Objective: To determine whether admission venous plasma lactate concentration, serially calculated lactate variables, or the Acute Patient Physiologic and Laboratory Evaluation (APPLE fast ) score could discriminate hospital survivors from non-survivors in dogs presenting to the emergency department with clinical signs of shock.Design: Prospective case series performed over a 24-month period.Setting: Large urban private teaching hospital.Animals: Seventy-one dogs admitted to the ICU with initial peripheral venous plasma lactate concentration > 2.5 mmol/L and clinical and hemodynamic parameters consistent with shock. Interventions: None. Measurements and main results: Heart rate, systolic blood pressure, temperature, initial venous plasma lactate, and APPLE fast score were recorded at admission. Lactate concentrations were serially recorded at predefined time points and used to calculate lactate variables, including lactime (time lactate > 2.5 mmol/L), lactate clearance ([lactate initial -lactate delayed ]/ lactate initial × 100), and LAC AREA (area under the lactate concentration versus time curve). Primary outcome was survival to discharge. Overall survival rate was 61%. Admission plasma lactate did not differ between groups