Dogs going through adolescence before they become service dogs often present the greatest challenges that owner trainers often face. As a result, I am ever hunting for more information about how to ease that stage for both dogs and handlers. In my research, I recently came across a study on goldens, labradors and German shepherd dogs and mixes of these.
Teenage Dogs? Evidence for adolescent-phase conflict behavior and an association between attachment to humans and pubertal timing in the domestic dog. It has important implications for training a dog, and particularly service dogs. 

When talking with students about dogs, some seem to have mostly clear sailing with their dogs through the adolescent period, while others have a moderate amount of challenges and others have a long drawn out period fraught with high level challenges. I suspected that the emotional environment the dogs were raised in played an important role as did genetics so in the past, I have always referred students back to their breeder to get more information about their specific lines. This study highlights the importance of a secure emotional attachment with the handler and its effects on the onset age of puberty, the length of the adolescent period and the intensity of unwanted behaviors during that adolescent period. The emotional interactions with a dog determines the quality of attachment. 

Here is an excerpt from the study.

"Owing to behavioural and physiological similarities between parent–child and owner–dog relationships, the aim of this study was to examine the extent to which adolescence in dogs shares characteristics of adolescence in humans. Specifically, we investigated owner–dog parallels of three proposed characteristics of human parent–adolescent relations: (i) an earlier puberty for female dogs with less secure attachments to their carer; (ii) adolescent-phase conflict behaviour exhibited toward their carer; and (iii) greater conflict behaviour in dogs with less secure attachments to their carer."

I think this study has implications for how a handler interacts with their dog and creates a secure attachment. Learning to respond appropriately to a dog's communication and behaviors (such as demanding behavior and frustration) in a way that creates a secure attachment to the handler is a key part of that. A previous study refined a base definition of what secure attachment looks like in dogs. Secure attachment in the study looked at the dog's ability to play with and longer duration when playing with new toys with the owner rather than a stranger in the room, the dog's closer proximity to the owner when playing with the toy than a stranger, and the handler providing social support for the dog in the presence of strangers,  In other studies, they also looked at the dog's behavior when separated from the handler during when stressful situations.

Hopefully, there will be other studies to follow that give human family members a clearer indication of what can be done to increase the age of puberty, shorten the adolescent period and decrease the intensity of unwanted behaviors during the crazy teen period for service dogs and pet dogs. That will decrease the conflict that occurs and possibly increase the success rate of service dogs in training for owner trainers.