The liver fluke has a complex, indirect life cycle. A freshwater snail is required as an intermediate host. Since these snails survive only in moist environments, liver fluke infections are typically limited to animals that have grazed on wet, damp pastures. In fields where sheep or cattle grazed the previous year, infections are even more common. On high sandy soils or well-drained pastures, liver fluke is not naturally found. However, liver fluke infection is always a risk in low-lying regions such as the western pasture areas. Keep in mind that even a single damp corner or ditch with water can be a source of infection.
The adult liver fluke lives in the bile ducts of the liver and produces characteristic eggs, which are excreted with the droppings. Depending on the ambient temperature and the presence of water, within 3 weeks a larva develops that swims in the water and actively seeks the intermediate host: a freshwater snail. The larva penetrates the snail and multiplies inside it. There, it further develops into the next stage, the so-called cercariae. These cercariae leave the snail and become infectious for your sheep or goat. At this stage, they are called metacercariae, which can remain infectious for several months. Once ingested, the young larvae penetrate the intestinal wall and migrate to the liver, where they wander for several weeks before settling in the bile ducts. The full cycle takes at least 4–5 months.
Infection with liver fluke can cause various symptoms. In severe, acute infections, your sheep or goat may die. In chronic infections, loss of condition and anemia are often observed. The development from larva to adult, egg-laying liver fluke takes 12 weeks in a sheep or goat. Therefore, in acute infections during late autumn or early winter, no eggs will be found in the droppings, even though the sheep or goats are already ill from the developing liver flukes. Chronic infections occur mainly in late winter and early spring, during which liver fluke eggs can be found in the droppings.
The diagnosis of liver fluke is not easy to establish. A correct assessment of factors that determine pasture contamination is very important. Therefore, actively monitor moisture and temperature. This history, combined with blood tests for liver enzymes, a worm examination, and the clinical picture of your sheep or goat, will lead to a probable diagnosis.
If a worm test is performed with a sufficient amount of stool and the correct technique, the diagnosis can be confirmed by detecting liver fluke eggs. At Worm&Co, we use the modified Dorsman method. This test is qualitative, which means we can determine with certainty whether or not the animal is infected.
If the worm test shows that your sheep or goat is infected with liver fluke, we will provide you with a personalized treatment recommendation. This way, the health of your animal(s) comes first and unnecessary worming is avoided. Feel free to contact our team if you have any questions; we are happy to help!
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