----------------------------------------------------------------------------------------------------------------------------------
Ragwort
poisoningYou can find more about horses here
Introduction
There are a large number of poisonous plants to be found, although their abundance will vary greatly from place to place. Horses and ponies at pasture are often at risk, especially when grass is in short supply. Perhaps one of the more common plants and unfortunately one of the more deadly is Ragwort. Ragwort (Senecio Jacobaea L.) poisoning is the most common cause of liver damage in horses. Ragwort is a hardy biennial. It flourishes in waste ground and roadside verges from where it invades nearby fields. The growing plant is not palatable to grazing animals and is usually ignored by horses, except when the grass is extremely poor. It thus has a competitive advantage over the other plants (including grass) and fields quickly become heavily contaminated.
Ragwort
How does ragwort affect animals?
Ragwort contains pyrrolizidine alkaloids which are poisonous to horses, other farm animals such as sheep and cattle and also to wild animals such as hare and deer. It is important for horse owners and horse pasture owners to recognise and control this potentially fatal plant. Unfortunately, some horse-keepers do not control ragwort growth and spread as they do not expect their horses to eat the plant and probably don't appreciate the reality of the suffering their animals could be caused. It is true that ragwort does have a bitter taste which often deters horses from eating it. However, if grass becomes sparse (e.g. following a period of hot dry weather) horses may resort to eating plants they wouldn't normally eat, including ragwort if it is present. Some horses develop a liking for the bitter taste and may choose to eat it even when there is sufficient palatable grass available to graze on. If eaten, as little as 2lb of fresh ragwort can be sufficient to cause fatal damage. Uncontrolled ragwort left growing in and around horse pastures exposes horses and ponies to poisoning and possibly death, and the infestation will increase each year as plants set seed.
Equines and bovines are more susceptible to ragwort posoning than other livestock. Young animals are more susceptible than mature animals. Ragwort poisoning can occur at any time of the year. The toxins in ragwort are cumulative and result in irreversible liver damage and digestive disorders. A small intake of ragwort over a long period can be just as damaging as a large intake on a single occasion. Ragwort remains toxic but becomes more palatable when dried and is particularly dangerous in hay and haylage. Little can be done dor an animal once the clinical symptoms appear.
Clinical symptoms
Loss of condition (weight loss, dull coat, depression), poor appetite and constipation, pain from gut area, swelling under the abdomen (oedema), photosensitation (sunburn, which is restricted to the white areas) and sometimes jaundice (yellow color to mouth and eye).
Terminal signs: nervous signs develop (yawning, head pressing and ataxia), restlessness and aimless uncoordinated movement. Animals may appear blind, pressing heads against solid objects, abnormal gait and stance. Most affected animals die after a period of illness varying from a week to several months.
Diagnosis
The disease can be confirmed by your vet in two ways. A blood test for specific liver enzymes (GGT and ALP) is the most usual, in cases where doubt arises a liver biopsy can be performed.
Treatment
Once actual symptoms have developed, especially any neurological symptoms, the prognosis is poor, however in the early stages careful dietary control and vitamin supplementation can be helpful.
Sources of Ragwort poisoning
• Livestock tend to avoid eating ragwort on good pastures.
• Where there is over-stocking and grass is scarce the weed will thrive and is unavoidably eaten.
• The poisons in ragwort are not destroyed by drying. Dried grass, hay and silage are common sources of ragwort poisoning, it can be undetectable and consumed readily.
• Ragwort becomes much more palatable when cut or wilted, as it loses its bitter taste.
How to recognise ragwort
Seedlings can be found from autumn onwards - the first leaves have a characteristic spade shaped blade, notched at the apex (10-15mm length).
The first true leaf is hairless, 10-12mm in length and oval shaped with a smooth edge. As the plant grows the leaves produced show a gradual increase in the degree of lobbing and waviness typical of the older ragwort plants. Leaves also become hairier as the plant gets older.
Rosettes can be found from early spring onwards - circular cluster of leaves, usually deep green on top and underneath covered in a cottony down, the leaves have a ragged appearance. The rootstock, basal leafstalks and lower parts of the stem may have a purplish/ red colour. (If biennial will over winter as a rosette and during the second year send up a single leafy stem, which will produce numerous flower heads.)
Mature plant reaches between 1-2m in height, the stems are tough and often tinged purplish/red near the base, but brighter green and branched above the middle. Flowering occurs May to late October. The bright yellow flowers are daisy-like. Most plants die after flowering, creating a gap suitable for immediate colonization by seedlings.
The seeds have a downy appendage making them readily dispersible by the prevailing wind, but can also be dispersed via water or spread by people and livestock.
How do you control ragwort in your pasture?
Control of ragwort is the only way to avoid ragwort poisoning. Over and under grazing create open patches where ragwort can readily establish itself.
Ragwort will not establish where there is a dense vigorous sward. Such a pasture can be best achieved though controlled grazing and/or regular fertiliser applications. This encourages root development of grasses and makes a valuable contribution to preventing re-infestation.
• It is important to remove all potential.
• To remove the danger to your animals a control strategy must be employed.
• The chosen method of control should be the one least damaging to the environment and human health, whilst still being an effective method of control.
Short Term Methods/ Small Ragwort Infestations
Digging/Pulling:
• Always wear gloves
• Needs to be done before flowering has completed
• Ragwort is more easily removed in the spring when the plant is immature or after heavy rainfall when the ground is soft
• Need to be carried out for at least 2 years as ragwort is a biennial, or if the pasture has a history of ragwort infestation this will have to be carried out annually due to the remaining seeds in the soil
• It is important to remove as much of the root as possible; ragwort can regenerate like docks from its root fragments
Cutting
• At the early flowering stage reduces seed production
• Acceptable in an emergency situation, but generally is not recommended since it encourages more vigorous growth
Never leave cut plants within reach of horses.
Long Term Methods/ Large Ragwort Infestation
Weed-killers
Ragwort can be spot sprayed with a selective weedkiller. This can be done all the year around but is best to spot spray when ragwort is at the rosette state - in winter months through to the end of July.
