SASKATOON -- Tanner Wilson has beaten the odds, living longer than doctors expected.

"We can't tell you if it's two months or two years, but spend every day like it's his last," his mother Leeanne Wilson said, as she described what doctors would tell her.

Tanner, now six, was diagnosed with Leigh's disease at age three. It's a terminal neurological disorder that attacks the nervous system. A vitamin compound serves as the condition's most common treatment.

Tanner is unable to consume anything by mouth. He ingests his cocktail of vitamins and food through a tube.

"He takes this cocktail and it gives him his energy for the day, for him to do functions, like he watches TV and rolls around on the floor," she said.

The prescription costs $500 a month. A cost that will increase as Tanner grows and requires larger doses.

Wilson is a stay-at-home mom and her husband Patrick's workplace benefits plan does not cover the vitamins.

The province's Ministry of Health has denied Tanner's application for coverage three times, Wilson said.

"It's kind of a shock right, because what made Tanner's case not be taken seriously?" Wilson said.

The family was feeling defeated until a "Christmas angel" intervened, offering to cover the entire cost of their son’s medication for the month of December.

The pharmacy shared the news with the family through a Post-it note attached to the boy's medicine.

"Hi, Tanner & family! A Christmas angel contacted us and has paid for this month's refills for Tanner's meds! The angel has asked to remain anonymous but wanted to share some Christmas joy with your family," the note said.

The news couldn't have come at a better time.

"We got our denial letter (from the ministry) in the afternoon and then Tanner's December meds got delivered at supper time," she said.

Ministry of Health spokesperson Colleen Book said in an emailed statement that coverage is reviewed on a case-by-case basis "to determine eligibility based on condition and the components of the cocktail."

"We do have an appeal process – if the physician can provide evidence that supports the use of this drug for this patient/condition, then we would take that under consideration," the statement said.

"Patrick and I will regroup and figure out our next step. Tanner never has given up in his battle against this mitochondrial disease, so Patrick and I won’t give up either," Wilson said.

While the family advocates for more awareness of Leigh's disease and the importance of vitamin-based treatments being taken seriously, for now, they're thankful for this moment.

"We don't know who it is, but whoever it is – thank you."