Results of intradermal tests in horses without atopy and horses with chronic obstructive pulmonary disease

Objective-To compare results of intradermal tests (IDT), conducted using en vironmental allergens, in horses without atopy and horses with chronic obst ructive pulmonary disease (COPD). Animals-38 horses (22 horses without atopy and 16 horses with COPD). Procedure-All horses were examined (physical examination, hematologic exami nation, serum biochemical analyses, examination of bronchoalveolar lavage f luid). An IDT was conducted, using a full panel of 73 allergens consisting of grasses, weeds, trees, molds, and insects. Results of the IDT were evalu ated 30 minutes and 4, 6, and 24 hours after injection of allergens. Horses without atopy were euthanatized, and gross and histologic changes of lung parenchyma were assessed. Results-Horses without atopy had a greater number of positive immediate and late-phase reactions than did horses with COPD. Horses with COPD did not h ave a significantly greater number of positive reactions than horses withou t atopy at any time period for any allergen group (grasses, weeds, trees, m olds, and insects). Conclusions and Clinical Relevance-Positive results of IDT document allerge n-specific hypersensitivity but do not necessarily distinguish clinically r elevant reactions from subclinical reactivity in horses with COPD. Interpre ting the clinical relevance of results of IDT requires a thorough knowledge of the medical history, physical examination findings, and environment of each animal.