Difference between revisions of "Culicoides Hypersensitivity"
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==Description== | ==Description== | ||
| − | Culicoides hypersensitivity, commonly referred to as ' | + | 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== | ||
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==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 | + | 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== | ||
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==Treatment== | ==Treatment== | ||
| − | + | ==References== | |
| − | + | *Wilson, A. D., Harwood, L. J., Björnsdottir, S., Marti, E., Day, M. J. '''(Detection of IgG and IgE serum antibodies to Culicoides | |
| − | * | + | salivary gland antigens in horses with insect dermal hypersensitivity (sweet itch)''' ''Equine Veterinary Journal 33 (7)707-713'' |
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[[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]] | ||
Revision as of 18:57, 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 the Culicoides midge 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 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
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
References
- Wilson, A. D., Harwood, L. J., Björnsdottir, S., Marti, E., Day, M. J. (Detection of IgG and IgE serum antibodies to Culicoides
salivary gland antigens in horses with insect dermal hypersensitivity (sweet itch) Equine Veterinary Journal 33 (7)707-713