Sweet itch: responses of clinically normal and affected horses to intradermal challenge with extracts of biting insects.
Abstract: In a study of the skin reactivity of horses with lesions of sweet itch, six clinically normal horses and seven affected horses were challenged intradermally with extracts of Culicoides, Stomoxys, Tabanidae and Culex species. All the affected horses and three of the normal horses responded strongly to the culicoides extract. The skin reactions in the affected horses reached their maxima within 4 h in the majority of animals. Skin reactivity to culicoides was transferred to normal horses with serum from affected animals confirming that the reaction was an immediate hypersensitivity reaction. Three of the seven affected animals gave both immediate and delayed reactions when challenged with the culicoides extract. When the dermal reactions of 12 clinically normal and 10 affected horses were compared at 20 mins and 1 h after challenge, the reactions produced by the culicoides extract were significantly (P less than 0.025) greater in the affected than in the normal horses. Individual horses gave strong reactions to extracts of Stomoxys, Culex and Tabanidae species, but no consistent response was evident among the affected animals. Serum from horses with sweet itch sensitised the skin of normal horses to challenge with extracts of the biting flies and the transferred antibodies remained bound to the skin of the recipient horse for 72 h or longer. Although some variation among the affected horses occurred in passive transfer experiments, the response to Culicoides species extracts was consistently greater than for the other insect extracts tested.
Publication Date: 1983-07-01 PubMed ID: 6884318DOI: 10.1111/j.2042-3306.1983.tb01788.xGoogle Scholar: Lookup
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- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates the skin reactivity of horses to various biting insect extracts and concludes that those afflicted with sweet itch have significant hypersensitivity, particularly to Culicoides extracts.
Research Methodology
- The study involved the investigation of skin reactivity in horses exhibiting symptoms of sweet itch. Participants included six clinically normal horses (group without the condition) and seven affected horses (those with the condition).
- These horses were intradermally (injected within the skin layers) challenged with extracts derived from various insect species, notably Culicoides, Stomoxys, Tabanidae, and Culex. Although all these insects are biting flies, their impact on the skin of horses varies.
Findings of the Research
- All horses affected with sweet itch, and three clinically normal ones, exhibited a strong reaction to the Culicoides extract. This implies that horses bearing symptoms of the condition present an extreme sensitivity to this particular insect aide.
- The skin reactions in affected horses peaked within 4 hours for most of the animals.
- The reactivity to Culicoides was transferred from affected to normal horses through serum, confirming the finding that this reaction is an immediate hypersensitivity type. Some horses showed both immediate and delayed responses to the extract.
- Statistical analysis emphasized a significantly greater reaction (P<0.025) in the affected horses than in the normal ones when challenged with the Culicoides extract, further reinforcing the hypothesis of hypersensitivity.
Further Insights
- Individual horses also showed strong reactions to extracts from Stomoxys, Culex, and Tabanidae species. However, these responses were not consistent among the affected animals, implying a specific hypersensitivity towards the Culicoides extract.
- Serum taken from horses with sweet itch could sensitize the skin of normal horses for a duration of over 72 hours. This serum contained antibodies against the biting flies.
- Despite some variation in the responses, the reaction to Culicoides species was consistently stronger than the reactions to other insect extracts tested, indicating a typical trait of the sweet itch condition in horses.
Cite This Article
APA
Quinn PJ, Baker KP, Morrow AN.
(1983).
Sweet itch: responses of clinically normal and affected horses to intradermal challenge with extracts of biting insects.
Equine Vet J, 15(3), 266-272.
https://doi.org/10.1111/j.2042-3306.1983.tb01788.x Publication
Researcher Affiliations
MeSH Terms
- Animals
- Chronic Disease
- Dermatitis, Atopic / diagnosis
- Dermatitis, Atopic / drug therapy
- Dermatitis, Atopic / etiology
- Dermatitis, Atopic / veterinary
- Horse Diseases / diagnosis
- Horse Diseases / drug therapy
- Horse Diseases / etiology
- Horses
- Humans
- Hypersensitivity, Delayed / diagnosis
- Hypersensitivity, Delayed / drug therapy
- Hypersensitivity, Delayed / veterinary
- Insect Bites and Stings / complications
- Insect Bites and Stings / veterinary
- Intradermal Tests / methods
Citations
This article has been cited 9 times.- Schwarz E, Jebbawi F, Keller G, Rhiner T, Fricker A, Waldern N, Canonica F, Schoster A, Fettelschoss-Gabriel A. Phenotypic Shift of an Inflammatory Eosinophil Subset into a Steady-State Resident Phenotype after 2 Years of Vaccination against IL-5 in Equine Insect Bite Hypersensitivity. Vet Sci 2024 Oct 5;11(10).
- Yoshida S, Matsuda A, Iwata E, Ono T, Hisaeda K, Ohzawa E, Hiasa Y, Kitagawa H. Allergen-specific immunoglobulin-Es for dermatitis in the Japanese native Noma horses. J Vet Med Sci 2024 Sep 1;86(9):938-945.
- Langreder N, Schäckermann D, Meier D, Becker M, Schubert M, Dübel S, Reinard T, Figge-Wegener S, Roßbach K, Bäumer W, Ladel S, Hust M. Development of an inhibiting antibody against equine interleukin 5 to treat insect bite hypersensitivity of horses. Sci Rep 2023 Mar 10;13(1):4029.
- Cvitas I, Oberhaensli S, Leeb T, Marti E. Equine keratinocytes in the pathogenesis of insect bite hypersensitivity: Just another brick in the wall?. PLoS One 2022;17(8):e0266263.
- Olomski F, Fettelschoss V, Jonsdottir S, Birkmann K, Thoms F, Marti E, Bachmann MF, Kündig TM, Fettelschoss-Gabriel A. Interleukin 31 in insect bite hypersensitivity-Alleviating clinical symptoms by active vaccination against itch. Allergy 2020 Apr;75(4):862-871.
- Fettelschoss-Gabriel A, Fettelschoss V, Olomski F, Birkmann K, Thoms F, Bühler M, Kummer M, Zeltins A, Kündig TM, Bachmann MF. Active vaccination against interleukin-5 as long-term treatment for insect-bite hypersensitivity in horses. Allergy 2019 Mar;74(3):572-582.
- Anderson GS, Belton P, Kleider N. The hypersensitivity of horses to culicoides bites in british columbia. Can Vet J 1988 Sep;29(9):718-23.
- Björnsdóttir S, Sigvaldadóttir J, Broström H, Langvad B, Sigurdsson A. Summer eczema in exported Icelandic horses: influence of environmental and genetic factors. Acta Vet Scand 2006 May 26;48(1):3.
- Larsen HJ, Bakke SH, Mehl R. Intradermal challenge of Icelandic horses in Norway and Iceland with extracts of Culicoides spp. Acta Vet Scand 1988;29(3-4):311-4.
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