Pyrrolizidine alkaloids are the most common cause of liver damage. Found in numerous plant species, pyrrolizidine alkaloids are most toxic for:
- Pigs (most toxic)
- Sheep (least susceptible)
These alkaloids cause photosensitization, liver and kidney damage and can also cause cancer and heart failure.
Animals will not readily eat plants containing pyrrolizidine alkaloids, unless no other forage is available. However, plants become more palatable when dried and will be readily eaten in hay, with little loss of toxicity.
Effects are cumulative, so symptoms may not appear until long after the toxic plant was eaten.
Common pasture plants causing pyrrolizidine alkaloid poisoning: