The intravenous halothane test as an experimental method for quantifying stress sensitivity in pigs

The venous blood pH, pCO 2 , lactate, pyruvate and haematocrit responses to an intravenous (i/v) infusion of halothane‐lipid emulsion were assessed in Pietrain, Pietrain X Norwegian Landrace and Gloucester pigs. Halothane‐induced lactacidosis was dose related in the Pietrain (stress sensitive) pigs between 0 and 82 μl halothane kg −‐1 , whereas the crossbred and Gloucester pigs did not show any lactacidosis. It is concluded that the i/v halothane test can be used to quantify a stress sensitive pig's reaction to the drug, and that the crossbred pig does not express halothane sensitivity even at a mild level. Carazolol pretreatment in Pietrain pigs increased the halothane‐induced lactacidosis, whereas in a separate study carazolol was found to decrease their rate of post‐mortem muscle acidification. This indicates that halothane activates a different mechanism from stress when inducing lactacidosis in stress sensitive pigs.