Bluetongue is an insect-transmitted viral disease of sheep causing painful oral and limb lesions, with vaccination programs providing essential welfare protection in endemic and at-risk regions.
Bluetongue in clinical form causes significant suffering across multiple body systems. Oral lesions make eating painful, leading to reduced feed intake that compounds debility. Coronary band inflammation causes severe lameness; affected sheep may be unable to walk to food or water without pain. Facial swelling impairs vision and normal behavioral repertoire. The combination of multiple painful sites, systemic fever, and debility creates a welfare burden that can persist for weeks in surviving animals. The preventability of bluetongue through vaccination, combined with the severity of clinical disease, makes vaccination programs one of the most clearly welfare-justified interventions for sheep in BTV-endemic regions. The challenge of serotype diversity requires active surveillance to identify circulating strains and deploy appropriate vaccines — a public veterinary health function with direct welfare benefits.