SINOATRIAL NODE ARTERIOSCLEROSIS IN 2 YOUNG-DOGS

Two 11-month-old 7-kg unrelated female Beagles had clinical signs refe rable to the cardiovascular system. Histologic studies in both dogs re vealed strikingly similar findings of sclerosis of the arteries of the sinoatrial node. Histologic changes included intimal thickening and f ibrosis, with marked luminal narrowing; medial hypertrophy, fibrosis, and smooth muscle cell proliferation; and elastic fiber disruption and reduplication. Possible differential diagnoses for this condition inc luded systemic necrotizing vasculitis (canine pain syndrome), coronary polyarteritis, and atherosclerosis.