Ragwort

Ragwort is ubiquitous on unimproved pastures and wasteland in Britain. Plants are 0.5 to 1.0m high and have dark green leaves which are deeply dissected with ragged edges. Ragwort flowers from June to October with large flat topped heads of yellow flowers. Two other species of the genus Senecio may also cause poisoning in Britain, marsh ragwort (S aquaticus) and groundsel (S vulgaris).

Ragwort (Senecio jacobaea) is the most common and economically important cause of poisoning by plants in Britain. The most common clinical signs are of chronic liver disease, although acute liver disease can occur. This progresses to cirrhosis and death.

Why is it poisonous?

Active ingredients are pyrrolizidine alkaloids which survive drying and are therefore active in hay and silage. They are thought to be transformed by the liver to toxic pyrrole derivatives which inhibit liver cell replication. Mature plants are not palatable and are usually avoided by grazing animals. However, ragwort may be ingested in spring when the plant is just emerging or if fed in conserved fodder.

Symptoms:

• Abdominal pain
• Diarrhoea, constipation and straining
• Drunken like behaviour
• Incoordination
• Yawning
• Head pressing
• Apparent blindness
• Collapse, coma, death
• Jaundice (not always)

Treatment

There is no specific treatment. When animals show severe symptoms euthanasia is the most humane course of action. Supportive treatment for liver disease includes:

• Antibiotics
• Vitamin/mineral supplementation - particularly B vitamins
• Provision of an easily digestible source of carbohydrate

Control

Ragwort is included as an injurious weed in the Weeds Act 1959, and landowners can be required to prevent spread of the plant. The plant can be controlled by hand removal of plants before seed production or by application of herbicides. Animals should not be allowed on to recently sprayed pasture as the palatability of wilted plants is greater than fresh plants.