Acute Rumen Fluke Infection

Look out for fluke!

Acute rumen fluke was diagnosed as the cause of death in a four-year-old ewe last week at Dumfries.  The ewe was the third to die in a group of 60, and the other ewes in the group were noted to be leaner than expected.  This ewe had scoured before death, and at post mortem intestinal content was watery and malodorous.  Very large number of immature rumen fluke were detected in the duodenum and jejunum, the surface of which was covered by fibrin.

  • It is worth noting that the clinical signs of acute malodourous scour and deaths particularly in adult sheep are quite specific, unusual and worth looking out for. 

For these cases to occur there has to be ingestion of massive numbers of metacercariae, followed by attachment of the immature rumen fluke to the small intestinal mucosa causing the severe diarrhoea seen.  The pictures below are of the duodenal damage and the appearance of the immature fluke.     Risk factors for rumen fluke are the same as for liver fluke.  These ewes were on a silage aftermath but areas of wet ground were also present.  Ewes on this field had experienced losses associated with liver fluke in autumn 2015.

  • The practice of putting grazing stock directly on to silage aftermaths after the fields have been cleared is a risk for acute fasciolosis and rumen fluke infection as stock will graze more intensively on the wetter areas and field margins where tractors and machinery can not travel.   

Oxyclozanide is the usual treatment for rumen fluke although the products have no licence claim against the parasite.  It is not effective against the juvenile stages of liver fluke.

Acute rumen fluke remains uncommon in this area (one previous outbreak was diagnosed at Dumfries in January 2012) but should be added to your list of differential diagnoses in cases of scour and death in sheep and young cattle.  The jury is still out on the significance of adult rumen fluke infection which is considered to be an incidental finding, with clinical disease rare.

  • Given that liver fluke remains the more important parasite in terms of disease and production loss, routine autumn treatments should continue to specifically target immature liver fluke. 

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