Winter is only just around the corner!!!!! - Westpoint Veterinary Group

Westpoint Veterinary GroupAutumn 2011Winter is only just around the corner!!!!!In this copy of Sheep Newes we will be looking at issuesthat could affect your flock over the coming autumn andwinter months. Abortion, Scab, Maedi Visna and Nutritionare all covered in detail, we hope you find this newsletteruseful.Sheep abortionSheep abortion can present as all or one of the following:A high number of barren ewes at scanning(more than 2.5% of those put to the tup)Losses in the weeks running up to lambing(more than 2% of those put to the tup)Still born/ mummified/ rotten lambings/ weaksickly non viable lambs(more than 5% of lambs born)If you think this is affecting your breeding season then callyour local vet for more advice and investigation.The 5 main points to remember when dealing with abortingsheep are:1. ISOLATE2. COLLECT all the abortion material (remembermany agents can cause illness in humans)3. TREAT any sick ewes (and the rest of the flock?)4. TEST to identify the agent involved5. CULL (identify all aborting sheep permanentlyat the time)Aborted lambISOLATEMost abortion agents are infectious to other sheep at thetime of abortion, with the exception of Toxoplasmosis. BUTas we don’t know the cause at the time all aborting sheepshould be isolated.Remember some of the agents can be present on thepasture and in bedding material for months after the sheephave gone. Isolation should be in an area that can becleaned and disinfected easily or a pasture that won’t begrazed by susceptible sheep this season i.e. ewe lambs!COLLECT ABORTION MATERIALAs soon as any abortion is noticed,collect all the afterbirth and deadlambs in a suitable container toprevent leaking. This sample canthen be frozen or at least kept coolfor the next few days. If there areany more abortions, all thesamples can be sent to the localVLA for post mortem.Very rotten samples are notsuitable, they won’t produceworthwhile results but you will still be billed.Toxoplasma gondiiAny abortion material not sent for sampling should bedisposed of through your normal dead stock collection.As well as breaching animal welfare codes leaving carcassesaround for wild life to feed on will just aid in the spread ofdiseases. Toxoplasmosis, for instance, will circulate inwildlife reservoirs.Most farmers know about the risks to pregnant womenaround aborting sheep but some of the bacteria causingabortion can cause disease in all humans. Campylobacter isthe 3rd biggest cause of abortion in sheep in the UK and isalso a “food poisoning” agent, as are salmonella and listeria.Always wear gloves and protective clothing when handlingabortion material and keep up good personal hygiene. Dowash your hands before tucking into your sarnies. The lastthing you want at lambing time is a dose of diarrhoea!Remember to inform all your staff about these risks as manyare young people wanting to gain experience or non farmingfamily members.

Sheep Abortion CONT...TREATOnce the sheep is isolated it should be treated if it is sick;campylobacter, salmonella and listeriosis will make ewes ill.Antibiotics and anti-inflammatory injections should begiven, consult your vet as to the most suitable for theclinical signs. Keep the ewe hydrated by drenching, addpro-rumen and propylene glycol to warm water, as mostewes won’t eat and drink when sick and it is oftendehydration related problems that can cause death.Discuss with your vet the pros and cons of treating the restof the flock. Some of the abortion agents will respond torelatively inexpensive drug treatment and may preventfurther abortions, especially if you have a protractedlambing period.However, many of the agents responsible will have alreadycaused the abortion so treatment at the time will havelimted effect: post-mortem or blood results will obviouslyhelp you make this decision.CULLAll aborting sheep should be permanently identified as such.She should not be used as a foster mother, as Chlamydiaespecially is known to be passed on through vaginaldischarge after lambing. If you want to keep the ewe to rearorphans, only adopt if lambs are destined for killing and cullher out at weaning.Some abortion agents the ewe can recover from, such ascampylobacter and gain immunity for the following year.But the commonest agent responsible for 50% of sheepabortion in the UK is contagious all year round.TESTIt is worth remembering that 2% of your flock can abortthrough “natural causes”, but no one knows at the start ofan abortion “storm” how many will abort. The moresamples you send to the VLA, the more likely you are to geta definitive answer as to the cause.If the first sign of a problem is a high number of barren ewesat scanning, or retrospectively you think a high number oflambs were lost from scanning to turn out, samples can betaken from a number of ewes, to identify an immuneresponse to the two commonest abortion agents. This againwill help make decisions on next year’s management.Chlamydia can be passed on through abortion material toother sheep at lambing time. Some ewes will become“carriers” intermittently shedding the organism in faeceswhich can then spread to other sheep throughout the year.It is thought that these carrier sheep could also contaminatelive lambs born to them or those in close contact such asfostered lambs. If these lambs are then kept asreplacements, they will suffer fertility or abortion problems.A sheep can be exposed to the organism at any point in theyear and will then abort at her next pregnancy.Sexually transmitted infection can affect tups. In the initialstages, the infection can be passed on to ewes throughsemen. In the long term it can cause abnormalities in thetesticles.Toxoplasmosis, however, is different. Once a ewe hasaborted it will acquire immunity and will not abort again norspread the infection to other sheep.The agent is carried by cats which ingest the organism frominfected sheep material or infected vermin. The cats excreteit in their faeces and urine which the ewe then ingeststhrough contaminated feed or pasture.Often, despite best efforts, responsible organisms are notidentified, or more than one can be responsible in onelambing season. So unless a clear cause of the abortion isidentified, culling all sheep that abort would be the bestpolicy.

Maedi VisnaMaedi Visna (MV) is a viral disease that affects sheep. Thename is formed from two Icelandic words that describe theclinical signs it produces: Maedi “laboured breathing” (therespiratory form) and Visna “wasting” causing neurologicalsigns (the rarer form). It is similar to HIV in humans as itattacks the immune system. CAE (Caprine Arthritis andEncephalitis) is a related disease affecting goats and there isevidence that cross infection can occur between species.The disease occurs worldwide and first entered the UKabout 20 years ago. It is an important disease both clinicallyand economically, as it is difficult to diagnose, there is nocure and no vaccine. Once the animal shows clinical signs itis invariably fatal. Affected farms have increased cullingrates, increased lamb mortality, reduced growth rates, aswell as increased incidence of arthritis, premature birth andreduction in conception.The disease is spread by inhalation and via colostrum andmilk. MV can infect sheep of any age, but mainly infectslambs and then they are infected for life. However, theymay not show any signs of disease until they are over 3years old. The clinical signs include:-Pneumonia - respiratory distress but no fever,exudate or depressionProgressive hindlimb paralysisNervous signsWastingArthritis/lamenessChronic mastitisDifferent breeds appear to have different susceptibility. Forexample the Texel appears to be more susceptible, whilethe Suffolk is more resistant to the disease.The disease can be tested for via a blood test to look forantibodies, and there is a MV accreditation scheme run bythe SAC (Scottish Agricultural College), which has around3,500 members. A flock can become MV Accredited Freewhen it passes two qualifying blood tests between 6 and 12months apart and has certification from a vet that the farmis complying with the scheme rules and conditions. OnceMV accredited, a proportion of the flock is blood testedevery 2 years and the member is issued with certificates ofstatus for selling or moving scheme sheep. Shows and salesare licensed to provide space for MV accredited sheep. AnMV monitored scheme is available for commercial flockmasters who are unable to totally isolate their flock.The benefits of the scheme are as follows:-Helps reduce the risk of your flock contracting MVGives membership of a nationally recognisedhealth schemeAllows export to certain countries free from MVGives added value to the flockAllows attendance at shows and sales from whichanimals would otherwise be bannedFor more information on MV, sheep or goat accreditationschemes, please contact your vet.Nutritional management of the pregnant eweNutrition of the pregnant ewe is an area that will have significant impact on production and therefore profit, and isdependent on four major factors, three of which can be managed between scanning and lambing time.Body Condition Score (BCS). This is the key to lamb survival and growth rate. We know that multiple bearing ewes that lambwith BCS less than 3 (1-5 scale) will have a lower lamb survival rate and will wean smaller lambs. Identifying low BCSmultiple ewes early gives time to rescue them before lambing. To add a single body condition score requires around 30kg ofdry matter (DM) over and above that required for maintenance and pregnancy. If this is not detected till after scanning thenthey will only have around 50 days meaning they will have to consume around ½ kg DM extra each day, but this requires theextra to be available…. do you know how much you have?Feed intake approaching lambing. Multiple ewes underfed in the last 5-6 weeks of pregnancy will have lower lamb survivaland will wean lighter lambs. This does not mean feeding excess (this can also be detrimental) but rather making sure thatthey hold condition. In grazing terms, if out at pasture, it means not grazing below 1100kg DM/ha; in housed ewes it iseasier to regularly check BCS to assess adequacy of feeding. Making sure adequate feed of good quality is available over thewinter months means pre-planning and if supplements are sourced early can mean savings in feed costs. Knowing if yourewes are single or multiple bearing is important as it will enable you to feed to demand; for example at 20 weeks ofgestation a 50kg ewe bearing twins will require approximately 30% more energy (MJ ME) than her counterpart with only asingle lamb! Adequacy of nutrition during the lead up to lambing will also help to reduce the risk of metabolic diseases,pregnancy toxaemia and will improve colostrum quality/absorption and therefore lamb survival and health.Adequate feed allocation at lambing. Lambing multiple bearing ewes on good pasture/with good feed allowances whenhoused will ensure maximal lactation performance. When housed it is important to make sure access to feed is notrestricted/limited due to space and when at pasture it is making sure grazing above 1200kg DM/ha with appropriatestocking densities. Pasture will need to be assessed for growth rate to ensure it can meet demand and determine if/whensupplements may be called for. The fourth factor is feeding after lambing and making sure it is of good quality and quantityin late lactation; it is vital to ensure adequate protein and energy to ensure good even growth. This will play a large part inweaning weights and therefore profit!

Sheep ScabSheep scab is an allergic dermatitis caused by the mite Psoroptes ovis and Psoroptes cuniculi. Known by several names theproper name is Psoroptic mange. Sheep scab seriously affects the welfare of sheep and has significant financial impactthrough its effect on the condition of ewes, the growth rate of lambs, damage to wool and reduced quality of sheepskins. Scabmites feeding on the skin surface cause intense irritation to the sheep that results in them rubbing and scratching. The diseaseis more common in the winter and spring when the sheep have full fleeces. In the early autumn or early winter, flock ownersshould look to assess their flock’s scab status and treat accordingly. Whenever possible, flock owners should co-ordinate anytreatment or control measures with their neighbours to gain the maximum benefit from their time and effort. This approachhas been employed successfully in Scotland and is promoted by the Scottish Sheep Scab Initiative. When assessing scab statusyou should consider:Is there evidence of scab?Were ALL introduced sheep treated for scab and held inquarantine for three weeks?Are boundaries secure – scab and sheep proof?Are neighbouring flocks infected or at risk of infection?The disease: The mange mites migrate to all parts of the skin. As theyfeed, they puncture the skin to drink the fluid that accumulates. In doingso they cause irritation through bruising, leading to the characteristicitching. The lesions ooze and scabs are formed. Left unchecked the scabscan spread over much of the body and ultimately to the death of thesheep.Transmission: The mites are spread primarily from direct contact from sheep to sheep. Infected premises can also possibly actas mechanisms of transmission as the mites can survive on pieces of wool in the environment.What to look for: In the initial stages of the disease, the lesions formed are very small (less than 6mm) and can be very hardto detect. What you will see are signs of itchiness i.e. biting, scratching and general unrest. If this is noticed it is best toexamine the skin surface in search of scabs. These scabs will usually have a thin yellow crust or will be red and oozing a clearfluid. Sites to look closely at are the ears, base of the horns and around the scrotum and anus in the ram.Sheep scabSheep scab miteTreatment and control: This requires careful planning and afarm strategy including:Environment - premises and fields should be left vacant fortwo weeks following sheep batches. This allows them to beregarded as clean. Any residual mites will have died andcross infection there by prevented.Quarantine and biosecurity - When new animals areintroduced they should be treated before entering the unitor mixing with other sheep.Dipping - sheep need to be immersed in the dip to ensurecomplete coverage. The dip requires careful monitoring fromhealth and safety regulations and to ensure an activeconcentration of the dip!Injection - injections of doramectin (Dectomax at 1ml/33kgonce) or moxidectin (Cydectin at 1ml/50kg twice, 10 daysapart) can be given under the skin. Both are effective atkilling the mites. In severe outbreaks, injections may need tobe repeated in 10 days time.Note: Careful planning following treatment is required. Treated or clean sheep must be put into fresh paddocks or sheds with no chance of contact with dirty animals.WESTPOINT VETERINARY GROUP Ltd.Dawes Farm, Bognor Road, Warnham, West Sussex, RH12 3SHTelephone: 01306 628086 Fax: 01306 628080www.westpointfarmvets.co.uk