Difference between revisions of "Ragwort Toxicity"

From WikiVet English
Jump to navigation Jump to search
 
(28 intermediate revisions by 3 users not shown)
Line 1: Line 1:
{{unfinished}}
+
{{OpenPagesTop}}
 
+
Also known as: '''''Senecio jacobea'' toxicity
{| cellpadding="10" cellspacing="0" border="1"
+
[[Image:Ragwort.JPG|thumb|right|250px|<p>'''Ragwort''']]
|Also known as:
+
==Introduction==
|'''Senecio jacobea<br>
 
|-}
 
 
 
==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.  
 
'''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.  
+
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==
 +
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==
 
 
 
===Clinical signs===
 
===Clinical signs===
 
*Weight loss
 
*Weight loss
 +
*Anorexia
 
*Hepatic insufficiency
 
*Hepatic insufficiency
 
*Hepatic encephalopathy
 
*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===
 
===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==
 
==Treatment==
 +
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.
 +
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==
 +
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.
 +
 +
{{Learning
 +
|flashcards = [[Liver_Flashcards_-_Pathology|Liver Pathology Flashcards]]
 +
|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]
 +
}}
 +
 +
{{Chapter}}
 +
{{Mansonchapter
 +
|chapterlink = http://www.mansonpublishing.co.uk/book-images/9781893441118_sample.pdf
 +
|chaptername = Rattlebox and Scenecio
 +
|book = A Guide to Plant Poisoning of Animals in North America
 +
|author = Anthony Knight, Richard Walter
 +
|isbn = 9781893441194
 +
}}
  
 
==References==
 
==References==
Line 32: Line 53:
  
  
==Hepatotoxicity==
+
{{review}}
**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 - Anatomy & Physiology|liver]]
 
*pale in colour
 
*very firm to section
 
 
 
====Microscopically====
 
*necrosis
 
*haemorrhage
 
*diffuse fibrosis
 
  
 +
{{OpenPages}}
  
[[Category:Hepatotoxicity, Chronic]][[Category:Horse]][[Category:Sheep]]
+
[[Category:Hepatotoxicity, Chronic]]
[[Category:To_Do_- lizzyk]]
+
[[Category:Liver Diseases - Horse]][[Category:Liver Diseases - Sheep]][[Category:Liver Diseases - Cattle]]
 +
[[Category:Neurological Diseases - Horse]][[Category:Neurological Diseases - Sheep]][[Category:Neurological Diseases - Cattle]]
 +
[[Category:Expert_Review - Horse]][[Category:Expert Review - Farm Animal]]
 +
[[Category:Toxicology]]

Latest revision as of 19:40, 14 November 2015


Also known as: Senecio jacobea toxicity

Ragwort

Introduction

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

Hepatotoxicity due to ragwort poisoining occurs mainly in horses and cattle grazing highly contaminated pastures or contaminated roughage over long periods of time.

Diagnosis

Clinical signs

  • Weight loss
  • Anorexia
  • 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

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. 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

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.


Ragwort Toxicity Learning Resources
FlashcardsFlashcards logo.png
Flashcards
Test your knowledge using flashcard type questions
Liver Pathology Flashcards
CABICABI logo.jpg
Literature Search
Search for recent publications via CAB Abstract
(CABI log in required)
Ragwort Toxicity publication



Sample Book Chapters
Publisher
Free chapter
Book
Authors
CRC logo small.png
Rattlebox and Scenecio
A Guide to Plant Poisoning of Animals in North America
Anthony Knight, Richard Walter
Buy book


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.




Error in widget FBRecommend: unable to write file /var/www/wikivet.net/extensions/Widgets/compiled_templates/wrt67240a5a269804_90901376
Error in widget google+: unable to write file /var/www/wikivet.net/extensions/Widgets/compiled_templates/wrt67240a5a3c98c2_68176643
Error in widget TwitterTweet: unable to write file /var/www/wikivet.net/extensions/Widgets/compiled_templates/wrt67240a5a505747_54983842
WikiVet® Introduction - Help WikiVet - Report a Problem