The South African striker, 33, played for Rangers' reserves in a behind-closed-doors match against Tottenham on Tuesday afternoon.
He did manage to score a goal but they were beaten 9-2 by a strong Spurs side which included Jonathan Woodgate, Jamie O'Hara and Robbie Keane.
McCarthy has not been able to hold down a regular first-team place since joining West Ham from Blackburn for £2.5million last January. He has made just 13 appearances, 10 as a substitute, without finding the net, while Upton Park chiefs also expressed concerns about the player's weight issues earlier this season.
Rangers boss Neil Warnock needs attacking reinforcements after strike duo Jamie Mackie and Patrick Agyemang suffered broken legs and has also been linked with a loan move for Newcastle winger Wayne Routledge.
But it is understood no deal is imminent for the 25-year-old, who left Loftus Road to join the Magpies in January last year.
Source: PA
Source: PA