Abstract

A 4-month-old North American river otter (Lontra canadensis) was unexpectedly found dead. Significant findings at necropsy included severe palmar/plantar ulceration, oral ulcers, interstitial pneumonia and pericardial and pleural effusion. Oral and skin lesions were the result of necrotizing vasculitis that was associated with endothelial intranuclear viral inclusions. DNA sequence was amplified by PCR from multiple tissues, including brain, liver, spleen, kidney and skin, using degenerate primers designed against adenoviral polymerase and hexon genes. Sequence analysis identified this as a novel adenovirus in the genus Mastadenovirus; California sea lion adenovirus-1 and bat adenovirus were identified as closest relatives, which shared 73% and 74% identity, respectively, to the novel otter adenovirus DNA polymerase gene. Ultrastructural analysis revealed icosahedral viral particles with a diameter of 60–80 nm, compatible with adenovirus, within the cytoplasm and nuclei of endothelial cells. In addition to the viral-associated vasculitis, there was diffuse alveolar damage with hyaline membrane formation in the lungs; viral inclusion bodies were not identified in these lesions. A source of the viral infection was not identified; conspecifics co-housed with the affected individual, including the dam and two littermates, were either negative for adenoviral DNA or remained asymptomatic.