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Mycoplasma ovis in sheep

Mycoplasma ovis in the Central West

25 August 2014

The Central West District has had several reports by lamb producers of lethargy and/or mortalities in lambs during handling or mustering. On further investigation it was found that the lambs had been affected by Mycoplasma ovis.

Mycoplamsa ovis (M. ovis) formerly known as Eperythrozoon ovis is a bacteria that affects red blood cells in sheep and goats. M. ovis is recognised worldwide and has widespread effects in sheep populations throughout Australia.

The bacteria attach to red blood cells which the immune system then recognizes as foreign and destroys those red blood cells often resulting in fatalities due to anaemia.

Symptoms

The first obvious sign of the disease will be a large tail end of the flock while mustering. Lambs may lag behind the mob or lay down and be reluctant to move.

On inspection of these lambs the gums will appear pale white and may have a yellow tinge (jaundice).

Jaundice can result in carcass condemnation in abattoirs. Presentation is similar to Barber's Pole Worm and is often mistaken for high worm burdens.

Other signs can include red/ brown urine (blood products in the urine) and ill thrift.

Lambs less than 12 months old will often present with a recent history of processing involving the transfer of blood between animals (eg. mulesing, shearing, marking). The clinical signs can be seen 4-6 weeks after processing and will last another 6-8 weeks after the onset of signs. The condition is rarely seen in adult animals.

Contact your local district veterinarian who will conduct the post mortem on an affected lamb and blood samples can be sent off for a definitive diagnosis.

Other things that will be considered are flock history, presence of clinical signs and a post mortem.

Pale mucous membranes

Pale mucous membranes 

Yellowing of subcutaneous fat

Yellowing of subcutaneous fat 

Yellowing of fat in the abdominal cavity

Yellowing of fat in the abdominal cavity. 

Management and prevention

  1. Prevent stressing of lambs for 10 weeks after mulesing, shearing or marking.
  2. If you think you may have a M. ovis or a high worm burden problem, call your local district veterinarian before any further actions are taken. If the flock is mustered for unnecessary drenching more animals will be affected. Do not disturb the flock until a diagnosis has been confirmed.
  3. There is no effective treatment but minimizing stress will reduce numbers of animals clinically affected.

Article prepared by Clancy Stone and Lucy Wonders, Veterinary Science Students from Wagga Wagga, currently undertaking a final year rotation with LLS Veterinarian Jillian Kelly.