Horse Sweet Itch Genetics and Management

Sweet itch is a hypersensitivity reaction to insect bites causing intense itching and self-trauma in genetically susceptible horses.

Key Facts

Sweet itch (Summer Seasonal Recurrent Dermatitis) is caused by hypersensitivity to Culicoides midge saliva
Affected horses rub mane, tail, and withers areas until raw, causing self-inflicted injury
There is a strong genetic component — breeding from affected horses increases offspring risk
Seasonal pattern matches midge activity — symptoms worsen in spring through autumn
Management focuses on midge avoidance — stabling during dawn and dusk, rugging, and insect repellents
Anti-histamines, corticosteroids, and emerging immunotherapy options provide varying levels of relief

Welfare Considerations

Sweet itch causes persistent, intense pruritus that drives affected horses to self-injure in attempts to relieve itching. During peak midge season, this can constitute a significant ongoing welfare problem — horses unable to rest without itching, with broken skin, hair loss, and secondary infections around rubbed areas. Welfare-centred management requires layered prevention — physical barriers against midges through appropriate rugging, stable management, and topical repellents — combined with medical management of symptoms during breakthrough periods. The chronic nature of the condition means welfare monitoring through the entire susceptible season is necessary, not just during acute flare-ups.

What You Can Do

Use sweet itch rugs and fly sheets designed to protect vulnerable body areas during midge season
Stable affected horses during peak midge activity at dawn and dusk
Apply effective insect repellents regularly, focusing on mane, tail, and belly areas
Discuss corticosteroid or antihistamine treatment with your vet for severe cases
Avoid breeding from severely affected horses — consider the welfare implications for offspring