Seasiders boss Appleton was without centre-back Cathcart for Friday night's 2-1 home defeat to Wolves due to illness, while the same bug left right-back Eardley unused on the bench as midfielder Chris Basham featured at full-back.
Fellow defender Ian Evatt (knee) and winger Matt Phillips (toe) remain sidelined.
"Cathers had sickness and diarrhoea and Neal Eardley almost wasn't in the squad and probably shouldn't have been on the bench because he was struggling for a few days as well," said Appleton.
"There was a couple of other lads with flu-type symptoms so hopefully they'll be refreshed come Boxing Day and from an injury point of view we're still pretty much where we are.
"Matt Phillips is still a way away, Ian Evatt's quite a way away yet. Even though we've got a big squad there's only a certain amount of players that I've been using that I think can affect things in the first team.
"We're a little bit light but we'll see what happens over the next couple of games."
The loss to Wolves in a game Blackpool dominated for long periods was their first in eight games since Appleton succeeded Ian Holloway in the Bloomfield Road hotseat.