Beautiful yellow flower is a dangerous livestock killer
In our glorious 2018 summer, when fodder availability became a serious issue, animals turned their attention to other available plants, shrubs and trees.
One is the common ragwort plant (Senecio jacobaea), with its beautiful yellow flowering head that we all can recognise. Sometimes, as we drive along, we can see fields covered with them. Usually, the taste of these plants is quite bitter. Normally, with lots of tasty grass available to them, animals tend to avoid the poisonous ragwort. But in the autumn, the ragwort dries out and loses its bitterness, so animals start eating ragwort, if fodder becomes scarce.
There was a tendency for this to happen in the recent very dry weather, and maybe we will see consequent problems in the months ahead. Horses, donkeys and cattle are the most susceptible to this poisonous plant, with sheep and especially goats at least risk.
Like all poisonings, ragwort poisoning is dose related.
Eating a lot in a short time will cause major problems, but so too will eating a small amount regularly over a long time.
One of the most dangerous ways animals come to eat this plant is when it is cut, dried and made into hay, haylage or silage. It can be next to impossible to identify it in the middle of a bale of hay.
Ragwort contains compounds that are harmful to the liver of animals, killing off the cells in the liver. This is not readily recognised in animals until things have advanced to the point of no return.
The poison does not accumulate in the animal’s body. But if ragwort is eaten continuously over a time, the amount of liver damage increases, and when 80% of the liver is damaged, the animal suffers liver failure.
The animal might begin to show as being a bit depressed and having lost its appetite.
Because the liver is so badly damaged, the animal might become sensitive to the sunlight and show a jaundiced look. We are now at an irreversible stage where treatment is of no benefit in most cases and the animal will begin to develop nervous signs like blindness and staggering. The odd animal will be saved if seen in time and given appropriate treatment. Blood can be taken to measure the extent of the liver damage.
Ragwort has a two-year growing cycle, with just leaves growing the first year, and the flowering head rarely appears before the second year.
Seeds from the flowering head are scattered on the wind much like the dandelion seeds, so it is important to control this plant before it reaches the flowering stage. The best control is pulling or digging the complete plant and bagging it.
If you put rock salt into the remaining hole, this will kill off any roots left behind.
Dead plants are just as poisonous as live ones; they should be burned when they have dried out. Herbicides can be used, but most of those rely on the animals being kept off the land for a considerable time. It is interesting to note, when you read through the literature, that ragwort is considered to be of ecological importance. It is a very attractive source of nourishment for many insects and flies, with some feeding only on the ragwort flower. For this reason ecologists like to see areas of the country where ragwort is allowed to grow freely.
- Paul Redmond, MVB, MRCVS, Cert DHH, Duntahane Veterinary Clinic, Fermoy, member practice of Prime Health Vets
