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Also known as Sweet Itch
Description
Culicoides hypersensitivity, commonly referred to as 'Sweet itch' is an intensely pruritic dermatitis of horses caused by a hypersensitivity reaction to the saliva of biting Culicoides midges. The condition may be seasonally recurring or continuous depending on the climate
Pathogenesis
The condition is thought to occur due to both immediate (Type 1) and delayed (Type 4) hypersensitivity reactions to Culicoides salivary proteins. These proteins are injected during feeding and susceptible animals respond to them by producing IgE antibodies.
- Grossly:s
- Papules, crusts, alopecia, excoriations, lichenification
- Microscopically:
- Superficial and dep perivascular dermatitis
- Many eosinophils
- Epidermal hyperplasia
- Hyperkeratosis
- Dermal fibrosis
- Possibly eosinophilic folliculitis, intraepidermal pustules and eosinophilic granulomas