Liver Fluke in Cattle                   

 During the past month I have heard from three farms that have had liver fluke detected in their cattle either at an abattoir or from a post mortem. One of these farms had not had a report of liver fluke before, the others do get them from time to time. Liver fluke has become more of a problem again lately. It is of concern that it can occur in even a fairly dry year after a cold winter on farms which do not have many wet areas where the cattle graze. Liver fluke can be a hidden disease, it turns up in cattle that have fattened well at grass often it might be one or two from a group of twenty or more that show signs of the disease. Adult fluke are a leaf like creature three centimeters long that live in the bile ducts of the liver. They are easy to find if you look in the right place. The juvenile form spends six weeks eating away at the structure of the liver before moving into the bile ducts where they start to lay their eggs. Cattle have large livers and can tolerate a moderate infestation while showing few signs of disease they will not usually become anaemic although they will not fatten or milk to their full potential. When you consider that each adult fluke in the bile ducts will shed 25,000 eggs each day there is a huge potential for pastures to become contaminated by the parasite.     

Complicated Life Cycle.                 

You will realise that fluke have a complicated life cycle involving a secondary stage that multiplies in a snail, that this takes a long time and always involves ground that is wet throughout the summer. It can be difficult to diagnose as it is usually a chronic disease in cattle. Liver fluke will not shed any eggs for six weeks during the juvenile stages when they are eating their way through the liver tissue. When this happens enzymes are released into the blood that may lead to suspicion of disease, but there are other conditions such as bracken poisoning that will also damage the liver. There is still a test that can be carried out on a bulk milk sample from dairy herds. This gives an indication of the early stages of infection and it is a good idea to do this at least once each year, better in the winter, when the adults are starting to mature in the bile ducts. Signs of chronic fluke can be difficult to detect from faeces samples, it is better to have at least six samples to get a representative picture of what is going on.                                         

Where do the fluke come from?   

There are three main ways that fluke can arrive on your farm. If you buy in adult cattle or a bull that have not been treated for the disease. If you have sheep grazing your farm in the winter or if you have a stream or river that runs through from neighboring ground that is grazed by sheep or cattle. This is a growing problem in Shropshire that is getting worse each year. The reasons for this are not fully understood. There has been a tendency in the past few years for environmental schemes to promote wet areas which in the past were drained. There is no real evidence that there are more movements of potentially infected animals into Shropshire as cattle and sheep have always come here from the west of the country. It might well be that some of our summers are wetter now, but there have been periods in the past when there have been wet seasons.       

Physical Control.                                 

If you are not restricted by one of the environmental schemes you may be able to fence off wet areas and stop cattle drinking from streams and ditches. Surface water for cattle is never a good idea because it encourages the spread of leptospirosis and stagnant water can be contaminated by salmonella bacteria. It is not acceptable to treat wet areas in the summer with compounds to kill off the snails because of the dangers to other aquatic species. If you cannot fence off wet areas you might be able to leave them until after the first frosts when the risk from the miracidia is reduced.  

Treatment Options.                       

There are now more drugs to treat fluke in cattle and sheep than there have ever been. We have drenches, injections and pour on products so it has never been easier to treat this disease for beef cattle and sheep. Last year the EU severely restricted the number of drugs that can be used on milking cows, but Zanil was reintroduced with a withdrawal time for milk of 72 hrs if you can manage a drench. Ivomec Super and its equivalents can be used at drying off as long as you are confident it will be at least sixty days before calving. Products containing Albendazole, Ovispec or equivalent, have the shortest withhold period for milk at 60 hours, but as this is a chronic disease you should be able to dose the entire herd when they are dry. Some products such as Closamectin work better on mature fluke and are best given after January when you can be sure all of the fluke have reached the bile ducts.                                               

Fluke Talk                                                 

This year’s Animal Health Road Show is all about fluke and how you can develop effective treatment and management strategies to minimize any financial losses from the parasite. The talk is hosted by the Moredun, but the nearest one to us is at Ruthin on the 12^th November. These are usually very practical talks and you should be able to find out what works and what is a waste of time.

Is your wormer working?                 

Wormers are expensive so it is worth doing the job properly. Are you giving the right dose? If you are not confident about the weight check the weight of two or three of the heaviest animals and dose the whole group to that weight. Is the drenching gun working properly? Make sure you wash it out every time you use it and always before you start set the dose. Check it is right with a plastic measuring cylinder or use an empty syringe to check the calibration. If you are giving 12 ml when you think you are giving 10 ml you could dose twenty extra lambs after the first hundred. Has the wormer been stored correctly? Most drugs should be kept below 25 degrees centigrade and not allowed to freeze so keep them out of vehicles and in a frost free building if you have any over or you might be better to throw it away and buy a new bottle each time. There is a lot of talk about worms being resistant to the drugs we use this does happen occasionally, more often the animals have not had the full dose or the wormer was old and not at it’s best.                                             

Mineral Deficiencies                                    

Also don’t forget about cobalt. Some soils are short of cobalt or it is bound to molybdenum or iron and is not available to the animal. Sheep that are short of cobalt stop growing and tend to scour so they look as if they have not responded to your wormer. Blood samples will confirm your suspicions or you could see if you get a response to a vitamin B12 injection. Cobalt is a cheap supplement that can be added to the ration and is sometimes included in the worm drench as it is safe to give to animals that do not really need it.

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