Veterinary Research Communications, 30(Suppl. 1) (2006) 309–312 DOI: 10.1007/s11259-006-0068-y C  Springer 2006 Ventricular Arrhythmia and Sudden Death in an Irish Setter Puppy with an Excessively Long Purkinje Fiber F. Porciello 1,∗ , N.S. Mo¨ ıse 2 , F. Birettoni 1 , E. Lepri 3 , M. Balducci 4 and G. Fruganti 1 1 Department of Pathology, Diagnostic and Veterinary Clinic, Section of Internal Medicine, University of Perugia, Italy; 2 Section of Cardiology, College of Veterinary Medicine, Cornell University. Ithaca, NY (USA); 3 Department of Biopathological Sciences, University of Perugia, Italy; 4 DVM Practitioner, Foligno (PG), Italy ∗ Correspondence: E-mail: fp1@unipg.it Porciello, F., Mo¨ ıse, N.S., Birettoni, F., Lepri, E., Balducci, M. and Fruganti, G., 2006. Ventricular arrhythmia and sudden death in an Irish Setter puppy with an excessively long Purkinje fiber. Veterinary Research Communications, 30(Suppl. 1), 309–312 Keywords: dog, Purkinje fiber, sudden death, ventricular arrhythmia INTRODUCTION Ventricular arrhythmias are a consistent finding in companion animal medicine both in association with cardiac disease and extracardiac disease (Braunwald, 1997; Mo¨ ıse, 2000). These arrhythmias are commonly described in the sudden cardiac death of the German Shepherd dog, in the Boxer and Doberman Pinscher cardiomyopathy, in association with Gastric Volvolu/Dilation syndrome and splenic masses and often cause syncope. Ventricular tachycardia has been found to be inherited in particular blood lines of German Shepherd with a high incidence of sudden death occurring during sleep or during rest after phys- ical activity (2) . Inheritance of this disease appears to be unrelated to the sex of the dog, neither to an autosomal recessive gene. Indeed the expression of the disease is influenced by age, with dogs of 4–18 months showing the greatest number of arrhythmic events, probably because of the complex interaction between the anatomical and functional de- velopment of the structures involved and stimulation of the autonomic nervous system. In human medicine different types of multifocal ventricular tachycardia, known to be respon- sible for syncope and sudden death, occur without overt structural cardiac abnormalities and show normal QT interval, but very short coupling time that increase the risk for the onset of ventricular fibrillation (Braunwald, 1997; Thakur et al., 1996). The so-called “Id- iopathic Left Ventricular Tachycardia” has been consistently correlated with the presence of false tendons (Purkinje fibers) within the lumen of the left ventricle, which have been supposed to be an anatomical substrate for the electric reentrant circuit (Thakur et al., 1996). We present a case report of ventricular arrhythmias and sudden death in an Irish Setter puppy with a long left ventricular Purkinje fiber. The clinical picture was similar to those described for the German Shepherds from the colony of Cornell University and this may play a role in comparative medicine in the comprehension of sudden cardiac death. 309