Changes in plasma cortisol, corticotropin, and alpha-melanocyte-stimulating hormone concentrations in cats before and...

In 6 cats, mean +/- SEM baseline plasma concentrations of cortisol, corticotropin, and alpha-melanocyte-stimulating hormone (alpha-MSH) were 87 +/- 16 nmol/L, 73 +/- 14 ng/L, and 129 +/- 12 ng/L, respectively. The cats were subjected to: handling and subsequent skin testing without anesthesia; anesthesia with 50 mg of ketamine HCl and 2.5 mg of diazepam given IV, immediately followed by handling and skin testing; and anesthesia and handling as previously described, but without skin testing. Significant (P < 0.05; multivariate analysis for repeated measures) increase in plasma cortisol, corticotropin, and alpha-MSH concentrations was observed until 20 minutes after the start of the experiments in cats undergoing physical restraint and subsequent skin testing with or without preceding anesthesia. These responses were largely abolished when anesthesia with ketamine and diazepam was only followed by handling. We conclude that, during stress in cats (in contrast to dogs), the pituitary intermediate lobe is activated to secrete alpha-MSH. In addition, the cortisol response after skin testing of cats under anesthesia may be a reasonable explanation for the reported weak skin test reactivity in cats.