Effect of chronic hypocortisolaemia on plasma cortisol concentrations during intravenous infusions of hydrocortisone sodium succinate in dogs.

Intravenous infusions of hydrocortisone sodium succinate (HSS) were given at 0.625 mg kg-1 hour-1 and 0.312 mg kg-1 hour-1 to six dogs. Plasma cortisol concentrations were measured by radioimmunoassay at 0, 15, 30, 45 and 60 minutes and then every 30 minutes for a further five hours. Chronic hypocortisolaemia was induced and maintained with mitotane and the HSS infusions were repeated after 31 and 50 days. No statistically significant difference was observed in the plasma cortisol concentrations after either period of hypocortisolaemia, but the plasma cortisol concentrations tended to be higher in most of the dogs.