Nightshade poisoning

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Nightshade Poisoning

Solanum Poisoning

Consumption of nightshades (from the Solanaceae family) is toxic to horses. Nightshades are a large group of plants which contain a variety of toxic alkaloids which are known for their adverse effects on the horse's nervous system and digestive tract. The two toxins which most frequently affect horses include glycoalkaloids and tropane alkaloids. Nightshades can present as small trees or small, weedy, erect shrubs. Many have white to purple flowers which produce round, fleshy, green berries that mature into a yellow or black color.

What Are Nightshade Plants

Common nightshade species that are often responsible for poisonings include Carolina horse nettle (Solanum carolinense), Hairy nightshade (S. physalifolium), Silverleaf nightshade (S. elaeagnifolium), Black nightshade (S. nigrum), American nightshade (S. americanum), and Jimsonweed (Datura spp). There are more than 70 species of native and introduced Solanum spp in North America alone. Nightshades are poisonous in both fresh and dried form, and sometimes are found in contaminated hay from a variety of grass species. They can also contaminate grain and grass cubes.


Excessive salivation
Increased respiratory rate
Weak pulse
Abnormal response to light
Increased heart rate
Loss of appetite
Inability to stand
Difficulty swallowing
Dilated pupils


  • History
  • Clinical signs
  • Physical exam
  • Laboratory testing



Supportive care


  • Check hay for nightshades prior to feeding to horse
  • Routinely walk pastures for possible toxic plants

Scientific Research

General Overviews

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Risk Factors

  • Letting horses graze on pastures containing nightshade plants
  • Purchasing poor quality, weedy hay and not inspecting it prior to feeding it to horses