Foreman-Worsley, R., Farnworth, M. J. A systematic review of social and environmental factors and their implications for indoor cat welfare. Applied Animal Behaviour Science 220, 104841.

Cats are one of the world’s most populous companion animals, yet little is known about how the home environment is adapted relative to their needs. Outdoor access is thought to be beneficial for both the physical and mental wellbeing of cats, yet as urbanisation increases, reducing owner access to outdoor spaces, an increasing number of cats are kept strictly indoors. The impact of an indoor lifestyle on feline behaviour and welfare is little explored and poorly understood. This study used a systematic review to assess scientifically validated knowledge concerning social and physical environments and their implications for indoor cats. A total of 61 papers were analysed. Only n = 21 papers directly addressed at-home indoor scenarios with the remainder consisting of shelter/cattery (n = 27) or laboratory (n = 16) (some papers explored multiple environments). Across studies there was little evidence of rigour or systematically controlled approaches. Methods frequently used were cat-stress-scores (CSS) and ethograms, neither of which were consistently standardised, substantially reducing the ability to compare findings among studies. Numerous studies explored similar variables (i.e. provision of hiding space (n = 9)) yielding little additional knowledge. Measures of welfare and behaviour were often assessed using single parameters in controlled environments. Although this may be useful and applicable to cat experiences within shelters, catteries and laboratories, the findings do not necessarily translate to dynamic and variable household environments. Major findings include the benefits of enrichment such as hiding boxes and vertical resting spaces, as often recommended by veterinarians and feline charities. However, other advice provided, such as the provision of feeding enrichment for psychological welfare, although not necessarily disputed, appears to be scientifically untested. Additionally, despite the social environment being likely to have a substantial effect on cat welfare, it is particularly under-studied in the home, especially in terms of its complexity (e.g. presence of young children or dogs). Overall, the review identified substantial gaps relative to cat experiences and welfare in multifactorial home environments. Understanding the impact of indoor lifestyles and promoting mechanisms to minimise any negative impacts whilst promoting positive ones, remains an important, yet underexplored, area of research.