McKay has sat out the last two weeks, with Voss confirming last week the left-footer needed time out from playing in the AFL.
Carlton had previously ruled McKay out of facing Hawthorn due to unspecified illness, later confirming it was mental-health related.
The 27-year-old trained on Tuesday, but was absent from Carlton's captain's run on Wednesday and was not named in the Blues' team.
"I probably won't go into the 'H' stuff," Voss said earlier on Wednesday when asked about McKay's availability.
"I think the important thing for us is that we don't get into dialogue weekly about where he's at.
"I think we've been pretty sound on our position as a club, that when he's named in the team he'll be ready to go."
When pressed if he knew whether McKay would be ready, Voss repeated his previous answer.
"I think as an industry, we have been really supportive, and I think for us that that's where we need to stay right now," Voss added.
After a 0-3 start to the season, Carlton's clash with their arch-rivals shapes as one of the most important matches of Voss's four-year tenure at Ikon Park.
Small forward Will White will make his AFL debut, just 38 days after being signed to Carlton's list as a replacement for No.3 draft pick Jagga Smith, who suffered an ACL injury in the pre-season.
After letting Matt Owies go to West Coast in the off-season, the Blues have struggled for goals out of their small forwards.
Carlton had just four goal-kickers - Brodie Kemp, Charlie Curnow, Lewis Young and Jesse Motlop - in last Friday night's loss against the Western Bulldogs.
Carlton have made three changes, with only utility Matt Cottrell injured and unavailable.
Small forward Francis Evans and defender Jordan Boyd make way for Ashton Moir and Cooper Lord.
Elijah Hollands, who took personal leave on the eve of the season, will make his comeback via Carlton's VFL team this weekend.
"Elijah's been able to take some time away from the club, but I guess over the last little while he's had more presence within our program," Voss said.
"I guess how he finds his way back into the team is by putting in a solid performance."
Collingwood have picked premiership player Billy Frampton as the replacement for injured young defender Reef McInnes.
Set for a breakout season, 22-year-old McInnes ruptured his ACL in the Magpies' last-start win against the Western Bulldogs and won't play again this year.
Premiership veteran Mason Cox has been axed in favour of forward Brody Mihocek, who missed the clash with the Bulldogs due to soreness.
After winning 10 of their last 12 matches against Carlton, Collingwood will start as warm favourites to move to 3-1 and send their bitter rivals to 0-4.
The Magpies won both games last season by combined tally of nine points
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