“…Several breed associations have been reported for SSS or similar diseases of the pacemaker and conduction system (Hamlin et al, 1972;James et al, 1975;Bonagura & DiBartola, 1983;Moneva-Jordan et al, 2001;Wess et al, 2006). Most cases of SSS are idiopathic, with degenerative fibrosis of the SA node, AV node, perinodal tissue and bundle branches the most common histological findings (Miller & Tilley, 1984).…”