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Farm Animal Final Year > Johne’s Disease > Flashcards

Johne’s Disease Flashcards

1
Q

What type of disease is Johne’s Disease?

A

Incurable disease of cattle and ruminants

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2
Q

What is Johne’s Disease caused by?

A

•Mycobacterium avium subsp. paratuberculosis (MAP)

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3
Q

What is Johne’s disease characterised by?

A
  • Wasting and diarrhoea
  • Granulomatous enteritis
  • Slow/long course
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4
Q

What is Johne’s Disease also known as?

A

paratuberculosis

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5
Q

What is the relationship between Johne’s disease and humans?

A
  • Controversial association with Crohn’s disease in humans
  • Some evidence both ways
  • Can find MAP in pasteurized milk
  • No convincing evidence of causality
  • Potential major reputational risk to dairy/meat industries
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6
Q

What is the course of disease for Johne’s Disease?

A

Infection - carriage - subclinical - clinical

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7
Q

What are the clinical signs?

A
  • Diarrhoea
    • Intermittent becoming chronic
  • Decreased production
    • i.e. milk yield
  • Weight loss/emaciation
  • +/- oedema (e.g. “bottle jaw”)
  • Disease normally develops at 2-6 years of age
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8
Q
  • Presented at routine farm visit
  • “Pet” high SCC cow, milk used to feed calves for last lactation
  • Calved 2 months ago
  • Appears to be losing a lot of weight
  • Diarrhoea evident
  • “Bubbly” appearance
  • Otherwise NAD on clinical exam….

What other diagnoses might we consider?

A
  • Nutritional problem
  • Liver fluke
  • Left displaced abomasum
  • PGE (gut worms)
  • Trace element deficiency
  • Toxic mastitis
  • Salmonellosis
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9
Q

What differentials do you consider for a cow with chronic D+, weight loss, reduced yield? (8)

A
  • Liver fluke
  • Parasitic gastroenteritis
  • Peritonitis
  • Displaced abomasum
  • Copper deficiency
  • Abdominal neoplasia
  • Chronic salmonellosis
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10
Q

What condition is usually a group problem and unusual in adults?

A

Parasitic Gastroenteritis

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11
Q

Why is peritonitis low on the differentials for a cow with chronic D+, weight loss ana reduced yield?

A

Would expect to find other signs e.g. abd pain, pain on rectal exam

TRP? – can be difficult to diagnose, norm no D+

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12
Q

Why is a displaced abomasum low on the differential list for chronic D+, weight loss and low yield?

A

Normally more acute, drop in yield more severe, low rumen turnover, “ping”

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13
Q

What type or problem and what else is seen (other than chronci D+, weight loss and low yield) for copper deficiency?

A

Usually a group problem

Would normally expect milder group level signs first (e.g. infertility)

+/- diarrhoea

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14
Q

Which 2 conditions are pretty rare?

  • Liver fluke
  • Parasitic gastroenteritis
  • Peritonitis
  • Displaced abomasum
  • Copper deficiency
  • Abdominal neoplasia
  • Chronic salmonellosis
A
  • Abdominal neoplasia
  • Chronic salmonellosis
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15
Q

What is the course of disease for Johne’s disease? Draw a graph

A
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16
Q

What are the sources of infection or Johne’s disease? state where the clinical significane is uncertain (5) (2)

A
  • Faeces from shedding cattle
  • Faeces from shedding goats/sheep
  • Colostrum/milk from infected cattle
  • Environment/fomites *
  • Wildlife reservoirs? *
17
Q

What are the 2 basic idea to approaching a Johne’s disease diagnosis?

A
  • Detect MAP in faeces
  • Detect immune response to MAP
18
Q

Name 3 advantages to detecting MAP for Johne’s disease diagnosis (4)

A
  • Demonstrates shedding/danger of transmission
  • Excellent specificity
  • Sensitive methods of detection available
  • Can use pooled samples
19
Q

Name 2 disadvantages for detecting AP for Johne’s disease diagnosis (3)

A
  • Faecal shedding…
    • Often doesn’t occur until late in disease
      • Is unpredictable and can be intermittent
      • Will detect very few animals early in the course of infection
  • Insensitive techniques for detection are also available!
  • Some tests have long turnaround times
20
Q

How can we detect MAP? (3) What are the positives and negatives of this?

A
  • ZN staining of faecal smear
    • Very low sensitivity
    • Dependant on skill of operator
  • Faecal culture
    • Reasonable chance of detecting MAP if it is present
    • Long turnaround time
    • Expensive
  • Polymerase chain reaction (PCR)
    • Good chance of detecting MAP if it is present
    • Cheaper and quicker cf culture
21
Q

How can we go about immunodiagnosis? Discuss the positives ane negatives

A
  • Currently only Ab evaluation commercially available
    • Blood or milk
  • More sensitive early in course of infection than faecal testing
  • Still not great chance of detecting asymptomatic carrier animals
  • Cheap, easy and quick
  • Specificity ~99%
22
Q

How do we approach treatment in an individual with Johne’s disease?

A
  • No treatment
  • Survival time from diagnosis very variable
  • May get brief remission
  • Usually cull as soon as possible
23
Q

What are the 2 main objectives when there is Johne’s disease in the herd?

A
  • Prevent transmission
    • Focus on replacement heifer calves
    • Several potential sources of infection (faeces>>colostrum>milk>other)
  • Maintain herd biosecurity
    • Prevent buying in disease
    • Still important for positive herds!
24
Q

What is the main ocus in a positive herd?

A

Prevent transmission

25
Q

What is the main focus in a negative Johne’s disease?

A

Maintain herd biosecurity

26
Q

What is the aim of preventing tranmision?

A
  • Aim: Separate youngstock up to 1yr of age from potential sources of infection…
    • Slurry
    • Colostrum, milk
    • Other species
    • Fomite spread
    • Contaminated pasture
    • Vertical
27
Q

How can we prevent new infection?

A
  • Can we try to “target” these measures?
  • Identify high risk cows?
  • Individual milk sample Ab testing
    • Reduces number of cows needing intensive calving management
  • Can we try to “target” these measures?
  • Quarterly individual cow milk Ab testing now common
  • Identifies animals at increased/high risk of shedding
  • BUT imperfect test!
28
Q

How can we maintain biosecurity?

A

Bear in mind potential sources
and animals susceptible to infection

Buying in stock!

  • Minimising the risk
  • Knowing about the source
  • Testing the individual?
  • Closed herd?
29
Q

What is the most common test and cull schemes?

A
  • Various ways to do
  • Blood Ab test the commonest for this
  • May speed up rate of eradication in herd
  • but won’t eradicate disease by itself!
30
Q

Name 4 problems of vaccinating (5)

A
  • Prevents disease not infection
  • Potential route to preventing new infection
  • Can import vaccine under license from Spain
  • Need to keep going for several generations
  • ??? Interference with TB test results ???
    • ? False positives
31
Q

What things do we need to discuss with a farmer if there is a confirmed case?

A
  • Calves fed on her milk
  • Where did she come from (home/bought)?
  • Look out for other clinical cases
32
Q

How can we prevent Johne’s on a UK level?

A

The National Johne’s Management Plan

33
Q

How does Johne’s present in other species?

A
  • Common in goats and sheep (probably under-diagnosed)
  • Disease looks similar
    • Often diarrhoea less noticeable, just wt loss
  • Routes of transmission and course of disease are similar
  • Control harder as more difficult to manage what happens around birth
  • Differential diagnoses will vary between species

Farm Animal Final Year (131 decks)

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