Project description:This study investigates the occurrence of erythematous lip lesions in a captive sun bear population in Cambodia, including the progression of cheilitis to squamous cell carcinoma, and the presence of Ursid gammaherpesvirus 1. Visual assessment conducted in 2015 and 2016 recorded the prevalence and severity of lesions. Opportunistic sampling for disease testing was conducted on a subset of 39 sun bears, with histopathological examination of lip and tongue biopsies and PCR testing of oral swabs and tissue biopsies collected during health examinations. Lip lesions were similarly prevalent in 2015 (66.0%) and 2016 (68.3%). Degradation of lip lesion severity was seen between 2015 and 2016, and the odds of having lip lesions, having more severe lip lesions, and having lip lesion degradation over time, all increased with age. Cheilitis was found in all lip lesion biopsies, with histological confirmation of squamous cell carcinoma in 64.5% of cases. Single biopsies frequently showed progression from dysplasia to neoplasia. Eighteen of 31 sun bears (58.1%) had at least one sample positive for Ursid gammaherpesvirus 1. The virus was detected in sun bears with and without lip lesions, however due to case selection being strongly biased towards those showing lip lesions it was not possible to test for association between Ursid gammaherpesvirus 1 and lip squamous cell carcinoma. Given gammaherpesviruses can play a role in cancer development under certain conditions in other species, we believe further investigation into Ursid gammaherpesvirus 1 as one of a number of possible co-factors in the progression of lip lesions to squamous cell carcinoma is warranted. This study highlights the progressively neoplastic nature of this lip lesion syndrome in sun bears which has consequences for captive and re-release management. Similarly, the detection of Ursid gammaherpesvirus 1 should be considered in pre-release risk analyses, at least until data is available on the prevalence of the virus in wild sun bears.

Project description:Early and accurate diagnosis of pulmonary tuberculosis (TB) is key to effective outbreak management, and in humans thoracic radiography is used extensively for screening purposes. In wildlife TB radiography is a relatively accessible diagnostic tool, particularly in under-resourced settings, however its use is limited by body size. Sun bears are susceptible to human-associated TB, and their small body size makes thoracic radiography feasible. However, there are no established guidelines on normal thoracic radiographs or radiographic manifestations of TB in this species. We provide a first description of thoracic radiographs from healthy and TB affected sun bears at a bear rescue sanctuary, including correlation with postmortem results for a subset of bears. Findings of two veterinary radiologists, blinded to clinical information, revealed high agreement on broad categorization of radiographic studies as normal, abnormal, or needing correlation with further information. Agreement was lower for the presence of specific lung patterns, reflecting inherent subjectivity when classifying these features. Very few studies were identified as definitively normal, however definitively abnormal studies were significantly associated with TB cases. Diffuse bronchial and/or bronchointerstitital lung patterns were commonly reported, with a high proportion needing correlation with age and/or clinical signs to further interpret. Interstitial, interstitial-to-alveolar, alveolar and nodular lung patterns, along with radiographic signs of lymphadenomegaly and pleural fluid, were almost exclusively found in TB cases, however the sensitivity of the presence of any of these changes for detecting TB was below 70%. Radiographic reporting of thoracic lymph node enlargement detected at postmortem was low (4/17; 23%), and aortic outflow tract dilation and positional atelectasis were differential diagnoses for radiographic changes that could also represent TB. Together these findings demonstrate the importance of developing species-specific criteria for interpretation, to differentiate between common findings and manifestations of TB, and to highlight areas where radiographic techniques can be optimized to assist this. Given TB remains a global health challenge in humans and other animals (wild or domestic), and detection is key to control, we recommend development of standardized approaches to radiographic studies and their interpretation to bolster diagnostic pathways for detecting TB in sun bears, and other novel or understudied hosts.

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Helarctos malayanus

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