Liver Fluke in Dairy Cattle
Fluke are parasites that migrate through cows livers causing large amounts of damage. They can cause huge economic loss through ill thrift, increased susceptibility to other diseases, condemnation of livers in the abbatoir and increase in vet fees.
Fluke problems are dependent on rainfall in the summer. A wet summer favours the lifecycle of the snail, Lymnaea Truncatula, which is heavily involved in the transmission of fluke to cattle.
It is important to understand the liver fluke life cycle in order to be able to plan an effective treatment protocol. This is simplified in the diagram below but I have tried to summarise it.
- Fluke eggs are passed in the faeces of infected cattle onto pasture
- The eggs hatch to produce miracidia (an intermediate life stage of the developing fluke) These are able to swim and search out the intermediate host – the snail – which they infect. It should be noted that the fluke eggs take about 9 days to hatch at optimal conditions (around 22°C) and they will not hatch if the temperature is below 10°C.
- Snails are mostly found in wet and boggy ground.
- The miricidia develops in the snail into the next stage of the life cycle (called the cercariae). These can swim and attatch themselves to grass blades where they develop into the final infective stage. From being passed in faeces to this final stage can take a minimum of 6-7 weeks (although it can take several months if the weather isn’t right!
- The infected grass is then eaten and the fluke encyst in the gut wall before migrating through the liver to the bile ducts where they mature and begin to produce eggs. This stage usually takes 10-12 weeks and the whole life cycle takes a minimum of 17-19 weeks in optimum weather conditions.
Fluke life cycle diagram coming soon!!!
If your cattle graze pastures that are at a high risk of fluke infestation ( wet, boggy or poor drainage) then potentially liver fluke are causing losses in your herd.
Adult dairy cows can show a lower than expected milk yield coupled with weight loss and poor fertility.
If you have had reports of fluke in the livers of cattle you have sent to the abattoir then potentially other cattle on your farm are affected.
Blacks disease is a clostridial disease triggered by fluke migration through an animals liver – these animals are usually seen as a sudden death and diagnosed by post-mortem. If this has occured on your farm then you can assume more animals are being affected by fluke.
In 2010 liver fluke was estimated to have cause around £23 million in losses annually to the cattle industry through lost production and condemnation of livers in the abattoir. Poor fertility, weight loss and low milk yields are other sources of lost income. There can also be an associated rise in cases of metabolic diseases post calving.
Chronic, heavy fluke infestations may cause death of an animal or require her to be culled from the herd.
Liver fluke in cattle can be diagnosed by identifying fluke eggs in the animals faeces. A blood sample can also be taken to identify whether an animal has been exposed to liver fluke.
A bulk tank milk sample can also give an idea of what the level of liver fluke infection in your herd is.
There are several products that kill liver fluke – these are known as flukicides. They vary in what stages of the flukes life cycle they act against (some don’t kill immature fluke whilst they are still developing). It is important to match your treatment protocol to that of your management of the cattle on your farm.
Discuss with your vet what products best suit your farm needs and when they should be used.
Prevention of disease usually revolves around having a sensible treatment protocol. Reducing exposure of cattle to fluke habitats by fencing off wet and boggy areas is rarely economical or practical (although if it is possible on your farm it can be a sensible precaution to take)