A plane with a banner including the words 'Cats Lives Matter' was flown over Anfield ahead of West Ham's game against Liverpool on Saturday evening.
West Ham are continuing to select Kurt Zouma despite a video having been posted online last month of the defender kicking and slapping his pet cat.
Zouma was named in the starting lineup by David Moyes for the game against Liverpool.
Shortly after footage of the incident emerged the RSPCA confirmed that Zouma's cats had been taken away from him.