A Comparison of Intradermal Skin Testing and Serum Insect Allergen-specific IgE Determination in Horses With Insect Bite Hypersensitivity From 2008 to 2016.

This research investigated allergy testing methods in horses, specifically comparing intradermal skin tests (IDTs) and multiple allergen simultaneous tests (MASTs) for insect bite hypersensitivity. Results indicated a good correlation between these tests for four of the tested allergens, with overall sensitivity of 72.6% and accuracy of 73.3%.

Context and Purpose of the Research

• The study aims to compare two methods primarily used to diagnose allergies in horses: the in vivo Intradermal Tests (IDTs) and the in vitro method, Multiple Allergen Simultaneous Testing (MASTs).
• These tests are specifically used to determine sensitivity to insect allergens, a common source of hypersensitivity in the equine population.
• The purpose of the research was to establish if one method was superior, or if both tests provided comparable results, thus enabling more flexibility and choice in diagnostic methods.

Methods

• The research was conducted utilizing horses of the Malopolski breed that demonstrated sensitivity to insects, specifically Insect Bite Hypersensitivity (IBH).
• The IDTs were performed between the years 2008-2016, alongside the MASTs which measured allergen-specific IgE serum concentrations using a monoclonal anti-IgE antibody.
• Allergens tested were Tabanus spp., Culicoides nubeculosus, mosquito (Culex spp.), Simulium equinum, and Stomoxys calcitrans.

Results and Interpretation

• The correlation between the IDTs and MASTs revealed strong agreement for four out of the five tested allergens (all except Stomoxys calcitrans).
• The correlation from the tests ranged between 0.413-0.589, indicating a moderate positive relationship between the two testing methods.
• Overall completeness (sensitivity) of the IgE insect horse panel from the MASTs compared to IDTs was 72.6%, specificity was 63.6%, and accuracy was 73.3%.
• In conclusion, MASTs seem to provide a reasonable alternative to IDTs for diagnosing insect bite hypersensitivity in horses.

Implications and Conclusions

• The study concludes that the newer technology MASTs are similarly effective as the traditional IDTs.
• Choosing either IDTs or MASTs for diagnosing IBH in horses can therefore be based on the convenience and resources available rather than effectiveness of the test.
• Further research could focus on improving the correlation for the allergen Stomoxys calcitrans and investigating the sensitivity and accuracy of both techniques with other allergens.