Abstract
58 dogs (29 males and 29 females) selected as healthy on clinical and biochemical evaluations were subjected to an ACTH adrenal function test 2 days after their admission to a veterinary hospital (t+0). Basal female serum cortisol concentrations were significantly higher than concentrations in males (77 nmol/l versus 43 nmol/l; P<0·01). Concentrations post stimulation were not statistically different (P>0·05) between males and females: 306 (±69) nmol/l versus 291 (±73) nmol/l, respectively. Twelve dogs (6 males and 6 females), randomly selected from the 58, were subjected to the same test 5 weeks later (t+5) and 12 weeks later (t+12). Basal cortisol concentrations were lower at t+5 or at t+12 than at t+0. Post stimulation mean cortisol concentrations were lower in males than in females at t+5 (162 versus 232 nmol/l; P<0·05) but not at t+0 (262 versus 320 nmol/l; P>0·5) and t+12 (188 versus 233 nmol/l; P>0·05). These findings are indicating an increased susceptibility of bitches to environmental stress.