As animals are recognised more and more for their therapeutic value, Laura Hanton headed to Dorset County Hospital to meet a very special visitor.

Three-year-old Crumble is part Labrador, part springer, otherwise known as a springador. Since April 2019, he has been visiting patients and their families at Dorset County Hospital in Dorchester, providing a much-needed dose of canine comfort. When I meet him, he is dressed for the job, wearing an official Pets As Therapy (PAT) neckerchief and a starry bandana which, I later learn, was a gift from the nurses, who love him almost as much as the patients do.

For Crumble's owner, Nicky Cumber, it was her own experience with a PAT dog that inspired her to get involved.

"My mum was unwell for four years and passed away in Joseph Weld hospice," Nicky explains. "I had been there for many hours when suddenly this PAT dog called Bramble came and sat with me. He did so much for me whilst I was there, and I thought, that's what I'm going to do, one day. I wanted to give something back."

On our way to Kingfisher Ward, where children are cared for, Nicky tells me about the process of joining Pets As Therapy.

"Any breed can be a therapy dog, so long as they're the right temperament," she says. "We had an assessment with the charity, who wanted to see how Crumble reacted to different people and environments, how he responded to loud noises and how we worked together. At the end of it, the assessor simply said, 'he's perfect.'"

That's easy to believe when I see how Crumble is with the children on the ward: he lights up a room and turns tears into smiles. We meet Noah, 10, who immediately jumps out of bed to stroke Crumble. He says: "I love dogs. Seeing them makes me happy."

Dr Phil Parslow, consultant paediatrician, agrees: "Crumble is the best," he says. "He brightens everyone's day, and just makes everyone feel a bit better."

Eva, 16, is equally delighted to see Crumble. "He looks exactly like my dog Honey," she says. "They could be twins."

Eva adds: "I'm here for two weeks, and I miss my dog, so it's so nice to have a visit from Crumble. Who doesn't love animals? They're so comforting."

The springador visits the hospital every Wednesday morning, before spending the afternoon at Joseph Weld. Until recently, he also visited pupils at Wyvern School in Weymouth, a specialist school for children and young people with learning difficulties, autism and healthcare needs.

"I love working with Pets As Therapy, it's so rewarding," Nicky, who lives in Dorchester, says. "When you see a child crying, and then they stop crying as soon as they see Crumble, it makes it all worthwhile."

We also pay a visit to Purbeck Ward, to meet some of the older patients in the hospital. Nicky recalls a time when she worked with a dementia patient whose demeanour completely changed in the presence of the dog: "She didn't recognise many people, but she recognised Crumble. She smiled, she laughed; she was a totally different person."

All breeds of cats and dogs can be part of a PAT team, provided they have been with their owner for at least six months and are over nine months in age. They must also be able to pass the temperament assessment to make sure they are suitable for this type of work.

Crumble is not the only PAT dog at Dorset County Hospital. On Tuesday afternoons, the wards are visited by a six-year-old Cockapoo called Duffy, and her owners, Sue and Loz Consalvey.

"She's a very active dog, but she's so good with the patients," Sue says. "We got involved with Pets As Therapy because we really liked the charity, and we thought Duffy would make the ideal PAT dog."

Similar to Crumble, Duffy has also been volunteering at the hospital for about six months, and is said to have taken to the role well. "She takes it all in her stride," Sue says, "and we get to chat to the patients too, which is lovely. Dogs are really good at getting through to people; some of the older patients in particular tend to open up when Duffy is there. It's very rewarding."

All PAT dog owners are volunteers and undergo DBS checks and inductions before attending the hospital. Hannah Robinson, volunteer coordinator at Dorset County Hospital, said: "They all come in freely and give up their own time to do the visits. We get so many requests from different wards who'd like a visit from Crumble or Duffy. It's been amazing to see what an impact they have."

The Pets As Therapy charity was founded in 1983 by Lesley Scott-Ordish, a former journalist who devoted much of her life to investigating and writing about the bond between humans and dogs. The organisation was established after Lesley became aware of the trauma experienced by many elderly people who were forced to give up their pet upon going into residential care.

These days, there are more than 9,500 dogs registered with the charity, and it is the largest organisation of its kind in Europe. Pets visit hospitals, hospices, nursing and care homes, special needs schools and a variety of other venues across the country, enhancing thousands of lives every single day.

For more information about Pets As Therapy, for details about joining the charity or to request a visit from a PAT dog, head to www.petsastherapy.org.