Having noticed so much of it about throughout the region over the past few weeks (including growing out of some roof guttering), we return this week to take another brief look at the poisonous plant ragwort.
Many species of animal are sensitive to ragwort poisoning but, clinically, it’s usually horses that are treated for this problem. Although given the choice most horses will tend to avoid eating the plant due to its bitter taste, once dried (in hay, for example, or just cut down in the field), it becomes more palatable but remains just as toxic. The younger plants are also believed to be less bitter so can be eaten accidentally, and if grazing is sparse for any reason this will also encourage horses to eat it.
Even if only small amounts of the plant are eaten on each occasion the problems lie with the fact that ragwort poisoning is accumulative. Most cases of ragwort toxicity are due to a gradual build-up over a period of time, rather than one single event.
As most people purchase horses already broken and often with a few years’ ridden experience, it’s quite possible the horse may already have liver damage due to it and so potentially not need to consume much more to cause problems . When the ragwort is eaten by the horse, its liver becomes damaged in the process of metabolising a certain part of the plant. The liver is remarkable in its ability to cope and compensate with what’s left but unfortunately what this often means is that the first sign of a problem is when the liver is so damaged it cannot function properly anymore and has gone into failure.
The end result is that for years owners may be oblivious to the damage occurring and, when finally this becomes apparent, there is nothing that can be done.
The initial signs may be weight loss and lethargy or abnormal, either bizarre or depressed-like, behavioural changes (these are due to a build-up of toxins that would normally be filtered out of the blood by the liver affecting the brain). Photosensitivity is also seen, which is where the skin becomes more sensitive to the light, so unpigmented pink areas will become sore and burned looking. Blindness and un-coordination may happen as the condition progresses.
Prevention is really the most important thing as, sadly, once the signs of liver failure are present it’s usually too late.
Care needs to be taken when removing the plant from pasture for your own protection and to ensure it is completely removed at the right time of year to minimise spread. There is useful guidance on how to properly and successfully deal with ragwort and also what the legal obligations are for landowners to try and control it, on the Defra (www.defra.gov.uk), British Horse Society (www.bhs.org.uk) and World Horse Welfare websites (www.worldhorsewelfare.org) with the last-named containing some useful photographs to help identify the weed at the critical point for removal, before it’s in flower.