An increase in the number of liver fluke in factory cattle has been highlighted this year and in light of this, the Department of Agriculture, Food and the Marine (DAFM) has made available advice to farmers on the treatment and control of both liver and rumen fluke in cattle and sheep.
As farmers will know, a high burden of parasites is one of the many factors that can reduce livestock performance and an effective parasite control plan is essential in all livestock farming systems.
Earlier this week, DAFM published a map detailing the predicted risk of disease caused by liver fluke (Fasciola hepatica) infection in livestock this winter. Click here to view this map.
In areas of high risk and on farms where liver fluke infection has been diagnosed or where there is a prior history, livestock owners should consult with their private veterinary practitioners (PVP) to devise an appropriate control programme.
Taking dung samples can help verify the presence of fluke in a herd of cattle or flock of sheep.
For sheep, a drug effective against early immature, late immature and mature flukes should be used to protect against acute disease.
Where cattle are being treated for fluke at the time of housing and the flukicide given is not effective against early immature fluke, then faecal samples should be taken six to eight weeks after housing and tested for the presence of liver fluke eggs.
This will determine whether a follow-up flukicide treatment is necessary.
Some farmers prefer to wait until six to eight weeks post-housing and then treat cattle with a product effective against mature fluke. Where farmers are unsure of the best course of action, they should contact their PVP.
Any cattle or sheep that are out-wintered are at risk of further fluke infection post-treatment and follow-up flukicide treatments may be necessary.
This is especially the case if they remain on high-risk pastures. In this case, it is advisable to monitor livestock for the occurrence of re-infection.
The intermediate host of the parasite, which is a mud snail (Galba truncatula), occurs in soil that is slightly acidic and muddy.
Areas with rushes or wet patches are particularly important with regard to liver fluke risk, as they can help to maintain a population of the infective stage of the parasite.
In addition, livestock owners should factor in prior fluke history on the farm as this is an important indicator of future disease risks.
Veterinary advice should be sought on treatment protocols and on the appropriate interval at which such treatments should be given.
Testing faecal samples for the presence of liver fluke eggs can help determine both the need for and success of flukicide treatments and this is especially important given that resistance to flukicides is becoming more common.
Where dairy herds are concerned, bulk milk testing for liver fluke antibodies may be useful to monitor variation in exposure.
Rumen fluke
The rumen fluke (calicophoron daubneyi), which has become more prevalent in Ireland over the last number of years in both cattle and sheep, uses the same intermediate host as the liver fluke.
Rumen fluke infection is extremely common, especially in cattle, but only causes disease or issues for herds rarely.
If clinical signs such as rapid weight loss or diarrhoea are seen, or if there is a history of previous disease from rumen fluke on the farm, livestock owners should consult with their PVP as to whether treatment for rumen fluke is required.
Challenges resulting from larval rumen fluke can cause severe disease typically but not exclusively in first season grazing cattle and in all ages of sheep.
If larval rumen fluke infection is suspected, farmers should request this test when sending a representative number of faecal samples for examination to a laboratory as routine parasite examination may not detect this stage of the parasite.
The presence of rumen fluke eggs in faecal samples of animals that are thriving and producing well does not indicate that treatment for rumen fluke is warranted.