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THE INDOOR/OUTDOOR DEBATE

Introduction

The indoor/outdoor debate is one of those contentious issues in feline circles which is not going to be resolved easily. I'm addressing it here because we've been on both sides of the debate, which has had a direct effect on Harpsie's lifestyle, so it seemed an appropriate topic for Harpsie's website.

I'm English, so my culture is that cats are allowed outdoors, and when we lived in the UK, we did allow our cats out. But in 2004 we moved to the USA, where the culture is the exact opposite, and our cats are indeed now indoor only (it's kind of hard not to be when you live on the 42nd floor).

Here is Harpsie surveying his empire, from the days when he could go outside. For some reason people who see this photo think Harpsie is massive! Actually, his healthy weight is 10 lbs, so he isn't a particularly large cat at all. He's always ruggedly handsome though.

Cultural Differences

I'm not entirely clear why there are such major cultural differences on this issue. I suspect it's partly because there are so many more risks for cats in the USA which can cause injury or even kill them. These include predators , such as coyotes, snakes, but also things like weather issues, such as hurricanes, extreme heat etc. (in England we just have rain). 

It's also partly because of different legal perspectives. In the USA it is common to have leash laws or laws forbidding animals to go outside at all, and/or to restrict the number of animals one person may keep. Not only is this unknown in the UK, but in fact cats have the right to roam freely, and in law a catowner is not liable for any damage resulting from the cat's behaviour.

The cultural differences are so entrenched that they even stretch to the differing approaches of shelters in the USA and Europe. In the USA, you are likely to be turned down by a shelter if you admit you plan to allow your cat to go outdoors. However, in the UK in particular, you are likely to be turned down if you admit you plan to keep your cat indoors! However, Cats Protection does not rush to place cats in high traffic areas, and in these instances it will work with potential adopters to find a cat more suited to the indoor lifestyle, for example an older, blind or deaf cat.

The Arguments For and Against

Much of what follows is based on two essays I wrote in 2002 whilst a post-graduate student at the University of Southampton. The emphasis is on welfare considerations, and I had a restriction on word count, so I do not cover certain issues specifically, such as predators.

You will see that I basically take the same information and alter the emphasis to reinforce my arguments. The fact that it is relatively easy to do this illustrates why there is no clear cut solution to this debate.

I do have full references which I used to make available upon request but I no longer do so because people were simply plagiarising for their own essays rather than doing their own research.

Not Permitting Cats Outdoors Raises Welfare Concerns: Arguments in Favour

Please see above for the basis on which this section was written.

• The commonly accepted definition of welfare is Broom’s: "the state of an individual animal as regards its attempts to cope with its environment". If that environment is one where a cat cannot perform its normal behavioural repertoire, it may cause stress; and keeping a cat indoors reduces its ability to show its full range of behaviours, such as hunting, roaming its range, interacting with other cats and being independent.

• The cat is a very efficient solitary predator - in a 1997 Mammal Society spring/summer survey, almost 1000 cats killed over 14,000 mammals, birds, reptiles and amphibians. Based on these figures, the Mammal Society estimates that domestic cats kill around 250 million animals a year. In order to exercise fully its hunting ability, a cat needs access to the outdoors.

• This ability does, however, raise questions about the welfare of other species. Opponents to outdoor cats are often concerned about the effect on songbird population in particular; but in the Mammal Society survey only 20% of the creatures caught by cats were birds; and in another study, 69% of birds died of other causes (Mead 1982). The RSPB has stated: "It is likely that most of the birds killed by cats would have died anyway from other causes before the next breeding season, so cats are unlikely to have a major impact on populations."

• Not all cats hunt, and those who do, tend to hunt less as they age - The Mammal Society admits that once past the age of two, the kill rates of most cats drops dramatically.

• Steps can be taken to protect wildlife, e.g. a large bell on the collar (The Mammal Society concedes that bells and sonic bells offer protection to mammals and birds); invisible fences; separate bird feeding. Keeping cats in at night also reduces the kill rate (the kill rate of two big killers in the survey fell by 80%) and reduces the amount of daytime hunting too, since cats are crepuscular and therefore tend to hunt at dawn and dusk in particular.

• A cat with outdoor access will usually have a home range of about 100m² and a territory of 500m – 2km (Leyhausen 1981). Cats kept indoors will have only a tiny fraction of that range, and thus are unable to exhibit normal feline ranging behaviour. This can be particularly stressful for a cat who is kept indoors after previously being allowed out (Turner 1995).

• Indoor cats also live at an extremely and artificially high density. Liberg & Sandell (2000) observed densities in outdoor cats from 1 cat per km² to 2000 cats per km². They did find that in ferals, density may increase around an area with regular supplies; but the density was nowhere near that found in one study of indoor cats (Bernstein & Strack, 1996) where there were 113,000 cats per km², i.e. 50 times greater than the highest densities observed by Liberg and Sandell. This density could cause stress to cats since it is so unlike the density which they would experience in the wild.

• Keeping cats in a confined area is also contrary to natural feline behaviour patterns. Cats tend to "timeshare" their territories, and will take efforts to use the space at different times to other cats sharing the territory: this is not possible for indoor-only cats. In addition, feral cat groups tend to be matrilineal, so keeping male cats indoors in groups creates an artificial and potentially stressful environment.

• Mertens and Schär (1988) believe there are three influences on a cat’s behaviour and relationships with humans – housing conditions, personality of cat and personality of owner. The owner is an important factor because s/he determines the living conditions, especially for indoor cats. If these are not ideal, an outdoor cat may be able to compensate to some extent, but this is much harder for an indoor cat (Turner 1995).

• Many behaviourists consider that behavioural problems are more common in indoor cats (Mertens and Schär 1988, Heath 1994, Hubrecht & Turner 1998). These cats may simply be performing normal feline behaviours which owners consider inappropriate indoors, but which might not be considered a problem when performed outdoors, e.g. scratching, climbing. There is also likely to be less cat fur in the home if the cat is permitted access outdoors. These issues, if unresolved, can strain the human-cat relationship and cause stress to both the cat and the human.

• Proponents of keeping cats indoors often claim that an outdoor cat lives a much shorter life than an indoor cat – an average of 3 years compared to 12+ years, largely because of traffic accidents (Overall 1997). However, in one study (Childs and Ross 1986), 90% of the animals killed by cars were entire - entire cats are more likely to have larger home ranges and are less likely to be owned - indeed, only 20% of the dead cats had definitely been owned. In addition, since most of these cats were not owned, their ages could not be known.

• It is also often claimed that outdoor cats are at greater risk of contracting diseases. This may apply to entire males who are more likely to fight, or to feral cats; but the majority of companion cats are neutered and well cared-for so are at lower risk.

• Even for those cats who do die young, it may be argued that it is better to have a short, happy life in which normal feline behaviour can be performed.

• Ensuring that indoor cats take sufficient exercise may be a problem (Broom 1989). This may lead to obesity and all its attendant health considerations.

• Barnard and Hurst (1996) advise "basing measures of welfare on what an organism is designed to do." Not permitting cats free access to the outdoors does not permit cats to behave in a way typical of their species and therefore does raise welfare concerns. It is for reasons such as these that many feline charities such as Cats Protection will only place a cat in a home which provides a safe outdoor environment for the cat.

• In the words of Dawkins (1988), "Despite the possible genetic differences that may exist between our domestic animals and their wild ancestors, domestic animals are not man-made for confinement." However, keeping a cat indoors at night, in order to protect both the cat and other species from harm, might be a reasonable compromise.

Not Permitting Cats Outdoors Raises Welfare Concerns: Arguments Against

Please see above for the basis on which this section was written.

1.0 Introduction

• The commonly accepted definition of welfare is Broom’s: "the state of an individual animal as regards its attempts to cope with its environment". If that environment is one where a cat cannot perform its normal behavioural repertoire, it may cause stress; but keeping a cat indoors does not necessarily reduce its ability to show its full range of behaviours, such as hunting, roaming its range, interacting with other cats and being independent.

• Although the cat is an efficient predator, some cats do not hunt at all. It varies from cat to cat - being influenced by early learning (Overall 1997) - and from breed to breed; some pedigree breeds have a diminished hunting drive which enables them to be content indoors (Heath). Thus being indoors only is not necessarily stressful to all cats.

• Indoor cats still may hunt and jump at windows (Overall 1997). Such cats that have the hunting instinct can be encouraged to play hunting games indoors, e.g. by hiding food and letting the cat find it.

• Not permitting cats outdoors enhances the welfare of other species by protecting wildlife (Overall 1997). Bells have little effect in protecting other animals, as do curfews (Barratt 1998). In the 1997 Mammal Society survey some less common species such as water shrews and harvest mice, and protected species such as protected dormice, were killed. The Mammal Society believes that "domestic cats could be a significant pressure on all of these mammals". The RSPB has stated that "it would be prudent to try to reduce cat predation, as, although it is not causing the declines, some of these species are already under pressure."

• Although cats kept indoors may have a smaller range than an outdoor cat, it is still possible to provide an environment with complexity, choice and unpredictability (Holmes 1993). It is particularly important to provide 3-D and vertical space, which can greatly increase a cat’s range even in relatively small homes. Picture windows can also be provided, perhaps with a birdfeeder to watch outside.

• The cats in Bernstein & Strack’s 1988 study were kept at an extremely high density (113,000 cats per square km, 50 times greater than the highest densities observed by Liberg and Sandell (2000). Their home ranges were naturally much smaller than those of feral cats, but the cats appeared to adapt well. The neutered males had a bigger home range (4-5 rooms out of 10) than females (3-3.6) but overall there were no problems associated with this high density – the cats still timeshared favoured spots, just as they would do outdoors in order to reduce potential conflict.

• In one study (Heidenberger 1997), cats who were allowed to go out only seldom or in good weather had more problems than those who never went out at all: "the opportunity itself (yes/no) to go outside produced no significant results".

• Turner (1995) has stated that being kept indoors can be particularly stressful for a cat who was previously allowed out; however, if a cat is kept indoors as a kitten, s/he will know no different and will rarely have any problems in adapting (Heath 1994).

• For people who work, an indoor cat will be there when they come home so they can interact with the cat and form a closer bond. When kept in relatively restricted environments, cats seek out and enjoy human attention (Turner and Stammbach-Geering 1990).

• Since indoor cats live longer, their owners can bond more easily without fear of the bond being suddenly broken because of loss of the cat in some way.

• Cats living without other cats are not necessarily deprived, because cats in groups spend most of their time alone anyway (de Monte & Le Pape 1997).

• An owner's relations with neighbours will probably be better, because the cat will not be able to use the neighbour’s garden as a toilet.

• Many behaviourists consider that behavioural problems are more common in indoor cats (Mertens and Schär 1988, Heath 1993, Hubrecht & Turner 1998). This may be because indoor cats are indulging in normal feline behaviours which owners consider inappropriate indoors such as scratching, climbing. However, there is no reason why these behaviours cannot be controlled – cats can be taught to use scratching posts, and vertical space can help with climbing, for example.

• Timid cats will feel safer in a secure home environment and this will encourage them to relax in their owner’s presence and form stronger relationships with them.

• The average outdoor cat lives a much shorter life than an indoor cat – an average of 3 years compared to 12+ years, largely because of traffic accidents (Overall 1997). In one study (Childs and Ross 1986), almost 3,000 cats were killed in Baltimore as a result of traffic accidents, and it was estimated that around 5,000 were killed in this way each year, particularly in densely populated areas.

• Keeping a cat indoors also negates the chance of fighting and resultant illness/disease such as FIV, FeLV or abscesses.

• Indoor cats run little risk of straying (unless they get out by accident) or theft or poisoning by cat-haters. They are less likely to get fleas or other parasites.

• Outdoor cats may have more than one home, and if fed by all their homes may soon become obese; in contrast, a cat kept indoors can have its food intake closely monitored, which is particularly important in the case of illness, when a prescription diet may be required. An outdoor cat would probably find it very hard to be kept indoors because of illness and/or the need for a special diet, but a cat who is used to being indoors would not.

• For these reasons, some rescue societies (e.g. Toronto Humane Society) will only rehome cats to indoor homes.

• Whilst indoor cats do tend to exhibit more behavioural problems than outdoor cats, these problems are not insurmountable, and by tailoring the environment properly, there is no reason why indoor cats cannot live their longer, safer lives contentedly. As Rochlitz notes, "It is likely that both neutered males and neutered females can be successfully housed indoors provided that there is sufficient quantity and quality of space".

Those Lifespan Statistics

Ah, those much quoted statistics! You know the ones I mean, where the pro-indoor brigade proclaim as absolute fact that indoor/outdoor cats only live an average of 2-3 years, whereas indoor cats live an average of 12 years. I see these statistics quoted all over the internet, yet nobody ever provides a source for them. And living most of my life in UK, I know for a fact that this oft-quoted statistic cannot be true of the average British cat.

As part of my essay-writing activities, I have done some research and I believe the original source may be Dr Karen Overall, who states in her 1997 book  Clinical Behavioral Medicine for Small Animals (p258):

"cats that are 'outdoor' live an average of 3 years, whereas 'indoor' cats live an average of 12 years; the difference is largely related to mortality caused by cars". 

She then cites two references. The first one is Patterns of trauma in urban dogs and cats: a study of 1000 cases (1974) Kolata RJ, Kraut NH, Johnston DE Journal of the American Veterinary Medical Association 164(5) pp499-502. I haven't been able to find the text of this, probably because it is so old. However, a later study by Kolata, Trauma in dogs and cats: an overview (1980) Kolata RJ  Veterinary Clinics of North America Small Animal Practice 10(3) pp515-22 states that approximately 13% of patients seen in two large veterinary hospitals were there because they were injured. "Approximately 35% of dogs and cats were injured severely, with an overall mortality rate of about 9% from either spontaneous death or euthanasia. The major factor that influences an animal's chances of being injured is the owner's management of the animal's environment".

The second study cited by Dr Overall is Urban cats: characteristics and estimation of mortality due to motor vehicles (1986) Childs JE & Ross L American Journal of Veterinary Research 4(7) pp1643-8. This study found that "the number of dead cats annually removed from Baltimore streets averaged 2,721 over 3 years". Since not all cats who were killed were retrieved, the authors estimated that in fact over 5,000 free-ranging cats were killed by cars each year in Baltimore. "Analysis of 212 dead cats removed from city streets showed that the majority were male (63%) and that most animals were sexually intact (90%). At least 20% of the dead animals was previously owned, and few kittens or juvenile cats were found in the sample."

Since Dr Overall mentions that the cause of an early demise in outdoor cats is usually road traffic accidents, I was interested to see the results from this more recent British study. Clinical study of cats injured and killed in road traffic accidents in Cambridgeshire (2004) Rochlitz I Journal of Small Animal Practice 45 p390 is a study of 128 cats involved in road traffic accidents in Cambridgeshire, a county in England with a human population of over 552,000 people.  In this study 12.5% (16) of the cats were dead on arrival, and the mortality rate for the remainder was 16% (21). Dr Rochlitz says: "Half of the cats were aged between seven months and two years, with more males than females affected. Most cats had moderate injuries; strays had more severe injuries than owned cats... Surgery was required in 51 cases. Most cats were hospitalised for between two and seven days and some required up to one month of treatment. The cost of treatment was less than £400 [around US$750] for 84% of cats."

This means that 28.5% of the cats in this study died; and 71.5% survived. According to the Pet Food Manufacturers Association, there were 9.2 million cats in the UK in 2003. In the Baltimore study, 90% of the animals were entire, with the majority being male. None of the above studies therefore convinces me that the oft-quoted statistics apply to UK cats, or even necessarily to the average American neutered family cat. I think the location where the cat is to be permitted outdoors is a major factor in longevity or otherwise of a cat permitted outdoors, as is the cat's sexual status (neutered animals are less likely to wander far).

Tips for Indoor Cats

Safety

It is a myth that indoor only cats are entirely safe. They are at risk from toxins, accidents, and fire. My cousin's cat was nearly killed by an arsonist who broke into her home and set several fires.

Feline Advisory Bureau has information about products commonly found in the home which are poisonous for cats.

Feline Advisory Bureau has information about poisonous plants.

Health

Indoor cats are still at risk from disease if you decide to introduce a new cat to the family. Never expose your resident cats to a new cat until you have had the newcomer tested for FIV and FeLV by your vet. Assuming the tests are OK, you should still quarantine the new cat in order to make sure s/he is not bringing infectious diseases such as cat flu into the home.

Introducing a new cat properly to the family is even more critical with indoor cats, who have limited opportunities to escape from the accompanying stress. See Feline Introductions for more information on introducing a new cat.

Indoor cats are also at higher risk of developing FLUTD (feline lower urinary tract disease) than cats permitted access to the outdoors. It is thought that this is related to stress.

Environmental Enrichment

Toys

It is important to provide indoor only cats with stimulation. Try to provide plenty of toys, and vertical climbing space. It can help to rotate toys, so your cats don't get bored with them.

Cat Dancer is Indie's favourite toy.

TV

I recently bought some DVDs for the cats. I did not expect them to react really, but sure enough within half an hour Karma was climbing on top of the TV. To the left you can see Karma and Indie watching one of their DVDs.

Pet A-Vision sells videos and DVDs for cats - these are the ones I bought. 

Amazon sells one of these DVDs, Video Catnip.

Adapting The Environment

The Cats House shows the ultimate in adapting your house to suit your cats' needs. Most people would not choose to go this far, but it is fascinating to see.

The Indoor Cat Initiativv at Ohio State University College of Veterinary Medicine has some very helpful information about the needs of indoor cats and how to prevent problems.

Feline Advisory Bureau has tips on creating a cat-friendly home.

Clicker Training

Clicker training is another way to entertain indoor cats. I actually began this when my cats were indoor/outdoor, and Harpsie and Indie were both very taken with it.

Karen Pryor is an acknowledged expert on clicker training. I highly recommend her book, Clicker Training for Cats, available from Amazon.

Cat Clicker List is a support list where you can discuss your attempts at clicker training and get support and tips.

Tips for Indoor/Outdoor Cats

It is definitely worth taking steps to protect your indoor/outdoor cat as much as possible. Naturally your cat should be neutered. A collar is a good idea, and microchipping is highly recommended. I personally believe cats who go outside should be vaccinated, including against leukaemia.

Feline Advisory Bureau discusses the indoor/outdoor debate.

Cats Protection discusses how to make your garden attractive to your cat so s/he is less likely to roam

Feline Advisory Bureau talks about collar safety.

Indoor Outdoor Cats List is a support list where you can discuss any issues you may have with others who also permit their cats to go outside.

Possible Compromises 

Leash Training

Some people have chosen to leash train their cats. This enables them to take their cats out into the fresh air whilst keeping them safe. We did not take Harpsie out for walks, but those who wish to do so might wish to check out Harpsie's chariot.

About discusses alternative ways of taking your cat outside.

About has some information about walking harnesses and leashes.

Kitty Walk Systems offers a variety of strollers.

Outdoor Safety Enclosures

Another possible solution is to set up an enclosed area in your garden, so your cat can go outside but s/he is safe from predators. Here are some US suppliers:

Cat Fence-In

Affordable Cat Fence

C & D Pet Products

Just 4 Cats

Katwallks

Purr-fect Fence

Kitty Walk Systems

The Feline Solarium has a build-out window so your cat can look around more easily.

Cat Terrace offers a larger version.

The Cat's Den offers an enclosed walkway for your cat.

Feline Advisory Bureau has information on catproofing your garden and building your own enclosure.

Conclusion and Our Approach

So, having tried both approaches, how do I view this debate? Well, I sit on the fence. When we lived in UK, I was never very good with the concept of free-ranging cats. If my cats were free-ranging I would be worried sick the entire time they were out. Fortunately this was rarely an issue for us. We have always made it a point to buy houses with fully enclosed gardens; and we've usually had Persians, who tend to be homeloving and who do not wander far. This has been an excellent compromise, because none of our Persians has ever left our garden (well, Tanya burrowed into the garden behind us once, and was so frightened she came straight back!). The cats certainly do not have a cat flap - they are only allowed outside when we are there to supervise.

Our garden (left) is safe for cats. It's not massively big, so I can keep an eye on the cats from indoors. And in the UK we do not have the same predators as are commonly found in the USA, such as coyotes and snakes. We do have foxes, but most foxes would not even think about tackling a cat. The other neighbourhood cats know this is my cats' territory and do not enter.

We did have some experience with free-ranging cats in the form of Thomas. Thomas was the local stray whom we trapped. We kept him indoors for a few weeks until he knew this was now his home, but then he got out one day and was so much happier. We allowed him to go out thereafter. Thomas had been the local stray for years, and was streetwise, otherwise he would never have lived as long as he did before we trapped him when he was about 12. In fact, he rarely went on the road, he merely wandered around our neighbours' gardens. But it truly was essential to his mental health for him to be allowed to go outside, especially in summer. He did not always wander, often he merely sunbathed in our garden, but the amount of enjoyment he derived from it was wonderful to see.

My three cats who moved to the USA coped surprisingly well with switching to an indoors only lifestyle. I think it helps that we are so far up that they cannot see grass close by. It probably also helps that they were a bit more mature (seven and older) when we moved. So I do not think the indoor lifestyle is necessarily a bad thing, particularly if you focus on environmental enrichment.

Having said that, I am so looking forward to seeing my cats' faces when we return to England and they sniff the air as they step outside, and chase butterflies in summer and leaves in autumn, and shake their little paws in disgust when they step in snow. I think having controlled access to the outdoors really gives them the best of both worlds, whilst providing me with peace of mind regarding their wellbeing.

*****

Here's Harpsie investigating a tree. In his younger years, Harpsie adored climbing trees, so much so that we nicknamed him Bonington after Chris Bonington, the famous British mountaineer. I'm sorry to say Harpsie was not as skilled as Chris Bonington though - he could get up quite easily but struggled with the getting down part, and often fell out of the tree on his way down.

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This page last updated: 20 February 2008

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