When times are tough or your health just isn't all that great, there's nothing quite like the wet nose of a happy pup to pep you right up.

Therapy dogs are becoming common place in hospitals, schools, and even in court rooms, but we're basically assuming they don't mind lending us emotional support. Fortunately a new study from the US can help put our minds at ease – they love it.

Past research has shown having a pet keep us company is good for our mental health and general well-being, but knowing whether we're taking things too far when we cuddle them in our sick beds is a good question if you're interested in animal rights.

Luckily, new research led by the animal welfare organisation American Humane has found that dogs involved in animal-assisted intervention sessions don't typically present signs of stress while performing most bedside tasks.

"What made this study unique was that it was multisite – it took place in five different hospitals across the country – and the fact that we visited over a hundred patients and 26 dogs participated, making it the largest of its kind in this field," the study's lead author Amy McCullough told Linda Lombardi at National Geographic.

Given dogs tend to make a mess of questionnaires, these therapy animals had their saliva analysed for cortisol, a hormone that spikes when animals like dogs and humans get stressed.

By comparing samples taken when the dogs were at home with those taken during various activities with children receiving cancer treatment, the researchers were able to get some sense of whether they were happy or anxious to be clocking off from cheering up sick kids.

Stress can come in a few different forms, though, and not all mean we're unhappy.

Sporting activities for both humans and hounds can also kick up cortisol levels, so it was important for the researchers to find other ways to check in with their subjects.

In addition with the hormone analysis, the team videotaped the dogs during the therapy sessions and looked for various behaviours that might indicate displeasure, such as licking their lips or whimpering.

The results were fairly straightforward, showing no signs that they were anything but perfectly happy keeping their patients company.

While previous studies have also concluded that therapy dogs seem to enjoy their work, the fact this study included the nature of the interactions adds much needed detail.

From playing with toys to taking selfies with their visitor, the way the children engaged with the dogs was all measured against stress levels.

"This is good information for handlers – they can lean toward the activities that they think their dog would enjoy," says McCullough.

For the record, the therapy dogs tended to display more affiliative behaviours when taken for walks. On the other hand, while nothing made them seriously unhappy, they also weren't over the moon about having their hair brushed.

Interestingly, the dogs who showed signs of being the friendliest also tended to be the ones who showed the most stress, suggesting the most important thing is for handlers to simply pay close attention during sessions.

Dogs aren't the only animals being put to work as calming companions, of course.

But until emotional support peacocks get their act together and unionise, we're going to assume they're also satisfied helping us cope with life's more stressful moments in exchange for food and a warm place to sleep.  

This research was published in Applied Animal Behaviour Science.