Radiographic findings in dogs with pulmonary blastomycosis: 125 cases (1989-2006)

Objective - To identify radiographic patterns in dogs with pulmonary blastomycosis and radiographic factors associated with outcome. Design - Retrospective case series. Animals - 125 dogs with pulmonary blastomycosis. Procedures - Medical records were reviewed, and for each lung lobe, the primary radiographic pattern and percentage of lobar involvement at the time of initial examination were recorded. Results - 79 dogs survived, 38 died, and 8 were euthanized without treatment. The initial radiographic pattern was variable and not significantly associated with outcome. Mean half-time for radiographic resolution of pulmonary infiltrates was 41.4 days for all patterns except masses, for which mean half-time to resolution was 90.8 days. Transient radiographic worsening was seen in 20 of 87 (23%) dogs but was not associated with a poor prognosis. Pulmonary bullae were seen in 20 (16%) dogs, most often in association with an alveolar pattern. Accuracy of using percentage of right caudal lung lobe involvement (≤ 20% vs > 20%) to predict outcome was 74.4%; accuracy of using number of affected lobes (< 4 vs ≥ 4) to predict outcome was 65.8%. Conclusions and Clinical Relevance - Results suggested that a nonuniform distribution of pulmonary infiltrates was equally as likely as a diffuse nodular interstitial pattern in dogs with pulmonary blastomycosis. On the basis of half-time for resolution of pulmonary infiltrates, follow-up radiography should be performed no more often than every 4 to 6 weeks in clinically stable patients. Transient radiographic worsening that occurred during the initial weeks of treatment was not associated with a poorer prognosis.