29 September 2022

1 minute read

Cause

Many plant poisonings, including ragwort poisoning, are most common in the autumn. The highest risk period for grazing cattle is when grass growth is poor, or when very young plants are present in the pasture.

However, the greatest risk is to cattle fed preserved forage, either as silage or as hay, because preserved ragwort is readily eaten but has lost none of its toxicity.

Ragwort contains a range of related toxins, all of which damage the liver. The more ragwort that is eaten the greater the damage. In cattle most cases of ragwort poisoning occur as a result of eating ragwort over a period of weeks or months but the signs can take up to 18 months to develop.

Clinical Signs

• Diarrhoea, with straining, is occasionally seen as is colic
• Jaundice – yellowing particularly of the whites of the eye
• Photosensitization – damage to pale areas of skin in response to sunlight
• Swelling under the skin and of the abdomen due to low blood protein
• Some animals will develop brain disease with staggering, circling and head pressing.

Death usually follows these signs within a few days.

Treatment

There is no specific antidote for ragwort poisoning. No treatment is of much value in affected animals.

Normal animals in the group should be switched to food that contains no ragwort.

Prevention

Limit access to pastures with ragwort, particularly if grazing is poor. Sheep are more resistant to ragwort so can graze such pastures, provided they are not too heavily contaminated.

Ragwort control by hand-pulling and burning before seeding and the strategic use of herbicide is the best method of prevention.

Ragwort is one of the five plants covered by the Weeds Act 1959. This does not mean that it is an offence to allow ragwort to grow on your land, but it is an offence not to control ragwort if asked to do so under the act.

Do not make hay or silage from pastures heavily contaminated with ragwort.