Difference between revisions of "Culicoides Hypersensitivity"
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==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 ''Culicoides'' midges. | + | 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. |
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| + | ==Signalment== | ||
| + | Although sweet itch may occur in horses of all breeds and ages, the disease has a peak age of onset of between 2 and 4 years. Most breeds are affected although sweet itch is rare in Thoroughbreds. | ||
==Pathogenesis== | ==Pathogenesis== | ||
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==Clinical signs== | ==Clinical signs== | ||
| − | The cardinal sign of Sweet itch is extreme, intense pruritus with characteristic distribution patterns. Commonly affected areas include the head, mane, tail, withers and ventral abdomen. Primary lesions are papules but self-excoration may lead to the characteristic lesions of sweet itch including alopecia, broken hairs, erosions, ulcers. In the chronic stages, lichenification | + | The cardinal sign of Sweet itch is extreme, intense pruritus with characteristic distribution patterns. Commonly affected areas include the head, mane, tail, withers and ventral abdomen. Primary lesions are papules but self-excoration may lead to the characteristic lesions of sweet itch including alopecia, broken hairs, erosions, ulcers. Lesions are frequently painful and In the chronic stages, lichenification, hyperkeratosis and scaling are common features. |
==Diagnosis== | ==Diagnosis== | ||
Revision as of 18:49, 1 September 2010
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This article is still under construction. |
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 insects. The most important causative agent is Culicoides spp but other insects including Simuliumspp, 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
Although sweet itch may occur in horses of all breeds and ages, the disease has a peak age of onset of between 2 and 4 years. Most breeds are affected although sweet itch is rare in Thoroughbreds.
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.
Clinical signs
The cardinal sign of Sweet itch is extreme, intense pruritus with characteristic distribution patterns. Commonly affected areas include the head, mane, tail, withers and ventral abdomen. Primary lesions are papules but self-excoration may lead to the characteristic lesions of sweet itch including alopecia, broken hairs, erosions, ulcers. Lesions are frequently painful and In the chronic stages, lichenification, hyperkeratosis and scaling are common features.
Diagnosis
Diagnosis is often based on the animal's history, seasonal clinical signs and the site and nature of the lesions. Other important differential diagnoses that should be ruled out include psoroptic and sarcoptic mange, other insect-related and dermatophilosis
Treatment
- 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