Health

THE SOUTHDOWN SHEEP SOCIETY

Index

Customer Support Group 01908 685685; website: www.intervet.co.uk

Barrenness, Abortion, Weak & Sickly Lambs

The main causes of all these problems are infections such as Toxoplasmosis and Enzootic abortion. Intervet is launching a new diagnostic service designed to help improve the management of pregnant ewes and reduce lambing losses.

"Barren Ewe Check" tests for toxoplasmosis during mid-pregnancy, typically at the time of ultrasound scanning. "FlockCheck" examines the causes of barrenness or abortions after the lambing period. Results of the FlockCheck service over the past five years have shown that toxoplasmosis is present in a large proportion of flocks across the U.K.

The "Barren Ewe Check" and "FlockCheck" will be available to vets from early 2007. Barren Ewe Check will run from January to April, and FlockCheck from March to the end of July. Contact your veterinary surgeon for details of either service and see the links below for more information from the Intervet website.

http://www.intervet.co.uk/species_pages/sheep/news.asp - for articles such as Pregnant ewe diagnostic service launched [Adobe Reader required]

http://www.intervet.co.uk/Species_Pages/Sheep/Literature.asp - for .pdf files (Adobe Reader required) such as The Flockmaster's Guide to Abortion & Vaccination and

http://www.intervet.co.uk/binaries/92_56639.pdf - for the Enzovax and Toxovax Leaflet [Adobe Reader required]

*Adobe Reader can be downloaded free from http://adobe-reader.download-click.at/uk/

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Polioencephalomalacia (CCN)

Early signs are blindness, isolation from the rest of the flock and aimless wandering. As the disease progresses over a period of 12 - 24 hours, sheep become recumbent and periodically flex their neck backwards and 'stargaze'. Untreated animals die within a few days.
Symptoms are caused by brain damage resulting from an induced deficiency of vitamin B1 (thiamine). Overgrowth of thiamine destroying bacteria in the rumen, which can occur following a change of diet, destroys the vitamin B1.
Most cases occur about 2 weeks after movement to lush pasture or other dietary change such as overnight yarding before anthelmintic drenching.
The disease occurs in both ewes and weaned lambs, but is uncommon in lambs under 12 weeks old.
If treated promptly response to intravenous injections of vitamin B1 and soluble corticosteroids is good. Further twice daily intramuscular injections of vitamin B1 for three days are usually required.
In many cases sheep are able to stand and eat within 24 hours but sheep which don't respond within 2 days should be euthanased.
Your vet can advise you about the treatment of CCN in your flock.

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Footrot Eradication

Various methods can be employed for the control of footrot, including foot bathing, trimming, antibiotic injections, vaccination, selection for resistance and eradication. In practice, footrot control is based on a combination of the above.

D. nodosus, the causative bacterium of footrot, only survives in diseased feet and will only live in the soil for a maximum of four days. It is, therefore, possible to eradicate footrot from affected flocks.
Eradication of footrot involves a combination of regular examination and separation of affected from non-affected animals, footbathing and strict culling of persistently affected sheep.

However, there are several pitfalls, and attempts to eradicate the disease are frequently unsuccessful:-

Eradication should only be attempted during dry weather conditions when transmission of D. nodosus is slow and sheep are unlikely to be in the early stages of the infection. Unfortunately, identification of such slow transmission periods is difficult in many parts of the UK.
Replacement animals should be quarantined for at least one month, during which time they should be inspected. However, despite treatment of any infected animals, it may be impossible to prevent the re-introduction of the disease.
Stray sheep from neighbouring flocks are another common cause of re-infection.
The organism can also be carried in the feet of goats. Some goat strains of D. nodosus are particularly virulent for sheep, so goats should be included in any eradication scheme.
The cost of eradication can be considerable when compared with the cost of management of endemic footrot in the flock. Eradication is, therefore, only suitable for closed flocks in drier parts of the UK.

Copyright © NADIS 2005
www.nadis.org.uk. NADIS is sponsored by
Meat and Livestock Commission, Elanco
Animal Health and Intervet
SUPPORTING BRITISH LIVESTOCK

By kind permission of the NSA Sheep Farmer, September/October, 2005

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Foot Control Checklist

While footrot remains the most common cause of lameness in a flock, there are other causes of lameness. Seek veterinary advice and ensure you have an accurate diagnosis of footrot, scald or CODD before commencing any treatment or control programme.
Footrot is a WHOLE flock problem and the aim should be to continually control its spread within the flock.
Employ control measures (regular foot bathing with 3% formalin or 10% zinc sulphate) where the level of footrot is low (<5%). If the level of footrot is greater, implement additional control measures.
Where foot bathing with 3% formalin is practised, footbaths must be sufficiently long so that all four feet have a chance to come into contact with the chemical. With 10% zinc sulphate, sheep must stand in the bath (follow manufacturers' guidelines on standing time). Provide a clean standing area after foot bathing and hold sheep until their feet are dry.
Vaccinate with Footvax before the peak risk period.
Treat any lame sheep (antibiotics and vaccinate) to cure the problem, but accept that some will be incurable and must be culled.
Foot paring is a useful aid to diagnosis, but is not a cure for footrot. It should only be used sparingly to maintain the integrity of the foot and must never be so drastic that it draws blood.
Check, treat and segregate any bought-in sheep.

Thanks to NSA Sheep Farmer, September/October 2005

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The Welfare of Sheep

Legislation/ Welfare Code/ Enforcement/ Advice for farmers

Page on the Defra website

Sheep & Goat Identification and Tracing

The European Commission has adopted Regulation 21/2004 which requires all sheep & goats born after 9 July to be double-tagged. The rules however allow a Member State to continue using their current system of identification if it provides traceability (the ability to determine where an animal has been in the past & what animals it has come into contact with) between holdings.

We believe that our existing system provides the necessary traceability required and have applied to the Commission to keep it in place. If we are successful in our application we will be able to continue using our existing identification system until 2008. More information is available on our EU Double-Tagging Exemption Application page.

Our application depends on our being able to prove that our system is effective and safe, so it is important for farmers to be aware of the latest requirements and how to implement them. Please take a few moments to read though our latest brochure which explains the rules for tagging sheep using plain English.

Are your animals properly identified? (86 KB) - 3 page leaflet.*
A ‘Are your animals properly identified?’ poster (101 KB) is also available. *
The Interim Flock Record (140 KB) is available, along with other movement documents. *
More information on their regulations is available on the European Commission site on the Identification of Ovine and Caprine Animals (sheep and goats).*

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Identification of Ovine and Caprine Animals (sheep and goats)

The basic objectives for Community rules on the identification of sheep and goats are:

the localisation and tracing of animals for veterinary purposes, which is of crucial importance for the control of infectious diseases; and
the management and supervision of livestock premiums as part of the reform of the common agricultural policy.

The current system for identification and registration of sheep and goats includes identification with an eartag or a tattoo at the latest before the animal leaves the holding, a register on each holding and a central register of all holdings.

The reinforced system for the identification and registration of sheep and goats, which was adopted in December 2003 and shall enter into force in July 2005 includes the following elements:

double identification before six months of age - two eartags or one eartag and a tattoo, mark on the pastern (for goats only) or electronic identifiers;
a movement document for each movement of groups of animals;
maintaining an up-to-date register on each holding;
a central register of all holdings or computer database at national level.

Legislation Council Directive 92/102/EEC Council Regulation (EC) 21/2004

From Europa - Animal Health and Welfare
http://europa.eu.int/comm/food/animal/identification/ovine/index_en.htm

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Animal Health

Defra has a website on animal health and welfare and veterinary surveillance in the U.K., where you can find out details about animal diseases, etc. This webpage can be found here.

And for the Defra Rabies Contingency Plan, click here

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Nematodirosis in Sheep

Nematodirosis is an important disease affecting young lambs managed on pasture grazed by young lambs the previous year. Nadis Sheep Bulletin, March 2007. More[Adobe Reader is required]

Nematodirosis is usually seen in young lambs and is characterised by acute onset profuse watery diarrhoea, lethargy, abdominal pain, rapid weight loss, dehydration and sudden deaths. Nadis Sheep Bulletin, April 2006. More

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Listeriosis and Laryngeal Chondritis in Sheep

For Nadis sheep articles on Listeriosis in Sheep click here and Laryngeal Chondritis in a Suffolk ram click here

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Feeding Lambs on Rape and Kale

NADIS Sheep Disease Focus Report

Rape and Kale are often used to effectively feed lambs over winter but they can lead to a number of specific diseaes in lambs.
More

[This can be printed off from .pdf format, which requires Adobe Reader to read it. Adobe Reader can be downloaded for free from http://www.adobe.com/products/acrobat/readstep2.html]

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Louping-ill in Sheep

By Dr. Hugh Reid (Moredun)

Louping-ill is a virus disease affecting sheep and most other domestic animals as well as man and red grouse. Because it is transmitted by biting ticks the disease is only seen on pastures where ticks are present and at times of the year when ticks are active. The outcome of infection in sheep is however unpredictable; in some infected flocks no clinical disease is observed while in others severe clinical disease and death is frequently seen. However, most wild grouse that become infected die and thus in some areas the purpose of control of louping-ill is to reduce grouse mortality to enhance the economic return from sporting activities.

An understanding of this disease requires knowledge both of the tick and how the virus infects both the tick and the animal host. The sheep tick has four stages egg - larvae - nymph - adult. After hatching the larvae actively seek a blood meal by climbing up grass stems etc and attaching to any passing animal or bird. They stick their mouth parts through the skin and feed for only 2-3 days. They then fall back into the vegetation and moult into nymphs which will not feed until the following year. After feeding nymphs moult into adults which feed the following year giving rise to the egg masses from which the next generation of larvae emerge. This whole process thus takes at least three years with only about 20 days being spent feeding. Critical to survival of the tick off the host is a moist habitat in a mat of decaying vegetation. Thus ticks tend to be found only on rough upland pasture and will not survive on well drained improved pasture.

Ticks feeding on animals with high levels of virus in their blood take in virus which can then be transmitted to other hosts when the tick next feeds after moulting. Thus it is only nymphal and adult stages of tick that can transmit virus as larvae emerging from eggs do not carry virus.

When a sheep becomes infected virus enters the blood stream reaching high levels which ensure that virus can infect other ticks feeding at that time as well as allowing it to enter the brain. It is not until the virus has multiplied in the brain some 6 to 10 days after infection that some sheep will show clinical signs including nervousness, difficulty in walking, paralysis, coma and in some death. Between 5% and 60% of infected sheep may develop clinical signs, but it is not clear why the outcome of infection is so variable. Certainly stress such as gathering and severe weather can increase the probability that disease develops and concurrent infection with tick-borne-fever greatly increases the severity of the disease. Particularly severe outbreaks may occur when susceptible sheep are first put onto a tick infested pasture or where louping-ill is introduced to a ticky pasture for the first time.

Animals that survive infection develop high levels of antibodies in their blood which provide solid protection for the rest of their lives. In addition such protection is passed on very efficiently in colostrum ensuring lambs can be solidly protected for the first 6 to 8 weeks of life.

Although all ages of sheep are susceptible, it is mainly lambs (not protected by colostrum) and yearlings, retained for breeding that become clinically affected. When disease is suspected, veterinary advice should be sought to confirm the diagnosis.

When losses are confirmed, vaccination should be considered. Though the vaccine is expensive it is highly effective and will provide good protection for at least two years. Repeat vaccination will give life-long protection and help to boost levels of protection in the colostrum. Normally it will only be the ewe lambs retained for breeding that will be vaccinated although whole flock vaccination should be considered when the disease occurs for the first time or when un-acclimatised sheep are introduced to an infected area.

Where total control of the disease is desired to reduce the impact of louping-ill and other tick-borne diseases of livestock (or to improve grouse stocks) it may be necessary to undertake a comprehensive control programme. This will involve determining the level of infection in areas by looking for antibodies in blood samples and embarking on an intensive programme to reduce tick numbers with the use of dips and pour-ons as well as vaccination. In addition it may be necessary to control access to wild species such as hares and deer which may host large numbers of ticks. Such programmes should, however, only be contemplated where the co-operation of farmers and shooting interests can be ensured across a defined area of ground bounded by natural barriers. Otherwise the investment is likely to have limited success and re-emergence of infection is very probable.

Finally although most cases of louping-ill are seen in animals, severe and very rarely, fatal disease can occur when humans become infected. Care should be taken when handling suspect clinical cases or carcases and ticks that attach should be removed from the person rapidly to reduce the chances of the tick injecting virus.

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Dr. Hugh Reid is a research fellow of the Moredun Foundation.
Moredun runs a membership scheme which aims to keep farmers
and their vets up to date with the latest developments in animal
health research. If you would like a free copy of an eight page
technical newssheet on louping ill or are interested in becoming
a member of Moredun, please contact Margaret Bennett at
The Moredun Foundation, Pentlands Science Park,
Bush Loan, Penicuik, EH26 0PZ or phone 0131 445 5111 or
log on to their website www.moredun-foundation.org.uk

By kind permission of NSA Sheep Farmer
November/December, 2004

Maedi Visna

In 1996/1997 three of the 217 flocks tested gave a positive result and 1.1% of qualifying flocks had MV positive sheep.

In 2002/20203 six flocks out of the 282 flocks tested were positive and 2.1% of qualifying flocks had MC positive sheep.

The Maedi Visna Accreditation Scheme provides the data and SAC which runs the scheme found that twice as many as many of the flocks tested positive in 2002//2003 than in 1996/1997.

There is no doubt that without the scheme MV would be much higher. The Goat and Health Scheme is offering free MV tests for commercial sheep.

SAC via the Farmers Weekly ( with permission )

For more details on the disease and on the Maedi Visna Accreditation Scheme, click here

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Keeping Sheep Clean

Dr Jenny Anderson, Sheep Scientist, Meat and Livestock Commission

The Pennington report recommends that farmers should be "fully aware of their responsibility to send animals to slaughter in a clean condition. This obligation lies with them and not slaughterhouses or the inspection services". It is therefore essential that farmers should be prepared to offer guarantees that they are willing to accept responsibility for their function within the food chain.

We are reaching times when the public are having a greater effect on animal production than ever before. With this increased consumer awareness of bacterial contamination of meat, the delivery of dirty sheep to abattoirs creates many problems within the sheep meat industry. These problems range from increased costs from returned animals and decreased line speed, to lowered quality end products. There is more chance of injury to the slaughter men via knife slippage while dressing heavily dagged (clagged) carcases. Heavily contaminated fleeces have a lowered commercial value to the by-products industry. Additional carcase trimming may be required to remove contamination from the carcase, leading to a decrease in deadweight. This becomes more significant when large batches from a single supplier are slaughtered. Contamination of the carcase also leads to a decrease in the shelf life of the product, through factors including increased microbial counts. Therefore, an inferior product is produced and there is also an increased chance of food poisoning; poor product perception has a detrimental effect on the whole meat industry.

Why should the fleece be clean?
A dirty coat has the capacity to contaminate a clean carcase during dressing. This capacity increases if the fleece is wet, because water provides a ready means of transport for microbes to spread from one area to another. Research conducted in UK and NZ has shown a direct relationship between the visible contamination of the coat and the microbial status of the finished carcase.

How can dirty fleeces be avoided?
It is unfortunate that few farming practices are totally clean. Animals, housed indoors become contaminated with faeces and bedding, while sheep kept outdoors are at the mercy of the weather and soil contamination. Often there is only a short space of time between the time when the sheep are taken from the field and sent to the abattoir. Some foodstuffs lead to greater contamination than others.

Keep sheep off land that can cause gross contamination, especially fields of roots or poached land.

Use good husbandry practices i.e. worming, clean grazing, correct stocking densities, and clean housing.

Feedstuffs should be carefully monitored. Silage, new grass, roots and brassicas can result in a greater amount of contamination. Changes of modifications should be carefully made to diets. It may be feasible to modify the diet before slaughter to decrease the amounts of contamination, however care should be taken that this does not affect the animals’ well being.

Consider housing or yarding animals through the winter. Housing should be well ventilated and maintained, bedded and cleaned to prevent accumulation of dirt, faeces and fluid. An appropriate stocking density should be allowed.

House animals for a period before sending them for slaughter.

Dagg fleeces before housing or before sending for slaughter. The essential areas are bellies, legs, tail and crutch area. Indeed some abattoirs are now insisting on lambs having their stomachs sheared before slaughter. This enables wet sheep to dry quicker and helps stop contamination of the carcase during pelting.

A fleece that is wet, but also clean, does not necessarily mean the animal is unacceptable for slaughter.

What happens to dirty sheep?
Animals that arrive at the abattoir in an unsatisfactory condition should be detained in suitable conditions until the Official Veterinary Surgeon regards them as hygienically fit for slaughter. In some cases the animals may be returned to source and subsequently have to be re-transported and re-presented for slaughter. Some abattoirs have facilities for remedial action such as clipping if suitable equipment is available. This means a lower price to the farmer, as a deduction will be made for cleaning up the lamb. Washing of animals is not normal practice in GB. It may, under some circumstances be beneficial to wash animals, but only if they are washed and dried before slaughter.

It must be remembered it is not the responsibility of the abattoir to remedy the problem of dirty sheep, but more advantageous to prevent the supply of dirty sheep in the first instance.

The latest in the MLC Sheep Management Series "Keeping Sheep Clean" is available free from Lindsay Tapp on 01908-844271.

Taken from the MLC web site at http://store.mlc.org.uk/index.asp?50572

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