Bushy Equine Vets



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Ragwort, ragwort poisoning and liver disease

Ragwort is a biennial plant (takes two years from seed to seed). During the first year of growth the plant is a flat rosette and produces no flowers, this makes the plant more difficult to identify at this time. During the second year flower clusters develop on stout stalks which may be up to one and a half metres tall. Each flower cluster is composed of many bright yellow flowers with 13 petals. A single large plant may produce up to 150,000 seeds which may lie dormant for as long as 15 years.

The characteristic yellow flowers and ragged leaves of ragwort.

All parts of the ragwort plant are toxic to all grazing animals. Livestock do not usually eat the plant in its green state as it is unpalatable though horses with no other feed will eat it and may actually develop a taste for the plant. The toxins in ragwort are called pyrrolizidine alkaloids are not destroyed by drying though the plant does become more palatable, this means that hay is the most dangerous source of ragwort poisoning for horses. Pyrrolizidine alkaloids cause liver damage and eventually failure.

The poison is cumulative meaning that repeated ingestion of even small amounts can eventually lead to poisoning. The first signs of poisoning are those of liver disease which can vary from vague lethargy and weight loss to manic behaviour, aggression, blindness, pressing the head against solid objects, aimless wandering and death. Treatment of ragwort poisoning is extremely difficult as clinical signs of liver disease only appear when 75% of the liver is destroyed. Early liver damage may be detected on a simple blood test performed by your veterinary surgeon but this is not specific for ragwort. Once clinical signs are apparent affected horses will usually die or be euthanased within a few days. In the very early stages of liver disease careful dietary control and vitamin supplementation may be of value-

Dietary Management of liver disease

  1. Feed a low protein diet. (the liver is responsible for breaking down proteins, if the liver fails to do this then toxic substances can accumulate in the blood stream) - Avoid cereals (barley, wheat and oats) - Avoid leguminous feeds such as clover rich hay or alfalfa - Avoid early cut (rich) hay
  2. Feed a high carbohydrate diet e.g. molassed sugar beet pulp plus maize (2:1 ratio) little and often up to 2kg/100kg bodyweight may be fed.
  3. Supplement with vitamins A, D, E and B12 as directed by your veterinary surgeon.