David Cantley relies on his dog Buddy to get him through difficult moments, but the 54-year-old veteran, who lives with PTSD, says he has been rejected from numerous businesses for having his accredited assistance animal by his side.

Key points: David Cantley spent 24 years in the Defence Force before being medically discharged and diagnosed with PTSD

David Cantley spent 24 years in the Defence Force before being medically discharged and diagnosed with PTSD He uses a support dog, Buddy, who calms him when he becomes agitated

He uses a support dog, Buddy, who calms him when he becomes agitated He says he has been rejected from several businesses in his hometown of St Helens, as well as in Hobart

Mr Cantley spent 24 years in the Australian Defence Force, including three combat deployments to East Timor and two deployments to Afghanistan, before being medically discharged and later diagnosed with post-traumatic stress disorder (PTSD).

He has had his accredited assistance dog Buddy for the past 12 years.

"If I get agitated, he just comes up and he gives me a nudge and he'll put his chin on my leg," Mr Cantley said.

"Or if I'm sitting, he will sit down and look into my eyes — it's amazing."

Mr Cantley said despite Buddy wearing an assistance dog jacket, he has regularly been asked to leave businesses in his hometown of St Helens in Tasmania's north-east.

"They'll yell across from one side of the shop 'Get that dog out of here! You can't have a dog!' and that instantly gets your hackles up," he said.

David has had his assistance dog Buddy for 12 years. ( ABC News: April McLennan )

"As soon as anyone says that, with my post traumatic stress, I'll instantly go into fight mode because it makes me feel that they are attacking me personally."

"I know they're not but that's just my reaction to it."

Mr Cantley said he had also had issues at Hobart's Wrest Point Casino in 2016, where he was confronted by multiple security guards after taking Buddy into a snack and drink area of the building to buy beverages for his wife and mother-in-law.

David Cantley working on a Black Hawk helicopter in East Timor in 2010. ( Supplied: David Cantley )

He said he produced his ID card with the explanation that he was legally allowed to bring his dog into the area.

"It ended up in another huge argument," he said.

"I ended up having a huge panic attack so I had to leave the casino and my wife and mother-in-law didn't even know where I was," he said.

The casino's general manager, Dominic Baker, said an assistance dog policy had subsequently been introduced.

"We are very supportive of any plans to standardise identification harnesses, tags and coats for assistance dogs which would mean our staff could clearly identify an assistance dog from a distance without having to approach the person, which protects the person's privacy and dignity," he said.

Misha the Labrador is an assistance dog who inspired the founding of a support organisation. ( ABC News: April McLennan )

Craig Gresham, who is also a veteran, founded Misha's Mates after adopting and training his own assistance dog.

Craig Gresham founded Misha's Mates to help veterans through the use of assistance dogs. ( ABC News: April McLennan )

He said he had also been refused entry to a couple of places, but chose his dog Misha — a black Labrador — because he thought people would be more accepting of the breed, commonly recognised as a guide dog.

He said Misha had made a huge difference to his life.

"Misha wakes me up if I have nightmares, or if I am having an anxiety attack she will separate me from that environment and take me away and I'll calm down," he said.

"We find that when guys leave the military, they leave behind a support network of friends."

"They are thrust back into the civilian world where everyone has their jobs and their roles, and they are a little bit lost.

"Having a dog in their life suddenly gives them a sense of purpose again."

Can you take an assistance dog into a business?

According to the Government-funded Health Direct website, owners of assistance dogs have the right to take their animals into all public places, as well as onto public transport such as buses and trains.

The website further states that the Disability Discrimination Act makes it unlawful to discriminate against someone with a disability who is using an assistance dog.

Assistance dogs must be accredited by an animal training organisation to help people with disabilities manage their conditions.

Mr Gresham said he has found most companies support assistance dogs.

"Legally they have the same rights as guide dogs under federal legislation … and most companies in Australia support that," he said.

But there are some areas they cannot go.

"They can't go into commercial kitchens, they can't go into any sterile environment like an operating theatre … or any wildlife reserve like a zoo."

David Cantley wants businesses to be better-educated about assistance dogs. ( ABC News: April McLennan )

There are also issues in proving an assistance animal is accredited, as there is no official register in Tasmania.

State Shadow Disability Minister Jo Siejka introduced a motion into the Upper House earlier this month, calling for changes to make it easier for people to take assistance animals into public places.

"In the motion we called on the Government to review the existing legislation surrounding assistance animals," she said.

"And the reason for that is, within Tasmania, we're actually the only jurisdiction that doesn't have a system at the moment for the accreditation and registration of assistance animals."

Leonie Hiscutt, leader of the Government in the Legislative Council's Upper House, responded to the motion.

"Representatives of the Tasmanian Government are currently actively participating in a national working group focused on achieving a nationally consistent approach towards assistance dogs to alleviate the barriers to training recognition, accreditation, identification and especially travelling between jurisdictions," she said.

Pia Struwe, an investigation and conciliation officer with Equal Opportunity Tasmania, said there was always room for improvement and understanding when it came to disability.

"Businesses are required to take reasonable steps to ensure that discrimination doesn't take place, that their people are aware of policies and procedures and have training in relation to discrimination of prohibited conduct," Ms Struwe said.

Mr Cantley said he wanted to educate the community to recognise assistance animals.