Kurt Zouma played the entirety of West Ham's game against Watford on Tuesday evening.
Many fans expected the Frenchman to be dropped after the extremely disturbing footage of him kicking his cat and laughing about it surfaced online.
But David Moyes said the footage and the public outcry had no effect on his decision-making.
"I am really disappointed and the club have taken all the actions they can do at the moment and working on it behind the scenes," the West Ham boss said, as quoted by MSN.
"My job is to try and pick a team which gives me the best chance at West Ham and Kurt was part of that team.
"For me yes [it was a moral decision] because I am a big animal lover and I think it is something that will have affected a lot of people so I am really disappointed with it but my job tonight was to try and win for West Ham and put the best team out I could to give me that chance.
"I always felt that I had to try and separate them and let the club do their side and do my side which is the football side."
West Ham defeated Watford 1-0.
