Black locust toxicity

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Black Locust Toxicity

Black Locust Poisoning

Black locust (Robinia pseudoacacia) is an ornamental tree which can reach 40 to 100 feet in height at maturity. Seedlings grow rapidly and are easily identified by long, paired thorns.
Leaves are dark green oval to rounded which alternate along stems in leaflets. In the spring, fragrant white flowers with yellow tips appear in drooping clusters. The tree is found frequently in thickets and waste areas and drained woods. All parts of the tree are toxic--seeds, leaves, bark and twigs. The main toxic component is robin--a plant phytotoxin similar to that found in castor bean and rosary pea. Horses usually don't eat parts of the tree, unless little other food is available to them. Consuming as little as 0.04% body weight can be fatal.


Labored Breathing
Rapid heart rate
Irregular heart beat


  • History
  • Clinical signs
  • Necropsy - Identification of robin or black locust seeds or plant components in gastrointestinal tract or blood.



Prevent further ingestion
Activated charcoal
Intravenous (IV) fluids


  • Make yourself aware of the weeds and plant species that can be invasive in pastures and/or poisonous to horses.
  • Take periodic walks around pastures to check for the presence of potentially poisonous plants
  • Check that hay does not contain dried up poisonous plants
  • If you borrow or hire farm machinery ensure it is clean prior to arriving on your property, the same goes for lending of your own equipment.
  • Quarantine new animals in a separate paddock the first 10 days to 2 weeks after arrival. Weed seeds can be passed through an animal's digestive tract.

Scientific Research

General Overviews

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Risk Factors

  • Allowing horses access to black locust trees in or around horse pastures.