In the 1960s, Afif and Weil showed that there is an association between elevated blood lactate concentrations in critically ill patients with increased mortality and morbidity. Lactate is an important intermediate product of the metabolism of carbohydrates: it is the end product of the degradation of glucose in the absence of oxygen (anaerobic glycolysis). Higher blood concentrations of lactate are an indirect evidence of tissue hypoxia, which may result in multiple organs dysfunction and death. Trauma patients may have organic abnormalities, that cause an imbalance between supply and consumption of oxygen in tissues, such as diminished tissue perfusion or decreasing the oxygen content in blood. Hyperlactatemia is a common finding in these patients and it is associated with high mortality in human patients. Therefore, the measurement of blood lactate is an important tool to detect early tissue hypoxia. The purpose of this study was to examine the admission values of blood lactate in dogs with multiple trauma, defined as injury of two or more organs, caused by the transmission of energy due to trauma. We conducted a retrospective study of dogs with multiple trauma admitted at the intensive care unit of the Pompéia Veterinary Hospital, São Paulo, Brazil, from January to November, 2008. Of these, we selected those with blood lactate was measured immediately after volume replacement with Ringer's solution (n = 32 dogs). Dogs were categorized in three groups: (I) dogs with blood lactate < 2.5 mmol/kg (the upper limit of the reference values); (II) blood lactate between 2.6 and 3.9 mmol/kg; and (III) blood lactate > 4 mmol/kg. The group I (n = 20 dogs) only 2 patients died. In Group II (n = 8), two dogs died and in group III (n = 4), three did not survive. Based on these data, we suggest that lactate measurement of dogs with multiple trauma can be used as a predictor of mortality.