Whinny’s Wisdoms

Springhill Equine Veterinary Clinic

Hey everybody, Whinny here! Horses can be exposed to and graze on plants that can be harmful or even fatal. More often than not, horses will choose good quality grass or hay over a toxic weed or plant, especially if they have a good mouse friend to keep them out of trouble. However, over grazed pastures and the natural environment of Florida can predispose horses to be exposed to some toxic plants. In this blog post, we’ll explore several poisonous plants commonly encountered by horses: Red Maple, Acorns, Nightshade, Pokeweed, Creeping Indigo, and Fireweed. Understanding these plants and their potential dangers is critical for ensuring the well-being of our equine friends.

Red Maple (Acer rubrum)

   Red maple leaves, especially when wilted, contain a toxin called gallic acid, which attacks red blood cells. Ingestion of even a small amount of these leaves can lead to hemolytic anemia, methemoglobinemia, and potentially death in horses. Symptoms may include lethargy, dark urine, blue colored mucous membranes, jaundice, and colic.

Whinny’s Wisdom: Immediate treatment is crucial, including intravenous fluids, and supportive care.

Nightshade (Solanum spp.)

  Nightshade plants, known for their bell-shaped flowers and berries, contain the toxic alkaloid, atropine. Our savvy readers may be familiar with atropine as a topical used in treating eye conditions to dilate the pupil in certain situations. Ingestion can cause dilated pupils, nervousness, and irregular heartbeat. Luckily, the plant is bitter and not often eaten if there’s other food available.

Whinny’s Wisdom: Promptly diagnose and treat nightshade poisoning to minimize symptoms and complications.

Acorns (Quercus spp.)

   Acorns from oak trees are toxic to horses, primarily due to the presence of tannins. Ingesting acorns can lead to gastrointestinal upset, colic, and kidney damage. Chronic exposure may result in metabolic issues and laminitis.

Whinny’s Wisdom: Managing pastures to minimize exposure and providing ample forage alternatives can help prevent acorn ingestion.

Pokeweed (Phytolacca americana)

   Pokeweed is a significant concern for horses, as all parts of the plant are toxic and contain saponins, oxalates, and phytolacine. It can lead to severe gastrointestinal issues, including colic and diarrhea.

Whinny’s Wisdom: Early intervention is key, and treatment may include fluid therapy and medications to manage symptoms.

 Creeping Indigo (Indigofera spicata)

    Creeping indigo poses a serious threat due to its palatability to horses. Horses that consume this plant may experience a wide range of symptoms that could include corneal edema, mucosal ulcerations or neurologic signs that can range from dull attitude to narcoleptic-like behavior.

 Whinny’s Wisdom: Immediate veterinary attention is necessary to address neurological symptoms and provide supportive care. Heavy trafficked or overgrazed areas can perpetuate the weed.

 Fireweed (Urtica chamaedroides)

  Fireweed, also known as Heartleaf Nettle, contains stinging hairs that can irritate the skin and mucous membranes of horses. Ingestion can lead to lethargy or difficulty swallowing. More commonly, horses are seen due to urticaria, or hives, from skin contact. This plant can cause severe discomfort to the skin and horses may appear to have colic or neurologic signs.

 Whinny’s Wisdom: Address skin irritation promptly with appropriate care and remove fireweed from pastures if it is identified. It can often be found in areas with sparse grass growth, like feeding areas or near fence lines.


As veterinarians, it’s my docs’ responsibility to educate horse owners about the dangers of toxic plants like Red Maple, Acorns, Nightshade, Pokeweed, Creeping Indigo, and Fireweed. Encourage pasture management practices that minimize exposure to these plants and emphasize the importance of early intervention in cases of plant poisoning. By working together, we can ensure the health and safety of our equine patients and provide them with the best possible care.

Until next week,


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Whinny’s Wisdoms is the official blog of Whinny the Clinic Mouse at Springhill Equine Veterinary Clinic in Newberry, Florida. If you liked this blog, please subscribe below, and share it with your friends on social media! For more information, please call us at (352) 472-1620, visit our website at SpringhillEquine.com, or follow us on Facebook!

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