A pilot study on the value of fallen stock necropsy to sheep farmers, with an emphasis on ewe...
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Transcript of A pilot study on the value of fallen stock necropsy to sheep farmers, with an emphasis on ewe...
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
BackgroundIn 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
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
1. Establish the diagnostic potential of material collected by fallen stock collectors
2. Identify risks and constraints, such as autolysis and cross-contamination
3. Collect pilot information on the approximate prevalence of certain ovine diseases (e.g. Johnes, OPA)
4. 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)
2006 2007 2008 2009 2010 20110
100
200
300
400
500
600
700
800
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
Frequency of diagnoses from a fallen ewe necropsy survey at a FSCC
0
5
10
15
20
25
Diagnosis
Fre
qu
ency
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 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
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%)
CaseousEndocarditis (1%) Neoplasia (6%) Lymphadenitis (1%)
Pasteurella bronchopneumonia (7%)
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:
1. EAE (Chlamyophila) (~£12 million)2. Toxoplasma gondii3. Campylobacter
The diagnosis is easy to make in all three cases.
Perinatal Mortality
Disease-related causes of perinatal lamb mortality:
1. Watery mouth2. Lamb dysentery3. Rotavirus4. Poor colostral intake5. Joint Ill
Diseases of Neonatal Lambs: Diagnosis
Disease Diagnostic critera Treatment/ control
Poor colostral intake
Visual + Refractometer
Management/ Nutrition
Watery mouth Visual + culture Appropriate antibiosis
Rotavirus Visual + PCR/ PAGE Supportive
Joint Ill Visual + culture Appropriate antibiosis
Necrobacillosis Visual +/- culture Management/ Nutrition/Appropriate antibiosis
Lamb Dysentery Visual +/- CP toxin detection
Vaccination of ewes
Growing Lambs
1. Worms2. Clostridial Disease (pulpy
kidney etc.)3. Coccidiosis4. Pasteurellosis5. Acute/ Chronic Fluke
…probably together account for 80% of losses (and are NOT hard to diagnose)
7.3. Diseases of growing lambs: Diagnosis
Disease 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 Treat & manage
Diseases of adult ewes
• Mastitis• Johnes Disease• OPA• Fluke• Haemonchosis (PGE)
Diseases of adult ewes: Diagnosis
Disease 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.
QUESTIONS/ DISCUSSION