Pathological study of an open Patent Ductus Arteriosus (PDA) in a 20-year-old Killer Whale (Orcinus orca)

Abstract

The ductus arteriosus is an anatomical structure present in the fetal heart which closes during the first months of life, in the case of humans, to ensure the proper function of the cardiovascular system. In cetaceans, more specifically in bottlenose dolphins, this structure is open at time of birth, stays open for months in yearlings, and closes during the first years of life. Therefore, reported cases of a patent ductus arteriosus (PDA) in juveniles and/or adult cetaceans are extremely rare, either in wildlife or in captivity (under human care). Herewith we describe the diagnosis of a PDA in a 20-year-old female Killer Whale (Orcinus orca). A complete pathological study was carried out. Necropsy and histology showed that the animal suffered a cardiovascular anomaly from birth classified as congenital/development heart defect. She presented a large and open PDA associated with lesions consistent with severe chronic pulmonary hypertension connected with chronic heart lesions affecting systemically to other organs which ultimately led to heart failure and death. To our best knowledge, this is the first time where an open PDA and the associated chronic systemic pathology, in a 20-year-old Killer Whale (Orcinus orca) which was born in captivity, is reported.