Changes

==Description==

==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 insects. The most important causative agent is ''Culicoides'' spp but other insects including ''Simulium''spp, ''Stomoxys'' spp and ''Haematobia'' may also have a role. In temperate climates, the condition occurs between spring and autumn (when midges are active) with a period of remission during the winter months.  

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 insects. The most important causative agent is the ''Culicoides'' midge but other insects including ''Simulium''spp, ''Stomoxys'' spp and ''Haematobia'' may also have a role. In temperate climates, the condition occurs between spring and autumn (when midges are active) with a period of remission during the winter months.  

==Signalment==

==Signalment==

==Pathogenesis==

==Pathogenesis==

The condition is thought to occur due to both immediate (Type 1) and delayed (Type 4) hypersensitivity reactions to Culicoides salivary proteins. The proteins are injected during feeding and IgE antibodies are produced in repsonse by susceptible animals.

The condition is thought to occur due to both immediate (Type 1) and delayed (Type 4) hypersensitivity reactions to Culicoides salivary proteins. The female ''Culicoides'' midge lands on the host and crawls down the hairs to the skin surface, using its mouthparts to pierce the skin. Saliva is injected into the site containing vasodilators, anticoagulants and pro-inflammatory mediators. IgE antibodies are produced in repsonse by susceptible animals.

==Clinical signs==

==Clinical signs==

==Treatment==

==Treatment==

 

 

*Wilson, A. D., Harwood, L. J., Björnsdottir, S., Marti, E., Day, M. J. '''(Detection of IgG and IgE serum antibodies to Culicoides

*Grossly:s

salivary gland antigens in horses with insect dermal hypersensitivity (sweet itch)''' ''Equine Veterinary Journal 33 (7)707-713''

**Papules, crusts, alopecia, excoriations, lichenification

**Superficial and dep perivascular dermatitis

**Possibly eosinophilic folliculitis, intraepidermal pustules and [[Skin Other - Pathology#Eosinophilic granuloma|eosinophilic granulomas]]

[[Category:Allergic Skin Diseases]][[Category:Dermatological Disorders - Horse]][[Category:To Do - Clinical]]

[[Category:Allergic Skin Diseases]][[Category:Dermatological Disorders - Horse]][[Category:To Do - Clinical]]

[[Category:To Do - Blood]][[Category:To Do - SophieIgnarski]]

[[Category:To Do - Blood]][[Category:To Do - SophieIgnarski]]