Johne's disease in sheep

Johne’s disease in sheep is an infectious and incurable wasting disease. It is caused by the bacteria Mycobacterium paratuberculosis.

Johne’s disease in sheep is a notifiable disease and must be immediately reported. See the  reporting animal disease page for instructions if you suspect Johne’s disease is present in sheep.

Clinical signs

Johne’s is an insidious and progressive disease. It is not easily detectable and often no clinical signs are evident for the first few years.

Clinically affected sheep show severe wasting. Sheep with the clinical signs of the disease usually die or are euthanised within 3 to 8 months.

The classical clinical signs of Johne’s disease is a distinct ‘tail’ to the mob. Cause of death from the disease may not be noticeable initially. It may be mistaken for sheep already in poor condition through being older in age or having internal parasite burdens.

Infected sheep may carry and spread the disease without ever showing clinical signs. Healthy looking animals can be shedding the bacteria for a considerable length of time prior to them becoming clinically affected. This is as a result of the long incubation period.

It is more than likely Johne’s disease is already well established within the flock when deaths are noticed that are obviously attributable to the disease.

Once the clinical phase occurs, the condition is always fatal.

Spread between animals

Johne’s Disease usually enters a flock when:

  • new infected sheep enter a flock
  • stray infected sheep enter a flock
  • sheep eat pasture contaminated by faeces from infected sheep
  • sheep drink water contaminated by faeces from infected sheep.

More information

Page Last Reviewed: 03 Jan 2018
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