Polar bears kept in captivity are known to be vulnerable to opportunistic pathogens that are not present in their natural environments. In early 2017 a four month old polar bear (Ursus maritimus) in Tierpark Zoo, Germany was suffering from diarrhoea and loss of appetite and subsequently died three days later. Routine pathology and diagnostic tests were inconclusive although a viral infection was suspected. In this study we investigated tissue and blood samples taken for the presence of viral pathogens using high throughput sequencing (HTS) coupled viral culturing. From the results, we identify a novel adenovirus present whose DNA was present in varying amounts in all tissue and blood samples tested.