A pilot study on the value of fallen stock necropsy to sheep farmers, with an emphasis on ewe mortality F. M. Lovatt & B. Strugnell Flock Health Ltd

Background In the UK, the Animal Health & Veterinary Laboratories Agency (AHVLA) provides: Disease surveillance Diagnostic service Currently this situation is being reviewed by consultation with the aim of Improving surveillance Reducing government budgets How can industry benefit more from disease surveillance and diagnosis?

Fallen 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?

Aims of Project Establish the diagnostic potential of material collected by fallen stock collectors Identify risks and constraints, such as autolysis and cross-contamination Collect 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

Why 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 level Losses usually not investigated because of low economic value of animals Area probably under-represented by current surveillance arrangements

Total 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

Materials & methods 11 sessions at a fallen stock collection Average of 10 necropsies per session Sessions staggered through the year. Breed, estimated age, body condition and degree of autolysis, gross findings recorded No clinical history collected for carcases Further testing commissioned as appropriate Data collated to be reported

Sample details

Results Diagnosis in 70% of ewes. Results for 106 ewes included.

Mastitis (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

Acute fasciolosis (7%) Acute fluke was a common diagnosis from October onwards Emphasised how valuable fallen stock necropsy could promptly alert farmers to the need to take action Useful at a farm or regional level Can treat after first ewe dies, not after tenth

Ovine Pulmonary Adenocarcinoma (6%) No useful test in the live animal & likely to be underdiagnosed Average of 28 diagnoses per year by AHVLA 2006-2011 Probably a large cost on high prevalence flocks Is there a place for an accreditation scheme for flocks selling breeding sheep – based on routine PM of fallen stock?

Johnes Disease (6%) Also probably underdiagnosed and a major cost on endemic flocks Average of 40 cases per year by AHVLA from 2006-11 Likely to be a significant ‘iceberg disease’ responsible for much premature culling, poor milk yields/ lamb growth rates. Some approaches for control. .

Chronic suppurative pneumonia (6%) Pasteurella bronchopneumonia (7%) Chronic suppurative pneumonia (6%) Caseous Endocarditis (1%) Neoplasia (6%) Lymphadenitis (1%)

Constraints Despite searing all surfaces prior to bacterial swabbing, and using charcoal transport swabs, bacterial culture results were sometimes overgrown with Proteus and/ or coliforms Contaminated environment. Lack of clinical history (might have been treated with antimicrobials) Attention to minimise this required.

The need for further testing

Further Applications to the sheep Industry Where are the health-related losses? Infectious Abortion Perinatal Mortality Lamb losses turnout-slaughter Ewe losses (mortality and morbidity) All of these should be relatively cheap to diagnose (with proper application of existing knowledge).

Infectious Abortion Three major causes of infectious ovine abortion account for ~80% of cases: EAE (Chlamyophila) (~£12 million) Toxoplasma gondii Campylobacter The diagnosis is easy to make in all three cases.

Perinatal Mortality Disease-related causes of perinatal lamb mortality: Watery mouth Lamb dysentery Rotavirus Poor colostral intake Joint Ill

Diseases of Neonatal Lambs: Diagnosis Diagnostic critera Treatment/ control Poor colostral intake Visual + Refractometer Management/ Nutrition Watery mouth Visual + culture Appropriate antibiosis Rotavirus Visual + PCR/ PAGE Supportive Joint Ill Necrobacillosis Visual +/- culture Management/ Nutrition/ Lamb Dysentery Visual +/- CP toxin detection Vaccination of ewes

Growing Lambs Worms Clostridial Disease (pulpy kidney etc.) Coccidiosis Pasteurellosis Acute/ Chronic Fluke …probably together account for 80% of losses (and are NOT hard to diagnose)

7.3. Diseases of growing lambs: Diagnosis Diagnostic critera Treatment/ control PGE Visual +WEC+ TWC Worm & manage Nematodirus Visual + SI TWC Worm (promptly!) Clostridial disease Visual +/- glucosuria +/- cp toxins Vaccinate Pasteurella Visual +/- culture Treat & vaccinate Coccidiosis Visual + WEC Treat & manage Fluke visual

Diseases of adult ewes Mastitis Johnes Disease OPA Fluke Haemonchosis (PGE)

Diseases of adult ewes: Diagnosis Diagnostic critera Treatment/ control Johnes Visual +/-PCR or ZN smear Manage/ vaccinate OPA Visual + Histopathology Manage/age stratify Fluke Visual Treat promptly Haemonchosis Visual +/- Abo wash Treat

The 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.

Conclusions: Fallen Stock Survey Material CERTAINLY diagnostic Can provide useful flock data to inform interventions Can provide useful national data to inform useful areas of future research

Conclusions: Further application of principles. It is more likely that losses will be pursued if to do so is EASY and CHEAP Sheep 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.

Acknowledgements Flock Health Ltd

QUESTIONS/ DISCUSSION