Tracheobronchial Lymphadenopathy in Dogs with Pulmonary Coccidioidomycosis

Abstract: Background: Tracheobronchial lymphadenopathy (TBL) is a common radiographic finding in dogs with pulmonary coccidioidomycosis. The time-to-resolution and predictive variables of this clinical finding remain unexplored in dogs.
Hypothesis/Objectives: To determine whether any baseline variables are associated with time-to-resolution of TBL after initiation of treatment with fluconazole.
Animals: Thirty-two client-owned dogs with newly diagnosed pulmonary coccidioidomycosis.
Methods: Prospective cohort study. Thoracic radiographs and other diagnostic tests were performed at baseline and once every 3 months after initiation of fluconazole administration until remission or for a maximum of 12 months. Severity of radiographic TBL was evaluated with a subjective and semi-objective classification scheme.
Results: Twenty-five (78%) dogs had TBL present on baseline radiographs. Resolution of TBL occurred in most dogs within 3 (72%, 18/25) to 6 months (80%, 20/25) of starting fluconazole administration. Only 1 (4%) dog failed to have TBL resolve within the study period. The median time-to-resolution of TBL was 96 days (range, 72-386 days). Cox’s proportional hazard univariate analysis identified increasing TBL severity (hazard ratio [HR] = 0.40, 95% CI, 0.19-0.84, P = 0.02) and semi-objective size, length:T4 vertebral body ratio (HR = 0.41, 95% CI, 0.20-0.82, P = 0.01) as variables associated with longer time-to-resolution.
Conclusions and clinical importance: Radiographic TBL should resolve in most dogs with pulmonary coccidioidomycosis within 3-6 months of initiating fluconazole administration. Dogs with larger radiographic tracheobronchial lymph nodes at the time of diagnosis have a higher likelihood of taking longer to resolve after initiating fluconazole treatment.