Abstract

Captive penguins are commonly affected with respiratory disease and are especially prone to fungal disease (e.g., aspergillosis), which may be difficult to detect and treat. In this prospective study, computed tomography (CT) was used to compare air sac and lung volumes in 25 Humboldt penguins (Spheniscus humboldti) in four different positions: awake ventral (V), anesthetized ventral (AV), anesthetized dorsal (AD), and anesthetized right lateral (ARL). This was performed to determine which position allowed for the greatest air sac and lung volumes, providing information on the most appropriate position for this species under anesthesia. Physiologic parameters under anesthesia were recorded in each position. Air sac and lung volumes were calculated from helical CT images using designated image analysis software. A repeated measures ANOVA was used to determine if air sac or lung volumes differed by position while controlling for recumbency order and sex. There was a significant difference in air sac volume by position; however, recumbency order and sex were not found to influence the results. Differences in air sac volume were found between V and AV, V and AD, AV and ARL, and AD and ARL. There was no difference between V and ARL air sac volumes. There was no significant difference in lung volume by position, and sex and recumbency order were not found to have a significant interaction. In conclusion, lung volumes were not affected by position; however, dorsal recumbency resulted in the lowest air sac volumes under anesthesia in spontaneous breathing Humboldt penguins.