Research into parasitic diseases produces more questions than answers, finds Peter Green MRCVS
Liver fluke is a large parasite that lives in the liver of grazing animals. Animals catch the infection on damp or marshy pasture where the intermediate host, a small snail, thrives. Cattle, sheep, goats and deer can be severely affected, and farmers regularly have to dose their stock to treat liver fluke.
In one survey in Ireland, 9.5% of horses at an abattoir were infected with liver fluke; in Spain, 60% of horses were found to be positive on a blood test. We know how cattle and sheep get the infection: they ingest the early stage of the parasite as they graze. It seems obvious that horses are infected this way, too.