Thoracic Computed Tomographic Characteristics of Canine Blastomycosis

While thoracic radiographic studies have described the broad thoracic findings of canine blastomycosis, thoracic computed tomographic (CT) findings have been minimally reported. This single-center, retrospective, descriptive case series study aimed to characterize thoracic CT features of canine blastomycosis. CT studies of dogs diagnosed with blastomycosis with confirmed or presumed pulmonary involvement were included and reviewed by board-certified radiologists. A total of 23 dogs met the inclusion criteria. Soft-tissue-attenuating pulmonary parenchymal lesions (nodules, masses, or consolidation) were present in all patients, with nodules present in 20 of 23 (87.0%), consolidation in 15 of 23 (65.2%), and masses in seven of 23 (30.4%), with 21 of 23 dogs having mixed lesion types. Soft-tissue attenuations were present in multiple lung lobes in 21 of 23 patients (91.3%) with no specific lung lobe predilection. Concurrent ground-glass attenuation was common (21/23, 91.3%), predominantly with a diffuse distribution (11/21, 52.4%). Intrathoracic lymphadenomegaly was present in 17 of 23 cases (73.9%), most of which involved the tracheobronchial lymph nodes (TBLNs) and, uncommonly, involved the cranial mediastinal and sternal lymph nodes. TBLN enlargement often involved two nodes, with the middle and left TBLNs being the most frequently enlarged. The largest lymph node was contrast-enhanced in all cases of lymphadenomegaly, with the majority showing moderate heterogeneous enhancement. In conclusion, the most common thoracic CT findings in this patient population were multilobar pulmonary nodules and consolidation, often accompanied by diffuse ground-glass attenuation and tracheobronchial lymphadenomegaly.