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Ragwort Poisoning

In a survey conducted by the BHS in consultation with the British Equine Veterinary Association, veterinary surgeons reported 284 cases of suspected or confirmed cases of liver failure in horses due to ragwort poisoning in 2002.

Ragwort Poisoning causes irreversible liver damage and an agonising death

This is however probably a gross underestimate of the true numbers because all horses and ponies dieing of ragwort poisoning are not reported to vets. The number of horses suffering what is an agonising death is probably much higher.

The Ragwort Control Act was initiated by the BHS in December 2002 when the society approached John Greenway, MP, to introduce a Bill on ragwort control. The Bill, which received royal assent in November 2003, made provision for a code of practice that could be used to support legal action against landowners who did not deal effectively with ragwort.

The code, also instigated by the BHS and due to be published to coincide with RAW 2004, is the first of its kind and has been subjected to extensive consultation involving the horse world, local authorities, conservationists, land owners and other relevant interest groups.

Ragwort Poisoning causes an agonising death

When the plant is in flower (see pictures) is a good time to remove and burn it.

Ragwort contains pyrrolizidine alkaloids which survive drying and are therefore active in hay and straw. The mature plants are not palatable and are usually avoided by horses unless there is no other source of roughage or food in the field. The dried plant is much more palatable.

The alkaloids are metabolised in the liver to toxic pyrrole derivatives which inhibit the division of liver cells so that the liver shrinks in size and is irreversibly damaged with little prospect of repair. There is no effective treatment. The amount of plant required to cause serious damage is very small. Often euthanasia is the most humane course of action.

It is very difficult to differentiate in hay. It can resemble other plants with a thick fibrous stem and can therefore be very difficult to recognise in hay or other drier forage. The leaves are deeply dissected with ragged edges. The large flat topped yellow flower head can be clearly seen when present. It may therefore be prudent to collect a plant now and dry it so that you will recognise the different parts of the dried plant in hay should it be present.

Control

Ragwort can be controlled by hand removal (by pull up the roots as well - we suggest that you wear gloves – purpose designed tools are available for removing the shallow roots) before seed production or the application of herbicides and removal of the dead plants (contact the DEFRA for advice). Animals (ragwort is toxic to all animals though ruminants are less susceptible) should be kept off sprayed pasture until the weeds are removed as the Ragwort plants are more palatable when wilted than fresh.

Clinical Symotoms

The symptoms of ragwort poisoning are of chronic liver disease but acute liver disease can occur:

  • Abdominal pain (colic)
  • Diarrhoea, Constipation and Straining
  • In-coordination
  • Skin Photosensitisation
  • Yawning
  • Head Pressing
  • Apparent Blindness
  • Collapse, Coma, Death
  • Jaundice is not a common feature

It is also worth bearing mind that an individual horse, pony or donkey can develop a craving for the fresh plant leading to a rapid unpleasant death.

There is no effective treatment. The amount of plant required to cause serious damage is very small. Often euthanasia is the most humane course of action.

Prevention

When the price of hay higher than usual there may be pressure to purchase hay which has been cut from pasture where ragwort has been growing. It is very difficult to differentiate in hay. It can resemble other plants with a thick fibrous stem and can therefore be very difficult to recognise in hay or other drier forage. The leaves are deeply dissected with ragged edges. The large flat-topped yellow flower head can be clearly seen when present. It may therefore be prudent to collect a plant now and dry it so that you will recognise the different parts of the dried plant in hay should it be present.

Ragwort can be controlled by hand removal (by pulling up the roots as well! - we suggest that you wear gloves) before seed production or the application of herbicides and removal of the dead plants (contact DEFRA for advice). Animals (ragwort is toxic to all animals though ruminants such as cows and sheep are less susceptible) should be kept off sprayed pasture until the weeds are removed as the ragwort plants are more palatable when wilted than fresh

Animed Veterinary Group is part of CVS (UK) Limited, a company which owns over 300 veterinary practices in the UK. Company Registration Number 03777473. Registered Office CVS House, Owen Road, Diss, Norfolk, IP22 4ER