Ragwort Toxicity
Revision as of 22:17, 7 June 2010 by Bara (talk | contribs) (Created page with '*''Senecio jacobaea'' *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 …')
- Senecio jacobaea
- 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