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

This research article investigates the difference in responses to intradermal tests (IDT) between horses with chronic obstructive pulmonary disease (COPD) and horses without atopy, using a full panel of environmental allergens. The study found that horses without atopy had a higher number of positive reactions than horses with COPD, indicating that positive IDT results reveal allergen-specific hypersensitivity, but do not necessarily separate clinically significant reactions from subclinical reactivity in horses with COPD.

Method and Participants

• The study involved 38 horses, out of which 22 were without atopy and 16 had chronic obstructive pulmonary disease (COPD).
• Each horse underwent a thorough physical examination, a hematologic examination, serum biochemical analyses, and an examination of bronchoalveolar lavage fluid.
• An intradermal test (IDT) was conducted on all horses using a complete panel of 73 allergens. The allergens included a wide range of environmental elements such as grasses, weeds, trees, molds, and insects.

Procedure and Data Collection

• The IDT results were evaluated at four different time intervals: 30 minutes and 4, 6, and 24 hours after the injection of allergens.
• After testing, the horses without atopy were euthanized, and any gross and histologic changes in the lung parenchyma were noted and assessed.

Findings

• The results showed that horses without atopy experienced a higher number of positive immediate and late-phase reactions compared to horses with COPD.
• The data also showed that horses with COPD did not have a significantly higher number of positive reactions compared to horses without atopy for any of the allergen groups at any of the evaluated time intervals.

Conclusions

• Based on the study outcomes, the research concluded that positive results of IDT indicate allergen-specific hypersensitivity. However, these positive results do not necessarily differentiate between clinically relevant reactions and subclinical reactivity in horses with COPD.
• Thus, interpreting the clinical importance of IDT results needs an in-depth understanding of each animal’s medical history, the findings of the physical examination, and the specifics of the animal’s environment.