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Spotlight on Science: What does science tell us about the indoor/outdoor debate?

06th April 2023

  •   Spotlight on Science
Spotlight on Science: What does science tell us about the indoor/outdoor debate?

Wherever you are in the world, whether you keep your cat indoors exclusively or allow to roam outside is a hot topic, with strong views from both sides about what is the best lifestyle for cats.

As with everything, there is no black and white, right or wrong viewpoint – it is all a matter of the individual cat and its circumstances. However, when in doubt regarding how to navigate through these important subjects, we look to science for answers.

Rachel (Rae) Foreman-Worsley is a co-author of the publication ‘A systematic review of social and environmental factors and their implications for indoor cat welfare’. She completed her PhD at Nottingham Trent University and is now working as a Feline Welfare Research Associate at Cats Protection in the UK. Rae is also a member of iCatCare’s Feline Wellbeing Panel. Vicky Halls, Head of Unowned Cats at International Cat Care asked Rae for her thoughts.

Rae Foreman-Worsley

Vicky: Thanks for talking to us about the welfare of cats kept indoors. Firstly, can I ask you to tell us a little bit about your background and why this subject is of particular interest to you?

Rae: So I originally started my career in a totally different field – human biochemistry – but after a few years of work and some volunteering in the rescue sector I realised that I wanted to pursue my passion for animal welfare full time. I gained an MSc in Animal Welfare Science, Ethics and Law, after which I found myself working in the rescue sector again. However, being a scientist at heart, I was really interested in research and so I kept an eye out for PhD opportunities. When I saw a PhD in feline behaviour and welfare advertised, specifically looking at indoor-only cats, I applied right away and was fortunate enough to be given the position. I was keen to explore the scientific evidence around indoor-only cats as I had seen first-hand how opinions could vary, even amongst professionals. I was also aware that UK trends show more cats are being kept as indoor-only, and I was motivated to find out whether this may detrimentally impact behaviour and welfare given the relatively low-levels of domestication that cats have undergone when compared to species such as dogs. I even managed to utilise some of my biochemistry background within my PhD, through exploration of hair cortisol as a physiological marker of stress.

V: Your study ‘A systematic review of social and environmental factors and their implications for indoor cat welfare’ (published in 2019), found that most of the papers included in that systematic review related to cats in different environments other than the pet home. Can you give me some examples of this and why this knowledge cannot be applied to the pet cat kept indoors?

R: A lot of studies so far have been done in the shelter environment. This is great as we need to ensure cats in this environment have good levels of welfare, however, there are major differences compared to a domestic home. If we think of it from a cat’s point of view, a typical shelter environment is likely to be a relatively small space, with less variation in terms of the objects available. There may also be a mixture of caretakers, potentially limited human-interaction and the cats in the wider environment are likely to change. In a household however, there is more space and variation in furniture and household objects, the social environment is often more stable, and caretaking responsibilities will be undertaken by a limited number of people. Thus, cats in these different environments may have varying needs due to the different levels of stress, meaning some findings from shelter research might not be applicable in the home, and other findings need to be applied with caution as we might not find the same results in a different environment.

An example could be that studies on the impact of providing hiding enrichment show it is well utilised by cats in a shelter environment, and that it has a beneficial effect in reducing signs of stress when compared to cats not provided with hiding enrichment. In a home, the opportunity to hide is still going to be beneficial for cats, so the findings are still applicable, however owners may find that the box or cat house they provide is ignored in favour of hiding under the bed. Similar has been found for vertical enrichment, we know cats like to climb up high and utilise shelves well in a shelter, however in the home they may prefer to climb atop of the wardrobe and so providing a route up might be most beneficial.

We can also use studies in different environments as a great starting point for future studies into welfare in the domestic home.

V: What do we know then, from peer-reviewed science, about the welfare of cats kept exclusively indoors?

R: Unfortunately, quite little is known about welfare specifically, and it is really hard to generalise across populations.

We do have an understanding of the major factors that are likely to impact behaviour and different measures of welfare in an indoor-only home, and we can apply this knowledge to the management of individual cases. These include aspects of the physical environment, such as the enrichment provided and the number of rooms a cat has access to; owner features such as age, gender and level of education; the social environment such as the frequency and duration of daily interactions with owners, other animals in the household and the length of time cats are left alone throughout the day, and cat features, such as neuter status or sex.

Additionally, we know that cats kept in an indoor-only environment are more likely to exhibit higher levels of owner-reported problem behaviours than cats with outdoor access. The definition of problem behaviours does vary across studies and can include behaviours deemed to be problematic to the owner, for example, furniture scratching which from a cats perspective is an essential behaviour, to behaviours that might be indicative of stress or poor health, such as overgrooming or toileting issues. There are several reasons these differences might be observed, including potential welfare compromises for indoor-only cats and inappropriate caretaking or that indoor-only cats may spend more time in proximity to their owners so these behaviours are more likely to be observed, but more studies are required to tease these reasons apart.

V: So many people ask, is it okay to keep my cat indoors as I am worried about their safety outside, how would you answer this question as there are so many factors to consider?

R: Ultimately this needs to be considered on a case-by-case basis, as there are cats that may settle into an indoor environment and others that would become very stressed by this.

For owners currently looking for a cat, I would advise seeking them from an adoption centre. Here staff will be able to advise on individual cats who may be better suited to an indoor-lifestyle than others, taking into consideration their previous life experiences and possibly how well individuals were reported to cope as indoor-only previously, alongside other factors such as age, temperament, health, sex and breed. Whilst this of course does not guarantee that cats will settle into an indoor-only lifestyle, there may be a greater chance of success than if purchasing a cat or kitten with an unknown temperament.

For owners already providing an indoor-only lifestyle, if there are means to expand this to an enclosed garden, there is some evidence to suggest this might be beneficial. It won’t offer the same freedoms or choice and control as full outdoor access might, but the additional space and variation in enrichment could be beneficial to welfare. For cats that are used to free-roaming outdoor access, do be aware that an enclosed garden may still represent a restriction in freedom for your cat, which may have negative consequences.

V: What would be your key messages to those owners who keep their cats exclusively indoors?

R: Ensure sufficient enrichment is provided so that your cat does not become bored or frustrated. Toys and puzzle feeders can be rotated to help them retain novelty, and there are plenty of DIY ideas for these that can be found online to help cut costs. Scratching posts come in a variety of shapes and sizes, such as horizontal or vertical, sisal or cardboard, and can help reduce furniture scratching in the house.

Ensure your cat has somewhere quiet that they are able to retreat to, away from other members of the household. Even if your cat has a good relationship with the adults, children, cats or dogs in the household, a quiet space with somewhere to hide is always beneficial.

Indoor-only cats should still be neutered, microchipped and vaccinated. There is always a possibility of cats escaping the home, and if they are unfamiliar with an outside environment they may be more likely to become lost; an up to date microchip can help to reunite cats and owners. Neutering has benefits for indoor-only cats in the way of health, and may also decrease behaviours such as aggression or spraying. Neutering also ensures that in a multicat household, or if they do escape the house, they do not risk becoming pregnant or impregnating others.

Finally, if you are concerned about your cat’s behaviour at all, seek advice from a veterinarian who will be able to check the health of your cat and refer you to a behaviourist if needed.


Foreman-Worsley R, Farnworth MJ. A systematic review of social and environmental factors and their implications for indoor cat welfare. Applied Animal Behaviour Science, 2019; 

Available to read here.


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