The Indoor/Outdoor Cat Debate

When I first planned my series on cat overpopulation, I thought I had picked three straightforward ways the average cat owner could help to reduce numbers. First, ensure your cat is spayed/neutered. Second, keep your house cat inside. Third, support Trap-Neuter-Release. When I began to research the reasons for keeping cats inside, however, I found myself being educated on how complicated the indoor/outdoor issue is. In this article, I’ll overview the history of the domestication of cats, as well as the pros and cons for keeping them indoors.


Cats began their relationship with humans over 10,000 years ago in the Fertile Crescent, which encompasses modern-day parts of Asia. Whether the Ancient Egyptians started the process of domestication or whether cats essentially domesticated themselves is anyone’s guess. What is agreed upon is cats helped to protect stores of grain from the growing rodent population. In doing so, they improved the quality of life for Egyptians who were so thankful that they turned the cat into a sacred creature to be worshipped.

As time passed, other ancient civilizations also began to also find the cat of use for keeping rodents away from their goods. All along the ancient Asian trade routes, cats were being desired by and finding acceptance among humans.

As to how cats came to North America, Alley Cats says that from Europe, cats boarded ships to the Americas, reportedly tagging along with Christopher Columbus, with the settlers at Jamestown, and aboard the Mayflower. Once in North America, cats continued their service as mousers, even serving as official employees of the United States Postal Service as late as 19th and early 20th century.

I’ve been able to confirm the history of domestication of cats through reputable articles such as ones by Scientific American, but the history of how cats became house pets is less substantiated. Alley Cats writes that towards the end of the 19th century, more Americans began to keep cats for their company as well as their mouser abilities, but emphasizes that during all this time cats were allowed to come and go freely from human households. They even quote Sam Stall, author of 100 Cats Who Changed Civilization and of The Cat Owner’s Manual, who writes: “Back in Coolidge’s day no one thought of confining cats indoors—not even one belonging to the president of the United States.” CatChannel (from the creators of Cat Fancy) expert Jeanne Adlon adds her own thoughts, stating that because of their mouser abilities, “Cats became a common fixture on farms and eventually their poise and personality got them inside to warm themselves in front of the fire.” Alley Cats claims by the end of World War I, cats were commonly accepted as house pets in the United States, more Americans began to keep cats for their company as well as their mouser abilities. Moreover, historians confirm that cat shows were being held in New York as early as 1877. Whatever the real date is, cat experts and scientists do agree that domestication didn’t come easy to cats.


If domestication didn’t come easy, and cats are still pretty much the same biologically as they were thousands of years ago, why do most cat experts in the United States promote keeping cats indoors? Repeatedly, the message is that keeping cats indoors protects them, us, and wildlife. How so?

Environmental Concerns

The nature of cats is that they love to hunt. Cat Behavior Associates reports that studies have shown when a cat is hunting, the brain chemical dopamine is released which creates a feeling of eager anticipation, and this release is initially triggered by the sound or scent of prey. As such, a cat’s prey drive is so strong that even well-fed cats will hunt birds and other small animals when given the opportunity.

While no one really seems to mind when cats catch rodents, and in fact barn cats are encouraged to take on this task, protest does arise when the predatory instincts of cats are directed toward birds. The impact made by one cat might be small, but the total impact of all the cats who are allowed outside could be more significant.

Safety Concerns

Times have changed since cats first caught rodents for Egyptians in the Fertile Crescent or even in colonial towns in America. There are many potential hazards outdoor cats face. Below is a rundown of them from the American Humane Association and Little Big Cat:

Animal cruelty: Roaming cats may be at risk for animal cruelty. They may end up being trapped and abused in the name of “sport”. Some people have been known to shoot and kill cats with arrows or guns.


Even a stopped car can be dangerous. Fan belts can rip the fur and skin right off the cat’s body and slashing through the muscle. Little Big Cat warns that, “Those few that survive carry the scars for the rest of their lives.”

Leaking antifreeze can also kill. A cat walking through even a small spill of antifreeze and then licking its paws has ingested a fatal dose.

Cats do not have an innate instinct to avoid busy streets. Few will look both ways, especially if startled or being chased, and they frequently do get hit by cars.

Loose dogs and wild animals: While cats may be good hunters, they also often wind up being the hunted. Injuries from these attacks can be serious and even fatal. The concern becomes even more serious for owners of declawed cats, because the lack of claws means cats have no ability to defend themselves.

Theft: Little Big Cat reports that an estimated two million pets are stolen every year. The site goes on to tell of an undercover investigation in 1990 of well-known biological supply companies and documented Class B licensed dealers delivering hundreds of live cats of unknown origin to those companies. According to the investigation, tens of thousands of cats die every year so that students can dissect them.

Toxins and poisons: Toxins from herbicides and pesticides that are sprayed on gardens are often ingested because they have a pleasant taste. Cats may also end up accidently exposed to rodent poisons when they hunt and eat rodents that have recently ingested poison bait.

Trees: Some cats that climb trees are afraid or unable to climb down. In some cases, they may be up in a tree for days until they become dehydrated and weak to the point that they fall and suffer severe or fatal injuries.

Health Concerns

While not necessarily life-threatening, several common parasites can be easily picked up by cats who are allowed to roam outside. These parasites can cause a variety of moderate to severe symptoms, such as scratching, skin infections, vomiting, and diarrhea. In addition, these parasites can transfer themselves from cats to other animals and to people. If they hitch a ride into your home, they can be difficult to eradicate.

Even more serious is the fact that cats will more likely become exposed to diseases outside, a number of which can be potentially fatal. Common examples include:

  • upper respiratory infections (or URI)
  • feline distemper (panleukopenia)
  • FIP (feline infectious peritonitis)
  • feline leukemia (FeLV)
  • feline AIDS (FIV)
  • FIP (feline infectious peritonitis)

Messy Beast states that the #1 disease of outdoor cats is an abscess resulting from a bite wound. Bite wounds usually become infected, causing large volumes of pus to accumulate beneath the cat’s skin, sending the cat’s temperature soaring and making it feel sick. Antibiotics and sometimes surgery are often necessary to help resolve the problem.

Overpopulation Concerns

Unaltered cats especially should be kept inside, because letting them out is going to result in unplanned litters. Why? Because many cats “come into heat” as often as once every few weeks. A fertile can produce an average number of two to three litters in a year, with four to six kittens being born per litter, for a total for 87 kittens in a single year. When you consider that half of those kittens will be female, and that each of those female kittens can also produce 87 kittens in seven years, the numbers add up quickly. One common stat is that a single unfixed cat and its offspring can produce 420,000 kittens in a seven year period.

In a perfect world, we might not need to spay/neuter our cats. But the reality is 1.4 million unwanted cats are euthanized each year. In addition, according to the American Society for the Prevention of Cruelty to Animals (ASPCA) there are an estimated 30 to 40 million homeless cats. Clearly, we have a pet overpopulation crisis, and the one message animal welfare experts keep repeating is this: spaying and neutering is the best way to change those numbers.

Bottom Line

Because of all of the above threats, the average lifespan of an outdoor cat is less than five years, whereas an indoor-only cat has a life expectancy of fifteen or even twenty years. Perhaps that’s the reason why, according to The Humane Society of the United States, the majority of pets owners choose to at least make their cat an indoor/outdoor cat.


If lifespan were the only factor, it would seem no one in their right mind would let a cat outside. But what about a cat’s emotional well-being? Most cat experts in the United States contend that cats who grow up inside tend to show no inclination to leave the safety of home. Furthermore, these experts point out that even cats who are used to being outside can learn to live a happy and healthy life indoors.

Case-closed, right? Not necessarily. The debate became a curiosity for me when I discovered that cat experts outside the U.S. don’t always agree with confining cats indoors. The journalistic side of me wanted to know why, and whether their logic was valid.

In Europe, writes Pete Wedderburn in The Telegraph, it’s common for people to feel that cats have a right to range freely. Indeed, Wedderburn elaborates, some Europeans feel so uncomfortable with the idea of cats been kept indoors that they feel that it’s equivalent to keeping a rabbit in a small hutch or a hen in a cage.

Messy Beast even warns that some indoor cats develop neurotic habits, and others become reclusive. Messy Beast claims that behavior problems of this type are rare in households, indeed in countries, where cats are regularly allowed out of the house. In contrast, “the highest incidence of neurotic behaviors in cats is in the United States where keeping cats inside is the most prevalent style of ownership.”

I don’t know about you, but this concerned me enough I had to keep reading about our European counterparts. According to Messy Beast, in Britain an estimated 88%-92% of cats have access to outdoors. Messy Beast moreover noted that British indoor/outdoor cats frequently reach their teens and a good number reach their twenties. Feral cats also apparently manage to live into their teens; the Cat Action Trust reported that one neutered outdoor cat living on communal vegetable gardens was 19 years old. The oldest feral on record at the time of the article was 28 years old and living as a free-ranging cat with access to a barn.

What about places besides Britain? A cursory examination of sources suggest a few commonalities. First, cats that are allowed to run loose are spayed/neutered. In fact, the aforementioned author who wrote about the British indoor/outdoor cat policy specifically emphasized the benefits of this procedure. While criticizing the claim that indoor cats live twice as long as outdoor cats, saying no one has yet produced enough statistical evidence to support this claim for house cats in contrast to feral, Messy Beast stressed that “neutered cats live longer and house pets are more likely to be neutered than free-living cats; but this longevity difference is due to neutering, not to indoor-living.” Second very few countries actually seem to abide by a strictly outdoor cat policy. Instead, cats most often seem to be labeled indoor/outdoor cats. When cats are allowed outside, the recommendation at least seems to be that cats are supervised, contained in outdoor run attached to the house, or walked on leashes. Three, in countries where cats have been part of society for a shorter time, the indoor lifestyle is becoming increasingly common due to potential problems of cat predation upon wildlife.

I read a few extensive documents about the differences in lifestyles between European and American cats, as well as some elaborate discussions on pet forums about the issue. From these, I pulled a couple additional points which I thought worth your consideration.

First, Groovy Cats & Dogs quotes cat fancier “Eyebrows McGee” as clarifying some cultural differences. For example, not only have cats been in Europe longer than they’ve been in the U.S., but there are fewer large predators (such as hawks, cougars, bears, and coyotes) in residential and urban areas. On a similar note, there are pathogens in the U.S. that do not exist in Europe, which American cats have not developed defenses against. McGee even says that the short existence of the cat in the U.S. (and other places such as Australia) hasn’t allowed for native animals to have evolved the ability to escape cats. Finally, car traffic in the U.S. is apparently faster and more prevalent than in Europe. Notes McGee, “There are few pedestrian footways connecting larger areas, and road crossings are not as pet friendly. Moreover, it is illegal in most incorporated areas of the United States for most pets to be off-leash, and therefore people are not looking for pets wandering even residential streets, in contrast to Europe where this is considered quite normal.” In other words, even if European cats truly do fare well outdoors (and not everyone from Europe seems to agree that they do), that doesn’t mean American cats should be allowed to roam.

A second issue, and the one which I’ll pay more attention to as part of subsequent posts this week, is the well-being of an indoor cat. Opponents to the indoor-only cat philosophy tend to mostly attack the unnatural limitations of this type of lifestyle. And, if nothing else, the debate has convinced me that they have a point. Cats have instinctive needs to express certain behaviors. If indoor life means that they cannot engage in these activities, they’re likely to become stressed. At a minimum, this can cause boredom and obesity. At the extreme, this can cause behavioral issues and sickness. Either way, the result is often unhappy owners, which can lead to cats being allowed to run loose or being dumped at a shelter to become someone else’s problem.

While researchers admit more studies need to be done to determine the exact reasons why more cats are abandoned and why fewer cats are retrieved from shelters than dogs, experts do agree that owners do have a responsibility to provide for the behavioral needs of cats which would normally be obtained in the natural environment. These include the need to hunt, the option to retreat and hide, the pleasure of climbing and, in general, to have a sense that they’re in control of their own activities.


In my introduction, I stated that I found myself being educated on how complicated the indoor/outdoor issue is. Although I still believe that cats should be kept indoors, I also appreciate how the great outdoors can be beneficial to our cats. This sentiments in mind, I’m excited to share a guest post with you about the safe ways to allow cats outside. On the flip side, my research also confirmed and expanded my belief that when environmental enrichment is used, cats and owners will feel such satisfaction that the outdoor issue will no longer become an issue. I’ll be offering some suggestions how in a post later this week. Stay tuned for more articles related to the outdoor/indoor cat debate!







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