Sweet itch is the most common allergic skin condition in horses, caused by hypersensitivity to Culicoides midge bites. The intense pruritus causes self-inflicted injury and chronic welfare compromise for affected horses.
Sweet itch causes sustained, intense suffering during the midge season. The pruritus (itching) drives horses to rub continuously against fence posts, trees, and stable fittings - to the point of causing raw, weeping skin lesions. Horses with severe sweet itch show clear signs of distress including agitation, difficulty concentrating, and reduced body condition from the constant discomfort. The chronic and progressive nature of the condition means that welfare deteriorates year on year without effective management. The welfare burden falls on horses that cannot remove themselves from the source of sensitisation, and who cannot communicate the severity of their discomfort except through the self-damaging behaviours the condition drives.