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The Sheep Page                                

Maedi Visna

Many of the diseases that sheep suffer from have wonderful names and Maedi Visna is a good example. This is a viral disease that was first seen in this country twenty years ago. Maedi Visna is difficult to control and not always easy to recognise, as there are a range of symptoms that are seen in different animals. It can sometimes take four years for the disease to become apparent. The virus can affect either the lungs or the joints of the animal, there is progressive weight loss and ewes will find it very difficult to move. The virus is very contagious, often by the time symptoms are apparent more that sixty percent of the flock will be carrying the disease.

Maedi Visna is the main disease that is monitored in the sheep health scheme. It can have devastating consequences if it is brought into a flock so pedigree flocks are blood tested every two years once they have been accredited to ensure that they are free from the infection. Accredited flocks have to ensure that there is no contact with other sheep and that any movements of animals onto the farm come only from flocks of a similar health status. When you buy rams in the autumn it is a good policy to purchase animals that are accredited for MV or have them blood tested before they go into the flock, as it could be several years before any problem develops.

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Scrapie

Scrapie is described as a non febrile, fatal, chronic disease of sheep that is characterized by the way it causes sheep to rub and walk in an abnormal way. Scrapie has been recognized as a condition for at least two hundred years in the United Kingdom and other countries. It is a cause of concern because it is a Transmittable Spongiform Encephalopathy and because of the way the connection to BSE in Cattle and Human brain disease is poorly understood.

Scrapie has been in the news lately partly because of the concern with BSE and also because of the new blood tests that are being used to reduce the chances of you having problems with the disease. Scrapie causes the body to produce an abnormal protein that affects the way the brain works leading to inco-ordination, weight loss and sometimes intense itching. 

Scrapie can take several years to develop in an infected animal. Some individuals may start to show signs of rubbing or an abnormal gait and then the disease will go into remission for a while before it progresses. It has long been noted that there is a strong tendency for Scrapie to occur in distinct families of sheep within a flock. In the past we have been able to eliminate it by keeping good breeding records and tagging all of the lambs as they are born. Within two or three years it will disappear as long as you send any relatives of suspect cases for slaughter as soon as cases are encountered. This has further been encouraged by the Compulsory Slaughter scheme that started in 1993 and Compensation scheme that has been operating since 1998. The disease is now quite rare in this area but is still seen on some farms.

Scrapie is difficult to control because the form of the infective agent and the way in which it is passed from sheep to sheep is poorly understood. It is thought that the disease can sometimes be transmitted by individuals that do not show any symptoms and the infective agent is resistant to heating and most disinfectants so it is difficult to eliminate it from affected farms.

Scrapie develops when the normal form of the Prion Protein in a sheep's brain converts into an abnormal form and the brain becomes damaged. This process is controlled by a part of a gene called a codon. It has been determined that three codons are involved on five different proteins so up to 15 different genotypes can be mixed up in the disease. The prevalence of different genotypes varies in different breeds. Research has shown that the ARR genotype is the most resistant and that animals that carry the VRQ genotype are the most susceptible to the disease. Other codons are involved but it is these two that are the most important.

The National Scrapie Plan

There is now a National Scrapie Plan that is fully financed by the Government that has been devised to reduce and eventually eliminate Scrapie from the National Flock. Similar schemes have been started in America, France and the Netherlands. This is a voluntary scheme at the moment. The way that it works is that pure bred rams are identified by the use of an Electronic Identification Device that is given by mouth and lodges in the rumen of the animal. Once implanted the rams are blood sampled so that their resistance to Scrapie  can be determined. Up to 40 animals can be tested at each visit. In smaller flocks some of the ewes will be sampled as well so that only the more resistant ones can be used for breeding.

At first animals with some resistance that carry the ARQ, AHQ and ARH genotype  will be allowed to breed until the end of 2007. The small number of rams which have been identified with the VRQ cannot be used for breeding and should be sent for slaughter.

It takes time to alter the genetic make up of your flock. You may well never have come across a case of Scrapie, but if you sell rams for breeding it is important that you find out about the genetics of your flock now. You could well find that the ram lambs you produce now will have no value for breeding so it is important that you take action this year as there is not very much time to put things right. The original plan was that all rams would be tested before the 2006 breeding season. This has been put on hold for the time being, eventually all rams will need to be monitored so that the genetic make up of their off spring can be predicted.

There is a new test now that is being carried out on the brains of fallen stock to detect the possible occurrence of BSE in sheep and to distinguish it from Scrapie. Should any of these animals ever show a positive reaction there is likely to be a huge conundrum as to how to proceed as the experimental disease has been shown to be present throughout the body in sheep not just in the central nervous system and some of the offal. It might well be that to have evidence that your sheep are of a more desirable genetic make up will be of vital importance in the future.

Buying a ram? Take a look at the Ram Register to find a breeder in your area that has an animal in group one or group two that you can use on your flock. There are usually a number of different animals to choose from

You can find out more about The National Scrapie Plan from their help line 0845 601 4858 that operates during office hours on weekdays. Or look at their website for the latest information.

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Ear Tags                                    

The Ear tagging requirements for sheep has changed again. All sheep tagged for the first time on or after 31st December 2009 must have two tags one of which must be an electronic identifier. The format of the tags is UK followed by your six digit flock number then a five digit animal number. These tags are yellow and both tags have the same number. You do not need to get an electronic tag reader to use the tags on your farm.

There is a concession for lambs that will be slaughtered within twelve months of birth. Lambs can go for slaughter with one tag, either conventional or electronic to identify the origin of a batch of lambs. These tags only need to have the flock number on them and the conventional ones can be of any colour.

I am sorry that this is so confusing. If you need help contact the Rural Payments Agency Livestock Helpline on 0845 050 9876

Even if you just have one sheep or one goat you will still need to register as a holding. You can do this readily by phoning the Animal Health Office in Worcester on 01905 767111.

There are more details about ear tags for sheep on the following link to the DEFRA web site.

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Sheep Scab

This is a serious disease caused by a mite Psoroptes ovis which is an obligate parasite of sheep. Affected animals develop an intense reaction to the parasite, stop feeding and spend all of their time rubbing and chewing at their fleece. Sheep scab rapidly spreads throughout the whole flock and can lead to severe welfare problems if it is not treated promptly.

Sheep Scab tends to spread more in the winter. Each female mite can be responsible for as many as a thousand eggs, each of which will mature within fourteen days. You must act quickly to stop this infestation. Mites can survive away from sheep for up to three weeks, but it is usually spread by direct contact between animals. They can be found on the edges of the lesions and can be seen as white dots that move about if you look closely through a hand lens.

Early Control Measures

Sheep Scab has a long history going back to 949 in Wales when King Hewel prohibited the sale of scab affected sheep between November and April each year and banned sheep from grazing on land where sheep scab had been found in the previous seven years.

Scab was also mentioned in the 14th and 15th centuries as causing problems with sheep from this country that were exported to Europe. It was not until the eighteen hundreds that a mite was recognised as the cause of the itching and it was first made notifiable in Great Britain in 1869. Numbers varied but in the first thirty years up to three thousand holding were reported to be infected each year.

The Introduction of Dipping

Compulsory dipping was first introduced in 1900 and varied from a single dipping to up to three each year depending on how much progress had been made. At first tar based dips and nicotine were used. Sometimes arsenic and lime sulphur was tried with a repeat dip after fourteen days to kill any emerging eggs. Once dipping was introduced there was a dramatic reduction in the numbers of reported cases. It was not until 1948 that an effective organo chlorine dip was found and rapid progress followed. The then last case of sheep scab was reported on a farm in Hereford in February 1952. This case involved a small lesion on one ewe noticed by an observant owner. The whole flock was dipped once and that was the last case seen in the whole of Great Britain for over twenty years.

Re Emergence

Sheep Scab continued to be a notifiable disease and there was some alarm when 40 cases were reported in 1973 and quickly increased to more than 100 new cases each year. The previously successful compulsory dipping rules was re introduced and newer and better drips were developed but little progress was made. Between 1987 and 1989 the numbers of reported breakdowns continued to rise. In 1992 there was considerable dismay in the Veterinary profession when the then Ministry of Agriculture Fisheries and Foods suddenly announced that Sheep Scab would be deregulated and it would not be necessary to report any further cases. From that time on in many flocks dipping stopped and there were a rising number of animals found with ticks.

From that time it has only been possible to intervene if sheep with scab were transported and noticed at an abattoir or a market. Since 1992 it has been impossible to determine how many outbreaks of sheep scab there are each year, the thought is that there has been a steady rise judging by what we see in this part of the world.

Injecting to Treat the Itching

In some ways the macrocylic lactone injections have made things worse. After just one intra muscular dose the itching will stop and you may think that you have conquered the infection. They are convenient to use but it is all too easy to under dose or miss the odd animal and it is usual to have to repeat the injection in the following years. Two injections ten days apart are better, but even then it is difficult to be confident that the flock is clear of infection.

We have sometimes noticed that lambs from chronically affected flocks will be covered in the mites but not show any signs of itching or rubbing. The scab mites seem to get inactive in the summer and become active at the colder times of the year. You may only realise that these animals have the infection when they start to rub in the winter or when you take them to a market and they are confined in a pen.

New Scheme in Scotland

Many people have been uneasy about this situation and the authorities in Scotland have now taken the initiatives to try and reduce the incidence of the disease in their country. On the whole most farmers are responsible and keen to keep on top of scab, the key to control measures it to get the co operation of the small minority who make no effort to stop the disease in their flock. From December 2010 when Sheep Scab is suspected or confirmed in Scotland movement restrictions are placed on the farm preventing sheep movements on or off the premises and measures are taken to prevent straying and contact with sheep on adjoining premises. Restrictions are only lifted when the flock has been treated and the flock has been found to be clear of the disease.

Monitoring Progress

It is admirable that Scotland is at least trying to tackle this disease again and has some means of monitoring the situation. Last year there were 144 cases notified and these have been found throughout the country including most of the off shore Islands. As time goes on and numbers of infected premises are reduced there it will be difficult to continue with this admirable scheme if no control measures are introduced in England and Wales as there is nothing to stop infected animals moving into the country.

Legal Aspects

Twenty years ago when dipping twice each year was compulsory and stronger dips were in use Scab had virtually disappeared from the National Flock. Unfortunately it is no longer a notifiable disease and there is no obligation to dip as a precaution or treat the infestation. It is an offence to move sheep with scab or take them to a market, but the disease has spread rapidly, especially with replacement ewes purchased in the autumn. It is not easy now to treat this disease.

When they were in use the Organo phosphorus Dips were the best defense that we had against this mite. It has become increasingly difficult to use these dips because of the need for the license and the restrictions on the disposal of the chemicals. All OP dips have now been withdrawn because of difficulties with the containers that they are supplied in and it may well be that we will have to cope without them. Because of this there will be more and more Scab about each winter and you must take precautions to keep it out of your flock.

Best Treatments

Try and buy replacement ewes only from a known breeder and ask about whether they have had any problems in the past. It is a good idea to keep new stock isolated from the rest of your animals for three weeks and dose them with either Dectomax, Cydectin or Ivomec to kill off any sub clinical infection. Each of these injections will also worm the ewes and make it less likely that any resistant roundworms will come onto your farm.

If you have scab it is the injections that you will have to use. It is difficult for an injection to conquer this infestation. Turn the odds in your favor by weighing some of the animals and make sure they have the maximum dose. Also make sure that they are all treated and that you do not miss inject even one member of the flock or the whole thing will not work. If you have a choice it is better to treat the flock in the late autumn after the lambs have gone because of the long meat withdrawal time of fifty-six days before anything can be sold. Treated animals should be moved onto fresh fields to avoid re infestation from wool that has been deposited on trees and fences.

In practice once you have Sheep Scab in your flock it will probably always trouble you to some degree so you will need to inject against it at least once each year. Scab is not easy to treat so it is essential that you are careful about where you buy your replacement stock.

There is a non-organo phosphorus dip Called Bayticol Scab and Tick Dip. This has to be used at a higher concentration than normal when combating Scab and you have to dip twice with an interval of two weeks between the sessions. We have had some experience with this product. It has no action against Blow Fly Strike and will hold Scab in check, but not clear it from the flock. The treatment tends to be quite expensive to use.

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Abortions

In the past some farmers have accepted that there will be a number of ewes that lose their lambs each year and have put up with the losses as something that you have to live with. This is not the case and it is far better to have the first two or three abortions investigated so that you know what is going on. Some of the infections cause lambs to be born alive before their time and are responsible for lamb losses in the first few days of life.

Enzootic Abortion is the most common. It is caused by bacterium called Chlamydophila abortus  (previously known as Chlamydia psittici) picked up from carrier sheep. The dead lambs produced by this infection are not usually decomposed, but the placenta is thickened. The infection damages the placenta of the ewe and starves the lambs of their nutrients; twins are more likely to be lost than singles. The disease does not start to affect the placenta until ninety days into the pregnancy. Studies show that an imbalance occurs in the hormones associated with pregnancy when a ewe is affected by this infection and it is thought this is what is responsible for the loss of the lambs.

If you can get an early diagnosis from an aborted foetus and placenta long acting oxytetracycline does help to buy some time and produce viable lambs. Some of these may be difficult to rear. For best results the injection should be given at day 95 and day 120 of the pregnancy. It is not always easy to time these treatments exactly.

Enzootic abortion is a complicated disease. Sheep pick up the infection from the fluids and discharges at the time of lambing. They hold onto this infection and it is not until the following year that the pregnancy is lost. Infected ewes usually only abort once with enzootic abortion, but they will carry the infection for the rest of their lives and pass the infection onto younger ewes every time they lamb. Using antibiotics may help to save lambs, but it does little to stop the spread of infection in the lambing pens.

The way to stop Enzootic Abortion is to vaccinate the whole flock at least one month before they go to the ram. You will need to have some patience with this disease as there will still be some ewes that loose their lambs in the following year. In subsequent years you should see the full benefits of your control measures. Ewes only need to have the Enzovax vaccine once and it is important to inject replacement ewes every year.

Toxoplasma is a parasite carried by cats that will cause the cotyledons to become thickened with small white spots on the surface. Depending on the stage of pregnancy that the ewe was first affected typically one twin will be born two or three days early along with a mummified foetus. Cats are involved with the life cycle of this parasite, they have a tendency to contaminate feed stores and hay with their faeces or the ewes may get the infection directly from the fields that they graze.

Ewes can pick up the infection at any time of the year and it has been shown that they need only the smallest amount of infection to cause pregnancy loss. Controlling this disease is not as simple as getting rid of your farm cats. This does not work as others will soon take their place. It is known that younger cats shed more of the oocysts that are responsible for the infection. The better way is to keep a healthy population of farm cats by having them neutered they should then help to keep younger ones away. 

Toxoplasma can cause significant losses on some farms and is often responsible for ewes failing to become pregnant. The vaccine works well, but you have to be a little careful how you handle it as it is a live vaccine that is given in the summer before the flock goes to the ram. 

Salmonella infections can sometimes cause ewes to abort. Ewes can be affected at any stage of pregnancy and will often be very ill with the infection. The source of the infection is either from contaminated feed or other livestock. Wild birds can sometimes carry salmonella, but it is difficult to keep them out of farm buildings.

Listeria will also cause a significant number of abortions when contaminated silage is fed. This is a soil organism that multiplies when the silage heats up. Take care not to set the cutters too low or make silage from fields where there are molehills. Listeria will also cause meningitis when it is fed to sheep.

You should suspect this disease if you have any ewes that seem to be blind and press their heads into dark corners. Ewes with meningitis will respond to aggressive antibiotic treatment in the early stages of the disease. Ewes that abort with listeria show few signs that they are ill until they lose their lambs.

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Schmallenberg Virus

Schmallenberg Virus is a new emerging livestock disease that has been detected in Belgium, Germany, the Netherlands and the UK.

It is one of the diseases that is transmitted by midges so it tends to occur in the summer and autumn when the vector is active. In adult animals symptoms are usually transient and mild, there is a temperature rise and animals will stop grazing for a short time and may suffer from bouts of diarrhoea. On most farms the initial symptoms will go un noticed the problems arise if the ewes are first infected in the early stages of pregnancy as this will cause problems with the developing foetus. It may not be until lambing time when  you will see lambs born with limb and head deformities, some ewes may abort if they have deformed lambs. Sometimes only one lamb of twins is affected and the ewe will go on to rear the surviving twin.

The Schmallenberg Virus was evident on a number of sheep farms in Shropshire last year. It was very unpredictable often affected farms had neighbours that were lambing at the same time and had no problems. Most ewes went on to rear at least one lamb.

There is a vaccine available now to give to ewes in the spring before the midges become active. There are other reasons for ewes to have deformed lambs and so far we have not had a positive diagnosis in 2014. The thought is that the virus has been circulating early in the summer months before sheep are pregnant and that they have been able to develop a good natural immunity to protect their lambs.

All the evidence currently suggests that the disease was brought into the UK from infected midges blown across the Channel. There is little evidence to suggest that it was from imported livestock. The hope is that this virus will have a declining impact on our flocks as time goes on.

 

Lame Sheep.

Foot Rot and Scald are the most common causes of lameness in sheep. It is impossible to avoid these all together, but they are easier to cope with if you have decent handling facilities. It is essential to have a footbath that you can stand the sheep in and a concrete yard where their feet can dry off before they go back onto the fields.

Scald is an inflammation of the skin between the claws. It occurs mainly in warm wet weather when the grass is long. The bacteria responsible Fusobacterium necrophorum is universally present in the soil and causes intense itching and severe lameness.

Foot rot is more serious, it often starts in the same way as Scald but another bacterium, Dichelobacter nodosus takes over invading the foot and causing the different layers of the hoof to separate and split. This bacterium cannot live in the soil for more than three weeks, it needs an infected foot to survive. Foot rot can spread in buildings during the winter housing period as long as the temperature is above ten degrees centigrade. We have had mild winters in recent years and it is quite common for these condition to occur throughout the winter.

Recently a more aggressive type of Foot Rot has been identified. This condition will often affect both claws and the whole horn may become detached. It is unclear as to the exact cause of this new problem, it is thought that the spirochete that is responsible for Dermatitis in cattle may be involved, certainly it responds to the same treatments. This New Virulent foot rot will cause a great deal of damage to the feet.

You should turn your sheep over regularly and trim away any excess dead horn, as this is where the infection lies. Take care not to over trim the toes, they should not bleed. Zinc sulphate is the best thing to use in a footbath. If possible the ewes should stand in it for fifteen minutes, then stand on concrete to allow their feet to dry. Divide the flock into groups and give the worst affected animals the most time in the footbath. If you have alot of lameness you will need to do this every week.

If they are very lame or more than one foot is affected an injection of either long acting oxytetracycline or penicillin and streptomycin will be required. When things are getting out of control try the antibiotic Lincospectin in the footbath, this does not have a product license of sheep, but it does a good job. There will be some animals that you cannot get right whatever you do and these should be culled, as they are a source of infection for the others.

You may need to use the footbath on a weekly basis. It is helpful if you can rest pastures for three weeks before ewes return to them, as this will reduce the amount of infection in the soil. Scald is made worse by the length of the grass and electric fences may help to keep the pasture short and reduce the number of cases.

Resistance to Wormers

Some farms are having problems because the commonly used wormers are not working as well as we would expect them to. A recent survey by the Moredun Research Institute has revealed that eight out of ten lowland sheep in Scotland carry worms that are resistant to the white worm drenches (Benzimidazole) It has long been realized that gut worms can also become resistant to Levamasole and occasionally Ivomectin as well. It is the worms that cause problems to ewes later in the summer that are the ones that become resistant. When you worm the flock and turn them onto a relatively clean pasture, it is only the resistant worms that survive and go onto contaminate the ground.

It has been shown that an untreated lamb will pass 74 million worm eggs onto a pasture in the course of a year. That could be 74 resistant worm eggs if you are using a wormer that is not working. Wormers will not work if you are under dosing.

Always weigh the five heaviest animals in the group and adjust the dosing gun according to their average weight not the average weight of the group.

Next take the barrel out of a 20ml syringe, put your finger over the end and squirt in the calculated dose. Is your dosing gun working as accurately as it says it is? If not make the necessary adjustments or replace it.

All of the studies on worm resistance have been done on the original licensed product and not a generic copy of the drugs. Modern wormers are sophisticated chemicals different manufacturers combine them with different carriers and they do not always behave in the same way under farm conditions. If you suspect that your wormer is not working as well as it should you should return to the original licensed product from the manufacturer that did all of the research into the product and not a cheaper alternative.

It is better if you can rotate the three different types of wormer each year for use on the adult sheep from July onwards. It is nematodirus that will cause lambs to scour when they first start to graze. Fortunately nematodirus has not become resistant to the white wormers Benzimidazole this can be used for the first worming dose for the lambs until July.

Worm any new arrivals, but do not turn them out onto clean pastures if you can avoid it. Best practice is to use a macrocyclic lactone (ivomec) type drug and levamisole. Do not mix the two drugs in the same dosing gun you will need to dose each animal twice. If possible keep the ewes on the yard for 48 hrs after dosing so that they can shed all of the eggs they are carrying away from your pastures.

If they do carry any resistant worms after you have dosed them it is better that they are exposed to some treatable worms so that there will be competition in the gut of the animals with worms that you know will respond to treatments. Turn them out onto a contaminated pasture, if there are any resistant worm eggs present it is better that they are only a small proportion of the eggs on the pasture and not the only ones present.

To find out if your wormer is working collect samples from ten ewes two weeks after a worm treatment. We will pool them together and find out if they still have a significant number of worms present in their gut.

There is more information about resistant worms on the National Sheep Association Site.

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Worming Strategies.

There are several things to consider when devising a worming strategy for your farm. It has been found that most farms can reduce their worming costs by one third and not see any reduction in lamb performance. 98% of the worms on your farm are on the pasture not in your sheep. There is a constant battle going on between the worms newly ingested by your sheep and their immune system. Well fed sheep are resistant to worms, moderate worm burdens will not affect the way that they grow.

The trick is to be aware of the likely worm status of your pastures. This will be affected by the stocking density of the flock and whether you are able to offer supplementary feed to boost the immune system of your animals. Is there any clean grazing available? Can you clean up some of your pastures with the help of older cattle that will be immune to most of the parasites? Also make efforts not to introduce resistant worms when you buy in replacement stock as this just complicate things for future years.

Nenatodirus can rapidly overwhelm the immune system of lambs. You will need to dose against this every three weeks when lambs first go out to grass if they are grazing pastures where there were lambs last year.

Single lambs that are doing well and are growing rapidly will continue to grow and will not need to be dosed as often as twins and triplets that have had a later start.

The flock will not take in so many worm larvae in dry summers when the grass is dry and larvae migrate down into the ground. They will pick up more worms in wet summers and when it rains in the autumn.

Well fed ewes with single lambs will not need to be wormed at lambing time. Save the drench for ewes that have doubles and triplets and any that are in poor condition.

There is little evidence to support dosing ewes at tupping time unless they are in poor bodily condition. If in doubt collect samples from ten average ewes and have a pooled worm count done.

Don't forget about fluke. Fluke will complicate things and make any worm problem worse. Treat in December or January to control this problem.

Wormers are expensive not just the cost of the drug but the time it takes to gather the sheep and dose the flock and return them to pasture once more. Some lowland farms have found that they have been able to reduce the number of worm dose in a year from five to three or less with only a 1.5% reduction in growth rate of their lambs. This has resulted in a significant cost saving.

There is more detailed guidance about worming strategies on the DEFRA web site.

Liver Fluke

Fasciola hepatica is a leafed shaped flat worm up to 5 cm in length that lives in the bile ducts of sheep and cattle. It can cause considerable often irreversible damage to the liver. Live fluke have a complicated two stage life cycle involving a snail as an intermediate host in which the larval stages develop and multiply. This is affected by climatic conditions so infection rates vary from year to year. There is mounting evidence that the incidence of disease caused by this parasite is on the increase in the United Kingdom, that is certainly the impression we get in Shropshire.

Each adult fluke can shed up to 50,000 eggs a day. Some chronically infected animals may harbor several hundred adults so the potential for pasture contamination is enormous. When the field temperature is above 10ºC a larval stage called a miracidium will develop in the egg after two to three weeks. After hatching these swim free and have enough energy to remain active for three hours in which time they will try to locate the small mud snail, Galba truncatula which is the intermediate host. After successfully penetrating the snail the larva emerges eight weeks later as the infectious stage called a cercaria. Each miracidium will emerge from the snail as several hundred, possibly as many as a thousand cercaria. The cercaria can swim at first and move up the stems of grass and vegetation to form a metacercarial cyst which will eventually be eaten by the final host. Metacercaria have been known to survive on pasture for up to a year.

Metacercaria only hatch when they detect the acid conditions which are found within the stomach. The juvenile fluke that are released penetrate through the gut wall into the abdominal cavity until they locate the liver. It is now that they damage the host as they penetrate the tissues of the liver. It will be another ten weeks before they mature in the bile ducts as egg laying adults.

Free ranging pigs also ingest fluke metacercaria, but the developing adults are not able to penetrate the tissue of the liver and remain trapped on the surface of the organ.

Acute Liver Fluke Disease

This is the form of fluke we see in sheep that have taken in large numbers of infective metacercaria in the autumn and early winter. The liver does have a capacity to repair itself but cannot cope when numerous juvenile fluke penetrate the organ at the same time. Sheep that die of acute fluke are often in good body condition and will not have any fluke eggs in their droppings.

Chronic Liver Fluke Disease.

This is the most wide spread and common form of the disease seen in both cattle and sheep. It is usually recognized in late winter and in the spring. Affected animals will loose condition and become anaemic. They may develop a swelling under the jaw which is characteristic of the condition. Cattle have large livers and can cope with a moderate fluke infection as long as they are well nourished. These are the animals that contaminate pastures and pass the infection on to your sheep.

Treatment and Control

Liver Fluke is a disease that has been around for a long time and there are at least eight different compounds that can be used to treat affected animals. Most will need to be given as a drench, but there are injectable treatments for both sheep and cattle and a new pour on treatment for cattle. At the moment there are no drugs that can be used on cows producing milk for human consumption. Most of the drugs are only active against the adult fluke in the bile ducts. Drugs that contain Triclabendazole are the most useful as this compound can kill immature fluke as young as two days of age before they have been able to cause too much damage to the liver of the host. In an acute outbreak the dose will need to be repeated every three weeks and if possible the flock will benefit from a move to drier pastures. If you have chronic fluke on your farm you should treat all of the sheep in October and again in January with Triclabendazole. It is the cattle that keep the infestations going so they will need to be treated in January as well when you can use either an injection or the pour on product as it is not easy to drench adult cattle safely.

Grazing Management and Drainage

On some farms it may be possible to drain wet areas or fence them off so they are not grazed in the spring and early summer. Often this is not possible and many environmental schemes encourage the development of ponds and wet areas to encourage wild life and different habitats. In out area wet summers occur more often than not so we have become more dependant on drugs to stop losses from Liver Fluke disease.

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Problems with Copper

Copper is essential for the health and well being of ewes and lambs, the problem is it can be toxic if too much is included in the diet so care must be taken to maintain the right balance.

Toxicity problems are most common towards the end of the winter when the ewes are housed. Texels, Charolais and Blue Faced Leicesters are the breeds that we have had problems with but toxicity can occur in any breed. Ewes should not be fed on a diet containing more than 10 part per million of available copper. Affected animals are depressed become anemic and are noticeable jaundiced. By the time you realize that there is anything wrong the liver of the ewe will be severely damaged and there is no effective treatment. You should not normally need to worry about swayback in pedigree sheep that are having supplementary feed on a regular basis. The only safe way to find out if you need  to give extra copper is to have some blood samples taken during the second month of pregnancy. Never feed a ration intended for cattle or pigs to your ewes, they cannot cope with this.

Shortages of copper are seen mainly in hill flocks. Scottish Blackface ewes and their crosses are the most at risk. The coating of the nerves develops in the second half of pregnancy and can only occur properly if there is an adequate amount of copper in the blood stream. Affected lambs may be born weakened or have difficulties controlling their rear end. Less affected lambs may not show signs until they are several months of age. Again there is no effective treatment for swayback, it is difficult to rear individuals that have been even  mildly affected. Preventative measures should be taken between the tenth and sixteenth week of pregnancy. The ewes are either injected or a soluble glass bolus is given to each ewe to provide the copper during the critical period. 

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Flock Health Plan

It is difficult to give concise information as to what you should be doing and when with your flock. Things will vary depending on whether you have a lowland or an upland flock and whether or not you are interested in lambing early. The way that you manage your ewes will also depend on your individual circumstances. With sheep there is always something that you should be doing to them throughout the year. It is easy to leave something out or do things at the wrong time. 

All flocks in the United Kingdom are now supposed to have a written health plan. You should be able to adapt your plan from the following which is based on a lowland flock that is trying for early lamb production. Try saving this guide on a disc, delete the parts that do not apply and add other things that you do and I have left out. Your Veterinary surgeon will be keen to see a printed version of your health plan and may suggest further things that you could do or leave out. Each year you might like to take a few minutes to edit your version and keep it up to date.

 

We will start when the lambs are weaned.

The udders of all of the ewes should be checked and one dry cow tube, Cepravin works best, should be used in the glands of each ewe that you intend to breed from next year. Chronic infections are not easy to detect and will flare up when the ewe has stopped producing milk.

In the early spring if the ewes are outside they should be wormed at least twice with a three week gap between doses.

The lambs should be wormed every three weeks and they should be on a creep feed containing a coccydiostat. An alternative is to drench them with Vecoxan from six weeks of age, repeating the dose three weeks later if they are tightly stocked or if the weather is wet.

When the youngest lambs are eight weeks of age vaccinate them with Heptavac P Plus. Repeat the dose four weeks later.

The ewes and rams should be sheared before the weather gets too hot and there is an increased risk from fly strike.

If you do not dip in the summer you should use a pour on insecticide every six to eight weeks to prevent blow Fly Strike and ticks.

Fifty days before expected breeding date implant ewes with Regulin at the base of one ear to encourage early breeding. Ensure ewes have a condition score of three to three and a half.

One month before breeding vaccinate replacement ewes against Enzootic Abortion taking care when you handle this live vaccine. Flocks that are affected by Toxoplasmosis should be vaccinated in a similar way at this time.

Check Rams, paying particular attention to their feet and check their testicles to make sure that they are equal in size and that there are no abnormal swellings. It is often Rams that bring Caseous Lymphadenitis into a flock. Be suspicious of any small swellings on their head and neck and have them properly investigated. 

Sixteen days before breeding. Insert progesterone sponges.

Two days before breeding. Remove sponges carefully (arrange for the spent sponges to be burnt) Inject PMSG to encourage ewes to ovulate Move flock onto small field with fresh grass and introduce vasectomised ram.

After forty-eight hours replace vasectomised ram with fertile rams, use one ram for every ten ewes if you can.

If you are not going for very early lambing a vasectomised ram can be used for two weeks before the planned mating time to get the flock cycling and compress the lambing period.

Change the raddle on the rams every three weeks.

Eighty to one hundred days after the first breeding have the flock scanned.

Consider blood testing a representative sample of the barren ewes to see if they have titres to Toxoplasma.

Continue to worm the lambs every three weeks into the autumn. Worm the ewes and rams late in the autumn before housing, use a combined fluke drench at this time if this is a problem on your farm.

If you are troubled by scab dip the whole flock in the autumn. If you have a small flock you might be able to control this problem by injecting one of the wormers. Remember the whole flock must be done and they must have an adequate dose so weigh some of the ewes first. It is sometimes better to wait until all of the lambs have been sold before these products are used because of the long meat withholding times.

Ten weeks before lambing dose the pregnant ewes with copper to prevent swayback in the lambs. It is hill farms that have particular trouble with copper, blood test should be done if you are unsure as to whether you have a problem.

Eight weeks before lambing vaccinate the whole flock against orf. It is not necessary to do this if you do not see this disease in the lambs each year. This is a live vaccine and should not be used in flocks that do not have orf.

Eight weeks before lambing vaccinate any newly purchased ewes with Heptavac P Plus to ensure that they have both parts of the course.

Save the concentrate ration for the ewes that are carrying twins and triplets. Introduce it six weeks prior to lambing and gradually increase the amount fed until the first lambs arrive.

Four weeks before lambing Vaccinate all of the ewes with Heptavac P Plus, the timing of this helps to protect the lambs when they are first born.

Two weeks before lambing watch out for shy feeders and ewes with the early signs of twin lamb disease. Drench any animals that you suspect may be affected before the viability of their lambs is put at risk.

Lambing time. This is always hectic and easier to cope with if the weather is dry even when you have good housing. Try to use as much clean straw as possible in the lambing pens to keep the ewes clean. Ewes are very susceptible to infections and every ewe that you have helped to lamb should be given an antibiotic injection.

Dose all newly born lambs with antibiotics to prevent watery mouth and joint infections. Probiotics are used on some farms when the lambs are first born, these always seen to make the lambs want to suck more vigorously.

If you have problems with white muscle disease dose lambs with a Vitamin E Selenium injection before they leave the lambing pens.

If you get particular problems with Orf in growing lambs they should be vaccinated with the live vaccine as they do not gain any immunity to this disease from suckling colostrum. The dose can be given from birth, but it is usually better to get a group of sixty to seventy lambs and vaccinate them from the one dispenser all at the same time. Remember to keep these animals away from lambs that have not been vaccinated as they can pass the infection on from the scratch sites.

Start to feed a coccidiostat to the lambs. Watch out for the early signs of mastitis in the ewes, check any animals that are reluctant to allow their lambs to suck.

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