Liver Fluke in sheep

Causes of liver fluke

Disease is caused as a result of the migration of large numbers of immature flukes burrowing through the liver tissues and/or from the existence of adult flukes causing inflammation in the bile ducts of the liver.

The liver fluke cycle involves two different hosts - the sheep and the mud snail Galba truncatula which need to be present to continue the cycle. The snail host is found in muddy, wet areas of ground with poor drainage. 

Signs of liver fluke

In sheep, liver fluke disease can be: 

• Acute - leading to sudden death 

• Subacute - rapid weight loss, anaemia 

• Chronic - long-term weight loss and anaemia 

The occurrence of liver fluke will be different depending on the time of the year.

Treatment

There are many products available to help with the control of parasites; getting the most from these active ingredients is key in ensuring ideal flock performance and reducing the risk of resistance. There are different flukicides available for different ages of immature and mature fluke. Incorporating a rotation regime of active ingredients into your health plan will help to minimise the risk of anthelmintic resistance and should be discussed with your veterinary surgeon or animal health advisor.

Triclabendazole is the most effective active ingredient against all stages of liver fluke. However, Anthelmintic resistance is widely reported in sheep. SCOPS have developed strategies which aim to reduce the rate of resistance development.

Control of liver fluke  

It is important to implement a range of on farm actions to control the spread of fluke worm. These actions include: 

• Fencing: Fence off wet areas and do not graze sheep on high risk pastures during periods of high risk 

• Only use flukicides when necessary: Take into account farm history, forecasting and specific diagnostics 

• Pick the right product: When treatment is necessary, chose the active based on the season and lifecycle stage of the fluke infecting your sheep 

• Dose properly: Ideally weigh individual animals 

• Expert advice: Together with your vet or animal health advisor, implement a quarantine strategy to reduce the risk of introducing fluke

• Quarantine: All animals entering the farm such as bought-in/replacement stock, and even those returning to the farm, e.g. from a show - should be quarantined. This will help prevent the introduction of internal parasites