Difference between revisions of "Ragwort Toxicity"

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Also known as: '''''Senecio jacobea'' toxicity
 
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[[Image:Ragwort.JPG|thumb|right|250px|<p>'''Ragwort''']]
 
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==Introduction==
 
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'''Ragwort''' (''Senecio jacobea'') is part of the daisy family, a flowering plant with completely yellow flowerheads. It commonly grows on wasteland and grazing pastures.
 
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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.
 
  
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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.
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{| cellpadding="10" cellspacing="0" border="1"
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|Also known as:
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|'''Senecio jacobea<br>
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|-}
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==Description==
  
 
==Signalment==
 
==Signalment==
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Hepatotoxicity due to ragwort poisoining occurs mainly in horses and cattle grazing highly contaminated pastures or contaminated roughage over long periods of time.
 
  
 
==Diagnosis==
 
==Diagnosis==
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===Clinical signs===
 
===Clinical signs===
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*Weight loss
 
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*Anorexia
 
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*Hepatic insufficiency
 
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*Hepatic encephalopathy
 
  
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===Biochemistry===
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===Cytology===
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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===
 
===Biopsy===
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A liver biopsy will reveal '''hepatomegalocytosis''' and '''bilary hyperplasia'''.
 
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===Post Mortem===
 
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On gross post mortem examination the liver is small, dense and fibrotic with prominent biliary tracts.
 
  
 
==Treatment==
 
==Treatment==
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There is no corrective treatment for the liver damage caused by ragwort poisoning, '''supportive''' treatment can improve quality of life and minimise some of the clinical signs by reducing the workload of the liver.
 
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Small, frequent feeds should be given 6 times a day and should consist of a high quality energy and protein source. Stomach tubing may be necessary if the horse is inappetent. Supplementary B vitamins may also be beneficial and can be given orally or parenterally.
 
  
 
==Prognosis==
 
==Prognosis==
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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.
 
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{{Learning
 
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|flashcards = [[Liver_Flashcards_-_Pathology|Liver Pathology Flashcards]]
 
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|literature search = [http://www.cabdirect.org/search.html?q=%28title%3A%28Ragwort%29+OR+title%3A%28%22Senecio+jacobaea%22%29%29+AND+%28title%3A%28tox*%29+OR+title%3A%28intox*%29%29 Ragwort Toxicity publication]
 
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}}
 
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{{Chapter}}
 
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{{Mansonchapter
 
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|chapterlink = http://www.mansonpublishing.co.uk/book-images/9781893441118_sample.pdf
 
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|chaptername = Rattlebox and Scenecio
 
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|book = A Guide to Plant Poisoning of Animals in North America
 
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|author = Anthony Knight, Richard Walter
 
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|isbn = 9781893441194
 
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}}
 
  
 
==References==
 
==References==
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{{review}}
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==Hepatotoxicity==
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plant toxin ingested over a long period of time
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*livestock
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**cattle and horses are more susceptible than sheep
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**livestock will not normally eat the fresh plant
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**most cases arise in horses and cattle consuming ragwort in hay or silage
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*'''pyrrolizidine alkaloids'''
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**toxic principle converted in the body to the toxic intermediate '''pyrroles''' and their esters
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**cause intitial and continued damage to hepatocytes
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**have an anti-mitotic effect whilst allowing continued synthesis within the cell and its nucleus
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***causes a marked increase in the size of parenchymal cells, a phenomenon termed ''''megalocytosis''''
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***these very enlarged hepatocytes can be up to 20 times bigger
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***the enlarged cells are closely apposed so that the sinusoids may not be evident
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*it is likely that the vascular component of the attempted repair of the chronic damage by fibrosis (really a type of granulation tissue) aids the shunting from the portal triads to the central vein and thereby bypassing the hepatocytes
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*other plant and fungal toxins perform in the same way
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====Gross====
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*slightly enlarged [[Liver - Anatomy & Physiology|liver]]
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*pale in colour
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*very firm to section
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====Microscopically====
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*necrosis
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*haemorrhage
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*diffuse fibrosis
  
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{{OpenPages}}
 
  
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[[Category:Hepatotoxicity, Chronic]]
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[[Category:Hepatotoxicity, Chronic]][[Category:Horse]][[Category:Sheep]]
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[[Category:Liver Diseases - Horse]][[Category:Liver Diseases - Sheep]][[Category:Liver Diseases - Cattle]]
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[[Category:To_Do_- lizzyk]]
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[[Category:Neurological Diseases - Horse]][[Category:Neurological Diseases - Sheep]][[Category:Neurological Diseases - Cattle]]
 
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[[Category:Expert_Review - Horse]][[Category:Expert Review - Farm Animal]]
 
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[[Category:Toxicology]]
 

Revision as of 15:57, 25 July 2010


 This article is still under construction.


Description

Signalment

Diagnosis

Clinical signs

Cytology

Biopsy

Treatment

Prognosis

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.


Hepatotoxicity

plant toxin ingested over a long period of time

  • livestock
    • cattle and horses are more susceptible than sheep
    • livestock will not normally eat the fresh plant
    • most cases arise in horses and cattle consuming ragwort in hay or silage
  • pyrrolizidine alkaloids
    • toxic principle converted in the body to the toxic intermediate pyrroles and their esters
    • cause intitial and continued damage to hepatocytes
    • have an anti-mitotic effect whilst allowing continued synthesis within the cell and its nucleus
      • causes a marked increase in the size of parenchymal cells, a phenomenon termed 'megalocytosis'
      • these very enlarged hepatocytes can be up to 20 times bigger
      • the enlarged cells are closely apposed so that the sinusoids may not be evident
  • it is likely that the vascular component of the attempted repair of the chronic damage by fibrosis (really a type of granulation tissue) aids the shunting from the portal triads to the central vein and thereby bypassing the hepatocytes
  • other plant and fungal toxins perform in the same way

Gross

  • slightly enlarged liver
  • pale in colour
  • very firm to section

Microscopically

  • necrosis
  • haemorrhage
  • diffuse fibrosis
Also known as: Senecio jacobea
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