Intradermal testing in healthy horses and horses with chronic obstructive pulmonary disease, recurrent urticaria, or allergic dermatitis.

The research paper investigates the allergic reactions to intradermally injected allergens in healthy horses and those with chronic obstructive pulmonary disease, recurrent urticaria and allergic dermatitis, and finds that affected horses are significantly more likely to show positive reactions to a higher variety of these allergens.

Objective and Methodology

• The objective of the study was to compare the allergic responses of healthy horses with those suffering from three different diseases: Chronic Obstructive Pulmonary Disease (COPD), Recurrent Urticaria (RU), and Allergic Dermatitis (also known as Atopic Dermatitis-Insect Hypersensitivity).
• A case-control study was conducted involving 86 horses to measure and compare their results from intradermal allergen testing.
• The testing involved the injection of various allergens, including molds, weeds, trees, grasses-crops, and insects, under the skin of the horses’ necks.

Results

• Findings show that horses with the aforementioned diseases display significantly more positive (defined as ≥ 3+) reactions to the injected allergens.
• The reactions were measured at different time intervals post-exposure: 30 minutes (immediate reactions), 4 hours (late-phase reactions), and 24 hours (delayed-phase reactions).
• Not just were there more reactions, but the variety of allergens causing these reactions was also significantly higher in diseased horses compared to healthy ones.

Conclusions

• The study concludes that a single reactionary allergen should not be used to conclude that a horse has hypersensitivity. Instead, the overall pattern of reactivity to multiple allergens should be considered.
• These patterns can aid in managing the horses’ diseases, but they should be considered together with the horse’s history and with evidence of exposure to potential allergens.
• The research provides important insights regarding environmental allergen hypersensitivity in horses, making a significant contribution to veterinary allergology by imposing the need of a more comprehensive approach for the diagnosis and management of equine allergies.