Pentalogy of fallot in a Crioulo foal

ABSTRACT

Background: Cardiac anomalies account for 3.5% of congenital defects in horses. Tetralogy of Fallot (TOF) is characterized by ventricular septal defect, pulmonary stenosis, dextroposition the aorta and right ventricular hypertrophy secondary. Pentalogy of Fallot (POF) is a variation and is characterized by a defect in the right atrioventricular valve or persistence of the ductus arteriosus, in addition to the other defects observed in tetralogy. Affected animals usually have stunted growth, exercise intolerance, weakness, lethargy, cyanosis, dyspnea and syncope. The aim of this study was to describe a case of POF, as diagnosed in a Crioulo foal in southern Brazil. Case Clinical signs were observed at the fifth day of life and were characterized by cyanosis, intense tracheal stertor, tachycardia, marked heart murmur, HR 160 bpm, RR 80 breaths/min, T 39.8C and syncope. These signs worsened with physical activity. Endoscopic evaluation of the upper airways revealed no anatomical conformation changes or tissue dysfunction. A cardiac ultrasound showed a loss of continuity of the interventricular septum, right ventricular wall thickening and a hyperechoic appearance of the area where the right atrioventricular valve (tricuspid) should be. The crises have become more severe and more frequent, the animal began to show signs of ischemia, such as loss of motor coordination and limited [...]