Selepressin is a new selective vasopressin V1a agonist for treatment of vasodilatory hypotension in shock. Its effect on coronary and aortic blood flow, hemodynamics, and electrocardiogram as an indication of drug safety in healthy dogs was compared with arginine vasopressin (AVP). Eight dogs were fasted, anesthetized, intubated, and ventilated. Following thoracotomy, coronary and aortic blood flows were monitored, left ventricular and peripheral arterial blood pressures were measured, and electrocardiogram was recorded. Selepressin or AVP was administered by dose-escalating infusions (1-300, 0.3-100 ng · kg(-1) · min(-1), respectively). Drug formulation analysis and plasma bioanalysis confirmed exposure. For each dose level, hemodynamic parameters, drug potency, and efficacy were determined. Selepressin and AVP induced a similar increase in mean blood pressure (+13% to 18%), a moderate decrease in aortic blood flow (-40% to 45%), and a slight decrease in coronary blood flow (-16% to 22%). These vasopressors displayed similar hemodynamic characteristics, with peripheral vasoconstriction and decreased aortic blood flow being more pronounced than the increase in coronary resistance and decrease in coronary blood flow. Importantly, selepressin bore no relevant coronary ischemic liability, suggesting that V1a receptor agonists are a potential pharmacological target for treatment of vasodilatory hypotension in shock.