SUMMARY The influence of venous blood in the determination ofthe anion gap was studied in 50 adult clinically normal horses in Santa Maria - Brazil. The results (mEq/1) were: Na - 140 ± 2.0; K - 42 ± 0.5; Cl -102 ± 24 and HCO3 - 26.9 ± 2.0. The results were similar but slightly different from those of other authors, but without significam difference, although these authors have used arterial blood. It was concluded that the venous blood can replace the arterial blood in order to determinate the anion gap in horses.
anion gap; venous; blood; equine
