Results of intradermal tests in horses without atopy and horses with atopic dermatitis or recurrent urticaria.

The research investigated the results of intradermal tests for environmental allergens in horses to compare responses in horses without atopic conditions, with recurrent urticaria, or with atopic dermatitis. The research found that horses with dermatitis or urticaria had a greater number of positive reactions, suggesting these conditions involve type-I IgE-mediated hypersensitivity. The results also help identify specific allergens for formulating immunotherapy strategies and allergen avoidance measures.

Methodology

• The study involved a total of 39 horses, divided into three groups: 22 horses without any atopic conditions (non-atopic), 10 horses with Recurrent Urticaria (RU), and 7 horses with Atopic Dermatitis (AD).
• For all the horses, the researchers obtained their medical history and conducted a physical examination, hematologic examination, serum biochemical analyses, and an examination of bronchoalveolar lavage fluid, which is a diagnostic method often used for respiratory diseases.
• The intradermal tests (IDT) were performed on each of the horses, using 73 different environmental allergens.

Findings

• Horses with AD or RU showed a significantly higher average number of positive reactions to the intradermal tests compared to non-atopic horses, thus providing evidence of type-I IgE-mediated hypersensitivity in these conditions.
• In all allergen groups and at all time intervals, horses with AD had a significantly higher number of positive reactions than non-atopic horses, except for mold allergens at 4 and 24 hours.
• Horses with RU also showed a greater number of positive reactions than non-atopic horses in all allergen groups, with the exception of molds at 30 minutes, 4 hours, and 6 hours; trees at 4 hours and 6 hours; and grasses at 4 hours.

Conclusion and Implications

• The study concluded that the significantly higher number of positive reactions for IDT in horses with either AD or RU compared to non-atopic horses provides evidence for the involvement of type-I IgE-mediated hypersensitivity.
• The results of the study could be beneficial in determining specific allergens that trigger reactions in horses with AD or RU. This can be used to formulate immunotherapy strategies, as well as to provide basis for creating effective avoidance strategies for different allergens.