Computed tomography (CT) is increasingly available for zoo species to aid in health assessment. Best CT interpretation is facilitated by establishment of species-specific CT baselines in health. Multi-detector CT (MDCT) provides high-quality images in a short time, eliminating the need for anesthesia in some patients.2 MDCT scans were performed in clinically healthy, nonanesthetized, standing little blue penguins (Eudyptula minor) to establish normal reference ranges for air sac and lung volumes and lung density. Unexpectedly, five out of 15 clinically normal penguins were diagnosed with pulmonary granulomas on initial MDCT scans. Granulomas were not visible on radiographs, even in cases where the entire normal pulmonary parenchymal architecture was effaced on the MDCT scan. In one penguin with suspected aspergillosis, granuloma regression was documented on serial MDCT scans after treatment with antifungal medications; however, follow-up MDCT scans in the remaining four penguins with granulomas revealed progression in granuloma size and numbers. Additional testing led to the diagnosis of mycobacteriosis in multiple birds. Serial MDCT scans in this cohort enabled detection of lesions prior to development of clinical disease and facilitated adequate localization for fine-needle aspiration of granulomas. Mycobacteriosis treatment was initiated early, and response to therapy was monitored by serial MDCT scans with minimal patient risk. Based on experience, nonanesthetized MDCT scans are a well-tolerated, noninvasive test modality that provides real-time results for otherwise difficult-to-diagnose diseases such as aspergillosis and mycobacteriosis in some penguins.1,3
The authors thank Raphael Costa, LVT for his expertise in operating the CT scanner and essential assistance in obtaining CT scans of the birds. Additionally, authors are grateful to the radiation oncology department at the Animal Medical Center for generously allowing use of their radiation planning software for volumetric and density measurements. Finally, authors thank the ornithology department at the Bronx Zoo, particularly supervisor Susan Schmidt, for their care of the birds and for their assistance in completion of this project.
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2. Marinkovich M, Quesenberry K, Donovan TA, Le Roux AB. Use of a standing computed tomography scan to aid in the diagnosis of a pulmonary adenocarcinoma in a scarlet macaw (Ara macao). J Exot Pet Med. In press.
3. Wallace R. Sphenisciformes (penguins). In: Miller RE, Fowler ME, eds. Fowler’s Zoo and Wild Animal Medicine. Vol. 8. St. Louis, MO: Elsevier Saunders; 2014:82–88.