The liver fluke is a type of flatworm that can cause problems for many different animals and also for human beings. In cattle it is the cause of the disease bovine fasciolosis. The adult flukes take residence in the liver of the animal and feed on the blood there. Although they only lay their eggs upon reaching the bile duct. Symptoms of liver fluke in cattle can include anaemia, diarrhoea, and oedema, for instance. Treatment for the disease includes anti-parasitic drugs but some preventative steps may be available to stop the ingestion of the parasites in the first place.
There are various different species of the flatworms known as liver flukes. The species responsible for fasciolosis in cattle (and in sheep) is Fasciola hepatica. The fluke is particularly likely to infect the cattle in marshy, low-lying, pasture, especially during the Summer and Autumn months. It has a two stage life cycle. In the first stage the fluke reproduces asexually inside a water snail. They emerge in a larval form known as cercariae that then swim into the marshy areas where they are ingested, inside cases known as metacariae, by the cattle.
Once inside the animal they break free of the cases and live for a while in the intestines. The parasite will then burrow into the lining. Eventually it will find its way to the liver tissue. Once there it will start feeding. This continues for up to six weeks. The life cycle will continue when the bile duct is invaded and the adult liver fluke will then lay its eggs there. As many as half a million eggs a day can be produced.
The acute form of bovine fasciolosis isn’t common in cattle but the chronic form of the disease is more common. The severity of the symptoms will depend upon how extensive the infection is. There are various symptoms to look out for. These can include anaemia, as well as oedema and cachexia. Problems such as constipation and diarrhoea can also be present.
Treatment for liver flukes in cattle could involve drugs that are aimed at killing off the adult flukes. The two drugs available at the moment are clorsulon and ivermectin. The exact combination and adminstration of the drugs will be decided by the vet with cost-effectiveness in mind. There are also preventative steps that can be taken, such as keeping the cattle away from pastures where they are likely to ingest the parasites.