A Comparison of Intradermal Skin Testing and Serum Insect Allergen-specific IgE Determination in Horses With Insect Bite Hypersensitivity From 2008 to 2016.
Authors: Wilkołek Piotr, Szczepanik Marcin, Sitkowski Wiesław, Adamek Łukasz, Pluta Michał, Taszkun Iwona, Gołyński Marcin
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Insect bite hypersensitivity remains a significant diagnostic challenge in equine practice, and clinicians now have two main testing options: intradermal testing (IDT), the traditional gold standard, and serum-based allergen-specific IgE assays, which offer practical advantages in horses that cannot be clipped or sedated reliably. Polish researchers compared these methods across 26 Malopolski horses with confirmed IBH over an eight-year period, using a panel of five insect allergens (Tabanus spp., Culicoides nubeculosus, Culex spp., Simulium equinum, and Stomoxys calcitrans) and found good correlation (0.413–0.589) between IDT and serum IgE testing for four of the five allergens tested. The in vitro serum assay demonstrated overall sensitivity of 72.6%, specificity of 63.6%, and diagnostic accuracy of 73.3% when compared to IDT, though individual allergen performance varied considerably (sensitivity range 30.8–91.3%). These findings suggest that serological testing based on monoclonal anti-IgE antibodies represents a reliable alternative for IBH diagnosis in most cases, potentially reducing the need for clipping and sedation whilst maintaining adequate diagnostic confidence—though practitioners should recognise that neither test is perfect, and negative results warrant clinical correlation with history and lesion distribution.
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Practical Takeaways
- •Serum IgE testing (MAST) can serve as a viable alternative to intradermal skin testing for diagnosing insect allergies in horses, offering convenience without loss of diagnostic accuracy
- •When using serum IgE testing, clinicians should be aware of the 72.6% sensitivity; negative results may warrant confirmation with intradermal testing if clinical suspicion remains high
- •Tabanus spp., Culicoides nubeculosus, Culex spp., and Simulium equinum show reliable correlation between both testing methods, making either approach appropriate for identifying these allergens
Key Findings
- •Good agreement and correlation (rho 0.413-0.589) demonstrated between intradermal testing and serum IgE testing for 4 of 5 insect allergens tested
- •Overall sensitivity of allergen-specific IgE panel was 72.6% (range 30.8%-91.3%) compared to intradermal testing
- •Specificity of 63.6% (range 50%-70.1%) and accuracy of 73.3% (range 48%-88.5%) achieved with serological MAST compared to intradermal testing
- •Monoclonal antibody-based serum testing shows promise as an alternative to intradermal testing for insect allergen identification in horses with IBH