Utility of Cytology of Spontaneously Expectorated Sputum Samples in the Diagnosis of Blastomycosis in Dogs.

backgroundBlastomycosis is a regionally important fungal infection primarily affecting dogs. Blastomyces enzyme immunoassay (EIA) on urine is commonly used for diagnosis but often takes days to report results. Cytopathology has been described as a method of definitive diagnosis when lesions are available for sampling. Dogs with pulmonary blastomycosis may have a productive cough, and sputum cytology could potentially be used for confirmation of Blastomyces infection in dogs. KEY

findingsSixteen client-owned dogs with cytology performed on spontaneously expectorated sputum samples were identified on retrospective review of records from two university teaching institutions. Blastomyces yeasts were seen in six of 16 dogs on sputum cytology. Of these 16 dogs, seven were diagnosed with blastomycosis via Blastomyces EIA, while nine dogs had negative Blastomyces EIA, non-sputum cytology, or necropsy. All six dogs with Blastomyces yeast identified on spontaneously produced sputum samples were among the seven dogs with confirmed blastomycosis EIA. SIGNIFICANCE: Cytology performed on spontaneously expectorated sputum samples can identify Blastomyces organisms in dogs with a productive cough. This novel diagnostic technique could be further evaluated to determine its use for earlier diagnosis and to determine its sensitivity and specificity.