Significant Morbidity and Mortality Findings in Gibbons (Hylobates and Nomascus spp.) Housed at the Smithsonian National Zoological Park
American Association of Zoo Veterinarians Conference 2011
Jennifer P. Gilbert1, BA; Jessica L. Siegal-Willott2, DVM, DACZM; Lee Ann Hayek2, PhD; Suzan Murray2, DVM, DACZM; Tabitha Viner3, DVM, DACVP
1Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, USA; 2National Zoological Park, Smithsonian Institution, Washington, DC, USA; 3National Fish and Wildlife Forensics Lab, U.S. Fish and Wildlife Service, Ashland, OR, USA


Gibbon apes (Hylobates and Nomascus spp.) are vulnerable or endangered.1,2 Knowledge of medical, husbandry, and nutritional issues in captive gibbons will ultimately aid in global conservation efforts.3 To evaluate significant medical concerns in the Smithsonian National Zoological Park (NZP) collection, a retrospective study was conducted on 68 gibbon apes during 1968–2009. The most common species was Nomascus leucogenys (previously known as H. leucogenys). Thirty-seven animals had incomplete or inaccessible records and were not included in the study. The medical records and necropsy reports on 31 captive gibbon apes were reviewed, and 318 cases of disease were identified. For all diseases and all body systems, the two age categories with the highest number of diseases were the geriatrics (21 to 41-year-old, 32%); and pubescents (5 to 10-year-old, 26%). Across all age groups, there were significantly (Fisher’s exact test, p=0.004) more gastrointestinal cases (41%), with parasites as the most frequently identified cause. Musculoskeletal cases accounted for 11% across all age groups, and dental disease accounted for 20% of cases across all age groups except infants. Pathology records of 12 of the 15 gibbons that died at NZP between 1968 and 2009 were reviewed. The age group most represented in this data set was infant gibbons (<2 years), representing 33% of all deaths reported. This information will help in overall captive management of gibbons at the NZP and will add to the SSP database on captive gibbon health and management.


The authors would like to thank the members of the primate team, Department of Animal Programs at the National Zoo for their care of these animals; and the Smithsonian Institution’s archival staff; as well as Lidya Montes, Management Support Specialist, for their assistance.

Literature Cited

1.  IUCN. 2010. IUCN Red List of Threatened Species. Version 2010.4. Accessed April 3, 2011.

2.  Geissmann T, Muller B. White-handed Gibbons Extinct in China. IUCN News. news/?1322/6. 2008. Accessed July 6, 2009. (VIN editor: link was not accessible as of 12/22/20.)

3.  Robbins PK. Gibbon SSP Report 2007. American Association of Zoo Veterinarians. 2007. Accessed June 21, 2009.


Speaker Information
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Jennifer P. Gilbert, BA
Cummings School of Veterinary Medicine
Tufts University
North Grafton, MA, USA

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