Liver Fluke in Cattle

There are concerns because the incidence of fluke in both cattle and sheep is still rising. Fluke or evidence of fluke damage in the liver is regularly detected in abattoirs. At best livers are rejected, but it also means that this animal hasn’t done as well as it should have if better control measures had been implemented. Fluke control should be more than deciding which drug to use. There are a lot of things that you can do to avoid losses.

Drainage and Fencing

Forty years ago pasture improvements concerned drainage and fencing. Grants were available and readily taken up to drain wet areas to make life difficult for the snails. I can remember there was encouragement to spray ponds and ditches with copper sulphate and other products but nothing like that can be used today. Now we have moved in a completely different direction. Wild life schemes encourage ponds and wet areas. The snails are abundant again and we should not be surprised that all of the progress we once made to control liver fluke has been lost.

Cattle and Snails

For fluke to spread the host animal needs to have contact with snails in the summer and autumn when temperatures are above 10 degrees centigrade. That means any wet field, pond ditch or water trough that is over flowing. Also consider that it takes immature fluke ten to twelve weeks to reach maturity so it may be possible to graze problem areas to finish lambs or fatten cull cows that you know will be leaving you after a couple of months. Fluke often come with brought in animals that have potentially grazed wet areas for at least one summer. Would it be possible to keep any stock with an unknown fluke history on dry pastures where any fluke eggs they pass will do no harm?

Treatment Options

As far as I can determine there are now thirty one different treatments for fluke in cattle and sheep. Most of these are a drench, but there are injections and a pour on cattle treatment as well. The choice is limited because there are just six different active ingredients. There has been talk of resistance to triclabendazole in sheep but no problems have been seen when cattle are treated with the drug. Whenever drenches are used there are concerns that some animals have not had an adequate dose over the back of the tongue and that some of the intended treatment has been lost.

Know the Potential of the Drugs

Triclabendazole when given as a drench can kill fluke as young as two weeks of age. As a pour on it dislodges the parasite from eight weeks of age. Albenazole and Oxyclozanide will only eliminate adult fluke and should be considered for long term management and not treatment of acute disease. None of the drugs have a persistent action in the way that we have come to expect for some worm treatments. Animals treated early in the autumn, unless moved to dry pastures, will continue to take in the metacercariae and will need a second treatment later in the year.

Strategic Dosing

Cattle are big animals with big livers and can tolerate moderate fluke numbers before they become ill. Your aim here should be to determine whether you have a problem in your herd from abattoir reports, bulk milk samples or possible faecal samples. If you find just one animal affected you will need to try and identify which fields it has come from and treat all of adult animals in the herd. We are very restricted with the treatment options for dairy cows. No body wants to throw milk away after treating their cows so the best option is to use the drugs when cows first go dry and aim to treat the whole herd in the course of a twelve month period.

COWS Web Site

For those of you who like to look up things on a screen there is a useful COWS web site for  the Control Of Worms Sustainability  which you can find at www.cattlleparasites.org.uk This may help you make better choices about how to control the worms and fluke on your farm

Tapeworms and Sheep

One parasite that gets little mention are the tapeworm segments that young sheep pass at this time of the year. These are the gravid segments containing eggs of the tape worm Moniesia expansa. On the pasture these segments attract the attention of a mite in which they develop further. The life cycle is completed when the mites are ingested by grazing sheep. Once infected lambs develop an immunity to this parasite. Older animals at worst have only a small number of the worms in their gasto intestinal tract and seldom pass any segments. Rarely has M expansa been found to cause disease and most infections resolve as the sheep grow.

Dogs Tapeworms and Sheep

Sheep also play their part as being the intermediate host of the tapeworms Echinococcus granulosus and Taenia species. These are potentially a more serious problem as they can sometimes affect us. Dogs are involved in the life cycle of these parasites for the infection to spread the dog needs to have access to a sheep carcass.

The Dangers of Bracken

It always amazes me that there is so much bracken about as it grows at such a prodigious rate and swamps any available grass. It has long been known that bracken contains toxins that depress the functions of the bone marrow reducing the numbers of white cells in the blood. It also contains toxins called plaquiluside in the spores and leaves that can lead to cancer of the bladder wall and sometimes in the intestines. The mature plant has a bitter taste and is only usually eaten if all of the grass has gone and there is nothing else available. It can be particularly hazardous if the plant is cut or if the roots are exposed by ploughing as the young plant and roots are  attractive to cattle. Affected animals loose blood either with their urine or as diarrhoea, they tend to strain a lot so it must make them uncomfortable. There is no treatment for bracken poisoning. In the initial stages you may see an improvement with antibiotics. Most animals deteriorate and have to be culled because of the weigh that they have lost. Bracken poisoning can affect sheep sometimes, but it is cattle that are most at risk from the plant.

Dangers of Ragwort

The other poisonous plant that makes an appearance now is Ragwort. This is also a plant that is not welcome where there is livestock particularly horses. It has been subjected to control measures since at least 1959 but somehow it still seems to be spreading along road side verges and railway lines as bad as ever. When it is growing ragwort has a bitter taste, sheep seem to be able to tolerate it. Horses will only eat it once it has been knocked over or incorporated in hay bales. This is not a difficult plant to recognise even when it is dry so it should be possible to avoid this poisonous plant.

Horses and Alkaloids

Ragwort poisoning does not have distinctive symptoms. It will cause destruction of the liver and any other ailment which affects the liver in the same way will cause the same symptoms. This is further complicated by the fact that the alkaloids that cause the problems are found in many other plants. In fact they occur in 3 percent of all flowering plants. It is actually the breakdown products of these alkaloids produced in the liver that cause the problem and there are other sources of these too. The symptoms can only be confirmed by a post mortem and these are often not carried out so the true number of horses that are affected each year is difficult to determine.

Lost File

Since the end of last year I have been unable to communicate with our Web Site because there was a file missing. I am not very good at finding things at the best of times. There is only so much you can do to find a file in a computer. I was about to give up when suddenly the lost file has turned up and it is working again now.                                                 C                                                                             

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