Horse Sweet Itch Immunotherapy and Management

Sweet itch (summer seasonal recurrent dermatitis) causes intense pruritus in sensitised horses during midge season, and immunotherapy offers a new approach beyond symptomatic management.

Key Facts

Sweet itch affects an estimated 5% of horses in the UK and is caused by hypersensitivity to Culicoides midge saliva
Affected horses rub mane and tail areas raw, causing hair loss, skin thickening, and open wounds
Heavy rugging and barrier creams are traditional management approaches to prevent midge bites
Allergen-specific immunotherapy (ASIT) involves a series of injections designed to desensitise the horse
ASIT has shown efficacy in reducing sweet itch severity in controlled studies in Europe

Welfare Considerations

Sweet itch causes intense, unrelenting pruritus during midge season that causes profound welfare compromise. Affected horses rub continuously against any available surface, causing self-trauma, secondary infection, and skin scarring. The behaviour is compulsive, driven by the immune response to midge saliva proteins. Traditional management reduces exposure but cannot eliminate reactions in highly sensitised horses. Immunotherapy addresses the underlying hypersensitivity and, when effective, provides welfare benefits beyond what symptomatic management can achieve. Genetic predisposition to sweet itch should be considered in breeding decisions.

What You Can Do

Stable sweet itch-affected horses during peak midge activity at dawn and dusk
Use fine-mesh rugs and fly masks to create a physical barrier against midge exposure
Discuss allergen-specific immunotherapy with a veterinary dermatologist for severely affected horses
Avoid breeding from horses with severe sweet itch to reduce genetic transmission