Trapattoni has named a provisional 29-man squad for the games against Sweden and Austria but there was no room for Keogh, who scored against Sheffield Wednesday on Saturday as Millwall picked up their first point of the season.
Keogh took to Twitter to voice his disappointment, saying: "Not even in the provisional squad, gutted, oh well might get called in last minute! £noloyalty."
The 27-year-old, who played in recent friendlies against Spain, in New York, and Oman, went on to reveal he only found out about his omission when the squad was announced
He added: "Not moaning bout bein left out jus gutted, lot of quality in the squad,maybe after Oman and NY a txt or phone call wud of been courteous !! (sic)"