Iceberg Diseases in Sheep: Identification and Management

A practical guide to identifying and managing iceberg diseases—Ovine Pulmonary Adenocarcinoma (OPA), Maedi Visna (MV), and Johnes disease—in sheep flocks, focusing on poor ewe body condition. Covers diagnostic steps including postmortem examination, blood and faecal sampling, and clinical signs: persistent weight loss in Johnes, respiratory issues or sudden death in OPA, and varied signs including pneumonia, lameness, and poor lamb growth in MV. Recommends avoiding breeding from positive ewes, reducing stock density, and limiting housing or trough feeding to limit spread. Notes limitations such as no blood test for OPA, challenges in control implementation, and differences in climate affecting Johnes management. Highlights benefits including improved productivity, ewe welfare, and healthier replacement stock. Relevant for flock health, nutrition, and management.