Study suggests sputum cytology may aid canine blastomycosis dx

A new canine blastomycosis paper is drawing attention to an old-fashioned sample type that may be easy to overlook: sputum. In a 2026 retrospective study, researchers reported that cytology of spontaneously expectorated sputum identified Blastomyces yeasts in six of 16 dogs evaluated, and those six dogs were all within the subgroup of seven dogs with confirmed blastomycosis. The study, discussed in a recent VETgirl podcast, suggests sputum could occasionally provide a quick, minimally invasive path to diagnosis in dogs with pulmonary disease and a productive cough. (pmc.ncbi.nlm.nih.gov)

That matters because blastomycosis remains a regionally important fungal disease in dogs, especially in endemic areas of North America, and diagnosis can be challenging when patients present with respiratory distress. Definitive diagnosis still rests on identifying the organism cytologically or histopathologically, but clinicians often rely on urine antigen testing because it is sensitive and easier to obtain. Earlier work has shown urine antigen detection sensitivity in dogs in the low-to-mid 90% range, though cross-reactivity, especially with histoplasmosis, remains a known limitation. (pubmed.ncbi.nlm.nih.gov)

The new study was authored by Chloe C. Apelgren and colleagues from UW–Madison and the University of Minnesota and published June 11, 2026, in the Journal of Veterinary Emergency and Critical Care. Investigators retrospectively identified 16 client-owned dogs in which sputum produced by spontaneous expectoration was submitted for cytology. According to the abstract, seven dogs ultimately met the study’s standard for confirmed blastomycosis, based on positive Blastomyces EIA, non-sputum cytology, or necropsy findings, while nine dogs had negative confirmatory testing. Sputum cytology detected yeasts in six of the seven confirmed cases. (pmc.ncbi.nlm.nih.gov)

What the paper does not show is that sputum should replace existing diagnostics. The sample size was very small, and the study population was limited to dogs that were already producing sputum, which narrows real-world applicability. It also doesn’t change the broader evidence base showing that bronchoalveolar lavage, transtracheal sampling, transthoracic aspirates, and antigen testing remain core tools in pulmonary blastomycosis workups. Prior veterinary studies have supported non-BAL options in unstable patients, while human literature similarly suggests sputum can be useful in pulmonary blastomycosis, even if BAL often has higher yield. (pubmed.ncbi.nlm.nih.gov)

Industry reaction so far appears to be educational rather than commercial. The VETgirl episode framed the study as a practical diagnostic pearl for clinicians, not a standard-of-care overhaul, and emphasized the question many frontline teams face: can a sample the dog is already producing help avoid a more invasive procedure? That framing fits the paper’s own conclusion, which described sputum cytology as a minimally invasive option that may be useful in endemic areas, while still leaving room for confirmatory testing. (podcasts.apple.com)

Why it matters: For veterinary professionals, this is less about a new test than about a new decision point. In a coughing dog from a blastomycosis-endemic area, especially one that is tachypneic or a poor anesthesia candidate, sputum cytology may be worth adding early if productive material is readily available. A positive result could accelerate antifungal decision-making and reduce the need for riskier sampling. But a negative result should not reassure clinicians too much, given the study’s size and design, and urine antigen testing, imaging, and other cytologic or histopathologic approaches remain essential parts of the diagnostic picture. (pubmed.ncbi.nlm.nih.gov)

There’s also a workflow implication for general practice and emergency teams: someone has to recognize that the coughed-up material is diagnostically valuable, collect it appropriately, and get it to a clinical pathologist quickly. That may sound simple, but in busy settings, sputum is easy to dismiss as incidental. This study argues it may sometimes be actionable, particularly when every hour matters and more invasive diagnostics are not immediately feasible. (pmc.ncbi.nlm.nih.gov)

What to watch: The next step is better definition of performance, ideally in larger prospective studies that compare sputum cytology directly with urine antigen testing, BAL, transtracheal sampling, and clinical outcomes, so clinicians can understand when this low-tech option is most likely to help, and when it isn’t. (pmc.ncbi.nlm.nih.gov)