Baseline and postprandial concentrations of cortisol and ghrelin in companion dogs with chronic stress-related behavioural problems: A preliminary study

Abstract

Ghrelin has been proposed as an essential element regulating the stress response in both humans and rodents. The aim of this work was to study the relation between cortisol and ghrelin in companion dogs showing chronic stress-related behaviour problems and the effect of the administration of high energy palatable food on these hormones. Baseline and post-prandial serum concentrations of both hormones were analyzed in a group of stressed companion dogs (n = 16) showing social conflict-related aggression (SCA, n = 10) or separation anxiety (SA, n = 6), and in a group of non-stressed control companion dogs (n = 16). Significant differences (p < 0.05) between groups emerged for post-prandial levels, with SCA dogs showing higher cortisol than the control group. The change in cortisol levels (%) after eating in this group was positive, differing from the SA and control groups, which decreased their cortisol after food consumption. Ghrelin also decreased significantly in SA dogs after eating. Taking together, these findings suggest that a parallel meal-induced decrease in both cortisol and ghrelin occurred in the SA group, but not in the SCA group, pointing towards a failure to suppress ghrelin (and cortisol) after intake in the latter. Thus, even though SCA and SA were considered chronic stress-related behaviour problems, their different nature may affect animals in their stress response to the administration of palatable food. The possible alleviatory effect of food consumption, particularly “comfort foods”, after the owner is back home in SA dogs, as well as the changes in dogs’ eating behaviour in response to emotional states or stress (“emotional eating”) will require further studies.