MORBIDITY AND MORTALITY REVIEW OF THE CAPTIVE EUROPEAN ASSOCIATION OF ZOOS AND AQUARIA EX-SITU PROGRAMME ORANGUTAN (PONGO SPECIES) POPULATION BETWEEN 2000 AND 2018.

Abstract

The morbidity and mortality analysis of captive orangutans (Pongo spp.) is of major interest to improve husbandry and welfare and to maintain a healthy and sustainable population. This study is a systemic, retrospective review of the morbidity and mortality data in orangutans in the European Association of Zoos and Aquaria Ex-situ Programme (EEP). Between 2000 and 2018, 233 orangutan deaths were reported and 121 postmortem reports from 45 institutions were available for analysis. Causes of death were classified by etiology and organ system. In addition, data were categorized and analyzed further by sex, species, and age. Morbidity data extracted from postmortem reports were classified by organ system. Postmortem reports were provided for 22 neonate (0-31 d old), 14 infant (31 d-2.5 yr old), 11 juvenile (2.5-9 yr old), 49 adult (9-40 yr old), and 25 geriatric (>40 yr old) orangutans. The most reported etiology was infectious-inflammatory (45.5%), except for neonates for whom the major cause of death was birth related (13.2%), mostly due to stillbirth. Overall, the most frequently affected organ system was the respiratory tract (27.7%), followed by generalized-multisystemic diseases (17.6%). A high prevalence of bronchopneumonia and airsacculitis in adults was recognized. Bacteria were the most frequently detected infectious agent. Cardiovascular diseases accounted for 10.1% of deaths, although cardiovascular lesions (myocardial fibrosis or atherosclerosis) were noticed in 80% of geriatric orangutans. Various organ systems were affected in geriatrics, with no particular tendency regarding the cause of death. Renal or urinary diseases were identified in half of individuals included in the comorbidity analysis. Sex (P = 0.51) and species (P = 0.77) had no particular influence over causes of death. This systemic pathology review emphasizes the importance of the standardization of postmortem reports and the systematization of data collection of orangutans across European zoos. Furthermore, the authors recommend close surveillance and research on respiratory diseases in the EEP orangutan population.