WEST Coast defender Brad Sheppard has announced his retirement after ongoing concussion symptoms forced a premature end to his accomplished 216-game career.

Sheppard, who was named All-Australian in 2020, leaves the game while still a top-line defender after weighing up medical advice and considering his long-term future beyond football.

The 30-year-old suffered two concussions in the second half of last season, missing the final round clash against Brisbane after experiencing delayed symptoms that have since been ongoing.

"We just heard him speak to the staff and players, and [it was] really emotional," Eagles coach Adam Simpson said.

"He's had a wonderful career that's been cut short. The way he spoke today was first class. He's going to be missed.

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"It's just really sad it finishes this way.

"There were plenty of games left in Brad. He still had plenty of good footy left."

A respected and popular member of the Eagles' squad, Sheppard was one of the most courageous players in the club's history and one of its finest defenders, despite being widely underrated across the competition.

He was sidelined for the club's 2018 premiership because of a hamstring injury, but Simpson said he considered the lockdown specialist a premiership payer because of his immense contribution that season.

"That's the sad part about it, he didn’t get to fulfil his full career. But he did achieve a lot and played over 200 games. The way we look at him, he’s a premiership player," Simpson said.

"He got a severe hamstring injury in the first 10 minutes of the first final and unfortunately missed out … but he was so much a part of that."

Simpson highlighted Sheppard's versatility as a 189cm defender who could play on the full range of forwards but excelled as a lockdown small defender.

His ability to cover injuries to the Eagles' key defenders in 2015 played a significant role in the team reaching that year's Grand Final, also earning Sheppard the nickname 'Sheptember'.  

"In 2015 he was playing on talls, playing on resting ruckmen, supporting others in the air. And then fast forward two or three years and he’s playing on the best small forwards in the competition and doing a very good job, so versatility comes to mind," Simpson said.

"The ability to adapt as a player, that’s what gives you longevity … and it wouldn’t have surprised me if he elevated to a bit more of a rebounding defender, because he has those capabilities as well.

"He was just too bloody good at stopping small forwards."

The Eagles have lost two players in the past six months to premature retirement because of concussion symptoms after premiership forward Daniel Venables called time on his short career in August.  

Simpson said he was not yet thinking about the toll Sheppard's absence would take on the club's premiership ambitions in 2022.

"It’s just dealing with the person at the moment," the coach said.

"He's one of our best players, so we’ve got to replace that at some stage. But I’m not in that mindset at the moment."

The Eagles have invited overlooked draft prospect Kade Dittmar and former Fremantle-listed ruckman Luke Strnadica to train with the club head of the Supplemental Selection Period.

Sheppard's retirement will also open a spot on the list that can be filled during that period, which runs from January 10 to March 9.