Infectious (Iceberg) Dx in Sheep

Question 1

Describe common viral, bacterial, protozoal ?

Answer 1

Question 2

Infectious causes of poor fertility?

Answer 2

- Chlaydophilia abortus AKA Enzootic Abortion of Ewes (EAE)
- Toxoplasma gondii
- * Campylobacter fetus fetus
* Salmonella
* Q fever
* Listeria monocytogenes
* Border disease
* Schmallenberg
* Bluetongue
* (Brucellosis- Brucella ovis)

Question 3

What do we mean by Iceber diseases?

Answer 3

• Low Clinical Visibility
• Lack of availability of effective diagnostic testing
• High Subclinical PResence
• Economic & Health Impact

Question 4

Jhone’s dx in sheep caused by ..?

Answer 4

Mycobacterium avium sbsp Paratuberculosis
Lon incubation , no tx

Question 5

Johne’s seen in?

Answer 5

animals >2.5yrs - weight loss

Question 6

CLS Johne’s ?

Answer 6

• Chronic weight loss despite normal appetite
• Poor fleece quality
• Bottle jaw in later stages

Question 7

What is NOT a sign of JOHNES

Answer 7

NO Diarrhoea

Question 8

What does Johnes indirect consequences?

Answer 8

More susceptible to other infections - mastitis etc
Lambs born to ewes in late stage = poor weight

Question 9

Transmission of Johne’s?

Answer 9

• Ingestion of contaminated faeces by lambs
• Acquired in utero- less common
• Animals shedding without clinical signs

Question 10

Jhone’s diagnosis?

Answer 10

Serum albumin and globin
- Profound hypoalbuminaemia
- Normal globulins
- PLE

Serum ELISA
- Low sensitivity & high Sp (high n° false neg)
- Individual testing expensive

Pooled faecal PCR (on cull animals to establish prevalence)

Question 11

Jhones Control?

Answer 11

• Probably in all UK flocks
• Regular BCS
• Culling
• Testing of thin sheep/culls (PM, Pooled faecal PCR)
• Cull & re-stock with low risk ewes
• Vaccination
• CLOSED FLOCK

Question 12

What is the agent for Caseous Lymphadenitis? (CLA)

Answer 12

Corynebacterium pseudotuberculosis

Question 13

Transmission of CLA?

Answer 13

• Direct sheep-sheep during close confirnement or shearing equipment
• highly infectious
• Able to stay in environment for long time

Question 14

What gross path of CLA?

Answer 14

Abscessation of superficial lymph nodes and LN of internal organs

Question 15

Transmission of CLA

Answer 15

• sheep:sheep in close conact
• through contaminated equipment
• Rams head lesions whilst fighting
• Aerosol
• Shared dipping

Question 16

Which superficial LNs affected by CLA?

Answer 16

• parotid, submandibular, popliteal, precrural and
  prescapular
• Easily spread when abscesses open
• Don’t often show clinical signs

Question 17

What does Internal CLs cause?

Answer 17

= spread to internal lymph nodes
- thin ewes syndrome
- associated clinical signs e.g. dyspnoea

Question 18

Diagnosis:

Answer 18

• Blood sample - western blor
• Interferon-Y
  -Bacteriology

Question 19

Tx & Management?

Answer 19

• difficult to treat as ABs can’t penetrate the fibrous capsule/ into abscess to work

Question 20

PRevention LDA?

Answer 20

• Biosecurity & testing
• Shearing equipment /other equipment
• buy from dx free flock

Question 21

Management of CLA?

Answer 21

Vaccination- not in UK-wont lead
to eradication
True positive Vs vaccinated
Test and Cull
Test entire flock at repeated
intervals and cull

Question 22

Describe Ovine Pulmonary Adenocarcinoma/ Jaagsiekte

Answer 22

• Viral-induced Adenomatous lung tumours
• Jaagsiekte sheep retrovirus JRSV

Question 23

Transmission of OPA?

Answer 23

• Horizontal transmission- ewe to ewe
• Aerosol and infected surfaces
• Prolonged incubation
• Age 2-4

Question 24

CLS of OPA?

Answer 24

• Non-specific
• Chronic weight loss
• Progressive dyspnoea
• Respiratory distress
• Crackles
• High pitched moist lung sounds
• Death
• Build up of excessive fluid
• Free flowing frothy nasal
  discharge
• Secondary bacterial infection

Question 25

Diagnosis of OPA?

Answer 25

* No serological test * PME lesions=diagnostic Ultrasound => * Early diagnosis (tumours >1cm) * Before clinical signs * Flock screening

Question 26

What can we do to 'find' OPA?

Answer 26

Wheelbarrow test -> fluid comes out

Question 27

Tx for OPA?

Answer 27

fatal/none

Question 28

Prevention/Control OPA?

Answer 28

- Closed flock - Buying from known dx free - history of no clinical cases - Quarantine?

Question 29

Management for OPA?

Answer 29

* Management of ewes in age groups * Remove lambs from clinical animals * Reduce environmental contamination

Question 30

Prevention of OPA?

Answer 30

* Culling out at earliest signs * Ultrasound screening

Question 31

Describe Maedi Visna Virus?

Answer 31

➢ Small ruminant Lentiviruses ➢ Long incubation ➢ Horizontal spread- aerosol, faeces & colostrum/milk

Question 32

CLS of Maedi Visna?

Answer 32

➢ >3 years old ➢ Progressive wasting ➢ Progressive Interstitial Pneumonia ➢ Progressive neurological signs ➢ Ataxia and incoordination – toe dragging ➢ Weakness ➢ Paralysis ➢ Asymptomatic carriers ➢ Chronic mastitis or poor colostrum/milk production

Question 33

what does MAedi Visna mean?

Answer 33

➢ Maedi = ‘laboured breathing’ ➢ Visna = ‘Wasting’ ‘shrinkage’

Question 34

Subclin dx of MAedi Visna?

Answer 34

* Production limiting effects * Lower conception rates * Reduced longevity * Lower milk yields * Poor lamb production * Chronic mastitis/inflammation

Question 35

Diagnosis of Maedi Visna ?

Answer 35

Clinical signs Postmortem- * Enlarged heavy lungs with grey discolouration * Impression of ribs * Secondary bacterial pneumonia * Raised mediastinal LNs * Histopathology to confirm Serology - Long time to seropositive conversion - Repeated testing (ELISA, AGIDT)

Question 36

How to go about Maedi Visna Diagnosis?

Answer 36

Question 37

MV control options?

Answer 37

Question 38

Control & prevention ? (pt 1)

Answer 38

* Run a closed flock where possible once flock health has been established. * Consider running shearlings/ewe lambs as a separate flock. This enables monitoring of older ewes and protecting replacements for as long as possible before mixing. * Fence off water courses and limit lambing in wet areas * Avoid mixing sheep close to tupping or during pregnancy (border disease). * Handle young sheep first at scanning/shearing/vaccination (contagious lymphadenitis). * Dagging/lambing shed hygiene is important (Johne’s disease).

Question 39

Control & prevention (pt2)

Answer 39

* Be vigilant with regards to fomites * Consider fencing – escapee sheep from infected neighbours are a real threat. * Take care with regards to pooled colostrum (maedi visna/Johne’s disease/ovine pulmonary adenomatosis) or cow colostrum. * Demand health status of purchased sheep * Avoid buying through markets or dealers mixing sheep from multiple sources.