Retrospective pathological survey of pulmonary disease in free-ranging Amazon river dolphin Inia geoffrensis and tucuxi Sotalia fluviatilis

Abstract

The Amazon river dolphin Inia geoffrensis and tucuxi Sotalia fluviatilis are classified as Data Deficient species. Despite very limited knowledge on health and disease aspects of these species, the main threats to their conservation include incidental mortality in fishing gear, population fragmentation, habitat loss and environmental pollution. It is also suggested that underlying diseases may contribute to their mortality rates. Herein, we retrospectively describe gross and microscopic pulmonary lesions in free-ranging I. geoffrensis (n = 24) and S. fluviatilis (n = 28) found dead. Nearly 85% of the examined animals presented some kind of primary lung disease, wherein the main etiological diagnoses were verminous pneumonia by Halocercus brasiliensis (25%), bacterial pneumonia (25%) and a single case of meconium aspiration syndrome (1.9%). An etiology was not determined in 36.5% (19/52) of animals. These results indicate a high incidence of pulmonary pathology in these species, raising concerns about population impacts and potential zoonotic implications in some instances. These data may provide a scientific basis for future medical and conservation efforts focused on Amazonian dolphins.