Evaluation of intradermal mould antigen testing in the diagnosis of equine chronic obstructive pulmonary disease.

Intradermal end-point titres for commercial aqueous extracts of Micropolyspora faeni, Thermoactinomyces vulgaris and Aspergillus fumigatus were determined in control and chronic obstructive pulmonary disease (COPD) affected horses. The intradermal end-point titres of control and COPD-affected horses were not significantly different and values for individual horses for M. faeni, A. fumigatus and T. vulgaris were not correlated with the pulmonary dysfunction or with the bronchoalveolar lavage fluid neutrophilia which had been induced by previous inhalation challenges with these antigens and by 'natural (hay and straw) challenges'. These findings suggest divergence of the dermal and pulmonary reactivities to M. faeni, A. fumigatus and T. vulgaris in the horse and indicate that intradermal mould antigen testing is of limited value in the investigation of equine COPD.