The aim of this study was to determine reference intervals (RI) for venous blood parameters determined with the RAPIDPoint 500 (RP500) blood gas analyzer using blood gas syringes (BGS) and to determine whether immediate analysis of venous blood collected into lithium heparin (LH) tubes can replace anaerobic blood sampling into BGS. The null hypothesis was that canine venous blood samples collected in BGS and in LH tubes are comparable. Jugular blood was collected from 51 healthy dogs into a BGS and a LH tube. The BGS was immediately analyzed followed by the LH tube. The RI were calculated from BGS results. The BGS and LH tubes results were compared using paired t-test or Wilcoxon matched-pairs signed-rank test and Bland-Altman analysis. To assess clinical relevance, the bias between BGS and LH tubes was compared with the allowable total error (TEa). Values derived from LH tubes showed no significant difference for standard bicarbonate (HCO3std), whole blood base excess (BE B), Na, K, Cl, glucose and hemoglobin (tHb). The pH, partial pressure of carbon dioxide and oxygen, actual bicarbonate, extracellular base excess, ionized Ca, anion gap and lactate were significantly (p.