Ark Veterinary Centre

Iceberg Diseases in Sheep

Nov 1, 2019

Do you have more cull ewes than you would expect? Are your ewes in poor condition despite parasite treatment and extra feeding? Have you had older sheep with pneumonia symptoms?

If so, it may be worth considering checking for the iceberg diseases. These diseases are a group of conditions given the name due to the nature of how they are seen on farm. The group includes Johnes disease, Maedi Visna, Caseous Lymphadenitis (CLA), Ovine Pulmonary Adenocarcinoma (OPA)/Jaagsiekte and Border Disease. Generally, only small numbers of clinically affected animals are seen, however significantly more can be infected. 

For example, with Johnes disease, for every clinical case it is thought there are another 10-25 subclinical cases (infected but with no outward symptoms); this large number of subclinical infections can have a significant impact on production. Testing can be difficult due to the complex cycle of disease and the bugs involved. Probably the easiest place to start is to screen 10-12 thin/cull ewes on blood/muck samples. If you would like some more information and to discuss testing give one of the vets a ring.