As always, I am studying but I came across a study by Odendall and Jeintjes (2003) which showed an increase in oxytocin (feel good hormone) and endorphins (similar) in humans following positive interaction with a pet.
The research abstract is as follows:
Abstract Few physiological parameters for positive human-companion animal contact have been identified and those that are established have all been in humans. The implication is that if the physiological reactions are mutual, dogs would experience the same psychological benefits from these neurophysiological changes as humans. Therefore, we have determined the role of certain neurochemicals during affiliation behaviour on an interspecies basis. Our results indicate that concentrations of beta-endorphin, oxytocin, prolactin, beta-phenylethylamine, and dopamine increased in both species after positive interspecies interaction, while that of cortisol decreased in the humans only. Indicators of mutual physiological changes during positive interaction between dog lovers and dogs may contribute to a better understanding of the human-animal bond in veterinary practice.
Details can be found here:
Neurophysiological correlates of affiliative behaviour between huma... - PubMed - NCBI
It is interesting, at least to me, to consider biological evidence of well-being that we
feel as pet owners.
Also, as the abstract points out, a better understanding of human-animal bonding in veterinary practice would be beneficial in that environmental stressors could be identified which could lead to assistance with behavioral correction, for example..
I am an advocate of the biopsychosocial approach which does not reduce behavior to only one cause but encompasses a holistic approach to include biology, psychology and social factors.
I don't know, I think I'm rambling now and need a nap. But, if you find the above info interesting, enjoy!