Veterinary Services

• Treat all animals at risk with a flukicide capable of removing immature and adult flukes in October and January
• Outwintered animals may need additional treatments between October and January – check the farming press for warnings or seek veterinary advice if unsure
• Vaccinate all animals at risk against Black Disease
• Investigate all cases of sudden deaths in sheep or cattle  this autumn by post mortem examination
• Investigate all cases of ill-thrift in cattle and sheep using individual or bulk liver fluke egg detection tests (for bulk fluke egg detection test, 10 individual samples should be submitted for pooling at the laboratory) and/or blood tests
• Monitor for presence of liver fluke regularly by having liver fluke egg detection tests (individual or bulk) carried out on faeces samples from mid-January
• Remember quarantine treatments for bought-in animals (see below)
• Review your control programme annually by checking for presence of liver fluke eggs in January
• Flukicide resistant liver flukes are an increasing problem. If you suspect flukicide resistance contact your vet or local SAC Veterinary Centre

SAC surveillance figures for 2010 continue to show widespread infection throughout Scotland, particularly in cattle. Summer rainfall in Scotland was variable with June and August having below average rainfall, but July was the third wettest in Scotland for 100 years. Summer temperatures were generally close to average. This has produced good conditions for snails and intermediate fluke stages. SAC therefore anticipates that the number of cases in autumn/winter in sheep and cattle will be as high if not higher than 2009. This is supported by our figures to date (January to August) which show an increase of 3.2% in percentage diagnoses in cattle compared with the same period in 2009 and 1.1% in sheep.

Untreated infection in cattle can increase problems for sheep by increasing the number of infected snails, therefore control measures should be applied to both sheep and cattle.

Figure 1 (see tio right-hand side) : SAC Figures : Liver Fluke Outbreaks as a percentage of diagnosable submissions

SAC figures show the increase in the prevalence of fasciolosis in sheep and cattle in Scotland to unprecedented levels in recent years.  This has resulted not only in deaths, clinical disease, poor growth rates and liver condemnations, but also subclinical disease in sheep and cattle. This increase has been associated with climate change causing increasing temperatures and higher rainfall.

The disease has now spread throughout Scotland to previously unaffected farms in both sheep and cattle. The geographic distribution of outbreaks in 2008 in both sheep and cattle illustrates not only the increased prevalence of the disease particularly in the west and north of the country, but also its spread throughout Scotland, accompanying climate change and the extension of the habitat of the intermediate host, the dwarf pond snail (figures 2 and 3 - see top right-hand side).
 
The number of farms on which liver flukes resistant to triclabendazole (Fasinex)  have been detected in sheep and cattle has also increased since first detected in Scotland in 1998. If resistance is suspected faeces samples should be submitted to your local SAC Veterinary Centre.

As there is an increasing problem of liver flukes resistant to treatment, faecal samples should be submitted to SAC Veterinary Centres 3-4 weeks post-treatment for post-dosing efficacy checks (PDECs). Alternatively, a faecal egg reduction test can be carried out on ten faecal samples taken from the same ten individually identified animals on the day of treatment and 3-4 weeks later or initial screening can be carried out on a group of ten samples which are bulked in the laboratory to reduce cost. 

In response to this threat to animal welfare, SAC Veterinary Services, with Scottish Government funding, conducted an extremely successful national campaign in 2003 to increase awareness of the disease, its treatment and control. Since then, SAC disease surveillance figures show that until 2008 the number of outbreaks in sheep had fallen, but the level of infection in cattle remained high. There were unprecedented levels in sheep in 2008 and 2009 with only a slight reduction in cattle in 2009. The widespread geographic distribution of outbreaks in sheep and cattle in 2008 is shown in figures 2 and 3 (see top right-hand side).

Acute liver fluke disease in sheep can cause sudden deaths with no prior warning and has already been recorded in sheep this year throughout Scotland. Sales figures for flukicides for cattle compared with sheep suggest that fewer cattle at risk are treated for fluke disease. This may be because some farmers still do not recognise that cattle performance is affected by the parasite. Liver fluke disease causes ill-thrift and is associated with increased susceptibility to other diseases in cattle and sheep, including Black disease, which can cause sudden death, metabolic disease, salmonellosis and paratuberculosis (Johne’s disease).

All cattle (and sheep) at risk of fluke disease should be treated in October and January to remove liver flukes and to break the life cycle of the parasite by preventing infection of the intermediate host, the dwarf pond snail Galba truncatula. A minimum period of 6 weeks after housing is required before treatment to ensure all liver flukes are killed. Outwintered animals are particularly at risk and an additional treatment in November/December may be required following the wet summer. Ill-thrift in any animals should be investigated, casualty animals examined post mortem and faecal samples regularly checked for fluke eggs.

Quarantine treatments are required to avoid the introduction of resistant liver flukes to farms with wet areas that can support the dwarf pond snail. Cattle (and sheep) from fluke areas, being brought onto such farms should be treated with a product effective against immature flukes. Ideally the treated animals should be held away from snail-contaminated pastures for 4 weeks. Monitoring for fluke eggs should be carried out in subsequent months and follow-up treatment 6-8 weeks after the initial treatment may be required.