Solubility of halothane in equine tissues at 37 degrees C

The solubilities of halothane at a concentration of 0.77% v/v in 5% carbon dioxide in air at 37 degrees C were determined for a variety of equine tissues. The mean values for the tissue/gas partition coefficients for visceral tissue taken from 36 horses were 5.42 for whole brain, 4.82 for grey matter, 7.41 for white matter, 4.18 for myocardium, 2.76 for lung, 8.51 for liver, 3.21 for kidneys, 2.66 for gastrointestinal tract, 1.77 for blood and 2.45 for spleen. The mean coefficients for eight different muscles taken from 23 horses ranged from 2.43 for extensor carpi radialis to 4.91 for psoas major. The values obtained were, with the exception of liver and brain, consistently lower than values in the literature for rabbit, dog, man and ox. Statistical analysis indicated that the condition of a horse was important in determining the solubility of halothane in its liver and muscles. The type of sex of a horse appeared to be important only in respect of the solubility of halothane in the gastrointestinal tract.