Patent ductus arteriosus in capybaras (Hydrocoaerus hydrochaeris) – a case report

The ductus arteriosus (DA) is an arterial connection between the pulmonary arteries and the aorta and is essential during the fetal life of mammals. Minutes after birth, this duct begins to close, however, when this does not happen, blood flow remains, which characterizes the patent ductus arteriosus (PDA). Patients with PDA can present significant hemodynamic alterations, such as ventricular systolic dysfunction and congestive heart failure. However, they can live with this heart disease without any clinical signs, depending on the size of the duct, blood flow volume, and pressure between arteries. Currently, this is one of the most common congenital heart diseases among dogs, however it had never been reported among capybaras. Thus, the objective of the present study was to report the occurrence of PDA in a female, 1 year-old, 40.1-kg, free-living capybara. The animal underwent chemical restraint using dexmedetomidine (8.72 mcg/kg) and ketamine (7.48 mg/kg), intramuscularly. After restraint, the animal presented a heart frequency of 67 bpm, regular rhythm, invasive systolic, diastolic, and mean blood pressure of 105/92/77mmHg, respectively, and the echocardiographic examination showed the presence of a continuous turbulent flow within the pulmonary artery, with maximum velocity of 3.90 m/s and a pressure gradient of 60.96 mmHg, from left to right, which characterized the presence of a classic aorta-pulmonary PDA. Given that this was a free-living animal that did not present cardiac remodeling, nor alterations related to the PDA regarding the parameters of the echocardiographic examination, no intervention was conducted.