Moore sustained a thigh problem in the 2-2 draw with Derby at the weekend while Thomas - who missed the County game - is out with a hamstring strain he picked up in training on Friday.
Boss Roberto Di Matteo may also be without the duo for the clash with QPR at The Hawthorns next Monday.
They join several first-teamers on the sidelines, brining the current total to six players.
Robert Koren is out after having an operation on a hernia problem and James Morrison has a heel injury.
Ishmael Miller and Neil Clement are still ruled out with long-term knee injuries.
Cardiff boss Dave Jones is sweating on the fitness of Joe Ledley and Michael Chopra.
Ledley had to be brought off with a groin injury in the victory over Preston and Gavin Rae, who replaced him shortly after the hour mark, is likely to step in.
Chopra is also a major doubt as the striker is suffering the effects of a stomach upset.
Fellow forward Jay Bothroyd will definitely miss out through suspension after picking up his fifth booking of the season.
Anthony Gerrard was taken off with a cut head against Preston but the defender is unlikely to be ruled out.
A win for Cardiff will take them to within five points of second-placed West Brom.
Sporting Life
