Hunter suffered a neck injury in a collision with young Eagle Luke Shuey during the first quarter of the Magpies' NAB Cup semi-final against West Coast at Patersons Stadium on March 5.
Hunter experienced a similar injury playing for Collingwood's VFL team in August last year that ended his season.
On his return from Perth, Hunter sought specialist medical advice which convinced him to end his football career.
"Obviously it was shattering - that's the best way to describe it," Hunter told The Footy Show.
"You work so hard for pretty much your whole life and then to be told that something you can't control is ending your football career - you don't wish it on anybody.
"I was pretty devastated and it hasn't sunk in [yet] and I probably don't think it will for a while. It's just sort of numb."
Hunter will remain at Collingwood for the rest of the year and continue to train with the club as he attempts to return to full fitness after his injury, but will not be available for selection.
The former Calder Cannon was diagnosed with congenital cervical stenosis, which is a narrowing of the spinal canal that limits movement of the spinal cord and can lead to severe pain.
"Whenever I get an impact to my head I tear some ligaments and hurt some nerves in there," Hunter said.
"I get some pretty bad tingles in my arms like glass is tearing at my arm.
"It's pretty unpleasant. I had a knock in August last year and that was pretty severe. The one in March this year was not as severe, but it was a warning sign and if it happened again I could lose [use of] an arm or have those bad tingles forever or not walk at all."
Teammate Heath Shaw said everyone involved at the club empathised with Hunter, but he pledged all the support the club could possibly muster as the youngster came to grips with the situation.
"He's going to be around the club for the rest of the year doing his rehab and we're going to keep him involved as much as we can," Shaw said.
"Having been involved in the club environment for so long, it's hard to be told you won't be doing that any more, but all the boys are fully supporting him and if he needs anything then we're there for him.
"It's going to be good to have him around the club and he's going to help out with the VFL and AFL teams as much as he can.
"It's a tough game football. We saw in the first round there were a few injuries and for Tommy it's pretty disappointing, but we're going to support him as much as we can."
Hunter was in his second year on Collingwood's rookie list and was picked in the starting 22 for the Magpies first three NAB cup matches.
