Down in Woolloomooloo, under the train tracks, are more people with dogs, cats, parrots and possums but no home to speak of. Barry Neville and his husky-rottweiler cross, Trixie, which has one blue eye and one brown, have been sleeping in the back of his ute over winter while Neville seeks work as a gas fitter. He has given over the front seats to his friend Joe Kumbley, and Joe's dog, Izzy. These pets all seem as healthy and happy as they might be, without a roof or kennel or corner to curl up in. Many eat before their owners do - sometimes there is not enough food to go round. Some homeless people sleep on the street rather than stay in short-term accommodation, where their pets are not allowed. People who have invariably struggled to look after themselves seem to find comfort in caring for another. Chris Curran left home when he was 13 and couch surfed for a time before sleeping rough on the streets. About three years ago he moved into a flat up high in a housing commission tower, in Redfern. His front-door buzzer is broken when I visit, so he meets me on the ground floor with his dogs and we go back up together. Tyson, at least, lives up to his name: fiery and fit and spitting for a brawl. He snaps his teeth on his mother's back, while Curran and I talk on the couch, next to a dog food bowl. "I had been doing drugs for six years, seven years, and I didn't want to be in that scene anymore." says Curran, who is lean and wearing old jeans and a trucker's cap. When a friend suggested he get a companion of some sort, he bought Princess. "She has taken my mind off the drugs. We go for walks and she's quiet at home, except when she hears the vacuum going," he says. "Otherwise I was by myself and I would earn money washing windows and I would spend it on drugs. Now I would rather spend my money on my dogs than spend it on drugs."

His dogs go where he goes. They spend more time together than most pets and their owners. "They make it easier for me to talk to people. Before I would screen myself away from everybody. Now I go down and sit on George Street and some people give me dog food. Someone once gave me an enclosure for the pups." A few months ago, veterinarian Mark Westman stopped on the street to pat Princess and to tell Curran about a free vet clinic he had started for Sydney's homeless in Darlinghurst. On the day I visit the Pets in the Park clinic, in the grounds of St Johns Anglican Church, volunteer vets and nurses help treat some 35 dogs and cats. The animals are dewormed or vaccinated, their eyes and teeth checked and nails clipped. A nurse hands out dog jackets. Tyson, who Curran has brought here to be microchipped, paws at a bag of puppy biscuits on the ground. "A lot of people will see someone homeless on the street with an animal and say they shouldn't have that animal. But the reality is these pets are better cared for than most pets," says Westman, who also runs a free clinic in Parramatta. "These animals are often the most important thing in the lives of their owners, and they go without to make sure they are looked after." Instead of going down to play the pokies or use heroin or smoke marijuana, you take your dog for a walk. Tony Vote, 37, lean with short dark hair, dressed in a brown hoody and shorts, reckons his shih tzu, Rubie, helped save his life. He was drug-addled and living in a tent under a bridge in Woolloomooloo, when another homeless person gave him the pup almost four years ago. "I didn't want the dog. I said 'I can't even look after myself'," he says. "But it just kind of grew on me. I was on drugs and I was majorly depressed. But she got me out of the house, because you have to give them a walk, and it gives you a responsibility."

I keep hearing the word "responsibility", even from those whom some might say have slapped every hand that has reached out to help them. At Pets in the Park there is a queue forming of people with their dogs and cats. Darren (Daz), 43, and Sunny, 39, line up with Lucky Lou, a mini foxy whippet cross, and Cookie, a Jack Russell, to have their dogs' nails clipped. Cookie is wearing a denim dog jacket. Lou is tottering about in a pink ballerina tutu. I ask them why they chose to look after an animal when they struggle to look after themselves. "It is easier to be responsible for an animal than it is for yourself, even though I'm still not 100 per cent clean or anything like that," Sunny says. "I had a child but it was a responsibility I knew I was going to f... up. My child is with my family, so Cookie is my family now. Even the cops look at me when I have her and say 'You must be doing something right' and don't search me for a change." Daz says having a dog to walk and wash and feed "fills out those empty times". "Your mind does wander to those vices but instead of going down to play the pokies or use heroin or smoke marijuana, you take your dog for a walk." Inside the church hall, Andrew Brooks, 37, waits with his cat Bunny in a travel cage. Bunny has been out of sorts since Brooks' other cat Tigger died from cancer in May. His voice breaks as he recalls how he rescued Tigger as a kitten from under a car, after she had been beaten by three teenage boys.

Now there is just Brooks, who studies community service work at TAFE, and Bunny and his two budgies (Tammy and Sammy), in his Darlinghurst housing commission home. "Bunny is my lifeline in a way," he says. "The other night she climbed into bed with me and she rubbed my nose and she curled up in her little spot at the end of the bed and stayed with me all night. To me, that means a lot." Tigger's ashes are kept in the entertainment unit, next to a donation jar for the RSPCA, which helped cover the cost of the cat's cremation. The RSPCA's Living Ruff program helps house the pets of homeless people who are in hospital or temporary accommodation. Among the animals in care when I visit the charity's Yagoona base is a Staffordshire cross who licks my fingers through her cage door. "These animals are very well adjusted, very well socialised," says Living Ruff team leader Sandra Ma. We walk past an Australian silky terrier, madly humping another dog. "He is a very friendly dog," Ma says. The silky has been here a month while his owner searches for permanent accommodation. Other owners have lost jobs and been evicted, or left homeless after a family breakdown. Some owners refuse to stay in a refuge, choosing to sleep on the streets rather than be separated from their animal, Ma says. Typically, short term and crisis accommodation providers in NSW do not allow pets. The St Vincent de Paul Society attributes this to occupational health and safety reasons, and the potential risk to other residents. The charity tries to find alternative accommodation for people with pets or assists them with temporary boarding for the pet, a spokeswoman says. But Lord Mayor Clover Moore says rules and regulations governing such accommodation need to be loosened. "It's shameful, really, because research shows people who have a pet are more physically and emotionally healthy."

Sandra Ma says demand is growing for the Living Ruff program, which started in 2011, as services struggle to find permanent accommodation for every person in need. The rate of homelessness in NSW rose more than 20 per cent between 2006 and 2011, according to the census, to 40.8 homeless per 10,000 people. The categories of homelessness include people who are living in boarding houses, couch surfing or in supported accommodation. Welfare agencies specialising in services for the homeless are strained. Reverend Bill Crews invites me along one evening to the nightly food van run by the Exodus Foundation in the city. He stops in the shadow of St Mary's Cathedral to point out the queue of people in need. "It's getting more entrenched," he says. Volunteers dole out stew and bread and fruit, along with pet food or blankets for those with animals. The Animal Welfare League of NSW offers similar assistance for homeless people with pets. "They don't trust other people but they trust animals," Crews says. "You think, if they looked after themselves the same way things would be better, but at least they are looking after something." Fifth in the line for food is Tim Hine, 58, with his enormous dog Sheena ("a bull mastiff cross"). A volunteer fills an ice-cream bucket with water for the dog. They have lived together in housing commission accommodation in Woolloomooloo for almost five years. Before then, Hine, a gregarious South African, slept on the streets. "She is like an unqualified social worker," he says of Sheena. "You are never alone with a dog, they pick your moods."

I recall hearing something similar at Pets in the Park from Katy Brownless, 26, who was carrying her injured dog, Dotty, in a pram she found by the roadside. Later, I meet Brownless at her housing commission flat in Stanmore. She has built a ramp from the carpet to her bed for Dotty, whose broken rear leg is in a plaster cast. "I like to say I rescued her from a pet shop," Brownless says. "She was reduced to clear." She is training Dotty to be a "mindDog", a companion animal for people with mental health disorders. When Brownless starts to experience a panic attack, Dotty might rest her paw on her feet to keep her calm or stand in front of her - her canine protector. "She has kept me out of hospital a whole year now," Brownless says. Loading Dotty gnaws a bone while perched on the bed next to Brownless, who is studying media and communications at TAFE. "She's not just a best friend. I feel empty sometimes when I'm not with Dot. She's my rock, really." Pets in the Park fundraising gala dinner: November 14, 2013. petsinthepark.org.au