Liver fluke control

The session aim was for the delegates to understand: the impacts of fluke on sheep/cattle health, the life cycle of liver fluke and climate change related changes, the avoidance and treatment options available. Phil Stocker (National Sheep Association): Chair This session was organised by the National Sheep Association (NSA)
Phil Stocker (NSA): chair.

Session summary

The session provided a very good understanding of liver fluke, a growing problem for all sheep producers since 2012. It became very clear that liver fluke control is complicated. The parasite’s (which looks a bit like a cornflake) life cycle includes an intermediary host, a mud snail so small that many farmers have never seen them. The diagnosis in the live animal remains difficult due to the differing effects of immature and mature fluke, but some non-evasive tests can be used, such as looking for clinical signs (including abattoir feedback), faecal egg counts and a new method tested based on (faecal antigen) is now available.

Liver fluke has always been a problem on some but not all farms in the West, but is now spreading to the East. Climate change, animal movements, preservation of wetlands for environmental reasons and drug resistance have all been identified as contributing factors, but difference in infection between farms in the same area indicate that there are also farm specific risk factors. This gives an indication that management can make a difference and the shared view by all speakers was that no farmers and certainly not organic farmers, should rely only on drugs.

The risk varies throughout the seasons. Acute liver fluke, when livers are heavily infected with young flukes, occurs mainly in the autumn and winter, particularly after a wet summer when high numbers of parasites have developed. Sheep farms in the West are mainly at risk, but it can also occur elsewhere and in cattle. The young parasites do not shed eggs so cannot be diagnosed by faecal egg counting. Chronic fluke occurs mainly in winter and spring and usually shows itself as if something not right with the animals, ill-thrift, sub-mandibular oedema (sheep is losing protein somewhere). This involves adult parasites.

All speakers agreed that a lot can be done with prevention, but if treatment becomes necessary using the right drugs is essential. Only one drug works against all life stages of the parasites, whereas most others are specific to immature or adult stages.

Key conclusions

The discussion that followed the presentations brought out the following points:

  • Fluke is difficult to diagnose and working with a knowledgeable sheep vet is good advice.
  • Knowing the fluke status of the farm by checking for fluke in fallen stock. Producers should make good use of the information that is provided from the abattoirs, and ask for it if it is not released.
  • Preventing pastures from becoming infected through avoiding eggs being shed, particularly on pasture that may host the mud snail (testing for eggs in faeces to stop the snail being infected).
  • Keep stock from at risk fields and consider timing of grazing and associated risk; get out the farm map, where there is water, there is risk. Some fields are high risk, in some fields the risk could be minimised if water can be fenced out;
  • Prevent the farm from becoming infected. Animals bought in should be quarantined for long enough (possibly housed or on temporary grass or grass about to be ploughed up during this period to avoid pasture/farm contamination) and their faeces tested. Infected animals should be kept separated from pastures with snails to avoid snails being infected.

Individual speaker presentations and abstracts

Kevin Thomas (Producer): The impacts of liverfluke
Phil Skuce (Moredun): Life cycles, climatic changes testing/analysis options, new developments

The liver fluke is a highly pathogenic flatworm parasite of grazing livestock, causing considerable animal health and welfare issues and significant economic losses to the livestock industry. It has a complicated life-cycle, involving a tiny mud snail intermediate host. As a result, fluke prevalence, seasonality and geographic spread are very much driven by the prevailing weather conditions, especially rainfall. Following one of the wettest summers on record last year, many farmers experienced significant losses due to liver fluke over the winter months of 2012-2013, with sheep farmers particularly badly hit. This presentation will describe the liver fluke’s complicated life-cycle, the role of climatic and other factors in its spread and implications for its management and control. Liver fluke is notoriously difficult to diagnose in the live animal, the various diagnostic options and their relative advantages and disadvantages will be explored. Finally, new developments, such as the emergence of rumen fluke, and recent fluke research findings will be discussed.

Fiona Lovatt (Flock Health Ltd): What can an organic farmer do to protect against liver fluke?

The control of liver fluke presents sheep farmers with a huge challenge due in part to its complicated life cycle. Environmental factors such as farm topography and the weather have a large part to play and it is important for all farmers to consider what control measures are possible by good management practices. As a part of this, it is necessary to understand which fields are high risk at which times of year and which categories of stock to put where. This presentation will discuss the principles of pasture protection, which aims to limit the contamination of fluke eggs on snail habitats, stock protection, which keeps susceptible animals away from high risk areas and whole farm protection, which ensures a robust quarantine policy for bought-in stock. We will explore how to use flock management, veterinary supported health planning and the strategic use of diagnostics to minimise the need for pharmaceutical products. We will discuss the responsible use of pharmaceuticals for those circumstances when they are necessary.


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