Cats: Inside or Outside?


If we love our cats, then why in the world do we expect them to cope with the harsh realities of life outside?

Defenders maintain there’s a tradeoff.

Multiple studies support that cats living only indoors live several years longer than cats who sometimes navigate life outside. Still, there’s a surprising medical revelation about a shortcoming of cats living indoors only.

Sixty years ago, cats being indoors vs. outdoors wasn’t an issue. Most cats could come and go as they pleased.

It wasn’t welfare issues that changed their world, encouraging more indoor cats in the U.S., it was mass-manufactured scoopable clumping cat litter. Back in the feline dark ages, prior to readily available cat litter, cat boxes weren’t sold, either. Some cat caretakers would improvise with plastic dish pans or even cooking pans, filling them with anything from coal to dirt, but most cat owners just allowed their cats to do their business outside. When it became clear that cats would use manufactured litter, more cats were eventually transitioned to life indoors only.

The advent of manufactured cat litter and boxes meant that cats could more easily be kept as indoor pets. And within only a few years, cats overcame their canine cousins as America’s most popular pet.

In 1994, after writing a popular book, Tribe of the Tiger, author Elizabeth Marshall Thomas, who was in rural New Hampshire, told me, “Choice is very important [as to whether cats can go indoors and outdoors]. I feel cats should control their own destinies, even if there’s some risk. Live by the sword, die by the sword.”

In the 1990’s, these comments weren’t particularly controversial.

By 2004, the American Pet Product Association’s National Pet Owners Survey indicated that just over half of all U.S. cats were strictly kept indoors (nearly twice the number of 20 years prior), about a third of all cats could go inside or outside as they pleased, and the remaining 17 percent were kept outside only. In 2014, about 70 percent of cats were defined as indoors only, about 25 percent could go inside or outside as they desired, and the remaining 5 percent were described as outside only.

Still, when you do the math, millions of cats continue to have the option to wander outdoors. Some cats might have been outdoors earlier in life and were then taken inside, but still demand to go out. Not being able to deal with a feline temper tantrum, these cat caretakers relent. Allowing these cats outdoors is one thing. It’s another view all together when cat caretakers insist that nothing bad can happen to their kitty outside, and even encourage their cats to roam. In truth, a lot can happen to cats when they’re outdoors.

While there are still rural places in the U.S. without nearby roads and lots of cars, those locations remain the exception.

For those who insist their cats are too clever to get in the way of a car, they’re dead wrong, with “dead” being the operative word. According to the National Traffic Safety Commission, 5.4 million cats are hit by cars each year in the U.S., and 97 percent of those cats die. There’s no data to reveal how many of these cats are owned or unowned, but these numbers clearly demonstrate that the notion that cats are too ingenious to get hit by cars is a myth.

Cars aren’t the only hazard for cats who venture outside. A few licks of sweet tasting antifreeze can kill a cat, unless it’s a pet-safe product. Cats can also nibble on plants treated with pesticides or plants that may be tasty but are also toxic.

In frigid weather cats seek heat, and slinking under a car hood can be a feline version of an electric blanket—until an unknowing driver starts the car. It’s not unheard of for veterinarians in cold climates to attempt to save mangled cats.

Another myth about outdoor cats is that they aren’t prone to tick disease. While Lyme disease may not make cats ill, there’s plenty that’s delivered by the blood-suckers that can. Here’s a hit list of tick diseases that can make cats sick: Cytauxzoonosis (sometimes called bobcat fever), Ehrlichiosis, Haemobartonellosis, Babesiosis, and Tularemia.  Indoor/outdoor cats might also transport fleas into homes of unsuspecting owners. Using a veterinary flea and tick protection might help to prevent tick disease and flea bites.

Mosquitoes carry heartworm, and the American Heartworm Society points out that all cats should be protected since mosquitoes can get indoors. And while it makes sense for all cats going outdoors to receive protection, few actually do. In cats, heartworm can cause feline-associated respiratory disease (creating asthma-like symptoms), and heartworm is the second most common cause of sudden death in cats.

While heartworm treatment is uncomfortable and expensive for dogs, in cats there’s a larger problem: There is no treatment for feline heartworm (short of prevention).

It’s not only the predatory parasites that threaten outdoor cats, there’s a long list of additional predators, including coyotes, fox, wolves, larger birds of prey, stray dogs, and even other cats, who may share infectious diseases, like feline leukemia or the feline immunodeficiency virus.

However, cats are also a threat to other animals, as cats are both predator and prey. Numbers floated by some bird organizations are often wildly exaggerated. For example, a frequently quoted report from a Smithsonian article suggests cats kill approximately 1.4 to 3.7 billion birds annually in the U.S. (Loss, Will, and Marra 2013). That’s crazy, since the total number of birds that reside in the U.S. is around 3.2 billion (Partners in Flight 2013). If this were true, there would be no birds existing in the U.S.

Cats are, however, opportunistic feeders. So where little lizards are abundant, they appear on feline menus. Cats don’t fly, and several studies confirm that cats overall prefer to hunt rodents over birds, particularly species described as a nuisance (Crooks and Soulé 1999, Kays and DeWan 2004, Mitchell and Beck 1992).

Still, cats do certainly kill birds and other wildlife. There is an ethical question about allowing cats outdoors. Even well-fed cats will sometimes bring home a “gift” to their owners.

What’s more, allowing cats to use neighbor lawns as their litter boxes is just plain rude. And, cats may use neighbor cars as a playground, scratching the car in the process. Also, just being in front of a neighbor’s home could cause the neighbor’s indoor cats to begin spraying when they see the other cats outside their windows. Inappropriate elimination is the most common reason for relinquishing cats to shelters. There are people who give up on their indoor cats, all because outdoor cats have wreaked havoc among those inside cats.

While indoor cats are safer, there’s one silent danger lurking inside the home that may cause or contribute to the likelihood of hyperthyroid disease in cats. Studies show that cats with hyperthyroid disease often have elevated levels of polybrominated diphenyl ethers (PBDEs) which are found on furniture treated with flame retardants and carpet padding. When diagnosed, hyperthyroidism can be treated and controlled or even cured in senior cats.

Cats are also experiencing cancers more often than they were 60 years ago. Cats are living longer, and cancer is generally a disease of the aged, but they share our environments. So, it’s possible the same environmental factors causing cancers in people may also be making our cats sick.

Dr. Tony Buffington, legendary veterinarian, emeritus professor of veterinary clinical sciences at The Ohio State University College of Veterinary Medicine, and clinical professor (volunteer) at the UC Davis School of Veterinary Medicine, discovered that unenriched environments are stressful to cats. As a result, boredom may actually make cats sick, causing idiopathic lower urinary tract disease (ILUTD), now dubbed “Pandora’s Syndrome.” And, ILUTD can be painful, causing some cats to urinate outside the litter box, which can lead to frustrated owners giving up their cats. Enriching indoor environments is necessary for optimal health of indoor cats. It’s true, boredom is never an issue for outdoor cats who have a whole outdoor world to explore.

Also, with more to do, indoor-outdoor cats tend be more active, and not as likely to be overweight or obese. Sixty percent of cats in the U.S. fall into the overweight/obese category, according to the Association of Pet Obesity Prevention. And, overweight cats are more likely to suffer from other medical conditions, like arthritis and diabetes.

It appears to me that the right balance for the benefit of neighbors, wildlife, and cats is to offer an abundantly enriched indoor environment without allowing cats to go outside from day one.