Sweet Itch in Horses: Managing Seasonal Allergic Dermatitis

Sweet itch is one of the most distressing skin conditions in horses, causing intense itching and self-inflicted injury from seasonal hypersensitivity to midge bites.

Key Facts

Sweet itch (insect bite hypersensitivity, IBH) is caused by allergic reaction to salivary proteins of Culicoides midges
Affected horses rub mane and tail areas obsessively, causing hair loss, skin thickening, and open wounds
There is no cure; management focuses on preventing midge bites and managing itch intensity
Full-body fly rugs covering mane and tail significantly reduce bite exposure in affected horses
IBH is heritable — certain breeds including Icelandic horses and British native ponies have higher prevalence
Corticosteroids reduce itch intensity but have significant side effects with long-term use

Welfare Considerations

Sweet itch causes extreme suffering in affected horses — the itch is so intense that horses rub mane and tail areas against any available surface until the skin is raw and bleeding, creating secondary bacterial infections. During midge season, an unmanaged sweet-itch horse may be in near-constant distress. Prevention of midge access through appropriate rugging, stabling during peak midge activity (dawn and dusk), and avoidance of high-risk environments near standing water reduces the welfare burden substantially. For horses with confirmed IBH, desensitization immunotherapy is emerging as a promising long-term management option.

What You Can Do

Invest in full-body fly rugs with neck and face coverage for horses with sweet itch
Stable affected horses at dawn and dusk during midge season when Culicoides are most active
Avoid grazing near water courses where midge populations are highest
Consult your veterinarian about emerging immunotherapy options for horses with severe IBH