2016 ACVIM Forum Research Abstract Program

In the population studied, a diagnosis of IAD was established in 84% of cases. A positive fungal culture was obtained in 49% of IAD+ cases and in 44% of IAD-cases. The most commonly isolated fungus were Aspergillus sp, Penicillium and Rhizomucor. No relationship could be established between positive mycology and cytologic evidence of fungal elements or active proliferation of fungi in the airways. However horses with fungal elements on the TW cytology had 3.8 more chances of having IAD than horses with no fungi (OR=3.8; 95% CI 1.8-7.8; P = 0.0003). Twenty IAD horses had signs of fungal proliferation in their TW and/or BAL, but all mycologies remained negative in these cases. Distinctive respiratory clinical signs such as cough, breathlessness or nasal discharge showed low sensitivity and high specificity for IAD diagnosis. Concomitant bacterial infection did not increase the risk of fungal isolation. The degree of inflammation (% inflammatory cells in BAL) was higher when horses were housed indoors, bedded on straw versus shavings (Mann-Whitney test, 25.53 + /-17.14 versus 19.9 + /-17.5; P < 0.001) or fed dry hay versus steamed hay (23.2 + /-17.5 versus 18.8 + /-18.9; P < 0.001).