from your property to safeguard the health of your horses.
Jimsonweed (Datura stramonium)
Datura plants are an intriguing sight to behold, yet their beauty belies a deadly threat to equine life. The plant’s toxic properties are attributed to three alkaloids: scopolamine found in immature roots, and atropine and hyoscyamine as the plant matures. These compounds combine to pose a significant risk to horses that ingest them.
Symptoms of datura poisoning can manifest quickly, including a rapid, weak pulse, enlarged pupils, loss of muscle coordination, tremors, and an uncharacteristically aggressive demeanor. The effects are eerily reminiscent of those experienced by humans under the influence of hallucinogens.
Dutchman’s Breeches (Dicentra cucullaria)
In regions where maple forests and pastures converge, a unique woodland flower often thrives unchecked. While some individuals cultivate it for aesthetic purposes, this perennial blooms freely in these mixed ecosystems across North America. Its presence is a natural byproduct of the symbiotic relationship between the forest’s deciduous trees and the surrounding grasslands.
When ingested, the plant’s toxic compounds can cause severe symptoms in equines like horses or cattle.
Typically, it takes 36 to 48 hours for the effects to manifest, characterized by tremors, convulsions, labored breathing, vomiting, frothing at the mouth, and diarrhea.
Deadly Nightshade (Atropa belladonna)
Nightshade is notorious for its ability to pop up in a multitude of untamed environments. It’s not uncommon to spot it sprouting forth in wild fields or abandoned pastures, where it can be seen scaling fences and posts with ease. While horses tend to steer clear of this plant, some may accidentally ingest it through contaminated feed like harvested silage.
As the toxin begins to take effect, horses will initially exhibit signs such as abdominal pain, a sudden loss of appetite, and altered pupil dilation. Muscle weakness is also a common precursor to more severe symptoms. If left untreated, these can progress to include diarrhea, followed by a precipitous decline into unconsciousness and ultimately, death.
Pokeweed (Phytolacca decandra)
In the Appalachian region, a certain woodland plant thrives in open meadows and forest peripheries. While its berries may appear deceptively edible, they pose a significant threat to humans, horses, and cattle – all of which can succumb to severe poisoning if consumed. The leaves of this plant contain toxic alkaloids, but it’s the seeds and roots that are particularly hazardous. If ingested, the effects of this plant on horses become apparent within two hours.
Horses will initially exhibit symptoms such as retching and vomiting, followed by convulsions, lethargy, and potentially life-threatening anemia. The consequences of exposure to this plant cannot be overstated.
St. John’s Wort (Hypericum sp.)
While St. John’s Wort is a valuable addition to many homesteaders’ medicinal gardens, it’s essential to keep in mind its potential risks when sharing the space with horses. While not typically fatal, consumption of this herb can lead to photosensitivity issues in equine animals. Prolonged exposure to sunlight after ingesting St. John’s Wort can cause unusual reactions, such as increased sensitivity on lighter areas like their noses and foreheads, leading to burns or discoloration.
Furthermore, affected horses may experience swelling, blistering, and peeling of their lips and tongues.
Avocado (Persea americana)
Avocado trees are notorious for their toxic nature, and it’s crucial to note that every single component is poisonous to horses. While twigs and bark share similar toxic compounds, the leaves are particularly hazardous when ingested by equines. The consequences can be severe, with affected horses displaying a range of symptoms, including loss of appetite, labored breathing, irregular heartbeat, and general weakness.
As the condition progresses, swelling may occur in the mouth, tongue, and face, accompanied by respiratory distress, fluid retention around the heart, and physical collapse.
Lambsquarters (Chenopodium album)
While lamb’s quarters is a palatable wild green for humans, it also harbors considerable amounts of oxalic acid. While horses typically don’t indulge in this plant, they may consume it if no other options are available. It’s reassuring to know that even excessive consumption would require an impractically large quantity to cause harm.
In the rare event a horse overindulges in lambsquarters, symptoms can include muscle weakness, renal failure, and respiratory distress, ultimately culminating in a coma.
White Snakeroot (Eupatorium rugosum)
Across North America, this perennial plant flourishes in riverbanks and wooded areas, boasting showy, fluffy flower heads that belie its toxic nature. Native to these regions, the plant’s beauty is matched only by its potency – a potent combination that poses a significant threat to equine health. Should horses ingest this plant accidentally, they may exhibit distress through arching their bodies with their hind legs together.
Other symptoms of poisoning include excessive salivation and nasal discharge, followed by vomiting. Affected animals may also experience labored breathing, lethargy, and depression.
Marsh Marigold (Caltha palustris)
Marsh marigolds, a common sight in North America’s wetlands, may appear harmless to the eye. However, if ingested by horses, these seemingly innocuous flowers can cause a range of unpleasant symptoms. The onset of these issues typically occurs within an hour of consumption and begins with colicky discomforts, followed by vomiting, labored breathing, and a weakened pulse. In severe cases, affected horses may exhibit twitching eyelids, diarrhea, or bloody urine, depending on the amount consumed.
Additionally, lactating mares may experience reduced milk production, with the milk taking on an unappealing reddish hue and bitter taste.
Sneezeweed (Helenium automnale)
Throughout the Midwest, you’ll commonly find vast expanses of this plant thriving in neglected areas like ditches, riverbanks, and overgrown fields. Missouri and Illinois are hotspots for its growth, while Kansas and Iowa also see it sprout up. Although considered toxic to horses, fatalities are relatively rare, making it more a cause for concern than an immediate threat. However, if left untreated, the consequences can be severe.
Horses may initially exhibit signs of distress such as labored breathing, excessive drooling, fever, rapid pulse, and convulsions. As the condition progresses, they may experience muscle weakness, lethargy, and even rapid weight loss.
Tansy Ragwort (Senecio jacobaea)
In the Pacific Northwest, this plant is commonly found in pastures, hayfields, and woodlands. Due to its unpalatable taste and unpleasant texture, equines such as horses and cattle generally steer clear of it unless they’re severely malnourished. However, it can occasionally infiltrate silage, posing a threat to the animals’ health. When ingested unintentionally, this plant typically triggers symptoms including chills, uncontrollable tremors, and a rapid, weak pulse accompanied by fever.
Affected horses may stumble around disorientedly before eventually collapsing. In severe cases or if left untreated, this plant’s toxicity can be fatal within days.
Bracken Fern (Pteridium aquilinum)
A common mistake among horse enthusiasts is confusing bracken fern sprouts with harmless fiddleheads. However, the former can be extremely toxic to horses, even deadly. These lookalike plants thrive in poor soil conditions found in heavily wooded areas. While the effects of consumption may not manifest immediately, symptoms typically emerge within a day or two. Initially, affected horses might exhibit a loss of appetite and display signs of weakness, such as staggering around.
As the poison takes hold, jaundice, nausea, and even hindquarter paralysis can develop, potentially leading to serious health issues.
Spurge (Euphorbia maculata)
If you’ve ever ventured into rural areas or pastures with depleted vegetation, chances are you’ve come across spurge before. This perennial plant is characterized by its clusters of greenish-yellow flowers growing atop fleshy leaves.
However, be cautious – the sap of this plant can cause significant discomfort to horses.
Direct contact may lead to blistering and redness on their skin, while ingesting any part of it could trigger a range of symptoms including swelling around the mouth, face, and eyes, as well as sweating, vomiting, diarrhea, and muscle tremors.
For lactating mares, spurge consumption can result in abnormal milk discoloration, often appearing red or pink.
Buttercup (Ranunculus spp.)
While it may seem counterintuitive given their common names, fresh buttercups are actually toxic to horses. In fact, they’re so potent that even a small amount can cause severe irritation on contact with both the oral cavity and gastrointestinal tract. The effects of consumption are not limited to these areas, as symptoms also include drooling, bloody diarrhea, and blistering around the mouth.
It’s worth noting that dried buttercups in hay are less hazardous, but it’s still recommended to avoid them altogether. In cases where horses have no other options for sustenance, they may ingest buttercups out of necessity, highlighting the importance of providing a diverse and nutritious diet to minimize the risk of poisoning.
Lily of the Valley (Convallaria majalis)
The lily of the valley, a delicate and fragrant flower, often emerges as one of the first signs of spring. Typically found in partially shaded, wooded areas, it releases its sweet aroma in the evening hours. However, this beauty holds a hidden danger – every single part of the plant is toxic to horses. If your equine friend has ingested lily of the valley, you may notice symptoms such as abdominal pain or colic, diarrhea, irregular heart rhythms, lethargy, or even sudden death.
Cockles (Vaccaria hispanica)
Cockles, also known as spring cockles, cow cockles, or dairy pinks, are a unique species that thrive in depleted soils, often found in fields previously used for wheat cultivation. One of the notable features of these plants is their vibrant pink flowers, which grow atop tall stems. However, this beauty is deceiving, as consumption of these flowers by horses, sheep, and other livestock can be fatal due to the severe liver damage they cause.
Prolonged exposure to cockles can lead to complete hepatic failure and ultimately, death. The early warning signs of cockle toxicity include diarrhea, weakness, and shaking.
Milkweed (Asclepias syriaca)
While it’s uncommon for horses to consume milkweed, they may resort to eating it if all other food sources are exhausted. The plant’s sticky sap, present in its stems, leaves, and pods, typically deters equines from feeding on it. However, when no alternative sustenance is available, horses might ingest milkweed, albeit reluctantly. Interestingly, this consumption can have adverse effects on the animals’ health.
Horses that eat milkweed may exhibit symptoms such as muscle spasms, loss of motor control, respiratory distress, a weak and rapid pulse, and general disorientation, which can be detrimental to their overall well-being.
Rhododendrons (Rhododendron spp.)
Many people cultivate rhododendron species like azaleas for ornamental purposes, but these plants have also naturalized in the Appalachian mountains and are native across the Pacific Northwest. While horses typically won’t consume rhododendrons, they may accidentally ingest them during winter when other forage is scarce.
The grayanotoxins present in the plants disrupt cardiac and nerve function, leading to a range of symptoms including weakness, excessive salivation, diarrhea, a weak pulse, lethargy, and paralysis. These effects usually persist for two to three days before either improving or progressing to coma and potentially fatal consequences.
Potato Leaves (Solanum tuberosum)
When it comes to growing potatoes on your homestead, it’s crucial to keep them out of reach from your equine friends. Every aspect of these tubers, including the leaves, poses a significant threat to horses due to their toxic properties. As members of the nightshade family, potatoes contain solanine, a compound also found in belladonna, which can be harmful to horses if ingested.
In fact, horses have been known to succumb to arsenic poisoning after consuming old, green potatoes that inadvertently rolled into their grazing areas. The risk is real, so it’s essential to maintain a safe distance between your potato crops and your horse’s living quarters to prevent any potential harm.
Tomatoes (Solanum lycopersicum)
When it comes to nightshade plants, tomatoes are often overlooked despite sharing similar properties to potatoes and datura when ingested. The leaves and unripe fruits of the tomato plant contain solanine and demissine, albeit in smaller amounts compared to their potato cousins. If consumed, this can lead to a range of unpleasant symptoms.
The initial signs of tomato poisoning include facial swelling, pupil dilation, and excessive drooling.
As the condition progresses, colic, diarrhea, weakened heart rate, and labored breathing may also occur. While death from tomato poisoning is extremely rare, it’s crucial to prioritize safety by maintaining a secure perimeter around your tomato garden.
Castor Beans (Ricinus communis)
If you’re a fan of Breaking Bad, you might recall the deadly potential of ricin, derived from the castor bean plant. This innocuous-looking plant harbors alkaloids that can shut down the central nervous system, rendering no antidote available to counteract its effects. If you own horses, it’s essential to familiarize yourself with the plant’s appearance and take immediate action by removing it from your property. The consequences of inaction are dire.
While ricin poses a significant threat, its ingestion can also trigger more immediate symptoms in horses. They may exhibit excessive thirst due to oral irritation and burning, leading to muscle weakness, fever, and profuse sweating. As the toxin takes hold, convulsions will ensue, ultimately culminating in kidney failure, coma, and death within 36 hours if left untreated.
Lupines (Lupinus polyphyllus)
Wild lupins may paint rural landscapes with vibrant purple hues each spring, but it’s crucial to keep your horses from grazing on these plants. The leaves, seeds, and pods of lupins contain quinolizidine alkaloids that can wreak havoc on a horse’s nervous system.
If your equine friends ingest lupins, they may exhibit symptoms such as confusion, dizziness, and muscle spasms that progress to full-body convulsions.
The toxins primarily target the respiratory system, which can ultimately lead to respiratory arrest and potentially even cardiac arrest as the animal is unable to draw breath.
Ground Ivy (Glechoma hederacea)
This perennial plant, while edible to humans, poses a significant threat to horses and rabbits due to its toxicity. As a member of the mint family (Lamiaceae), it may seem appealing to equine and rabbit grazers. However, if ingested by horses, symptoms can quickly develop, including rapid breathing, excessive drooling, frothing at the mouth, sweating, and tremors. While rare, fatal outcomes are not unheard of.
Moreover, long-term consumption in large amounts can result in kidney damage, highlighting the importance of keeping these plants out of reach from vulnerable animals.
Chokecherry (Prunus virginiana)
Prunus genus plants, including plum, peach, apricot, and cherry trees, pose a significant threat to horses due to the toxic nature of their leaves and twigs. Wild cherries and chokecherries are particularly lethal, as they contain a cyanide-producing compound that can be fatal in small quantities. When ingested, this toxin prevents oxygen from reaching the bloodstream, effectively suffocating the animal at a cellular level.
Horses that consume these plants will initially exhibit signs of anxiety and distress, including weakness, muscle tremors, and labored breathing. As their condition worsens, they may experience loss of urinary and bowel control, followed by seizures and collapse. Prompt veterinary attention is crucial to preventing fatalities, making it essential for horse owners to be aware of the risks posed by these plants.
Marsh Arrow-Grass (Triglochin palustris)
Along the Northwest and Northeast coasts of the USA and Canada, you can find this unassuming wetland plant thriving in boggy soils. Although horses tend to dismiss it in favor of more palatable options, this plant has a dark secret: it’s highly toxic to equines if ingested. The consequences of consumption are swift and severe. Within hours, affected horses may exhibit symptoms such as a racing pulse, labored breathing, and an unusual almond-like scent to their breath.
In extreme cases, they might drool or foam at the mouth, and in worst-case scenarios, collapse with their head tilted to one side and wide, unblinking eyes.
Larkspur (Delphinium spp)
The lovely flowers in question harbor significant amounts of delphinine. While the young leaves, branches, and buds are the most toxic components, it’s essential to note that even mature blooms possess a deadly potency. The initial signs of toxicity include behavioral changes such as nervousness and confusion, accompanied by rapid heart rate and breathing.
Afflicted horses may exhibit excessive salivation and twitching before their muscles start to weaken, leading them to stumble around until they eventually collapse. If left untreated, death can strike suddenly.
Tobacco (Nicotiana tabacum)
The allure of nicotine in tobacco products can be intoxicating for many individuals, but its effects on equines are far more sinister. Horses require a significant amount of this toxic substance to manifest harmful consequences, and prompt veterinary intervention is crucial upon detection. Initial signs include confusion, excessive drooling, and impaired coordination, gradually escalating into muscle tremors, seizures, and labored breathing before the animal eventually collapses.
In these cases, veterinarians typically administer activated charcoal and establish an IV drip to facilitate toxin removal. While mortality rates are relatively low, prompt action is still essential in ensuring the best possible outcomes.
Red Maple Leaves (Acer rubrum)
The vibrant red maple leaves that dominate the autumn landscape may seem picturesque, but they pose a deadly threat to horses if ingested. The toxins present in these leaves can rapidly destroy equine red blood cells, and even small amounts can be fatal for a full-grown quarterhorse. It’s crucial to note that fallen and drying leaves are particularly potent, with a higher toxicity than fresh ones.
To ensure your horse’s safety, consider removing any nearby maple trees or avoiding areas with high concentrations of maple foliage between September and December.
The early warning signs of maple leaf toxicity include a rapid heart rate, shallow, rapid breathing, and discoloration of the gums, which may appear blue or yellowish. As the condition progresses, anemia, depression, and other symptoms can emerge, including dark brown urine, tremors, collapse, and ultimately, death.
Red Oak Leaves (Quercus rubra)
While oak leaves’ acidity makes them beneficial for enhancing soil pH or treating wounds, they also pose a threat to equines. Unfortunately, this same acidity renders them toxic to horses, with red oak acorns being particularly hazardous. Ingestion of significant amounts can lead to a range of uncomfortable symptoms in affected animals, including colic, pale mucous membranes, darkened or blood-tinged urine, diarrhea, lethargy, and tremors.
If the horse has consumed substantial quantities, it may also exhibit edema in the neck, chest, and abdominal regions. Prolonged kidney damage can ultimately result in collapse and even death.
Sorghum (Sorghum bicolor)
Sorghum, a seemingly harmless crop for homesteads, conceals a sinister secret: its toxicity to horses. Unlike other poisonous substances that trigger immediate reactions, sorghum’s effects unfold over time, quietly devastating the equine nervous system by causing spinal cord neuron degeneration. The first signs of poisoning are disorientation and urinary incontinence, which can have severe consequences for pregnant mares. In these cases, spontaneous abortion or birth defects in foals may occur.
While death is a rare outcome, horses may develop chronic urinary tract infections and cystitis, with full recovery being an unusual occurrence.
Bermuda Grass (Cynodon dactylon)
Bermuda grass, although not inherently toxic, can harbor a blight called ergot that poses significant risks to horses. This fungal infection can induce symptoms such as tremors, convulsions, tongue and eye rolling, and full-body paralysis in extreme cases. Furthermore, pregnant mares may experience spontaneous abortion due to the presence of ergot. Moreover, this grass can lead to impaction colic and bloat, necessitating prompt veterinary attention.
In some instances, nasogastric tubing with mineral oil and water may be effective in alleviating the issue; however, emergency surgery is often required to remove the obstruction. Interestingly, Bermuda grass hay carries a significantly higher risk of inducing colic in horses and rabbits compared to other types of hay – roughly 6-10 times greater. As research continues to unfold, it’s possible that additional species may be added to this list in the future. Stay tuned for updates!
By sharing our knowledge with others and staying vigilant, we can work together to ensure the well-being and safety of our equine friends.
