A systematic review of social and environmental factors and their implications for indoor cat welfare

•61 papers on indoor cat behaviour and welfare have been published since 1991.•Hiding enrichment, single vs group housing and stress over time are well-explored.•Most studies conducted in controlled environments leaving homes underexplored.•Limitations include inconsistent methods, repetitive studies, small samples and N = 1 studies.•Knowledge gaps include cat-child and cat-dog relationships and complex studies.