Background: Caseous lymphadenitis (CLA), caused by the gram-positive bacteria Corynebacterium pseudotuberculosis, has been present in Great Britain since the 1980s and is now considered endemic. CLA is considered to be an iceberg disease; that is, it is a production-limiting disease, characterised by slow insidious onset, that has production-limiting effects in a larger proportion of the flock than is exhibiting clinical signs at any given point in time.Aim of the article: The disease has been previously reviewed in In Practice (Baird 2003). In this article we consider updates in our understanding of the pathology, risk factors for flocks and the challenges of initiating control where the cost of the disease is still relatively unquantified.

Background: Maedi visna (MV) is considered to be one of the ‘iceberg diseases’ of sheep; a group of infectious, production-limiting diseases which are endemic to the UK. Characterised by slow, progressive onset, these diseases lie undetected and can have a large impact on flock efficiency. This group of diseases also includes border disease, caseous lymphadenitis, ovine Johne’s disease and ovine pulmonary adenocarcinoma. The prevalence and effects of these diseases within different UK flock types remains unknown.Aim of the article: To highlight the increasing importance of MV within the national flock. Here, we discuss the production effects, diagnosis and control options for MV.

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