Intradermal Skin Testing May Not Be Reliable for Diagnosing Heaves

Allergens in the pasture and barn are believed to trigger chronic obstructive pulmonary disease (COPD or heaves) in horses. It is unclear whether simply developing an allergy leads to COPD, or if a horse must
be born susceptible to the disease. In an attempt to answer this question, researchers at The Ohio State University recently gathered 38 horses, some with and some without COPD, and tested them for allergies using standard intradermal skin testing with 73 common allergens.

The results indicated that horses with COPD were no more likely to have positive reactions to allergy testing (proven allergies) than horses without the disease. In fact, horses without COPD had a greater number of positive reactions, despite being clinically normal. These findings suggest that developing an allergy to an environmental antigen alone is not enough to trigger COPD. It might be that horses with COPD inherit some unknown susceptibility to the disease, which is then triggered by antigens in the environment. Until the genetics of COPD are better understood, positive intradermal skin test results must be interpreted with caution.

American Journal of Veterinary Research, 62(3), 389-397, 2001.

About the Author

Susan Piscopo, DVM, PhD

Susan Piscopo, DVM, PhD, is a free-lance writer in the biomedical sciences. She practiced veterinary medicine in North Carolina before accepting a fellowship to pursue a PhD in physiology at North Carolina State University. She lives in northern New Jersey with her husband and two sons.

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