Pneumonia and Pleurisy in Lambs

(principal researcher Kathy Goodwin of Epicentre, Massey University with collaboration of AgResearch, Agriculture NZ, Epicentre, Massey University and farmers from Southland, King Country and Northland)

The study objectives were to determine the effect of Chronic non progressive pneumonia (CPN) on:

  1. lamb growth and quantify the cost to farmers
  2. Identify on farm factors likely to have an influence on CPN
  3. Features of the Pneumonia/Pleurisy spectrum
  4. Develop methods for capturing reliable information in meat works

All the above, are necessary steps towards improved control programmes.

The trial was conducted in the King Country (6 farms), Northland (4 farms) and Southland (6 farms).
400 lambs per farms with 200 allocated to random and 200 to normal slaughter groups.
Pneumonia status was scored at slaughter.
Lambs weights were regularly taken.
Measures of management and environmental factors were recorded.

Although Pleurisy/Pneumonia are of limited importance from a public heath point of view it is an important disease to farmers due to the downgrading of carcasses and for the meat export industry because of the extra inspection cost and time involved to trim the carcass affected.

The disease can be split in three distinctive categories:

  1. Acute fibrinous pneumonia, which is:
  2. Chronic non progressive pneumonia (CPN), which is:
  3. Pleurisy

Chronic non-progressive pneumonia (CPN) has multiple factors involved all rather poorly understood. There are a range of different micro organisms involved, which makes vaccine control unlikely. But lambs inherit maternal immunity and develop a natural resistance. Environmental factors such as management, nutrition and other diseases play a role.

CPN has a higher prevalence in late summer/autumn but occurs in all seasons in healthy lambs (3 to 10 months old).
CPN prevalence which commonly thought to be about 30% in autumn may actually reach up to 70% in some flocks.
CPN seems to affect lambs when the maternally derived effect is likely to be waning.

Micro-organisms associated with Lamb pneumonia:

Possible risk factors:

There are many proposed but confirmatory evidence is lacking.

Possible protective factors:

All very poorly understood.

Summary conclusions:

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