Equine Summer Sores: Welfare Management in Tropical and Subtropical Regions

Summer sores (cutaneous habronemiasis) are caused by larval migration of stomach worm larvae deposited in wounds by flies, causing intensely pruritic and painful skin lesions in horses in warm climates.

Key Facts

Habronema and Draschia species are the causative stomach worms of summer sores
Lesions appear when larvae are deposited in wounds, eyes, or on moist skin by Musca flies
Summer sores are intensely pruritic, causing self-trauma and wound enlargement
The condition is seasonal in subtropical climates but year-round in tropical zones
Ivermectin treatment kills migrating larvae; wound management addresses the lesion directly

Welfare Considerations

Summer sores cause intense pruritus and pain in affected horses, with the characteristic self-mutilation causing wounds to enlarge dramatically through self-trauma. The frustration of intense itch combined with inability to effectively relieve it causes significant negative affective states. Lesions around the eyes cause particular welfare concern. Fly control through management of manure, use of fly masks, and topical repellents reduces larval deposition. Prompt treatment with ivermectin and wound management prevents lesion progression and chronic suffering.

What You Can Do

Implement comprehensive fly control programmes in yards and stables in affected regions
Apply fly masks and topical repellents to reduce fly-mediated larval deposition
Seek prompt veterinary treatment if summer sore lesions are identified
Follow complete ivermectin treatment and wound management protocols
Maintain rigorous manure management to reduce fly breeding sites year-round