Sweet Itch 2025: Managing Culicoides Hypersensitivity in Horses

Sweet itch (summer seasonal recurrent dermatitis) caused by hypersensitivity to Culicoides midge saliva is extremely common and causes severe welfare impacts. Management has improved significantly.

Key Facts

Sweet itch affects approximately 5% of horses in the UK, with Icelandic horses having the highest prevalence
Culicoides midges are most active at dawn and dusk and in humid conditions near water
Affected horses develop intense pruritis especially over the mane and tail dock, causing severe self-trauma
Biologics targeting IL-31 signalling are under clinical evaluation as potential novel treatments

Welfare Considerations

Sweet itch causes significant, seasonal welfare deterioration — affected horses rub obsessively causing hair loss, excoriation, skin thickening, and secondary bacterial infection. The compulsive nature of the pruritis prevents rest and normal behaviour. Welfare management involves multiple simultaneous strategies: fly rugs covering the neck and belly, stabling during midge activity periods, antihistamines, topical soothing preparations, and in severe cases corticosteroids. Desensitisation immunotherapy is available with variable efficacy.

What You Can Do

Implement sweet itch rugs covering neck and belly from March through October in affected horses
Stable horses during dawn and dusk when Culicoides midges are most active
Discuss corticosteroid use for severe cases with your vet — welfare benefit must be weighed against long-term risks
Support clinical trials for novel sweet itch treatments by enrolling affected horses through your vet