Longevity & Causes of Death in Pet Cats

Basic epidemiological research, identifying the most common diseases and causes of death and risk factors for these, is the foundation of preventative medicine. Unfortunately, such research is often scarce in veterinary medicine. Collecting data on a large population of animals over an extended period of time is expensive and time-consuming, and since there is generally no direct economic incentive for doing so and little private or government funding for such research, studies like this are seldom done.

Some longitudinal data have been collected by insurance companies, large corporate practices, and some non-profit organizations supporting veterinary research. A recent paper has reported some information from another source, VetCompass. This is an effort of the Royal Veterinary College to collect clinical data from private veterinary practices and use this data to improve our understanding of health and disease in veterinary patients. This is a potentially rich source of information, and such efforts could contribute significantly to the evidence base needed to improve healthcare for our pets.

O’Neill DG, Church DB, McGreevy PD, Thomson PC, Brodbelt DC. Longevity and mortality of cats attending primary care veterinary practices in England. J Feline Med Surg. 2015 Feb;17(2):125-33. doi: 10.1177/1098612X14536176. Epub 2014 Jun 12.

A brief version of the results can be found on the VetCompass site. The study used data from over 100,000 cats at 90 different practices in England, which allowed for some pretty robust statistical analysis. A random sample of cats who had died was used to investigate longevity and causes of death

A couple of interesting patterns emerged from these. The median longevity was 14 years, but this did vary quite a bit by breed, and there were two peaks in mortality—one at 1 year of age and another at 16 years of age (Figure 1). This suggests that cats pass through a period of relative high risk at about 1 year, but those who get through this time have a could chance of living well into their teens.

longevity chart

The leading cause of death is listed as trauma, which I initially found surprising (Table 2). However, when causes of death are broken down by age group, this is the #1 cause for cats under 5 years of age. It is still #6 for cats over 5, which suggests a higher proportion of outdoor cats than I typically see in my area. For the young cats, trauma accounted for 47% of the death (half of these from road accidents), far more than the second-leading cause of death, viral infectious disease, which accounted for only 6.6%.This is a reminder of why an outdoor lifestyle is a very risky one for domestic cats.

For cats over 5 years of age, kidney disease was the leading cause of death, accounting for 13.6% of the deaths evaluated. Unfortunately, the second-leading cause was the rather uninformative category of “non-specific illness.”

mortality cats

The study also used a linear regression analysis to evaluate factors associated with longevity. In addition to finding that mixed-breed lived longer than purebred cats, the data did show a longevity benefit to neutering. Neutered female cats lived roughly six months longer than intact female cats. Intact male cats, however, died nearly two years younger than neutered male cats. The reasons for this difference are likely multiple. While neutering has been associated with greater longevity in a variety of species, and there seems to be some underlying physiological factor that contributes to greater longevity in neutered individuals. However, there are also likely other differences that have more to do with husbandry than biology. If, for example, neutered male cats are less likely to be allowed outside than intact male cats, which is almost certainly the case, then the risk of being an outdoor cat will confound any apparent effect of neuter status on longevity.

There are, as always, limitations to this study. The accuracy of causes of death could not be independently verified, and many were lumped under the vague heading of “non-specific illness.” The evidence that comes out of retrospective studies of medical records is only as good as the information that goes into the records, so there is always a significant risk of error when dealing with a large and diverse group of clinicians who haven’t all been trained in the same way to use the same record-keeping practices.

The results of this study also apply only to the population studies, which means cats of this particular mix of breeds, lifestyles, and those with similar husbandry and environmental circumstances. The results likely would be different in some significant respects from, for example, an urban U.S. cat population. Nevertheless, the accumulation of such information from different sources over time provides valuable knowledge about the factors that influence health, disease, and longevity in our pet cats, and more such research is critical to improving the care we provide and the health of our pets.

 

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20 Responses to Longevity & Causes of Death in Pet Cats

  1. v.t. says:

    We’ve been trying for decades to convince our friends across the pond to adopt the indoor-only initiative – they always deny the statistics and anthropomorphize how horrible it is to keep a cat “penned up inside”. Too bad studies like this (or in the future) aren’t convincing enough.

    Likewise, I’m guessing the “non-specific illness” category includes any illness in which the owner cannot afford diagnostics and treatments, not much different than here.

  2. Art Malernee says:

    Declawing laws may be one reason cats are let outside more in the UK . I never got a good answer why people in UK put up with cats scratching up the furniture but usa people will not. Maybe they let them outside to save the furniture in the UK since they cannot declaw them.

  3. v.t. says:

    Maybe, Art, but I’m not convinced. Also, we have a fair amount of pet owners who still let their cats outdoors (declawed or not), left intact, and still don’t take them to a vet unless or until it’s absolutely necessary.

  4. Jen Robinson says:

    It’s interesting that the Animal Rights people get very excited about high rates of accidents in greyhound racing but haven’t picked up on the very high mortality of domestic cats due to trauma. I’m all for transparent reporting of greyhound accidents. But it would be good if the same standard were adhered to for domestic cats.

    Too bad similar data aren’t available for dogs. The Finnish Kennel Club has unusually good reporting on cause of death (though the ’cause of death not specified’ category is much larger than desirable). It seems to show that in some breeds, eg., the American Staffordshire Terrier, the accidents result in more deaths than old age, and the combination of accidents and euthanasia due to behavioral problems . . . both of which are most common with young dogs . . . bring the average lifespan down to below six years. See http://jalostus.kennelliitto.fi/frmTerveystilastot.aspx?R=286&Lang=en

  5. Pingback: Benefits and Risks of Neutering–An Evidence-Based Approach | The SkeptVet

  6. kitty says:

    Declawing laws may be one reason cats are let outside more in the UK . I never got a good answer why people in UK put up with cats scratching up the furniture but usa people will not.
    As someone living in the US who considers declawing barbaric, I don’t think this is an issue at all. The vast majority of cats in the US are not declawed anyway – I read the statistics is some 75% are not declawed and 25% are, and then there are some owners who declaw and let their cats out.

    I think it’s more philosophical difference. I think in Europe – and I grew up in Europe – the mentality is different as far as cats go. Also, I think Europeans are more used to free roaming cats and also have their own native wildcats subspecies, they do believe that it’s cruel to keep cats indoors. In some sense, I don’t think it has to do with anthropomorphizing, but more with believing that this is cats’ true nature – to hunt live pray. Even though I keep my cats’ indoors, I think I’d be the first to admit part of my reasons are selfish. I consider “I don’t want to lose them” a selfish reason as well as practical matters of cats’ not bringing home fleas and needing fewer vaccines.

    Keep in mind also, that in Europe cats are not “invasive species” as many Americans view them. Europe has its own wildcats, and having watched videos of wildcats, our cats’ behavior is indeed very very similar. It’s not like dogs and wolves, I seriously doubt too many people will even be able to look at say European wildcat and distinguish it from our tabbies. So to me there is something hypocritical in saying “wild cats belong in the wild” and “domestic cats belong indoors” because behaviorally there is very little difference, they even interbreed. Yes, nature is cruel, but quality of live matters too, and no matter how many toys my cats have and how much I try to play with them, they probably are still bored part of the day. Also, watching how my male reacts when he sees a wild pray even a bug that got into the home as opposed to toys that bore him quickly, I think it might be fairly frustrating for a cat to see prey in the window and not being able to get to it.

    Personally as a cat owner – I keep my cats indoors, but I really think of it as a choice and also depends where one lives.

  7. simba says:

    I think it’s just a perception of what is humane. The objection to declawing, the desire to keep cats outdoors, both come from something of the same place- cats have their own nature and needs, if you get a cat part of it is accepting that.

    It is seen as barbaric and inhumane, unnatural, to declaw cats- if you have a cat let it be a cat, treat it like one, don’t expect it to be a stuffed animal. The thing that Americans find hard to understand is that the same is seen about a blanket policy of keeping cats indoors.

    Sure, if your neighbourhood is dangerous, people keep cats indoors- but even then there’s a sense of ‘this is not the optimal situation for the cat’.

    I don’t think it’s anthropomorphizing, the people who are least likely to do that to cats will still tut over cats kept solely indoors. I think it’s just a reflection of the idea that an animal should be free to express natural behaviours and get adequate enrichment and stimulation. That, and the practical idea that cats are wanted to hunt mice and rats.

    The idea of keeping a cat indoors all the time is seen as a reflection of people’s desire for a ‘suitcase dog’ (as Terrierman put it), people wanting animals to suit their lives and not considering the animal. Or considering the animal but thinking of it as a furry human or an accessory, something to be inside and on a lap and behaving in human-like ways rather than in cat-like ways.

    When a local rescue had a ‘cats indoors’ policy, people were horrified. They couldn’t understand why someone would keep a cat imprisoned in a little space for their life- it was considered to be like keeping a dog outdoors on a chain and not walking it. People also expected the cats to have more behavioural problems, because of that.

    I’m not saying one viewpoint is correct, and I’m not dismissing the idea of cats kept indoors. I’m just saying that the view that people kick cats outdoors to save the furniture, or because they anthropomorphize, is inaccurate. They genuinely think they are doing what is best for the cat, as a cat.

    I have a 15 year old indoor-outdoor cat. He’s been in the same neighbourhood all his life. He has never had any real tendencies towards scratching furniture. I could be falling into the ‘it worked for me’ testimonial trap, but he’s happy and healthy and fit.

  8. skeptvet says:

    The welfare argument, however, cuts both ways. Outdoor cats on average live much shorter lives filled with more disease and injury. What is “natural” is not necessarily what is best. It is natural for people to live as hunter gatherers, to be continuously infested with parasites, and to have high infant mortality and a life expectancy in the 30s or 40s. Yet we choose to live in a way that reduces the burden of disease and suffering even though it might be argued to be “unnatural.” So are cats happier indoors or outdoors? The answer is not as obvious as you seem to think, and as someone who sees the suffering of cats who go outside, I think a strong case can be made that indoor cats can live fulfilling and happy lives. (This does not, by the way, mean such cats should be declawed. That’s an entirely separate issue. The vast majority of cats I see are both indoors and fully clawed).

    Anyway, I don’t think the term “natural” has any real meaning. How can anything we, as an evolved animal species, do be “unnatural?” What distinguishes the behaviors that are natural and those that aren’t? I think it’s a largely meaningless term. In animal behavior, we often use the term “species typical” to describe the behaviors animals of a given species usually express, and there is a sense that well-being is associated with the ability to express the full range of species-typical behaviors. So in this sense, some outdoor activities (e.g. hunting) might be an important part of well-being. But, of course, then you can get into the ethical issues of the impact of artificially bred and sustained cats on truly “natural” wild ecosystems. It’s all a bit more complex than you seem to suggest. I understand why people feel cats are better off going outside, I just think they may be overlooking important welfare and ethical issues associated with this under the false belief that “natural” is a meaningful concept that can guide our ethical decisions making about these issues.

  9. v.t. says:

    Outdoor hazards in terms of health and longevity far exceed indoor hazards (providing owners know how to keep their homes safe for cats). Feline communicable disease, weather hazards, parasites and their associated diseases, fighting, roaming, mating/unwanted litters, HBC’s and other fatal “accidents”, poisons/toxins, getting lost or picked up or trapped by AC (or others) to face death in shelters, or the occasional angry or psycho neighbor who poisons pets. And that’s just a sampling.

    I can no longer count the number of times I’ve heard the “but my cat always stays in the yard”, or, “but my cat is never gone more than a few hours” etc.

    Indoor cats can live long, healthy and happy lives providing that owners enrich their environments, and properly care for them. Even outdoor cat containment systems are available for those wanting to allow their cats outdoors. Like skeptvet, until you see nearly every working day the sad and painful (and oftentimes fatal) evidence of multiple outdoor hazards, to most owners it is an out-of-sight, out-of-mind thing. Until it happens to them.

  10. kitty says:

    Outdoor cats on average live much shorter lives filled with more disease and injury.
    How much shorter? Is there any statistics that is actually reliable and verified? While my own cats are indoors only for my reasons which include yes, safety, and also not wishing to see dead squirrels on my doorstep, I’ve seen a couple of neighbors with indoor-outdoor cats. It’s purely anecdotal, but their cats have lived just as long. People who manage feral colonies – and these guys are always outside, say that cats in managed colonies live 12-13 years. Besides – quality of live matters. I so what I can to enrich their environment (outdoor enclosure is out of the question in a townhouse condo), but I do see a huge difference between how my cats view toys and how they get when they see a live pray. I know my cats are looking in windows quite a lot, running from window to window when something outside interests them. Does it make them frustrated? I feel guilty sometimes for keeping them indoors.

    Scottish wildcat also lives twice as long in captivity, and is healthier, but nobody suggests that it’s better to keep Scottish wildcats in zoos. Of course, Scottish wildcats are endangered and we want them to reproduce, and we don’t want strays mating with them, and yes, we need to neuter our cats. Also, when we look at people who keep Servals or Asian Leopard Cats as pets, we say “these cats belong in the wild”. But I bet these cats also live longer indoors. What is the difference?

    Behavior-wise are our cats that different from small wild relatives? Sure, they are domesticated, but unlike dogs, for most of their domestication they were semi wild mousers in a barn. The domestic pet cat that lives indoors and eats cat food is less than 100 years old, not enough to change their behavior or nature.

  11. v.t. says:

    The differences are – indoor pets are (we assume), taken well care of, receive regular veterinary care to prevent (or treat) disease, are domesticated (and seem to appreciate human-cat bonds and relationships), and ultimately, kept in a safe environment.

    Outdoor cats face numerous hazards on a continual basis (no direct supervision or safety measures).

    Regarding feral cat management – it depends on the caretaker and their resources to maintain a colony – spay/neuter (i.e., TNR), vaccinations, food and shelter, monitoring, potential kitten adoptions etc, helps those cats live safer and longer lives. That said, a caretaker’s resources are mainly out-of-pocket, so doing something is always better than doing nothing to help those cats.

    As for servals, asian leopard cats and other exotic cats, you can mainly thank breeders for that, and some owners who have no clue how to take care of them and provide proper and structured environments for them (i.e., their energy levels require more commitment, space etc)

    Lifespan of indoor cats vs outdoor cats – I don’t have studies handy, but it is obvious and well-known that an outdoor cat has a higher risk of contracting feline-specific diseases, parasitic disease, harm from other animals and humans, environmental toxicities, and all the other hazards of the outdoors. Without treatment for those diseases, malnutrition, accidents, and so on, you can see an outdoor cat has less chance for survival than an indoor cat.

    It’s ok to feel guilty if your cats cannot go out and catch prey. It’s also ok to feel satisfied your cats are safe from harm and have the best chance to lead a long and healthy life indoors. Enrichment of their environment is up to you, and I’m sure your cats can appreciate those efforts more than you give yourself credit for.

  12. Lisa says:

    I live in Canada and my cats are kept indoors. I don’t believe this is selfish, and I don’t think cats should be allowed outdoors to roam in Canada. Ever. My reasoning is that studies have shown that predation by cats kill are large number of wild birds (and other wild animals) annually. A recent study stated:
    “Predation by house cats (Felis catus) is one of the largest human-related sources of mortality for wild birds in the United States and elsewhere, and has been implicated in extinctions and population declines of several species.”; and
    “These estimates suggest that 2-7% of birds in southern Canada are killed by cats per year. Even at the low end, predation by house cats is probably the largest human-related source of bird mortality in Canada.” Blancher, P. 2013. Estimated number of birds killed by house cats (Felis catus) in Canada. Avian Conservation and Ecology 8(2): 3.
    Unfortunately, it seems a large number of cat owner’s believe this continued impact is acceptable because the cat ‘should/needs to’ be outside.

  13. simba says:

    Like I said, I’m not saying all cats should be outdoors, it’s safer etc or that whatever’s ‘natural’ is best- arsenic is perfectly natural.

    I’m saying people aren’t keeping outdoor cats, in places where that’s a common practice, because they think they’re furry people or they want to protect the furniture at the expense of the cat’s lifespan. In a way it’s more hopeful than that: lots of people with outdoor cats would probably be amenable to doing whatever is best for the cat if they only can be convinced it IS best for the cat. They have reasons they think are valid; if you want to reach them, address those reasons.

    The idea that animals should have the opportunity to express ‘natural’ behaviours, for me, doesn’t necessarily fall within the naturalistic fallacy. More just a recognition that different species have different behavioural needs.

    Sparked by what you were saying, Skeptvet- it ties in a bit with owner’s perception of risk, for example. Pet owners who allow pets to do risky things will probably underestimate the potential of harm compared to vets because vets see all the sick animals, owners only see when their own n=1 animal gets sick. Like for the various treatments you write about- people see their own pet getting better after x, they don’t see how many animals you see who didn’t.

  14. skeptvet says:

    I absolutely agree, both that owners of outdoor cats are doing what they feel is in the best overall interests of the pet and that there is nothing inherent fallacious about the argument that animal welfare is greater where animals have as much opportunity as possible to express species-typical behavior, within some limits. The question is simply whether or not cats are truly better off being allowed outdoors or if the risks outweigh the benefits. I tend to feel they do, but it’s an ethical decision and so not something we can easily settle empirically or quantitatively.

    I’m still looking into the evidence concerning relative life expectancy, but my current understanding is that life expectancy is dramatically shorter in cats allowed to roam outdoors, and that is a factor in my sense that overall cats may have a better life if not allowed outdoors. But I don’t intend to suggest it’s a simple or obvious decision.

  15. Pingback: Evidence Update: PBDEs and Hyperthyroidism in Cats | The SkeptVet

  16. Having just lost a cat to CKD, I am interested in the causes. Is the cause food or something else.

    So I have started a survey. With enough entries, what will it show?
    http://www.Torrens.org.uk/Forms/ckd-form.html

    Our cats are outdoor ones – we take them for regular walks. Lts of info on my www site!

  17. Robin Painter says:

    My two cats have always been indoor/outdoor cats-not necessarily by choice but because with three children coming in and out and leaving doors open, it was inevitable. The female cat has a natural range limited to the porch/yard. The male (neutered) cat was more of an aggressive hunter, roaming freely in the woods behind our house. I always felt guilty about letting them outdoors for the reasons articulated above. Last year we were having work done in our house and moved into an apartment with no outside space and voila-we had two indoor cats. It was definitely difficult for them. No matter how many toys and games we provided (at one point the entire apartment was an elaborate maze for them!), they were bored and pretty miserable. Both gained weight and they started fighting quite a bit, demolishing the furniture, always begging for treats, etc. I was very happy for them when we moved back into our house and they were free to roam. The change in their dispositions was remarkable and immediate. Unfortunately, after a few months at home, our male cat disappeared-likely a victim of a predator. We were heartbroken and guilt ridden. However, upon reflection I think longevity in a sub -optimal environment where he was miserable, at least for him, was not preferable to his shorter life span where he was happy and engaged. There is no right answer here in my mind. Perhaps if a cat raised indoors, and has the appropriate disposition, keeping them indoors could be the right answer. But quality of life should not be discounted either. Very tough call.

  18. skeptvet says:

    I agree. Longevity itself is not the only factor that matters. And quality of life is difficult to assess. One could argue that a truly feral cat with no owner lives the purest, most “natural” life for a cat. Yet such cats are often plagued by parasites, infections, malnutrition, frequent injuries, and many other problems which arguably make their quality of life less than that of many owned cats who don’t have access tot the outdoors. Yet despite the risks, there are also elements of being allowed outdoors that enrich a cat’s life. It is, as you say, difficult to make broad generalizations about what is best.

  19. Judy says:

    I don’t doubt that cats that are used to going outdoors will be unhappy when they’re suddenly forbidden to go out. But the cats I’ve had as indoor only their whole lives (aside from some harness walks to explore) don’t seem to feel a lack. One of them was a neighborhood stray; she begged at our door to be let in, and once we capitulated, she never wanted to go out again (though she’ll accompany me on the patio if invited). In our neighborhood, with a busy street nearby and coyotes lurking at night, there’s really no other option.

    My husband thinks cats ought to be able to go out sometimes, but agrees the risks where we live are too great. He grew up with indoor/outdoor cats, but not one of them died at home or of known causes. They all just failed to come back one day. He’s never even known an elderly cat until now (ours are 11, 16 and 19). I don’t think there’s a one size fits all answer, though I do certainly lean toward indoor cats if the particular cat can be happy indoors.

  20. Dr V says:

    This is in very belated response to Lisa’s post of March 21 2015. I am saddened that you are the only one who has mentioned predation by cats as a reason to keep them indoors, and that your post has gone without comment. I think we as veterinarians are too timid to bring this up with our clients, and that we ignore the big picture at our own peril. I swore an oath to speak for those who can’t speak for themselves, that this includes the wild animals affected by cats. Thank you for your comment, Lisa.

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