Disseminated Blastomycosis in a 3-year-old Doberman Pinscher
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A 3-year-old Doberman Pinscher was presented to the Cornell Anatomic Pathology Service on October 3, 2016 following euthanasia for suspected disseminated mycotic infection. The patient lived in the Adirondacks and had a 9-month history of progressive bilateral carpal effusion and lameness, and a 5-month history of coughing and sneezing. He was referred to Cornell’s Emergency Service for respiratory distress. Radiographs obtained by the referring
veterinarian showed aggressive bone lesions in the radius and ulna of both thoracic limbs, and a diffuse miliary nodular lung pattern. Given the severity of his clinical signs and that Blastomyces is endemic in the Adirondacks, he was euthanized due to a poor prognosis.
Complete post-mortem examination confirmed the radiographic findings in the lungs and forelimbs. Impressions smears of the lungs and carpal effusion revealed large numbers of 10-12 um diameter yeast-like cells with thick double-contoured refractile walls and occasional single broad-based budding characteristic of Blastomyces dermatidis. Histopathology examination confirmed the presumptive diagnosis of severe granulomatous bronchopneumonia together with a similar inflammatory process of the subcutaneous soft tissues surrounding the carpal joints that also involved the draining axillary lymph node with bilateral osteomyelitis of the distal radius, ulna and areas of the calvaria.
Blastomyces dermatitidis is a saprophytic, dimorphic fungus, endemic to certain areas of North America, especially along river valleys and lakes. In the environment, B. dermatitidis forms conidia which are inhaled by the host, and transforms into yeast within infected tissues. Dissemination to other organs occurs via hematogenous or lymphatic spread, with lymph nodes, eyes, skin, bones, subcutaneous tissues, and prostate being the most commonly affected tissues in dogs. Clinical signs vary depending on the affected organs, but respiratory signs are most common. This case presentation will discuss imaging, gross and histologic findings of disseminated blastomycosis in a dog.