QT Syndrome is a rare cardiac disease associated with sudden death. The disease predisposes to fatal ventricular arrhythmias. Affected dogs exhibit no other cardiac symptoms before death. Some affected dogs may have a detectable systolic murmur or increased heart rate upon auscultation. The most characteristic sign of the disease is a prolonged QT-interval on ECG. The disease has been reported in the English Springer Spaniel. The mode of inheritance is most probably autosomal dominant. [from MyDogDNA]