Infectious (Iceberg) Dx in Sheep Flashcards

1
Q

Describe common viral, bacterial, protozoal ?

A
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2
Q

Infectious causes of poor fertility?

A

- 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)

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3
Q

What do we mean by Iceber diseases?

A
  • Low Clinical Visibility
  • Lack of availability of effective diagnostic testing
  • High Subclinical PResence
  • Economic & Health Impact
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4
Q

Jhone’s dx in sheep caused by ..?

A

Mycobacterium avium sbsp Paratuberculosis
Lon incubation , no tx

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5
Q

Johne’s seen in?

A

animals >2.5yrs - weight loss

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6
Q

CLS Johne’s ?

A
  • Chronic weight loss despite normal appetite
  • Poor fleece quality
  • Bottle jaw in later stages
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7
Q

What is NOT a sign of JOHNES

A

NO Diarrhoea

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8
Q

What does Johnes indirect consequences?

A

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

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9
Q

Transmission of Johne’s?

A
  • Ingestion of contaminated faeces by lambs
  • Acquired in utero- less common
  • Animals shedding without clinical signs
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10
Q

Jhone’s diagnosis?

A

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)

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11
Q

Jhones Control?

A
  • 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
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12
Q

What is the agent for Caseous Lymphadenitis? (CLA)

A

Corynebacterium pseudotuberculosis

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13
Q

Transmission of CLA?

A
  • Direct sheep-sheep during close confirnement or shearing equipment
  • highly infectious
  • Able to stay in environment for long time
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14
Q

What gross path of CLA?

A

Abscessation of superficial lymph nodes and LN of internal organs

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15
Q

Transmission of CLA

A
  • sheep:sheep in close conact
  • through contaminated equipment
  • Rams head lesions whilst fighting
  • Aerosol
  • Shared dipping
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16
Q

Which superficial LNs affected by CLA?

A
  • parotid, submandibular, popliteal, precrural and
    prescapular
  • Easily spread when abscesses open
  • Don’t often show clinical signs
17
Q

What does Internal CLs cause?

A

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

18
Q

Diagnosis:

A
  • Blood sample - western blor
  • Interferon-Y
    -Bacteriology
19
Q

Tx & Management?

A
  • difficult to treat as ABs can’t penetrate the fibrous capsule/ into abscess to work
20
Q

PRevention LDA?

A
  • Biosecurity & testing
  • Shearing equipment /other equipment
  • buy from dx free flock
21
Q

Management of CLA?

A

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

22
Q

Describe Ovine Pulmonary Adenocarcinoma/ Jaagsiekte

A
  • Viral-induced Adenomatous lung tumours
  • Jaagsiekte sheep retrovirus JRSV
23
Q

Transmission of OPA?

A
  • Horizontal transmission- ewe to ewe
  • Aerosol and infected surfaces
  • Prolonged incubation
  • Age 2-4
24
Q

CLS of OPA?

A
  • 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
25
Diagnosis of OPA?
* No serological test * PME lesions=diagnostic Ultrasound => * Early diagnosis (tumours >1cm) * Before clinical signs * Flock screening
26
What can we do to 'find' OPA?
Wheelbarrow test -> fluid comes out
27
Tx for OPA?
fatal/none
28
Prevention/Control OPA?
- Closed flock - Buying from known dx free - history of no clinical cases - Quarantine?
29
Management for OPA?
* Management of ewes in age groups * Remove lambs from clinical animals * Reduce environmental contamination
30
Prevention of OPA?
* Culling out at earliest signs * Ultrasound screening
31
Describe Maedi Visna Virus?
➢ Small ruminant Lentiviruses ➢ Long incubation ➢ Horizontal spread- aerosol, faeces & colostrum/milk
32
CLS of Maedi Visna?
➢ >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
33
what does MAedi Visna mean?
➢ Maedi = ‘laboured breathing’ ➢ Visna = ‘Wasting’ ‘shrinkage’
34
Subclin dx of MAedi Visna?
* Production limiting effects * Lower conception rates * Reduced longevity * Lower milk yields * Poor lamb production * Chronic mastitis/inflammation
35
Diagnosis of Maedi Visna ?
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)
36
How to go about Maedi Visna Diagnosis?
37
MV control options?
38
Control & prevention ? (pt 1)
* 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).
39
Control & prevention (pt2)
* 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.