Summer sores (cutaneous habronemiasis) are intensely irritating wound infections in horses caused by fly larvae, causing significant discomfort if not detected and treated promptly.
Summer sores cause relentless local irritation that drives horses to rub and traumatize affected areas, creating a destructive cycle of self-inflicted worsening. A horse with an active summer sore lesion near the eye or on the sheath is experiencing genuine suffering - the itch-inflammation-scratch cycle is distressing and progressive. Early detection through regular wound inspection during fly season is critical. Once summer sores develop, prompt veterinary treatment with appropriate dewormers and wound management prevents the significant welfare burden of chronic, worsening lesions. Fly control measures that reduce fly contact with wounds provide the most effective prevention.