Tetralogy of Fallot in a three-month-old lamb: clinical, ultrasonographic and laboratory findings

TETRALOGY of Fallot (TOF) was first described by Niels Stenson in 1671. The prevalence in human beings is 0.28 per 1000 live births, and males and females are affected equally. TOF is a rare complex congenital cardiac defect characterised by a ventricular septal defect (VSD) with an overriding aorta and pulmonic stenosis that develop a compensatory right ventricular hypertrophy. The most common cardiac anomalies in ruminants include VSDs, persistent ductus arteriosus, aortic or pulmonic stenosis, and dysplasia of the atrioventricular valves (Dennis and Leipold 1968, Gopal and others 1986, Maxie and Robinson 2007). In contrast to other cardiac defects, TOF is almost always a lethal condition in farm animals. This short communication describes a case of TOF in a lamb, describing the two-dimensional characteristics using echocardiography and the flow pattern with Doppler. A three-month-old male Rasa Aragonesa lamb was referred to the Veterinary Faculty Ruminant Medical Service at the University of Zaragoza, Spain, with a history of respiratory distress (45 bpm). On physical examination, dyspnoea, exercise intolerance and cyanosis of all the mucous membranes were found. On thoracic auscultation, a grade 5 out of 6 holosystolic murmur was heard at the left basilar region of …