THE RADIOGRAPHIC AND ENDOSCOPIC ANATOMY AND DIGESTIVE MECHANISMS OF CAPTIVE AFRICAN PENGUINS (SPHENISCUS DEMERSUS).

The anatomy of the avian gastrointestinal (GI) tract is uniquely suited to each species' dietary requirements. African penguins (Spheniscus demersus) are charismatic and popular exhibit animals. As their prevalence grows, there is a need to understand their unique digestive tract to diagnose abnormalities. Reference material specific to the digestive tract of piscivores is scant, and knowledge of the GI tract of a healthy penguin is based on information from other birds. The purpose of this study is to determine the normal gross anatomy, transit time, and histopathologic structures of the penguin GI tract. Twelve clinically healthy penguins were selected for this study from the colony at the Maryland Zoo in Baltimore, which, at the time of this study, consisted of 55 birds. All penguins underwent a barium contrast study, and radiographic images were obtained until the entire GI tract was empty. Approximately 2 wk later, each penguin was anesthetized, and an endoscopic evaluation of the anterior GI tract was performed. Time from barium administration to defecation ranged from 17 to 70 min, and on average, barium clearance was 17.6 hr (range, 5-36 hr). Fluid from the ventriculus had an average pH of 2.75 and contained a mixed bacterial population. Koilin presence and thickness appreciated on endoscopy did not correspond with the thickness determined on histopathology. The results of this study provide a comparative baseline to use during diagnostic workups and help guide treatment decisions.

FACTORS AFFECTING ABNORMAL MOLTING IN THE MANAGED AFRICAN PENGUIN (SPHENISCUS DEMERSUS) POPULATION IN NORTH AMERICA.

Abnormal molting, including partial or incomplete molt, arrested molt cycle, or inappropriate frequency of molt, is a primary concern for the managed African penguin (Spheniscus demersus) population and is documented across institutions. To identify factors associated with increased odds of abnormal molts and characterize intervention opportunities, a comprehensive survey evaluating numerous husbandry and medical parameters was created. Survey results represent 45 North American African penguin holding facilities and 736 unique animals. Of these individuals, 135 (18.3%) demonstrated an abnormal molt over the 5-yr study period (2012-2017). Increased odds ratios for abnormal molt included biologic (age, sex, etc.), geographic (elevation, latitude), and husbandry (exhibit design, diet, etc.) variables. The mean age of affected animals was 15.2 yr (1-45 yr, n = 135) compared with 9.92 yr (4 mo-38 yr, n = 601) for unaffected animals. In addition, although statistically insignificant, males were overrepresented in the affected cohort compared with a near even distribution among unaffected animals. Identified factors with increased odds for abnormal molting included advanced age and facilities using freshwater pools. Normally molting penguins were more commonly found with saltwater pool access and natural lighting exposure. Anecdotal medical intervention attempts are discussed, although further research is needed to define their use. Of attempted interventions, subcutaneous 5.4-mg melatonin implants placed in anticipation of environmental molting cues showed the most promise at inducing catastrophic molt, with 14 of 17 (82.3%) of affected individuals molting normally following this treatment. Survey analysis indicated that abnormal molt is a complex, multifactorial process, and modifiable factors that may predispose animals to abnormally molt exist. Addressing these factors in future exhibit design may mitigate the prevalence of this condition. Despite these efforts, it is likely that medical interventions will be required to aid in the treatment of abnormal molting in this species.