Mr McGowan, 53, said the dogs - Hey Zeus and Essie Girl - were wearing coats clearly marked with the words 'service dog' when the train pulled in at about 8.25am on February 14.

"The driver shook his head and started gesturing with his hands that he was not going to let the dogs on the train," Mr McGowan said.

The doors were closed.

"For me to step onto any bus or train it already gives me anxiety because of how I've been treated before.

"I felt like I had broken glass flowing through my veins."

Mr McGowan said he had received a diagnosis of complex PTSD after a Marist brother sexually abused him at primary school.

He is a sheet metal worker by trade, but is now on the disability support pension and sleeping rough after his car broke down.

"Essie Girl wakes me up before I have my nightmares and Hey Zeus knows when I'm upset," Mr McGowan said.

"They give me something to focus on.

"They give me responsibility, I have to toilet them, walk them, go to Woolworths and buy food for them.

"They keep you engaged in society.

"They give me a reason to get out of bed in the morning rather than hide away from the world.

"My life is enriched by them and they give me quality of life."

Mr McGowan has trained both his dogs himself and carries with him letters from his GP about why he has the dogs, the dogs' vet about the animals' hygiene and behaviour and from the Minister for Transport's office apologising for previous mistreatment on buses and trains.

But Mr McGowan said it continues to happen.

He said he and the dogs boarded a bus at John Hunter Hospital around 10.30am on January 15, but the driver said he couldn't take dogs and did not accept Mr McGowan's paperwork.

Mr McGowan said the driver told all the passengers to get out of the bus and called the police.

He said Keolis Downer sent a second driver, who drove him as the only passenger in the bus to his destination.

The Newcastle Herald asked Transport for NSW why Mr McGowan was treated this way on the train and the bus, especially given he has not had any problems on the Newcastle light rail.

"Transport for NSW recognises that animal companionship may provide many benefits to individuals with a disability, including improved psychological state of mind," a spokesperson said.

"In order to protect the safety of other passengers and staff on NSW Transport services we need to ensure that assistance animals meet the training and hygiene standards referred to in the [Commonwealth Disability Discrimination Act 1992].

"This includes ensuring that sufficient evidence is provided to ensure that these standards have been met."

Mr McGowan said it seemed Transport for NSW employees had not received consistent training regarding passengers with assistance animals or service dogs, possibly due to differences between state and federal legislation.

The Commonwealth act defines assistance animals as either accredited under a state or territory law as being trained to assist a person with a disability to alleviate the effect of the disability; accredited by an animal training organisation to do so; or trained to do so "and to meet standards of hygiene and behaviour appropriate in a public place".

Transport for NSW requires applicants for Assistance Animal Permits to provide medical evidence of the disability; evidence the animal is trained to alleviate the effects of the disability; and crucially, "documentation from an accredited training organisation verifying that your assistance animal has been assessed as meeting the appropriate behaviour and hygiene standards for a public place and that you are trained to handle your assistance animal".

"I can't get any of those organisations to certify my dogs, one told me a few years ago it would cost between $8000 and $12,000 and I can't afford that," he said.

"It's indirect discrimination. I'm living below the poverty line. The whole thing is supposed to reduce stress levels, not increase them."

Mr McGowan has long called for the introduction of a national public access card.

He said he has been discussing the issue with politicians in Canberra on February 13.

He said senators Louise Pratt, Rachel Siewert, Jordon Steele-John and MP Julie Owens joined them for the last leg, from Old Parliament House to Parliament House, where they met senators Jim Molan and Jacqui Lambie.

He and his dogs had left Sydney on January 17 "walking for a national approach to service dogs and to raise awareness of discrimination we face on a daily basis".

"What happened to me is also happening to veterans who fought for our freedom, former firefighters, police officers and ambulance officers, to people with guide dogs.

"We just want to travel without constant harassment."