3BackgroundIn the UK, the Animal Health & Veterinary Laboratories Agency (AHVLA) provides:Disease surveillanceDiagnostic serviceCurrently this situation is being reviewed by consultation with the aim ofImproving surveillanceReducing government budgetsHow can industry benefit more from disease surveillance and diagnosis?
4Fallen Stock Do these carcases have diagnostic value? In UK all fallen stock must be collected by a licensed collector and disposed of according to Animal-By-Products legislation.Carcases are taken to a central location (cost met by farmer)Do these carcases have diagnostic value?
5Aims of ProjectEstablish the diagnostic potential of material collected by fallen stock collectorsIdentify risks and constraints, such as autolysis and cross-contaminationCollect pilot information on the approximate prevalence of certain ovine diseases (e.g. Johnes, OPA)Propose how information gained may be used in the longer term
6Why adult ewes? 15 million breeding ewes in UK Annual ewe mortality rates estimated at ~5% (0.75 million)Causes can be estimated from a few sources but not known at flock or national levelLosses usually not investigated because of low economic value of animalsArea probably under-represented by current surveillance arrangements
7Total ewe necropsies by AHVLA 2006-2011 (England & Wales) Most was ~750/ year in total (2009). Deaths (5% of 10 million)= ~500,000/ year.i.e. ~0.15% of total
8Materials & methods 11 sessions at a fallen stock collection Average of 10 necropsies per sessionSessions staggered through the year.Breed, estimated age, body condition and degree of autolysis, gross findings recordedNo clinical history collected for carcasesFurther testing commissioned as appropriateData collated to be reported
10ResultsDiagnosis in 70% of ewes. Results for 106 ewes included.
11Mastitis (11%)Most common diagnosis in this study (mainly in May & June)Only 0.3% of all diagnosable submissions to AHVLA (VIDA 2012)Farmer diagnosis hence national data currently lost to surveillance
12Acute fasciolosis (7%)Acute fluke was a common diagnosis from October onwardsEmphasised how valuable fallen stock necropsy could promptly alert farmers to the need to take actionUseful at a farm or regional levelCan treat after first ewe dies, not after tenth
13Ovine Pulmonary Adenocarcinoma (6%) No useful test in the live animal & likely to be underdiagnosedAverage of 28 diagnoses per year by AHVLAProbably a large cost on high prevalence flocksIs there a place for an accreditation scheme for flocks selling breeding sheep – based on routine PM of fallen stock?
14Johnes Disease (6%)Also probably underdiagnosed and a major cost on endemic flocksAverage of 40 cases per year by AHVLA fromLikely to be a significant ‘iceberg disease’ responsible for much premature culling, poor milk yields/ lamb growth rates.Some approaches for control..
16ConstraintsDespite searing all surfaces prior to bacterial swabbing, and using charcoal transport swabs, bacterial culture results were sometimes overgrown with Proteus and/ or coliformsContaminated environment.Lack of clinical history (might have been treated with antimicrobials)Attention to minimise this required.
18Further Applications to the sheep Industry Where are the health-related losses?Infectious AbortionPerinatal MortalityLamb losses turnout-slaughterEwe losses (mortality and morbidity)All of these should be relatively cheap to diagnose (with proper application of existing knowledge).
19Infectious AbortionThree major causes of infectious ovine abortion account for ~80% of cases:EAE (Chlamyophila) (~£12 million)Toxoplasma gondiiCampylobacterThe diagnosis is easy to make in all three cases.
25Diseases of adult ewes: Diagnosis Diagnostic criteraTreatment/ controlJohnesVisual +/-PCR or ZN smearManage/ vaccinateOPAVisual + HistopathologyManage/age stratifyFlukeVisualTreat promptlyHaemonchosisVisual +/- Abo washTreat
26The importance of early diagnosis and intervention Most sheep farmers will wait until a few have died before wondering whether to investigate.In some cases this is OK but in some cases further preventable losses ensue.Fluke and nematodirosis highlight the potential effectiveness of intervening early and with minimal cost and effort to the farmer.
27Conclusions: Fallen Stock Survey Material CERTAINLY diagnosticCan provide useful flock data to inform interventionsCan provide useful national data to inform useful areas of future research
28Conclusions: Further application of principles. It is more likely that losses will be pursued if to do so is EASY and CHEAPSheep farmers are lucky in that the diseases responsible for most of their (disease related) losses are EASY and CHEAP to diagnose.This knowledge just needs to be applied in the correct situation (i.e. promptly when disease occurs).The proposed approach is one way to achieve this.