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

Objective-To compare responses to a variety of intradermally injected aller gens among healthy horses and horses with chronic obstructive pulmonary dis ease (COPD, recurrent urticaria (RU), and atopic dermatitis-insect hypersen sitivity allergic dermatitis [AD]). Design-Case-control study. Animals-86 horses. Procedure-Results of intradermal testing for horses with COPD, RU, or AD we re compared with results for healthy horses, Results-Compared with healthy horses, horses with COPD, RU, and AD were sig nificantly more likely to have positive (greater than or equal to3+) reacti ons to intradermal allergens (molds, weeds, trees, grasses-crops, and insec ts) 30 minutes (immediate reaction), 4 hours (late-phase reactions), and 24 hours (delayed-phase reactions) after exposure. In addition, diseased hors es reacted to a significantly higher number of allergens in each allergen g roup than did healthy horses. Conclusions and Clinical Relevance-Reactions to individual allergens should not be used to determine that horses have hypersensitivity. Overall patter ns of reactivity to intradermal allergens may be helpful in management when used in conjunction with a compatible history and evidence of potential ex posure to allergens in horses with conditions associated with hypersensitiv ity to environmental allergens.