Media playback is unsupported on your device Media caption Katie the stray has found her vocation as a therapy dog

Katie's start was as rough as they get. She spent a year as a stray in the Irish countryside and was seriously emaciated by the time she was rescued.

But now Katie is making a huge difference to people recovering from injuries in hospital.

They get better faster, out of hospital sooner and are less likely to need social care, according to the team at Barnet, Enfield and Haringey Mental Health NHS Trust in London.

So how is she doing it? And should every hospital have a pet pooch?

The first thing you notice is Katie is like a glamorous celebrity.

When she walks on to the ward at St Michael's Primary Care Centre in London, the patients only have eyes for her.

Everyone here is having occupational and physiotherapy to help them deal with fractures, surgery, early stages of dementia or multiple sclerosis.

The sessions are aimed at increasing their range of movement - how far they can walk, how many steps they can make, how far they can reach.

Image copyright James Gallagher Image caption Kathleen is being helped to get back on her feet after breaking three bones

Kathleen Edwards is a charismatic 92-and-a-half-year-old with nerve damage and numbness in her feet.

She tripped and broke three bones. "I didn't enjoy myself at all," she told me.

When she's not craftily sneaking mints to Katie - "she loves them" - Kathleen's sessions are aimed at getting her on her feet again.

She said: "I just did some walking, and she [Katie] walked with me, she makes me feel quite happy, it's just fun.

"She's a beauty she really is, I just love her, we never had dogs, and she makes you feel 'Aah.'

"I shall want to take her home."

Image copyright James Gallagher Image caption Martin Ross strokes and brushes Katie to help his stroke recovery

Katie has a similar effect on Martin Ross, 58, who is regaining movement after a stroke.

His sessions are aimed at arm movement and reaching down, which will eventually help with putting on socks and shoes.

His sessions involve stroking and brushing Katie.

He said other recovery clinics were "more like work, and this isn't as you're actually enjoying yourself".

He said: "I was stretching a lot more and not even realising what I was doing and just enjoying time with the dog.

"Spending time with Katie makes you happy."

Kathleen and Martin illustrate the two main benefits Katie brings - she makes people happy, more social and makes them push themselves further.

Image copyright James Gallagher Image caption Katie is helping occupational therapists help their patients

Marianne Welsh, senior occupational therapist, said: "It's lovely, we see a lot of physical improvements, but also you can see she lifts the mood.

"Rehab is hard for our patients, they've got pain and often anxieties about not being at home or they're fearful for the future.

"She enables them to progress without realising, so they'll spend more time reaching forward, bending down further, mobilising further because they're focused on Katie."

And this is important - recovering the movements that let them get washed, dressed, out of bed or go to the toilet allows people to live independently.

"That helps us reduce the referrals to social services for care," said Marianne, who is also Katie's owner.

Katie had needed a lot of tender loving care herself after she had first been rescued, but had also been a "very adoptable dog", Marianne said.

And she had immediately thought Katie had the temperament to train for Pets as Therapy.

It's a long journey from being a stray in Ireland and "when the patients hear her history, there's a bit of an affinity there", Marianne added.

Proof?

The personal experience of the medical staff suggests Katie is helping.

"Pet-assisted therapy has made a huge difference in trying to get patients out of hospital," said Kavita Shastri, a senior physical therapist.

The clinic has been interviewing patients, and their answers also suggest having Katie around is boosting their recovery.

But what is still lacking is concrete scientific proof.

Kavita told me: "It's unfortunate that the research around this is not that huge.

"Unfortunately in the UK there's not a lot of randomised clinical trials and specific research to objectify this and I think that's what's really required."

But at St Michael's Primary Care Centre at least, they're all convinced dogs could have a big role in NHS care.

Video production by Hannah Gelbart