Western Bulldogs coach Luke Beveridge has shared injury updates on young pair James O'Donnell and Sam Darcy after each suffered ailments during the Dogs' narrow defeat to the Sydney Swans on Thursday night at the SCG.

O'Donnell was substituted out of the game in the second quarter due to a concussion, meaning, consequently, he will enter the AFL's protocols and automatically be sidelined for next week's season-defining clash with Essendon.

"James will go into concussion protocols, he hit a body late and it shook him up, so that's the deal with him," Beveridge told the media post-game on Thursday.

A former cricketer, O'Donnell was scooped up by the Bulldogs at the beginning of the season as a Category B rookie, going on to play eight games in his rookie season thus far.

Meanwhile, father-son defender Sam Darcy was also ruled out of the contest mid-game after suffering 'a little bleed in his thigh'. Beveridge wasn't able to provide a return-to-play timeline for the promising defender.

"Sam copped a knock on a knock and he had a little bleed in his thigh, he couldn't go after half-time, so we had to get him out of the game pretty quickly," said Beveridge.

While O'Donnell and Darcy's impending absences are losses in themselves, Beveridge's side suffered a massive blow to their top-four chances after falling two points short of the Swans on Thursday evening, still needing to solidify their finals positioning as the end of the home and away campaign draws nigh.

"If we had have won, they'd (Sydney) say it was one that got away, and we probably feel like that," Beveridge continued.

"At the end, I still thought we were going to win it, so it's really disappointing from that point of view."

"We won a lot of the key aspects of the game, but ultimately they won the main one."

The Bulldogs are scheduled to play Essendon at Marvel Stadium in Round 19.