The Princess’s brother said he gave Kate Middleton a dog to help her and her family cope with the illness.
James has bred six litters, giving two puppies to Kate – Lupo, from James’ dog Ella’s first litter, in 2011 sadly died at the age of nine, and more recently Orla.
James, 37, told Hello magazine: “I know how much the dogs, for me, have helped in taking your mind off something.
“So I’m certain that for them, Orla is doing her job in supporting her family.”
The Princess of Wales’s brother added that their family is very close and prefers to tackle issues together.
“That was the experience I had through my challenges, and I certainly feel like it’s something that her [Catherine’s] family and our family are doing too,” he added.
James sent the dog to the family after revealing in his latest book how his loyal companion saved his life during his battle with mental health.
Kate was yesterday spotted for the first time since revealing her chemotherapy was over, on her way to Crathie Kirk Church near Balmoral Castle in Scotland.
The Princess of Wales sat in the passenger seat of a car while Prince William, 42, was seen driving.
The mum-of-three, 42, looked well and appeared to be wearing a khaki hat.
They joined King Charles, 75, and Queen Camilla, 77, at the small parish church.
Crathie Kirk Church is a regular place of worship for the Royal Family when they are in residence at the nearby Balmoral Castle.
It comes as Kate returned to work at Windsor Castle just days after revealing she had completed her chemotherapy.
She held her first official meeting in more than nine months hosting a chat with early years charity chiefs.
Last week the princess revealed she had completed her treatment and was set to appear at a handful of engagements before the end of the year.
The official Court Circular, which lists all royal engagements, read: “The Princess of Wales, Joint Patron, The Royal Foundation of The Prince and Princess of Wales, this afternoon held an Early Years Meeting at Windsor Castle.”
There were no photos of the meeting but it is understood she was joined by members of her household team and representatives from the Royal Foundation Centre for Early Childhood.
Kate launched the centre in June 2021 to drive awareness of and action on the extraordinary impact of the early years, to transform society for the future.
She had been kept up to date with the early years scheme while having cancer treatment.
In May, sources close to Kate said she was “excited” after being well enough to be briefed on the findings of a task force she set up to help the under 5s.
She had read a 60-page report on her early years project and said to have been “kept up-to-date” with the work which has been published, it was understood.
The Windsor Castle bash is the first meeting that has been noted in the Court Circular since her health scare, the palace said.
It is actually her first meeting listed on the register since December 6.
In January she spent 13 nights in the London Clinic for planned abdominal surgery, before later revealing in a video statement she was being treated for cancer.
She made her public comeback appearing at Trooping the Colour celebrations in London in June.
Then wowed crowds as she took centre stage in the Royal Box to watch the men’s tennis finals at Wimbledon in July.
Kate has earmarked joining her family at Armistice Day in November where in previous years she has watched over the King and Prince William lay wreaths from the balcony of the Foreign Office building.
And she is expected to have a role in her annual Christmas carol concert at Westminster Abbey in December.
During an emotional video last week, Kate described her “relief” at finishing cancer treatment and said: “Staying cancer-free is now my focus”.
