Manager Russell Slade has said Cardiff are looking at whether Juan Cala broke club discipline rules on social media.
Aston Villa boss Paul Lambert has defended his decision to send striker Darren Bent out on loan to Brighton.
Rigg joined the Barclays Premier League strugglers from Manchester City last season to renew his partnership with then Rangers boss Mark Hughes.
But following Harry Redknapp's appointment as Hughes' successor last month the club have opted for a further change.
They confirmed Rigg's departure in a brief statement on their website that said: "Queens Park Rangers Football Club can confirm that it has been agreed that Mike Rigg will leave his position at Loftus Road."