Difference between revisions of "Ragwort Toxicity"
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It is poisonous to livestock with Horses and cattle being more susceptible than sheep. When ingested over long periods of time it causes hepatotoxicity which in the severe form is invariably fatal. Exposure to the toxin is usually via ingestion of contaminated hay or silage as the animal will avoid it in the fresh form. | It is poisonous to livestock with Horses and cattle being more susceptible than sheep. When ingested over long periods of time it causes hepatotoxicity which in the severe form is invariably fatal. Exposure to the toxin is usually via ingestion of contaminated hay or silage as the animal will avoid it in the fresh form. | ||
| − | The toxin is a pyrrolizidine alkaloid. | + | The toxin is a pyrrolizidine alkaloid which is converted in the body to the toxic intermediate '''pyrroles''' and their esters which cause intitial and continued damage to hepatocytes. They have an anti-mitotic effect whilst allowing continued synthesis within the cell and its nucleus resulting in a marked increase in the size of the hepatocytes. The attempted repair by fibrosis aids the shunting from the portal triads to the central vein, thereby bypassing the hepatocytes and resulting in the clinical signs associated with liver failure. |
==Signalment== | ==Signalment== | ||
==Diagnosis== | ==Diagnosis== | ||
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===Clinical signs=== | ===Clinical signs=== | ||
*Weight loss | *Weight loss | ||
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===Biopsy=== | ===Biopsy=== | ||
A liver biopsy will reveal hepatomegalocytosis and bilary hyperplasia. | A liver biopsy will reveal hepatomegalocytosis and bilary hyperplasia. | ||
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| + | ===Post Mortem=== | ||
| + | On gross post mortem examination the liver is small, dense and fibrotic with prominent biliary tracts. | ||
==Treatment== | ==Treatment== | ||
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* Knottenbelt, D.C. '''A Handbook of Equine Medicine for Final Year Students''' ''University of Liverpool'' | * Knottenbelt, D.C. '''A Handbook of Equine Medicine for Final Year Students''' ''University of Liverpool'' | ||
*Rose, R. J. and Hodgson, D. R. (2000) '''Manual of Equine Practice''' (Second Edition) Sauders. | *Rose, R. J. and Hodgson, D. R. (2000) '''Manual of Equine Practice''' (Second Edition) Sauders. | ||
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[[Category:Hepatotoxicity, Chronic]][[Category:Horse]][[Category:Sheep]] | [[Category:Hepatotoxicity, Chronic]][[Category:Horse]][[Category:Sheep]] | ||
[[Category:To_Do_- lizzyk]] | [[Category:To_Do_- lizzyk]] | ||
Revision as of 16:49, 25 July 2010
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This article is still under construction. |
Description
Ragwort (Senecio jacobea) is part of the daisy family, a flowering plant with completely yellow flowerheads. It commonly grows on wasteland and grazing pastures. It is poisonous to livestock with Horses and cattle being more susceptible than sheep. When ingested over long periods of time it causes hepatotoxicity which in the severe form is invariably fatal. Exposure to the toxin is usually via ingestion of contaminated hay or silage as the animal will avoid it in the fresh form.
The toxin is a pyrrolizidine alkaloid which is converted in the body to the toxic intermediate pyrroles and their esters which cause intitial and continued damage to hepatocytes. They have an anti-mitotic effect whilst allowing continued synthesis within the cell and its nucleus resulting in a marked increase in the size of the hepatocytes. The attempted repair by fibrosis aids the shunting from the portal triads to the central vein, thereby bypassing the hepatocytes and resulting in the clinical signs associated with liver failure.
Signalment
Diagnosis
Clinical signs
- Weight loss
- Annorexia
- Hepatic insufficiency
- Hepatic encephalopathy
Biochemistry
Rasised liver enzymes (AST, GGT, AP and LDH) and elevated bilirubin and bile acids indicate liver disease, however in very severe, chronic cases where active damage is no longer occurring, liver enzymes may be normal.
Biopsy
A liver biopsy will reveal hepatomegalocytosis and bilary hyperplasia.
Post Mortem
On gross post mortem examination the liver is small, dense and fibrotic with prominent biliary tracts.
Treatment
Prognosis
Horses with chronic liver failure due to ragwort poisoning have a poor prognosis for survival as the damage to the liver is severe by the time clinical signs are obvious.
References
- Knottenbelt, D.C. A Handbook of Equine Medicine for Final Year Students University of Liverpool
- Rose, R. J. and Hodgson, D. R. (2000) Manual of Equine Practice (Second Edition) Sauders.
| Also known as: | Senecio jacobea |