Ricciardo, who returned to the F1 grid in July after replacing Nyck de Vries at AlphaTauri, broke a bone in his hand during practice at the Dutch Grand Prix in late August.
The Australian has not featured since and although he is making progress in his recovery, next week’s race in Lusail looks like it will come a bit too soon.
“I would say probably less likely than likely at the moment,” Horner said, when asked by Sky Sports News whether Ricciardo would feature in Qatar.
"His recuperation is going well but he’s fixed in the seat for next year, does he need to rush a hasty return for Qatar where maybe another couple of weeks for Austin, which is a hell of a bumpy circuit anyway, it might be better to use that time in preparation for Austin.
"I know he’s got his sights fixed on Qatar, he’ll drive the simulator next week and then we’ll make some decisions based on that."
In Ricciardo’s absence, Liam Lawson has filled in and impressed, especially with his ninth-place finish in Singapore which secured Red Bull’s sister team their best result of the season.
“He’s done a great job; he’s really impressed us,” Horner said of Lawson.
"He’s done exactly what we could have asked for in terms of grabbing the opportunity in Daniel’s absence to really show his capability. That’s turned some heads and it’s done him a lot of good.
"We’ll keep developing him when he goes back into that test and reserve role and he’ll be a candidate certainly for 2025."
Despite his good form, as it stands Lawson willnot be on the grid next year, with Ricciardo and Yuki Tsunoda keeping their seats at Alpha in 2024.
Lawson has, however, been linked with replacing Logan Sargeant at Williams, with the American’s seat the only position on the grid yet to be confirmed for next year.