It was just a few lines within 367 pages, but it was enough for one veteran to call budget day a "monumental day."

The 2018 budget proposes expanding the medical expense tax credit to recognize costs for psychiatric service dogs.

"It helps restore my faith in the Canadian value system," said Royal Canadian Air Force veteran Medric Cousineau, who also said his own service dog, Thai, changed his life.

Cousineau has relentlessly lobbied the government for exactly this credit for five years.

"We as Canadians, we don't discriminate. That's not what our society is based on, and yesterday I got that sense again," Cousineau said.

It takes approximately 16 months to train a psychiatric service dog. Every program is different, but Cousineau said it costs about $15,000 for the dog and training for the animal's handler.

Currently, tax relief is provided for owners of dogs trained to assist with blindness, deafness, severe autism, severe diabetes, severe epilepsy, or a severe and prolonged impairment that restricts the use of the patient's arms or legs.

'It's been a horrible fight'

Cousineau, who lives just outside Halifax, said the credit is about achieving equality.

"We were not being treated the same as other service dog handlers, and it's been a horrible fight," he said.

Cousineau was diagnosed with PTSD after he was lowered onto a fishing vessel in distress to rescue a group of fisherman, including two who were seriously injured, in 1986.

Medric Cousineau and his service dog, Thai, in their home just outside Halifax, in August 2017. (CBC)

He said his service dog wakes him from night terrors and helps steer him out of anxiety-inducing public situations.

Cousineau estimates her care costs him about $250 a month, meaning the 15 per cent tax credit should save him roughly $450 a year.

Cousineau's organization, Paws Fur Thought, which matches service dogs with veterans in partnership with the Royal Canadian Legion, was directly mentioned in the budget.

Steve Wessel, chairman of the veterans' outreach program for the Legion in Nova Scotia and Nunavut, said it's about time veterans and others who live with PTSD are included in this kind of tax relief.

"They have enough on their plate already, dealing with the situations that they're under and the stress of having to deal with everyday life," he said.

'It is an evolving science'

The tax credit will cover things like the cost of the dog itself, costs for its care and maintenance, including food and veterinary care, as well as some travel expenses incurred for a patient to attend a facility that trains patients in the handling of such animals. In order for expenses to qualify the animal must be specially trained.

"When somebody says, 'You're only one guy and can you really make a difference?' The answer is, 'Yes, if you apply enough force.'" - Medric Cousineau

Cousineau, who is on vacation in Arizona, got a call from Veterans Affairs Minister, Seamus O'Regan, the day the budget was unveiled.

"I'm happy that we can find room for this, because it's important. It's important to a lot of people," O'Regan told CBC News, commending Cousineau for his advocacy. "We continue to learn more and more about post-traumatic stress disorder. It is an evolving science and therefore the solutions to that science are evolving and I think service dogs are an important part of that solution."

Veterans Affairs Canada is in the process of evaluating the use of psychiatric service dogs as a safe and effective treatment for veterans with PTSD. The government said the results from the first phase of the study have been largely positive.

Medric Cousineau said he feels vindicated.

"When somebody says, 'You're only one guy and can you really make a difference?' The answer is, 'Yes, if you apply enough force.'"