Elsevier

Hormones and Behavior

Volume 128, February 2021, 104901
Hormones and Behavior

Endocrine changes related to dog domestication: Comparing urinary cortisol and oxytocin in hand-raised, pack-living dogs and wolves

https://doi.org/10.1016/j.yhbeh.2020.104901Get rights and content
Under a Creative Commons license
open access

Highlights

  • Cortisol is higher in dogs and affected by feeding, reproductive phase, and agonistic behaviors.

  • Oxytocin is marginally higher in dogs than wolves and affected by feeding and affiliation.

  • Specific gravity is more reliable than creatinine to control for urine concentration.

Abstract

Dogs are exceptionally well adapted to life close to humans, and alterations in their endocrine system during the domestication process may be an underlying mechanism. In particular, it has been suggested that low circulating cortisol concentrations in conjunction with simultaneously high oxytocin concentrations may have resulted in dogs' increased docility (‘selection for tameness’ hypothesis) and heightened propensity to interact and form relationships with humans (‘hypersociability’ hypothesis) compared to wolves. To investigate this, we analyzed cortisol and oxytocin metabolite concentrations from urine samples of hand-raised, pack-living domestic dogs and their non-domestic relatives, grey wolves. Based on the hypotheses outlined above, we predicted lower cortisol but higher oxytocin concentrations in dogs than wolves. In contrast to our prediction, we found higher cortisol concentrations in dogs than wolves. However, oxytocin concentrations were higher in dogs compared to wolves although the effect was relatively small. Indeed, male dogs had the highest oxytocin concentrations while female dogs' oxytocin concentrations were comparable to wolves'. Feeding status, reproductive phase, and conspecific social interactions also significantly affected cortisol and oxytocin concentrations. Furthermore, we compared two methods of correcting for variable water content of urine samples. We discuss our results in light of physiological and behavioral changes during domestication and highlight the importance of accounting for confounding variables in future studies.

Keywords

Oxytocin
Glucocorticoids
Cortisol
Wolf
Dog
Domestication
Urinary
Creatinine
Specific gravity

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