Pets living longer, better
By Kim Campbell Thornton
September 30, 2009
There aren’t any actual statistics on increasing longevity in dogs and cats, but ask any vet or pet owner and you’ll 
hear tales of dogs living to be 15 or more and cats reaching the age of 20 or even older. An informal and completely unscientific survey of people I know who have dogs turned up a number of pets who were living well past the 12 to 14 years that we tend to think of as the average lifespan. Some of those were small breeds, which tend to live longer anyway, but medium-size breeds such as Beardies and Corgis were up there at 15 and 16 years and sometimes more. I even heard about a 15-year-old Mastiff.
So I was happy to address the subject in my column this month, although many of my questions went unanswered. Why do smaller dogs live longer than giant-breed dogs but elephants and whales live for many years? Apparently, we don’t really know. One of the things we know about dogs, says Martha Smith, DVM, director of veterinary services at Boston’s Animal Rescue League, is that longevity directly corresponds to breed size, but within a group–Labrador Retrievers, for instance–smaller Labs don’t live longer than larger ones. So you can’t make any predictions based on the size of an individual dog versus another individual of the same breed.
And how do we know that pets really are living longer? Any statistics on that? Not really, Smith says.
There is no comprehensive study that has looked at that. I think the only way to gather all that data would be to get into the records of various veterinary hospitals throughout the United States. It’s a really complex data search that would be required.
Pets are living longer, veterinarians think, because of improvements in veterinary care, nutrition and the human-animal bond. Leash laws and keeping cats indoors, for instance, mean fewer pets get hit by cars. The attitude that the pet is a member of the family means he spends more time indoors, more time in the company of his family and thus gets looked at more closely. Little things that might turn into big problems are more likely to be seen and treated by a veterinarian before it’s too late to manage them.
That said, the number-one reason dogs die is cancer, says Johnny Hoskins, DVM, who has spent much of his career studying pet longevity. For cats, the main cause of death is usually related to some type of organ failure, such as kidney or heart. The key in animals as it is in humans is early detection and management, Hoskins says.
One of the things Smith and I talked about was how to estimate age in pets. Being a shelter veterinarian, she has to do that frequently. Time was, people relied on looking at the teeth and body condition. But that can be misleading.
Both of those factors are influenced by what their life experience has been. You can have a very fit animal with great teeth that’s quite old or you can have an animal who’s kind of loose and floppy and has bad teeth and is young.
A new technique has veterinarians looking into the eyes for answers. With training, they can shine a light through the lens, which creates patterns that can be tracked. The spot of the light diffuses at different rates depending on the animal’s age, and a chart was created to help establish the age based on the pattern.
Will we ever be able to predict lifespan? Smith wonders if canine genetic tests might play a role in that someday.
I’ve just learned that the makers of one of the big canine genetic tests has started to market the fact that they can predict a dog’s size based on his genetic profile when he’s a puppy. So if you adopt a mixed-breed puppy and you’re hoping he’s going to be under 25 pounds, but you’re not sure, you can send out a blood sample to find out based on breed composition how big he’s going to get. I wonder at some point if they’ll be able to make lifespan predictions.
That would be cool.
One thing my editor wanted to know was a formula for calculating a dog’s age in human years. The old “multiply by 7″ rule doesn’t really apply because different breeds age at different rates. But knowing that number isn’t essential. Other things are more important, Smith believes.
For me, it’s immaterial what they are equivalent to people’s age because they’re not people. They’re dogs and cats and they are what they are. Are they fit? Are they happy? Are they enjoying life? Are they enjoying your company? Are they active? Those are the important questions to ask, not what numbers we should assign to them.
Tell it, sister!
Although not an exhaustive study by any means, I think this link might prompt you to re-think your conclusions about “pets living longer,” at least if those pets are purebred dogs. http://users.pullman.com/lostriver/longhome.htm
Comment by Miki — September 30, 2009 @ 12:57 pm
Yes, I’ve seen that before—and aside from all the other problems, of lumping all “purebreds” together without distinguishing between puppy mill dogs and dogs from responsible breeders who health screen etc., the numbers of dogs for a great many of the breeds are the very definition of “statistically meaningless.” For a breed near and dear to my heart, for instance, the Chinese Crested, the median lifespan is based on fourteen (14) total dogs. My own dog’s breeder and the other breeders I talked to while looking for a dog, not only have collectively a much larger sample; they individually, over breeding careers of up to thirty years, have samples as large.
Comment by Lis — September 30, 2009 @ 1:11 pm
I had a sheepie that lived to 16 - that’s a good 4 years past their “lifespan”
Comment by Sarah — September 30, 2009 @ 1:47 pm
I think it’s one of the things tha tmakes me most annoyed about the whole ‘purebreds are sickly and have shorter lives’ argument is that well, it just seems like the data sample is so limited. My Lizzie’s grandam was 8 when her mother was born and is still going strong now, AFAIK, at ~14.
Case in point: Maggie (CH Kingsbury’s Carbon Copy) - shown here - http://farm4.static.flickr.com.....af0696.jpg - in the ring at the CWCCA national this year - at SEVENTEEN - and Carbon (CH Coedwig Carbon Blue), who is something like 15 himself. These two dogs are arguably the most influential dogs in the last two decades for this breed.
Comment by Cait — September 30, 2009 @ 2:29 pm
The Papillon Breed Surveys cited were very problematic - I know because I was one of the people filling it out (or attempting to) at the time, and I complained about all the precision inherent in the questions. One of the worst was that the way the questions were structured, it was impossible to tell if the information applied to one dog, to ALL dogs (in the case of an owner with more than one) or just to some dogs - and if so, which ones.
To my horror (and that of more than a few other Club members, not only was the survey published online, but the information it contained was cited in at least one book I’m aware of, and an unkown number of online websites.
The author of the website Miki posted acknowledges there were major problems with the statistical methodology of this survey, but then goes on to cite the “data” anyway.
This whole situation highlights for me once again the difficulties inherent in collecting good data under less than scientifically-stringent conditions, and the perils implicit in the potential misuse of the “data” so collected.
Comment by The OTHER Pat — September 30, 2009 @ 3:30 pm
I meant to add that the Doberman Pinscher Club of America has a longevity program for tracking dogs that live to be 10 or more. It got cut from the column.
Comment by Kim Campbell Thornton — September 30, 2009 @ 3:31 pm
CORRECTION: My first sentence should read ” I know because I was one of the people filling it out (or attempting to) at the time, and I complained about all the IMPRECISION inherent in the questions.”
Comment by The OTHER Pat — September 30, 2009 @ 3:31 pm
While I admire the intent, I find it appalling that a Doberman is considered “long-lived” for reaching the grand age of TEN.
Tells you something about what the Dobe folks are up against. Also where they have chosen to set the bar.
But years ago, an otherwise apparently sane DPCA member who was instrumental in this longevity hall of fame opined on the canine genetics list (the old one out of University of Ottawa server — when it was GOOD) that opening the studbook in order to address the restricted gene pool was out of the question, and that she could never own a dog with one iota of something else crossed in, even if it added years to the dog’s life and eliminated the chronic health conditions and was totally undetectable cosmetically and behaviorally — she would know it wasn’t pure. And that would just, you know, ruin everything.
This from someone who claimed to love both the breed and the individuals who make it up. A breed cobbled together a century ago from a dozen kinds of unrelated dogs.
I agree that one cannot generalize about the lifespans of “purebreds,” not so much based on different lines within breeds, but across different breeds. Border collies — large worldwide population, open registry, performance selection, exceptionally low COI’s — live a relatively long time. Dobermans, Bernese Mt. Dogs, CKCS — smaller populations, closed registries, cosmetic selection, high COI’s — live much shorter and sicker lives than other dogs of the same size.
Breeds vary in the number and diversity of founders and their initial genetic load, the number of historical bottlenecks in their populations, the severity of selection for cosmetic traits, the amount of pedigree fraud that had the salutary effect of increasing heterozygosity on the sly.
Almost 20 years ago, I passed on a Berner pup that we had our hearts set on when the breeder admitted that she’d never had a dog live past age SIX. This Sunday I spoke with two Berner owners who had each had five or six dogs since that time — because theirs, too, died at five or six years old, and they had to keep replacing them.
One was adamant that Berner people were going to lick the problem of dying young with better nutrition and less vaccination. Once again, the idea of judicious outcrossing was received as if I’d just suggested mating them with goats.
Comment by H. Houlahan — September 30, 2009 @ 5:01 pm
The person at the adoption place told me that my little Inca was 5 yrs. old, just what I wanted.
When I took her to the veterinarian, I was told she was at the most 2 and l/2 years old, at the most.
Go figure! I love my little cat, anyway, whatever age she is.
Comment by Colorado Transplant — September 30, 2009 @ 7:54 pm
I’m not sure about the best fed and great genes idea of longevity. Before I knew better - I had a household of 2 dogs and 1 cat. All ate pet food purchased at the grocery store plus other stuff. The terrier mix loved reese’s mini peanut butter cups and would steal them any chance he got. He also loved Olive Garden salad - onions and pepperoncinis included. He got in the garbage and ate the paper towel that was used to make the microwave bacon. The purebred, pet store poodle was the Houdini of the kitchen and was a piggy. He ate a whole package of frozen hot dogs once. The mixed breed cat would supplement her diet with pigeons and lizard tails. None of them ended up at the vet for any intestinal issues. All lived until they were 17. My Grandmother had a mean siamese that roamed and lived until he was 21.
Comment by cheryl — September 30, 2009 @ 8:06 pm
Yes, I asked the DPCA for a comment on how well their longevity program was working since it was established a dozen years ago, but oddly enough I didn’t get a reply.
Comment by Kim Campbell Thornton — September 30, 2009 @ 8:34 pm
In lots of purebred breed, like my own, the life expectancy is actually dropping.
There was a comprehensive study of the golden retriever and its average life expectancy had dropped from around 12 years to 10.5 years.
Comment by retrieverman — October 1, 2009 @ 8:02 am
Scottish terrier lifespan has dropped to 10.15 years: http://www.tartanscottie.com/p.....column.pdf
Golden retriever median lifespan has also dropped to 10.5 years: http://www.vet.purdue.edu/epi/.....inal22.pdf
I can tell you that some early dogs in the golden retriever breed in this country lived well into their teens in the 1930’s, and I had two that lived to be 13 and 14 respectively.
Comment by retrieverman — October 1, 2009 @ 8:11 am
Most of what this article provides is anecdotes, but there are lots of different empirical studies that suggest otherwise.
Comment by retrieverman — October 1, 2009 @ 8:13 am
I think Heather Houlahan said it best— an open registry systems sounds like “let’s breed ‘em with goats” to most “responsible dog breeders.”
Comment by retrieverman — October 1, 2009 @ 8:32 am
The reason why cats live longer than dogs, I suspect, is that cats generally aren’t part of a closed registry system. Those cats that are, from my own anecdotal experience, tend to live rather short lives— 13 yeas is a good age for a Persian.
Comment by retrieverman — October 1, 2009 @ 8:33 am
But then how do you explain the longevity of breeds like Cardis? They started out with a tiny gene pool (~50 dogs, IIRC). Same thing with the Spitz, to a great degree. I suspect that it has more to do with lack of popularity than anything else.
Comment by Cait — October 1, 2009 @ 8:39 am
From the Other Pat - “This whole situation highlights for me once again the difficulties inherent in collecting good data under less than scientifically-stringent conditions, and the perils implicit in the potential misuse of the “data” so collected.”
So what’s the answer? Reliance on brags by breeders and owners about their oldies and deafening silence about the ones who die young or even just earlier than those special oldies? In a perfect world, owners and breeders would be perfectly honest about what they know about the longevity and health of purebred dogs. We don’t live in that world.
Re: vet care and longevity - I have no doubt better and more vet care contributes mightily to longer living pets, including my 9 y.o. Addisonian/calcium-oxalate-stone-forming/chronic pancreatitis/IBD/ARD standard poodle.
Comment by Miki — October 1, 2009 @ 8:42 am
Cardis are an exception to the rule. But just because there are exceptions, doesn’t mean that there is no rule.
But if you take a flat-coated retriever, the life expectancy is even lower than that of the golden. The flat-coat actually started out with a bigger gene pool— black and liver are dominant colors and easily bred for. Yet, it’s in an even worse state than the golden.
Comment by retrieverman — October 1, 2009 @ 8:44 am
The website Miki referenced includes results from MANY different studies. Again, here it is:
http://users.pullman.com/lostriver/trends.htm
The disturbing results indicate low average longevity and/or a decrease in average longevity in many breeds despite advances in veterinary medicine.
Many of the studies were conducted by breed clubs or kennel clubs. That means the results are skewed toward registered dogs owned and produced by serious breed enthusiasts. The notion that the results can be tossed aside due to puppymill dogs is wishful thinking.
Comment by LauraS — October 1, 2009 @ 12:30 pm
Cait, you criticize studies based on dozens and in some cases hundreds of dogs each with the comment “the data sample is so limited”, and then use three anecdotal examples to refute it?
Comment by LauraS — October 1, 2009 @ 12:44 pm
Laura, for Chinese Cresteds, the claimed sample size is fourteen. Now, the number fourteen may likely be described as many things, but “dozens” is not one of the options there.
Is there a reason I should take seriously a longevity “study” based on fourteen dogs?
For some breeds the sample sizes are of respectable size. For others, they’re not much larger than the Chinese Crested sample, and in some cases even smaller. And we already know that the life expectancy of different breeds, even closely related breeds, can vary widely, so you can’t even make a convincing case for generalizing the results from the decent sample sizes to other breeds.
Comment by Lis — October 1, 2009 @ 1:44 pm
The sample size is clearly listed for each study.
http://users.pullman.com/lostriver/breeddata.htm
Dr. Cassidy discusses the importance of experimental design, and among these is that a representative sample is as important as sample size. A particular breeder who is familar with many dogs from a small number of bloodlines may not be familiar with a representative sample.
http://users.pullman.com/lostr.....eports.htm
Some of the breed studies had small sample sizes — see for example those that are clearly designated with LSS, i.e. <20 dogs. But many of the studies did indeed have dozens of dogs and in some cases hundreds of dogs. The fact that some studies involved small samples does not detract from those studies that had large samples.
Lis wrote: "you can’t even make a convincing case for generalizing the results from the decent sample sizes to other breeds."
I made no case to that effect.
Comment by LauraS — October 1, 2009 @ 2:50 pm
Laura - what Lis said. Also, read The Other Pat’s comments about how poorly designed the ‘studies’ conducted by a lot of breed clubs are!
Comment by Cait — October 1, 2009 @ 2:56 pm
Cait, I suggest reading the content on the website. Study design is discussed.
Comment by LauraS — October 1, 2009 @ 3:16 pm
I know firsthand only about how poorly-designed the Papillon survey was. However, that experience causes me to want to know more about any of the other “studies” conducted by other breed clubs. (I may even still have that original questionnaire around somewhere - don’t remember where at the moment though.)
And it just still ticks me off (in an “I told you so!” kind of way) every time I see that Papillon “data” cited.
Comment by The OTHER Pat — October 1, 2009 @ 4:43 pm
Among other things, Dr. Cassidy’s website says of the Papillon study “This survey had one of the most poorly written reports of the breed club surveys I read.”
Comment by LauraS — October 1, 2009 @ 5:59 pm
Right. So why did she even bother including it?
Comment by The OTHER Pat — October 1, 2009 @ 6:14 pm
Because lousy design or not, at least it came to the “right” conclusion! :)
Comment by Lis — October 1, 2009 @ 6:34 pm
Again, I suggest reading Dr. Cassidy’s website rather than just tossing bricks at it. Dr. Cassidy didn’t say the study has a “lousy design,” but rather that the report is poorly written in part because it has no methods section. There’s no way for Dr. Cassidy to know whether or not the study was poorly designed. The results of the study are included with an appropriate caution. I see nothing wrong with that. There is no “right conclusion.”
Comment by LauraS — October 1, 2009 @ 9:44 pm
But, LauraS, Dr. Cassidy says the Papillon report was very poorly written—and you admit that he has no idea whether the design was any good or not.
The OTHER Pat has personal knowledge that the Papillon study design was very bad.
The Chinese Crested “study” consisted of fourteen dogs—absolutely meaningless.
Other breed “studies” included not many more, or even fewer, dogs than the Chinese Crested “study.”
Other breeds do have larger sample sizes, potentially statistically valid—but we know only two things about the designs of those “studies”:
1. Most of them were questionnaires, not vet school studies.
2. Statistical lack of validity and reasons to suspect the quality of the design (e.g., the Papillon “study” couldn’t even produce a decently written report) would not be, in Dr. Cassidy’s mind, reason to omit the study.
And yet, this indiscriminate collection of “studies” (mostly questionnaires) of unknown quality and in some cases obvious statistical invalidity, is cited as “evidence” that canine lifespans are declining.
Without more attention to the quality of the data, it’s not evidence of anything except your desire to believe your conclusion.
Comment by Lis — October 2, 2009 @ 5:18 am
And with regards to those who conducted the Papillon study, I want to emphasize here that their hearts were in the right place. But this was a volunteer effort, and the results show. They showed then, and they show now.
I’ve gotta believe - considering that dog clubs are pretty much ALL volunteer-run organizatons - that there is a high probability that any one of these other studies may also suffer from the syndrome of “good intentions gone awry”.
The average person just doesn’t know how truly difficult it is to design survey questions that yield unambiguous data. Heck - as I recall, the woman who did the “study design” for the Papillon study was touted as being a “statistician” (which was all the club leadership needed to know - they refused to listen to any criticisms of her work). But being a “statistician” does NOT automatically translate into being a competent pollster. And to this fact, the VERY ambiguous of the Papillon “study” speak for themselves.
Again - without access to the original questionnaires (to see what questions were asked and how they and the overall questionnaires were structured) who knows how often a similar scenario might have played out in any of the other studies?
Comment by The OTHER Pat — October 2, 2009 @ 7:18 am
Final sentence of second to last paragraph SHOULD read:
And to this fact, the VERY ambiguous results of the Papillon “study” speak for themselves.
Comment by The OTHER Pat — October 2, 2009 @ 7:20 am
And here I thought this month’s column would just be a fun little noncontroversial piece, bouncing off the news that the “world’s oldest dog” had died and offering a few tips on how to help your pet live longer. I will just say that in my many years of looking at breed club websites as I researched various breeds for profiles, I have yet to see a breed club health study that I thought was especially useful or well designed. Most recently, I’m appalled at the almost complete lack of health information, or at least useful health information, on so many breed club websites.
Comment by Kim Campbell Thornton — October 2, 2009 @ 7:48 am
Lis, the black helicopters you see flying overhead are not real.
Dr. Cassidy, not me, included the Papillon and Chinese Crested studies in his/her website. Dr. Cassidy’s inclusion of those studies is not evidence of anything that I “desire”.
NO ONE used the Papillon study or Chinese Crested study as “evidence that canine lifespans are declining.” NOBODY. Again, I suggest you actually READ the website before throwing bricks. Once again, here is the page that has the longevity trend data, and there’s nothing about those two breeds. Nada.
http://users.pullman.com/lostriver/trends.htm
Dr. Cassidy cannot read the mind of The OTHER Pat. If The OTHER Pat wishes to make his/her feedback about the Papillon study known to Dr. Cassidy, there is an Contact button clearly indicated on the website. Dr. Cassidy included feedback from others who participated in breed surveys.
As far as your comment “Most of them were questionnaires, not vet school studies”… there are two types of vet school studies included in Dr. Cassidy’s site:
1) Patronek et. al. which used the VMDB (Veterinary Medical Database) as its data source. As Dr. Cassidy clearly indicated:
“[The VMDB] is a biased sample. Dogs referred to vet schools often have uncommon conditions or conditions for which treatment is too specialized for most veterinary practices. Vet schools are also less likely to see dogs euthanized for “old age” and no vet practice sees dogs that die of “old age” at home (unless the dog is necropsied).”
2) The questionnaire-based studies completed by vet schools. They include those done by Professor Larry Glickman of Purdue University, and Professor John Armstrong of the University of Ottawa.
You imply that questionnaire-based studies aren’t valid. Not true. For more information, I suggest contacting Professor Larry Glickman at Purdue University. His contact info is easy to find on the Purdue University website, and I’ve found him to be very approachable. Dr. Glickman is one of the world’s preeminent veterinary epidemiologists. He also participated in the Patronek study. [Dr. John Armstrong is deceased]
You are mistaken regarding what is known about the design of most of the studies. A lot is known about most of them, because most of them included a discussion about Methods. I suggest reading the studies. The Purdue University breed studies, for example, are packed with interesting information, as is Dr. John Armstrong’s Canine Diversity Project website.
The studies that you are dwelling on are only two of the dozens of studies referenced by Dr. Cassidy. If you choose not to believe any study that included fewer than 20 dogs, 30 dogs, 50 dogs, 100 dogs, or whatever arbitrary cutoff you wish to apply, then that is easy to do because the number of dogs included in each study was provided on Dr. Cassidy’s website. But let’s not confuse your arbitrary choice with “statistical validity”.
Comment by LauraS — October 2, 2009 @ 8:21 am
“I will just say that in my many years of looking at breed club websites as I researched various breeds for profiles, I have yet to see a breed club health study that I thought was especially useful or well designed.”
For starters….
http://www.vet.purdue.edu/epi/.....inal22.pdf
http://www.vet.purdue.edu/epi/akita_final_2.pdf
http://www.vet.purdue.edu/epi/.....evised.pdf
http://www.vet.purdue.edu/epi/wpg.pdf
Comment by LauraS — October 2, 2009 @ 8:25 am
Call me kooky, Laura, but those look like breed health studies designed by Purdue, not by the breed clubs. And most of what’s included in Dr. Cassidy’s website are not vet school studies. If they were mostly vet school studies, I’d be more prepared to take Dr. Cassidy’s site seriously.
Comment by Lis — October 2, 2009 @ 9:08 am
Call me kooky, Laura, but those look like breed health studies designed by Purdue, not by the breed clubs.
The referenced studies were co-developed by the breed clubs and Purdue University. For example:
II. Methods
The Health and Genetics Committee of the Golden Retriever Club and Dr. Larry Glickman from Purdue University School of Veterinary Medicine developed the questionnaire used in this survey. The club mailed the questionnaire to all members and placed a copy on the club’s home page on the World Wide Web in 1998. Each owner was asked to complete a separate
questionnaire for up to five dogs that were alive on January 1, 1993. Seven hundred and forty six owners submitted usable responses directly to Purdue University for 1444 Golden Retrievers.
Just curious, but what useful information do you glean about canine longevity from the Patronek vet school study?
Comment by LauraS — October 2, 2009 @ 9:26 am
The referenced studies were co-developed by the breed clubs and Purdue University.
Yes, exactly.
Not by well-intentioned amateurs with no input or guidance from people who actually knew what they were doing.
Comment by Lis — October 2, 2009 @ 9:30 am
And, btw, no, the fact that I recognize the much greater likelihood of getting a quality study out of trained, professional researchers than out of well-intentioned amateurs does not mean that I have to regard every vet school study as excellent in order to avoid being inconsistent or hypocritical. Truly, it does not.
Comment by Lis — October 2, 2009 @ 9:32 am
Not by well-intentioned amateurs with no input or guidance from people who actually knew what they were doing.
You have no basis for making that sweeping generalization. You are the one in this thread who has been twisting evidence to support “your conclusion”.
Comment by LauraS — October 2, 2009 @ 9:33 am
The study that Dr. Cassidy refers to as the British Owner Survey was also conducted by a professor at a vet school. This study was published in the refereed scientific journal “The Veterinary Record”.
Comment by LauraS — October 2, 2009 @ 9:44 am
You have no basis for making that sweeping generalization. You are the one in this thread who has been twisting evidence to support “your conclusion”.
Laura, you are missing the rather central point that I don’t have “a conclusion.” We really have no idea whether dogs, either as an overall average, or within particular breeds except the few for which there have been genuinely good studies, are living longer lives, shorter lives, or lives of similar length compared to forty or fifty years ago.
And surveys conducted by breed clubs without the collaboration of professionals are, whatever you choose to believe, far more likely than not to be utter crap, because the average person has no idea how to design a survey so that it produces meaningful, useful results.
Finally, the fact that Dr. Cassidy includes (and especially, includes without caveat of any kind) a ‘study’ in which the sample size was fourteen dogs, and includes another “study,” the Papillon breeder survey, with a report that Dr. Cassidy admits was extremely badly written and which someone who attempted to fill out that survey reports was extremely confusing and badly designed, really does undermine the credibility of the rest of the “information.”
If that isn’t clear enough for you: Obvious statistical invalidity and an extremely poorly-written report that ought to have cause a serious person to ask if the study design was any better, were not regarded as reasons for excluding a ‘study’ from the compilation. Therefore, the fact that a study was included, does not mean we should take it seriously or can extrapolate anything at all from it. Inclusion of obvious bad data means that we can’t rely on any of the data, except in cases where we can personally look at the actual surveys and their results—and we can’t extrapolate from those to any other breeds than the ones they specifically studied.
Comment by Lis — October 2, 2009 @ 10:05 am
On the contrary, Lis, you do have conclusions, which you stated above. You find 2 studies lacking, so by some kind of bizarre guilt by association you diss most of the rest of the studies. Without evidence you dismiss any study not done by a vet school as being done by the “average person has no idea how to design a survey” and therefore the study is “utter crap”.
You know next to nothing about the people who did most of the studies. It might come as a surprise to you what kind of people serve on breed health committees. It’s not unusual for these committees to include people with medical or scientific backgrounds. People like Denise Wall, PhD, who has served on her breed’s health committee.
Furthermore, based on the comments you’ve made in this thread it’s obvious that you haven’t bothered to read the studies or very much of the content on Dr. Cassidy’s site. Yet you feel qualified to attack their work nevertheless. That’s not how science works.
There is considerable evidence that many breeds have a shorter median or average longevity than one would expect given the typical size of the dogs in those breeds.
There is evidence that breeds for which longitudinal data are available are not living any longer in recent years than they were in the past. As Dr. Cassidy said:
“Even with consideration of possible methodological problems with some of the studies, the data are very discouraging. There have been dramatic improvements in veterinary medicine, particularly in treatments of the most common killers of dogs (cancer and heart disease). If breed health is staying about the same, then breed life spans would be expected to be increasing because of improved veterinary care. If breed life spans are staying about the same, then improved veterinary care may only be compensating for declining breed health.”
Comment by LauraS — October 2, 2009 @ 10:46 am
No, Laura, not just two studies. It’s just that the Chinese Crested is the breed nearest and dearest to my heart, and The OTHER Pat had specific information about the incredibly bad design of the Papillon study.
Other breeds for which the “studies” had sample sizes under three digits. (I have included a few where two studies combined may be over three digits, but none where any single study was over three digits, or where there were three or more studies)
Leonberger 47 dogs (and another with 78 dogs)
Russian Black Terrier 4 dogs
Hovawart 19 dogs
Chinese Crested 14 dogs
French bulldog 71 dogs
Schipperke 36 dogs
Tibetan Terrier 95 dogs (an another with 7 dogs)
Affenpinscher 21 dogs
Brussels Griffon 71 dogs
English Toy Spaniel 22 dogs
Havanese 3 dogs
Japanese Chin 38 dogs
Lowchen 9 dogs
Maltese 42 dogs
Pomeranian 29 dogs
Silky Terrier 3 dogs
Toy Manchester Terrier 19 dogs
Toy Poodle 20 dogs (and another with 11 dogs)
Yorkshire Terrier 63 dogs
Basenji 46 dogs
Pharaoh Hound 15 dogs
Basset Fauve de Bretagne 15 dogs
Basset Griffon Vendeens (all sizes) 76 dogs (with a note saying see Petit and Grand)
Grand Bleu de Gacogne 6 dogs
Hamiltonstovare 6 dogs
Miniature Dachshund (all coat types) 21 dogs ( with note saying See also Dachshunds (all varieties))
Otterhound 41 dogs
Petit Basset Griffon Vendeen “N probably 45”
Smooth-haired Dachshund 75 dogs (See also Dachshunds (all varieties))
Wire-haired Dachshund 46 dogs (See also Dachshunds (all varieties))
Borzoi 87 dogs
Rhodesian Ridgeback 10 dogs
Sloughi 1 dog
Anatolian Shepherd Dog 23 dogs
Estrela Mountain Dog 3 dogs
Giant Schnauzer 39 dogs
Komondor 10 dogs
Maremma Sheepdog 19 dogs
Australian Cattle Dog 11 dogs
Australian Shepherd Dog 22 dogs
Briard 71 dogs
Canaan Dog 2 dogs
Cardigan Welsh Corgi 53 dogs
Polish Lowland Sheepdog 11 dogs (and another with 19 dogs)
Rough Collie 51 dogs
Swedish Vallhund 7 dogs
Welsh Corgis (both breeds combined) 13 dogs (See also Cardigan Welsh Corgi and Pembroke Welsh Corgi)
Bullmastiff 96 dogs (and another with 7 dogs)
Dogue de Bordeaux 5 dogs
Greater Swiss Mountain Dog 71 dogs
Mastiff 94 dogs
Tibetan Mastiff 10 dogs
Chow Chow 7 dogs (and another with 31 dogs)
Finnish Lapphund 5 dogs
Finnish Spitz 42 dogs
German Spitzes (all varieties) 43 dogs
Norwegian Buhund 17 dogs
Shiba Inu 3 dogs
Greenland Dog 2 dogs
Braco Italiano 1 dog
German Long-haired Pointer 2 dogs
German Wire-haired Pointer 41 dogs
Italian Spinone 47 dogs
Large Munsterlander 69 dogs
Small Munsterlander 31 dogs
Wire-haired Vizsla 15 dogs
Chesapeake Bay Retriever 45 dogs
Curly-coated Retriever 40 dogs
Portuguese Water Dog 6 dogs
Field Spaniel 68 dogs (and another with 71 dogs)
Irish Water Spaniel 95 dogs
Kooikerhondje 7 dogs
Sussex Spaniel 42 dogs
Miniature Bull Terrier 20 dogs (and another with 53 dogs)
Bedlington Terrier 48 dogs (another with 6 dogs)
Cesky Terrier 9 dogs
Dandie Dinmont Terrier 62 dogs
Fox Terriers (all varieties) 44 dogs
German Pinscher 24 dogs
Glen of Imaal Terrier 6 dogs
Russell Terriers (all varieties) 75 dogs (See also Jack Russell Terrier and Parson Russell Terrier)
Sealyham Terrier 12 dogs
Skye Terrier 37 dogs
The sad truth is you can’t extract any meaningful information from these tiny studies. Such small samples could be distorting the results in either direction. They, literally, don’t tell us anything.
Comment by Lis — October 2, 2009 @ 12:02 pm
Lis, you do not know what the sample size is for “meaningful information” to be derived from these kind of studies. You use phrases like “statistical lack of validity” without even reading the studies or knowing what that means. “Three digits” is not some magic threshold in order to be “meaningful”.
Comment by LauraS — October 2, 2009 @ 1:15 pm
Indeed. You can have study with a sample size in the tens of thousands, and still have no statistical validity or usefulness.
But sample sizes in the tens, are just laughable.
And a sample size of one, is just trying to make it look like you have more results than you really have.
Comment by Lis — October 2, 2009 @ 1:51 pm
But sample sizes in the tens, are just laughable.
That simply isn’t true, and therein lies the source of your misunderstanding.
The required sample size depends on what question is being asked and on the nature of the data.
For example, let’s consider a hypothetical breed, the Andean Shepherd Hound (ASH).
40 years ago, ASH had a median longevity of 7.0 years.
15 years ago, ASH had a median longevity of 10.0 years.
Now lets consider another hypothetical breed, the Tundra Hairless (TH).
40 years ago, TH had a median longevity of 9.5 years.
15 years ago, TH had a median longevity of 10.0 years.
What sample sizes for ASH and TH populations are required to determine these trends?
The required sample sizes for the ASH populations will be smaller than for the TH populations, because the longevity change for the ASH was larger than for the TH.
Beyond that, the +/- longevity spread in each population also affects required sample sizes.
I once did a statistical comparison of two dog breed populations, and it only required sample sizes of 30 each to reach the commonly accepted p<0.05 threshold for statistical significance. Increasing sample sizes beyond 30 each reduced the p value as expected, but it did not change the calculated difference between the two populations to any meaningful extent. This happened despite the fact that the calculated difference between these two breed populations was relatively small.
There is no simple answer to what the required sample size is for a dog breed longevity study. To use your phrase, it isn't "statistically valid" to dismiss a study that sampled "tens" rather than hundreds or thousands.
Comment by LauraS — October 2, 2009 @ 2:44 pm
But sample sizes in the tens, are just laughable.
That simply isn’t true, and therein lies the source of your misunderstanding.
The required sample size depends on what question is being asked, and on the nature of the data.
For example, let’s consider a hypothetical breed, the Andean Shepherd Hound (ASH).
40 years ago, ASH had a median longevity of 7.0 years.
15 years ago, ASH had a median longevity of 10.0 years.
Now lets consider another hypothetical breed, the Tundra Hairless (TH).
40 years ago, TH had a median longevity of 9.5 years.
15 years ago, TH had a median longevity of 10.0 years.
What sample sizes for ASH and TH populations are required to determine these trends?
The required sample sizes for the ASH populations will be smaller than for the TH populations, because the longevity change for the ASH was larger than for the TH.
Beyond that, the plus/minus longevity spread in each population also affects required sample sizes.
I once did a statistical comparison of two dog breed populations, and it only required sample sizes of 30 each to reach the commonly accepted p less than 0.05 threshold for statistical significance. Increasing sample sizes beyond 30 each reduced the p value as expected, but it did not change the calculated difference between the two populations to any meaningful extent. This happened despite the fact that the calculated difference between these two breed populations was relatively small.
There is no simple answer to what the required sample size is for a dog breed longevity study. To use your phrase, it isn’t “statistically valid” to dismiss a study that sampled “tens” rather than hundreds or thousands.
Comment by LauraS — October 2, 2009 @ 2:55 pm
My Siberian cat lived almost 18 years. Many people says that it’s very long for cats. But he never looked like old cat in his last years. On the contrary he was very energetic and joyful
Comment by Kiolva — October 5, 2009 @ 9:13 pm