As she speaks, Joshua appears at her side, cuddling her tight. Cathy says they are "attached at the hip", and he refused to let his dad stay during his most recent hospital admission.
"It had to be me so it was seven nights cooped up in a tiny hospital room together."
Cathy is full of praise for Tauranga Hospital and the Bay.
Steven's parents live at Papamoa and the Dales decided to move south after visiting and enjoying the change of pace.
Soon after Cathy and Steve bought a house in Te Puke, three volunteer firefighters from the town competed in the Sky Tower stair challenge to raise money for Joshua, the gesture making the family feel part of "a real community".
Cathy has found two "lovely ladies" who provide in-home care for Joshua and his sister (the cancer put an end to crowds at daycare), but Joshua is usually too unwell to make it more than once a week.
His compromised immune system means he is susceptible to bugs and has been hit hard by illness since shifting to Te Puke, contracting norovirus and a chest infection, as well as the shingles.
Appearances are deceptive, though, and despite a runny nose on the day
Bay of Plenty Times Weekend visits, the 4-year-old looks healthy.
Cathy says if he is not sick, the month between each IV chemo in hospital can lull her into forgetting about his cancer.
"[But] going into hospital once a month you're brought back to reality."
For Joshua, the reality is that his condition can change in an instant - and often does.
"The thing with kids like him, if they're going to go downhill, they go downhill fast ... So basically if he gets a fever, we're off to hospital."
I didn't know anything about childhood cancer until Joshua got sick.
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Being confined to a wardroom can be tough on a 4-year-old, as are some of the procedures.
He has a port in his chest to administer IV medications, Cathy saying his veins would otherwise collapse under the constant pressure.
"Even now, he freaks out with port accesses and de-accesses, but everything else, he's fine," she says. "He walks into theatre and says hello to all the anaesthetists, tells them where to put the sleeping milk, which is what he calls the anaesthetic. He's like, 'Good night Mummy, I'm going to bed.' Everyone in theatre loves him because he's just so cruisy and relaxed."
While Joshua is au fait with the hospital drill, 2-year-old Rosalie feels his and Cathy's absence keenly.
"She loves her brother and she's at the age now where she has more awareness of everything, and especially me going for seven days, it's hard on her."
The job of holding the fort goes to Steven, who is at work when we visit, but talks two nights later on the phone.
"He's amazing," Steven says of Joshua. "He's worth waking up for every morning. And so is Rosalie too. She's been through the wringer and back. She might not be sick but she got passed around like a rugby ball for the first couple of months."
Steven says one of the struggles of having a child with cancer is effective parenting of all the children in a family.
"When Josh was in hospital a couple of weeks ago, Rosalie wanted to go to her hospital because she felt she was missing out," says Steven. "It's a balancing act to keep her growing but you can't say no to her and give into him."
When Joshua was diagnosed, the oncologist spoke to Steven about the importance of boundaries for child cancer patients.
"One thing the doctor said was, 'Yes, they've got this, and you need to do this and this, but you've still got to discipline them at 14'."
It is 8.30pm when our chat begins and Joshua is making noises in the background, needing to stay awake to take his medication at the prescribed time.
"He used to be in bed at 6 so sometimes he comes up at 7 o'clock [and says] 'I'm tired, I want to go to bed.' You say, 'Well, you can't'," says Steven.
It is a reminder of how Joshua's cancer never sleeps and the constant demands it makes on his parents.
Says Cathy: "I didn't know anything about childhood cancer until Joshua got sick and I think that's sad that people don't know how common it is and how much it affects not only the kids, but their families, their siblings, friends, everyone. It affects a whole community when a child gets sick."
Steven agrees, saying when Joshua was first on steroids, he had hourly cravings for "pasta, peas and cheese" which the oncologist advised Steven to cater for.
"One, 2, 3 o'clock in the morning he'd eat pasta, which I thought I'd cooked enough of at 3 o'clock in the afternoon. It's like, 'How could you have gone through a kilo of pasta, a kilo of peas and a kilo of cheese in 12 hours?'"
Steven jokes that 2014, with all that it brought for his family, was a "vintage" year.
When told it's admirable he still has a sense of humour, he says. "You've got to laugh. If you don't laugh, you'll cry."
Steven is delighted to have moved to "this beautiful part of the country" and have a job with Towbar Guy, a mobile tow bar installation company.
But he admits it is difficult being the sole breadwinner and echoes Cathy in saying the impact of Joshua's cancer stretches to his employer and beyond, particularly when Joshua is in hospital and he needs time off and help to care for Rosalie.
With Joshua responding well to his treatments, can Steven see the light at the end of the tunnel yet?
"No, there's still a year to go. A lot of families say the last year's the worst because your children are so broken, so depleted and so immune-deficient. I suppose there's a little glimmer of light but [it's a matter of] taking every day as it comes."
Steven and Cathy have been told Joshua has an 80 per cent chance of beating the leukaemia, and although he is classed as high risk and there is always the chance of relapse, Cathy says they have good reason to be optimistic.
"Of all the leukaemias to get, he's got the best one at the best time, so the prognosis is really good."
During their journey, the family have forged strong friendships with families of other child cancer patients.
"We've [also] lost a lot of friends," Cathy says. "It's just part and parcel of making friends with people who have cancer. Some of the kids don't make it. It's very sad."
By contrast, some of their old friends cut ties in the wake of Joshua's diagnosis.
"I guess some people just couldn't cope and they didn't know how to be around us any more. I lost my best friend. She just disappeared."
For Cathy, the hardest part about Joshua's cancer is the social isolation. Although she makes an effort to talk to neighbours, she is unable to take her kids to coffee or play groups because Joshua is not supposed to be around crowds of people.
"You just don't get out much and it's hard because you want to say to people 'come over, come over, come over' but even doing that, you're taking the risk of them bringing bugs in here. People who don't have an immune-suppressed child don't realise that just a simple cold can be so dangerous for kids like Josh."
Joshua turns 5 in February and Cathy is hopeful he will go to school but says her and Steven are in the process of assessing the risk.
Since their son became ill, Cathy has become a staunch advocate of immunisations and feels dismayed every time she reads about an outbreak of measles or other disease for which there is a vaccine.
"There are kids out there who can't be immunised and if they get these diseases, they will die. Because of that, kids like Joshua can't go to the supermarket. We can't go to the mall without having that cloud over our head, 'What if one of these people isn't immunised and is going out and about with something that could kill'?"
It is a subject she tackles on her Facebook page, Joshua's Leukemia Journey, which she set up to keep family and friends updated on Joshua's progress by recording his treatments.
" I just wanted people to know about him and increase awareness of childhood cancer."