The effect of sampling technique on acid-base balance and other blood parameters in the sheep.

The effect of 4 sampling routines--venipuncture, intravenous cannula, intravenous cannula following the administration of a tranquiliser (xylidino dihydrothiazine hydrochloride), intravenous cannula following exercise--were compared. Blood pH and base excess values were similar after venipuncture and cannula sampling, but higher (P less than 0 with 05) after the administration of the tranquiliser and lower (P less than 3 with 05) following exercise. Blood haemoglobin, haematocrit and lactate levels followed this pattern, while plasma protein levels were similar for all treatments except after exercise, where they were higher (P less than 0 with 05). The recovery of various blood parameters to normal values after a period of exercise was also studied: acid-base balance had returned to near normal within 60 min, while haemoglobin and haematocrit levels had returned to normal within 10 min.