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Monday 18 December 2017

How to spot the signs of ragwort poisoning

Caitriona Murphy

Caitriona Murphy

THE clinical signs (or symptoms) of ragwort poisoning tend to only become apparent when liver failure has occurred.

There is often no warning of impending failure. The signs of liver failure are a direct reflection of the loss of liver function.

A principle sign is bizarre or depressed behaviour due to altered mental status. This is thought to occur because the liver is no longer able to remove chemicals or toxins from the blood that have harmful effects on the brain.

A second common clinical sign is inflammation of white, unpigmented areas of the skin when they have been exposed to sunlight, known as photosensitisation.

The degradation of grass in the intestines produces a photodynamic agent that reacts to sunlight. This agent is normally removed and eliminated by the liver.

However, in hepatic (liver) failure this does not occur and concentrations of the agent increase in the body. In areas of unpigmented skin the activation of the photodynamic agent by sunlight causes damage to and inflammation of the skin. This is not the same as the common problem of sunburn, as suffered by some horses.

Other clinical signs of liver failure may also occur; these include jaundice, weight loss and diarrhoea.

Diagnosis of liver failure can be aided by laboratory analyses of blood samples that often show evidence of liver damage and reduced liver function.

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Performing a liver biopsy can make a definitive diagnosis but is difficult and potentially dangerous. It is hoped that a simple blood test will soon be available to detect early signs of ragwort poisoning before significant, untreatable damage is done to the liver.

Treatment is difficult once liver failure has occurred. It relies on supportive therapies in the hope that the liver can regenerate.

Unfortunately, in many cases the liver is too damaged for this to occur, although some horses can survive.

Irish Independent