Tetralogy of Fallot in a Young Ferret (Mustela putorius furo)

A 17-month-old albino, castrated male domestic ferret (Mustela putorius furo) was presented for evaluation of a heart murmur. The murmur was first auscultated when the ferret was 12 weeks of age, coinciding with its first known evaluation by a veterinarian. At the time of diagnosis, the ferret was reported to have mild exercise intolerance. The clinical findings on the ferret were within normal limits other than a right parasternal systolic murmur (grade 4/6) that radiated to the left parasternal region. The ferret was not receiving any medications. All 4 features of tetralogy of Fallot (TOF) were identified with echocardiography. Thoracic radiographs were suggestive of TOF with mild right-sided enlargement of the cardiac silhouette and small pulmonary vasculature. A serum biochemistry profile and complete blood count were within the reference ranges for domestic ferrets. At that time atenolol (3.25 mg, every 24 hours, orally) was prescribed to treat the clinical condition of the animal. At a 1-week follow-up examination, the patient's heart rate had decreased from 240-300 beats per minute to 180-260 beats per minute. The owner reported that the ferret was sleeping more frequently during the first week of therapy but had normal activity when awake. At a 5-month recheck examination, the patient was reported to be completely normal at home. This is the first case report of TOF in a ferret.