Various combinations of tests are used to confirm the diagnosis of canine sino-nasal
aspergillosis (SNA) because false-positive and false-negative results can occur with each test. Therefore, the aim of this study was to evaluate whether detection of
fungal DNA in blood and nasal tissue samples was of value in the clinical diagnosis of this disease. Four groups were included in the study (dogs with SNA, lymphoplasmacytic
rhinitis or nasal
neoplasia, and control animals). Real-time PCR assays detecting
DNA from all Penicillium and Aspergillus species (PenAsp assay) or species-specific
DNA from A. fumigatus, A. terreus, A. flavus and A. niger were applied to whole blood and nasal tissue samples. Results obtained by PCR were compared between the groups. Sensitivity, specificity, positive and negative predictive values (PPV and NPV) for
fungal DNA detection were compared with those for alternative diagnostic procedures including histopathology, serology and fungal culture. Significantly more
fungal DNA was detected by the PenAsp assay in tissue biopsies from dogs with SNA than in the three other groups. Sensitivity, specificity, PPV and NPV for this method were 1.00, 0.06, 0.32 and 1.00. A. fumigatus
DNA was detected in seven tissue biopsies from dogs with SNA and in one biopsy from a dog with a nasal tumour. Sensitivity, specificity, PPV and NPV for this diagnostic test were 0.50, 0.97, 0.87 and 0.82. No significant difference was found between the groups with respect to the amount of
DNA detected in blood by the PenAsp assay. Sensitivity, specificity, PPV and NPV for this method were 0.71, 0.24, 0.31 and 0.64. A. fumigatus
DNA was detected in the blood of three dogs with SNA and sixteen dogs without SNA. Sensitivity, specificity, PPV and NPV for this diagnostic tool were 0.21, 0.45, 0.15 and 0.54. Detection of A. fumigatus
DNA in nasal tissue had the highest specificity, PPV and NPV but sensitivity of this method was low. Detection of
fungal DNA in whole blood was of no value in the diagnosis of SNA.