Ragwort (Senecio jacobaea) in Horses (Equis) | Vetlexicon
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Ragwort (Senecio jacobaea)

ISSN 2398-2977

Synonym(s): Scenecio, Groundsel, Butterweed, Tansy

Podcast: Ragwort (Senecio jacobaea)


  • The genis, Senecio, contains more than 1200 species, of which at least 25 are known to be poisonous.
  • Tansy ragwort is biennial and abundant in western US and UK   Ragwort: Spring    Ragwort: flowering  .
  • 30-100 cm high.
  • Found in wasteland, besides roads and in pastures.
  • Bright yellow daisy-like flowers (July-September) and jagged lobed leaves.
  • The most important species of Ragwort (all equally dangerous) are:
    • Senecio jacobaea (common ragwort).
    • Marsh Ragwort (Senecio squalidus and Senecio eruciferius).
    • S. flaccidus.
    • S. riddellii.
    • S. vulgaris.

 Geographical distribution

  • Worldwide.
  • Classified as injurious by The 1959 Weed Act - it is an offence to allow it to spread.


  • All parts of the plant contain pyrrolizidine alkaloids which cause irreversible liver damage Toxicity: pyrrolizidine alkaloid.
  • Poison is not destroyed by drying or storing.
  • Has bitter taste so horses usually avoid it unless grazing in short supply.
  • The liver injury builds on itself over time.
  • Usually acute disease with liver failure Liver disease: overview occurring after a course of 1 year.

Clinical signs

  • Signs of poisoning are usually difficult to detect and only when the greater part of the liver is damaged will clinical signs appear.
  • Depression.
  • Loss of appetite.
  • Poor haircoat.
  • Digestive disturbance.
  • Abdominal pain Abdomen: pain - adult.
  • Diarrhea Diarrhea: chronic.
  • Constipation Ileum: impaction.
  • Restlessness.
  • Incoordination.
  • Paralysis.
  • 'Sleepy staggers'.
  • Jaundiced mucous membranes.
  • Most severely affected horses show nervous signs, eg:
    • Head-pressing.
    • Ataxia.
    • Ascites.
    • Aimless walking.
  • Although horses may recover, some injury is permanent.


  • Emphasis should be on prevention, ie proper pasture management.
  • Check pastures regularly for ragwort and pull up and remove any plants.
  • Ensiling reduces the toxicogenic alkaloids.
  • Early diagnosis and treatment are essential otherwise the condition may be fatal.
  • Supportive treatment for severe cases should include correction of acid-base imbalance, reduced protein diet.
  • Treatment is unrewarding in severe cases.

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • de Lanux-Van Ggorder V (2000) Tansy ragwort poisoning in a horse in southern Ontario. Can Vet J 41 (5), 409-410.
  • Cook R R (1999) Ragwort poisoning. Vet Rec 145 (8), 236.
  • McDowell D M (1999) Ragwort poisoning in horses. Vet Rec 145 (5), 148.
  • Milne E M, Pogson D M, Doxey D L (1990) Secondary gastric impaction associated with ragwort poisoning in three horses. Vet Rec 126 (20), 502-504.
  • Leyland A (1985) Ragwort poisoning in horses. Vet Rec 117(18), 479.
  • Garrett B J, Holtan D W, Cheeke P R, Schmitz J A & Rogers Q R (1984) Effects of dietary supplementation with butylated hydroxyanisole, cysteine vitamins B on tansy ragwort (Senecio jacobaea) toxicosis in ponies. Am J Vet Res 45 (3), 459-464.
  • Giles C J (1983) Outbreak of ragwort (Senecio Jacobaea) poisoning in horses. Equine Vet J 15 (3), 248-250.

Other sources of information

  • Allison K (1999) A Guide to Plants Poisonous to Horses. J A Allen & Co Ltd. ISBN 0851316980.
  • Burrows G E & Tyrl R J (2001) Toxic Plants of North America. Iowa State University Press, Ames, Iowa.
  • Allison K & Day C (1997) A Guide to Plants Poisonous to Horses. British Association of Holistic Nutrition and Medicine.
  • Cooper M R & Johnson A W (1998) Poisonous Plants and Fungi - An Illustrated Guide. The Stationery Office. ISBN 0112429815.


  • Cornell University - Poisonous Plants Informational Database. Website: www.ansci.cornell.edu/plants.
  • ToxicologyOnline.com. Website: www.toxonline.com.
  • Veterinary Poisons Information Service (VPIS), London Center, Medical Toxicology Unit, Avonley Road, London SE14 5ER, UK. Tel: +44 (0)20 7635 9195; Fax: +44 (0)20 7771 5309.
  • Veterinary Poisons Information Service (VPIS), Leeds Center, The General Infirmary, Great George Street, Leeds LS1 3EX, UK. Tel: +44 (0)113 245 0530; Fax: +44 (0)113 244 5849.