Livestock

Respiratory Viral Disease in Sheep: Welfare and Management

Welfare guide to viral respiratory diseases in sheep -- maedi-visna, OPA, and respiratory syncytial virus.

Key Facts

Maedi-visna is a lentiviral disease causing progressive pneumonia in adult sheep -- no treatment exists
OPA (Ovine Pulmonary Adenocarcinoma) is a retroviral lung tumour causing progressive weight loss and death
Both diseases are lifelong infections with progressive welfare deterioration over months to years
Affected sheep become progressively breathless, lose weight, and eventually cannot keep up with the flock
Biosecurity -- preventing introduction of infected animals -- is the only effective prevention
Test and cull programmes can eliminate both diseases from a flock over several years
Welfare monitoring of chronically wasting or breathless sheep should lead to prompt euthanasia decisions
Clinical disease in both conditions is invariably terminal -- affected animals require timely welfare decisions

Welfare Significance

Maedi-visna and OPA cause prolonged progressive welfare deterioration with no recovery possible. Affected sheep experience months of increasing breathlessness, weakness, and weight loss. The welfare imperative is early identification and prompt euthanasia of affected animals -- prolonging life in these cases only prolongs suffering. Biosecurity prevents introduction; test-and-cull eliminates it once present.

What You Can Do

Test all breeding sheep for maedi-visna and OPA before purchase -- buy only from accredited flocks
Implement a test-and-cull programme if either disease is present in your flock
Euthanase any sheep showing progressive respiratory signs that cannot maintain body condition
Consult your vet about enrolling in the MV Accreditation Scheme to achieve and maintain accredited status