Tuesday, 5 June 2012

Purebred v crossbred longevity - your questions answered


There was a big response to my blog on VetCompass's data comparing purebred to crossbreed longevity (see here), with several questions and some querying the validity of the data. Dan O'Neill from VetCompass has followed the comments with great interest and has kindly agreed to respond.

Over to Dan...

Many thanks to Jemima for posting the VetCompass preliminary canine longevity study and to all of those who commented. VetCompass is a collaborative not-for-profit research project prioritising companion animal welfare. As such, it is important to gauge and include the opinions and interests of breeders and owners into ongoing research. All VetCompass research output aims to have immediate applicability to improve animal welfare and is not designed to just adorn the pages of esoteric veterinary journals.
Although it is not possible to reply to all those who commented, I would like to make a few general replies. The results of most scientific studies contain two main parts. The first is a descriptive component that aims to describe the situation observed, without trying to explain it. In this study, the descriptive component described overall longevity of purebreds versus crossbreds and also the longevity of individual breeds. That crossbreds may outlive purebreds is just a basic fact from this study and does not try to explain why this may be the case. It does not necessarily follow that any differences seen are related to basic hybrid vigour or genetics.
The second part of most studies is the analytic phase where the problem is taken apart and analysed to understand how it works and tries to explain the descriptive findings. There are many factors which may affect the longevity differences seen for crossbreds and purebreds; and these often turn out being counter to what might be expected.  To the point where this study was blogged, we had examined the influence of variables such as sex, neutering and insurance status on longevity. For example, intuitively, one would expect insured animals to live longer than non-insured since higher health care standards should give an advantage in life. Interestingly, the reverse is the case and insured dogs live over 1 and a half years fewer than non-insured. This may be because people insure unhealthy individuals or breeds but, regardless, it does highlight the importance of gathering data before making assumptions. Many commented that body size/weight may explain away the difference in longevity of crossbreds and purebreds. The beliefs are that crossbreds are smaller than purebreds and that small dogs live longer. This aspect is already being studied and will be very interesting to see the effect.
Another comment regarded the selection criteria for breeds included. VetCompass collects data on all dogs attending vet practices. The only criterion for the breeds included was the number of them seen; enough dogs of reported breeds were required to provide statistically reliable results.  Apologies to owners of less common breeds, but these will be included in future studies as the overall dog numbers increase.
The use of median instead of mean age was also questioned. The ‘mean’ refers to adding up all the ages and dividing by the number of dogs. The ‘median’ refers to ranking all the ages and selecting the centre age. The median is a better descriptor for this study because there are two peaks of death, one in year 1 with a higher one at year 14.

A thread also discussed whether vets are made aware when dogs have died at home. In general, vet practices would be aware since clients may bring the bodies to their practice for cremation or at least notify the practice to submit final insurance claims or to stop vaccine reminders being issued.
Finally, in response to the comment regarding 'right censoring': if we were following a group/cohort of dogs from birth to when they died, then right-censoring becomes an issue, because some may not have died during the study period.  However, this study was in essence a cross-sectional study, picking out all animals that had died regardless of when they were born. Right censoring (loss of information on what happens to dogs after the time period of study) is, therefore, not an issue for this study since all the dogs had died and thus none were censored.

So far, over 200 practices are collaborating with VetCompass but I would be very happy for information on the project to be passed onto readers’ vet practices to further encourage vet participation. The more practices that get involved, then the more robust and useful the studies that can use this information.
Finally, may I once again thank the readers of Jemima’s excellent blog for their comment and hopefully you will allow me to delve into your combined wisdom again for future studies. 
Many thanks Dan.  
A pdf containing information on VetCompass  can be downloaded here.

48 comments:

  1. I just looked at this and the previous post, and while I'm not necessarily disputing the data, I am curious about a couple of things:

    1) The poster says that Border Collies and English Springer Spaniels live longer than crossbreeds, but the difference is not considered statistically significant. In that case, it would seem to me that any breed that scores around 13 years is ALSO in the "not statistically significant" range (so really, Jack Russells and Shih Tzus don't live significantly shorter lives than crossbreeds).

    2) That's a very short list of breeds on the poster. Where can we access the full list of breeds that they got significant data for?

    3) I'd like to see the data sliced and diced based on what the dogs died OF. "Neoplasia" is kind of vague as a diagnosis. I would like to know how many dogs in the reports died of cancer, at what ages. I also think death from an accident should be dropped from all the breeds and crossbreeds or grouped separately, since accidental death skews the results (it doesn't prove a thing about the relative health/longevity of breeds or mixes that an individual got out and got hit by a car at 3 years old).

    I just can't look at this data and be horrified (or relieved) without a little more information and analysis.

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    1. I agree that it would be interesting to know an actual cause of death for each dog, but remember that many diagnoses are presumptive. Owners often decline advanced diagnostics on pets. A vet may be able to reasonably determine that a pet has some kind of neoplastic process going on, but without diagnostic imaging, biopsies, etc they may never know which exact cancer is happening. A lot of diseases can have similar symptoms that may take a lot of investigation before or after death to really pinpoint - and not all people are willing or able to do that.

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    2. Granted, but I had a 17-year old Sheltie whose cause of death was PROBABLY some kind of cancer. However, he was 17 years old, and had given no signs of illness until a few days before his death. *I* would have called his death "old age", because that's a good long healthy life. How would reporting vets have classified it? OTOH, a 5-year old Golden Retriever who dies of cancer--that's a problem.

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  2. The author seems to be basing his reply to the "right censored data" issue on faulty premises. Right censored data are a problem wherever analyses are based on death records only, which is clearly the case in the poster.

    Methodologically, every study that studies life expectancy necessarily includes birth cohorts. The problem occurs when the authors choose to disregard this fact: When one collects death data only, which does not include information on dogs in the same birth cohort that are still alive, this results in an underestimation of life expectancy.

    Take, for the sake of argument, all dogs who died in 2010. Obviously, most dogs born in 2009 were still alive then, so you will only get the dead ones that died at around one year old and younger from the 2009 birth cohort when using the author's method. The bias thus created is is obvious when we look at the 2009 birth cohort, but becomes masked when we consider this birth cohort as part of the 2010 death cohort.

    References demonstrating the maths behind the problem as well as further reading are provided in the J Sm Anim Pract reference I quoted.

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  3. Thanks for making results available. May the effort live, grow, and prosper.
    Longevity is complex and multi-causal.
    Is the public, or the scientific community, ever going to get to work with the raw data? Until 'crossbreed' is better described, I'm not real interested in the differences in longevity between pure and X breeds. I would very much like to see what happens when data is thrown through cluster analysis (eg, PCA) . . . how do breeds group in terms of causes of death? age of death? I'd love to see more on high and low quartiles. Why do so many Staffies die young? Is there anything in common among the large number of small dogs who live to extreme old age? Is there ever going to be a way to account for degree of inbreeding when considering purebred dogs? There's so much we have opinions on, but lack the data to convert our opinions to honest hypothesis and put them to the test.

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  4. I think that one of my main points has not been addressed (and if so I missed it). In fact, the response makes me more alarmed at what it misses. There is a spike in deaths at around age 1, yet many more cross-breds than pure-breds are sent through the shelter system, and purebreds who do go through shelters are more likely to be placed. Are euthanized dogs in shelters counted in this? If not, you are weeding out a lot of the least healthy or worst behaved dogs from the mixed-breed category, more so than the pure breeds. "VetCompass collects data on all dogs attending vet practices" does not sound like it includes shelters.

    If I manage a shelter in the States and I have a pit bull mix come in at one year of age showing signs of hip dysplasia and dog aggression, what do you think will happen to that dog?

    If I have a Golden Retriever come through with the same issues, and I have about a dozen people on a list saying they are waiting for a Golden, what do you think will happen to THAT dog.

    And so the one-year-old bully/whatever mix with early health problems is likely put down and never sees a vet practice. The Golden in the same circumstance finds a home and visits the practice of a vet and so the age of death makes the study.

    Unless I'm missing something, I would think this skews the data a great deal. Many dogs are euthanized in shelters, the least adoptable are the first to go, and adolescence is the prime time for dogs to be turned over and corresponds with a peak age of reported deaths at practices.

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    1. It clearly does not include dogs euthanazed at shelters as these ould not be done by a vet practice in most cases. The source of the data, and it's limitations have been discussed. It is what it is and no more. It is an interesting start.

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  5. The number of dogs euthanised by rescue centres in the UK is very small in proportion to the total dog population compared to the US. We have fewer dogs coming into rescue, and most rescue centres have a policy of euthanising only the very old and seriously ill dogs, and a small number of dogs with behavioural problems that make them too risky for rehoming. I doubt whether the numbers of younger dogs euthanised in rescue centres in the UK would make much difference to the figures in the survey

    The main problem with discussing a topic like the longevity of purebreed v crossbreds is that people most likely to join in the discussion dont start with open minds, they already have a perspective one way or the other, either that purebred dogs MUST be healthier because they are more likely to be from health tested parents and their breeders are "responsible" breeders, or that crossbreds MUST be healthier because they suffer less from inbreeding depression, and recessive gene conditions are unlikely to produce affected dogs. Which makes it hard to look at the comparative data objectively if it doesnt confirm what one wants to believe. If one doesnt like the results, one is going to pick holes in the methodology, the research should of course have been done in a way that would have confirmed what one wants to believe

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  6. "The number of dogs euthanised by rescue centres in the UK is very small in proportion to the total dog population compared to the US. We have fewer dogs coming into rescue, and most rescue centres have a policy of euthanising only the very old and seriously ill dogs, and a small number of dogs with behavioural problems that make them too risky for rehoming"

    YEAH RIGHT!!!! If only!!! Do you seriously believe that.

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    1. The most recent (2009) figures for England and Wales show the percentage of healthy dogs coming into rescue (or into local authority pounds) being put to sleep was about 3%

      http://www.politicalanimal.org.uk/key-facts-and-figures/pet-animal-indicators/euthanasia-of-dogs

      US figures put dog euthanasia at around 60% of shelter intake but they don't distinguish between healthy and sick animals (or at least I haven't succeeded in tracing a survey that did).

      http://www.petpopulation.org/faq.html

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    2. Interesting. However, I imagine the PTS figures have increased enormously over the past few years - rescues are now struggling to rehome the dogs.

      I can't help but wonder if part of this is because their rehoming policies are just a little bit OTT: the dog has to be neutered; every dog and cat you currently own also has to be neutered; every dog and cat you own has to be up-to-date with its vaccinations (they want proof that you've done annual boosters); booster vaccinations must be done each year on the rescue dog (unnecessary expense and potentially has serious health implications); they won't rehome to people who work longer than 4-hours per day. [The Retired Greyhound Trust will rehome to full-time workers.]

      None of these things (apart from length of time spent with owner), mean one jot to the dog. What's important to the dog is: a comfy bed; lovely daily walks of a length appropriate to its breed; healthy food; training so the dog understands what its owner expects; necessary veterinary care; companionship. What I'm trying to say is, people could tick all the boxes for a rescue dog and then still not take it for a walk!

      I wouldn't like to run a rescue for the same reason that I couldn't breed dogs; I'd lie awake at night worrying about whether they were happy, well-fed and walked.

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    3. Perhaps Cambtreasurer would like to explain if only 3% of dogs are destroed in shelters here that its only recently that the RSPCA said that with FIVE YEARS they wont be putting down any healthy dog in THEIR CARE? perhaps if they cut down on their political lobbying and silly studies (the dog licence where its £35 for only responsible owners to pay for those who cant be bothered) or the sponsorship of PETA linked seminars abroad?

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    4. Here are the RSPCA healthy-animal euthanasia figures: http://www.rspca.org.uk/in-action/pledges/pledge2

      As you can see, there has been an increase but it is still fewer than 1500 healthy dogs a year - UK-wide. That's 1500 too many, but it's a drop in the ocean compared to the problem in other countries.

      The RSPCA's pledge to within five years no longer put any healthy dog down is a brave one - although no doubt will be helped by their new policy of concentrating on cruelty cases rather than more general taking-in of dogs for rehoming.

      As far as I'm aware, the RSPCA has never sponsored a PETA-linked seminar abroad. I suspect you are referring to last year's Washington conference co-sponsored by HSUS.

      Jemima

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    5. Fact is, the number of healthy dogs put down does not really have an impact on my argument that an unhealthy mongrel is more likely to go through the shelter system and be put down at a young age (and therefore not be in the stats) than an unhealthy purebred. Just sayin'....

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    6. The number of dogs put down in rescue, does not reflect the number of dogs put down in the pound. If rescues can't rehome the dogs in their care fast enough, then they won't have room to take more from the pound.

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  7. "For example, intuitively, one would expect insured animals to live longer than non-insured since higher health care standards should give an advantage in life. Interestingly, the reverse is the case and insured dogs live over 1 and a half years fewer than non-insured. This may be because people insure unhealthy individuals or breeds but, regardless, it does highlight the importance of gathering data before making assumptions."

    Insurance companies have no idea when dogs that were previously insured, but have reached the age of 8+ and are no longer insured due to the massive hike in premiums and excess that arises at that age, die. Therefore one would expect a LOWER lifespan from insurance data, because they can't give information about the many previously insured dogs that live into their teens.

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  8. More data is better. Even if it's biased. If you can figure out the biases, you can correct for them. If you can't, there are usually often useful things you can do with the data.

    I am bothered by 'Crossbreed' as a category. It includes at least three different populations, which you would expect to have different demographics:
    1) Designer dogs. These are mostly crosses between small breeds, often long lived small breeds.
    2) Oops puppies. These are selected, either by ability of the sire and/or the dam to escape confinement, or the naivety of their owners ("I thought she was too young to get prego".) Hard to say how this affects longevity. I'd guess ability to escape is probably more widespread in healthy, hardy individuals; and that giant breeds tend to be more carefully fenced, cause neighbours are more likely to complain when a mastiff or dane gets out than when a small terrier gets out . . . and vet bills are awful when a big dog gets hit by a car.
    3) Deliberate crosses done for performance: Coursers, bandogs, cross bred earthdogs, even the deliberate breeding of two much loved family dogs cause people want to have a pup. Again, selection is likely to be biased toward relatively healthy, hardy dogs.

    If cross breeds live longer, therefore, it may simply reflect that they are selected from relatively healthy segments of the purebred and mix-breed canine population. More and better data analysis is required to see if 'hybrid vigor' or greater heterozygosity imparts a longer lifespan. Eg, do shih tzu x Malteses have longer lifespans than shih tzus and Malteses? Does this vary if the purebred dogs are separated into high and low COI's?

    Please, please, as more data accumulates, make the raw stuff available to others.

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    1. >Does this vary if the purebred dogs are separated into high and low COI's?

      The canine diversity project's survey on poodles showed a correlation between higher COI and lower life expectancy.

      http://web.archive.org/web/20110717024720/http://www.canine-genetics.com/lifespan.html

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  9. My beautiful weimaraner will be 9 at the end of the month. She will not make her full life expectancy as I have just found out that she has mast cell cancer - the tumour removed was grade 3 and more than likely already in her lymph system. Weimaraners are among 'prone breeds' to this condition and many good people in the breed have been conducting studies and research. Good breeders obviously take account of these. My beauty's breeder seemed to tick all the right boxes 9 years ago but I would not even consider buying from them now. Our health reports have been sent to the breed health co-ordinator and to members of the breed club so that they can be part of the big survey. 'Longevity' is a waiting campaign - many weimaraners do live to 13, 14 and even 15, and good research eliminates bad breeders and unhealthy puppies from the gene pool. Mine will not make 10 :'(

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  10. I would like to see a record of what the dogs have been fed over the years. This may be tricky for those owners who keep changing brands, but many owners tend to stick with the same dog food.

    The reason why I would like this to happen? The biggest complaint about raw feeding is that it hasn't been 'tested'. However, as most people feeding raw get their food from butchers or a raw meat suppliers, they have no vested interest in doing studies on its effectiveness, nor do they have that kind of money. They simply buy books on the subject, speak to someone whose been feeding raw for years, or join one of the online support groups.

    They panic initially because they've been brainwashed into believing the advertising hype that only commercial food can be balanced, and then quickly get over it, once their dogs SHOW their health with their shiny coats, clean teeth, fresh breath, lack of fleas, faster recovery times from injury, and energy levels without being hyper. My dogs also eat as much as they want and then walk away when they're full; because they receive high quality protein, it doesn't leave their bodies craving more. Beaks and feet which is used in most commercial dog foods, are not high quality, digestible protein.

    It may also show which commercial dog foods are more/less likely to cause disease, which would enable dog owners to avoid those foods. Like the certain, popular brands which are known by dog behaviourists to cause behavioural/aggression problems in dogs.

    Of course, if VetCompass is being sponsored by commercial dog food companies, then unfortunately this won't happen.

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    1. There was an excellent study done on quantity of food as affecting longevity (on 48 Labradors).
      See:
      http://www.avma.org/avmacollections/obesity_dogs/javma_220_9_1315.pdf
      A quick summary
      Objective—To evaluate the effects of 25% diet restriction on life span of dogs and on markers of aging.
      Design—Paired feeding study.
      Animals—48 Labrador Retrievers.
      Procedures—Dogs were paired, and 1 dog in each pair was fed 25% less food than its pair-mate from 8 weeks of age until death. Serum biochemical analy- ses were performed, body condition was scored, and body composition was measured annually until 12 years of age. Age at onset of chronic disease and median (age when 50% of the dogs were deceased) and maximum (age when 90% of the dogs were deceased) life spans were evaluated.
      Results—Compared with control dogs, food-restrict- ed dogs weighed less and had lower body fat content and lower serum triglycerides, triiodothyronine, insulin, and glucose concentrations. Median life span was significantly longer for dogs in which food was restricted. The onset of clinical signs of chronic dis- ease generally was delayed for food-restricted dogs.
      Conclusions and Clinical Relevance—Results sug- gest that 25% restriction in food intake increased median life span and delayed the onset of signs of chronic disease in these dogs. (J Am Vet Med Assoc 2002;220:1315–1320)

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    2. Indeed -- the single most important quality of dog food is its QUANTITY. Fat dogs die younger and sicker. Just about any nutritionally balanced dog food will do, whether commercial or home-made.

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    3. Jean Dodds did a study comparing dogs fed on 'raw' homemade diets to dogs fed on dry food. There were found to be no obvious advantages to it. There is also a study on feeding cats rabbits, a study of a disease in greyhounds caused by feeding raw meats, and a study of foxhounds, all of which had negative results. Undoubtedly many other studies have been done by the proponents of homemade diets, but not published because they presumably showed no advantage or even a detriment. If you use one of these diets and are happy with the results that's all very well, and there's little evidence that such diets are harmful. But please don't buy in to the miracle panacea/ naturalistic fallacy stuff -- there's no evidence for this and it just perpetuates the unsavoury conspiracy theories banded about by struck-off vets and quacks hawking self-published diet books.

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    4. Anonymous, do you by any chance have links or more information on those studies? I would be interested in reading them.

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    5. Beth, the study on feeding cats raw rabbit can be found on Wikipedia under raw feeding. It is, however, flawed. In the same way that you or I would not solely eat one food item for months on end and not expect to become deficient in essential nutrients, neither do raw feeders feed one meat exclusively. The cats became deficient in taurine - no surprises there. Yes, raw diets can be deficient, but raw feeders know this and therefore feed a wide variety of fresh foods.

      Here is how I see it, people are advised by human nutritionists to eat a wide variety of fresh foods and avoid processed foods as much as possible. Yet kibble is a processed food, but somehow this good advice for a healthy balanced diet for people, doesn't apply to dogs.

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    6. There is also the Pottenger's cats study which did show an enormous difference in the health of cats fed raw meat compared to those fed cooked. http://ppnf.org/store?main_page=product_info&cPath=0&products_id=228

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    7. Fran, I don't want this to turn into a raw feeding debate. However, the Pottenger's cat study turns out to have shown us a lot about taurine in cats (obligate carnivores) and is not applicable to dogs (carnivorous omnivores).

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    8. Beth, take what you will from the Pottenger study. However, the high incidence of allergies and arthritis in the domestic dog, parallel Pottenger's findings with cats that were fed cooked meat.

      My own dogs also rarely get fleas now they are on a diet - yet did get fleas on kibble - something else which mirrors Pottenger's study. This isn't an anomaly, it is a common occurrence amongst raw-feeders.

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    9. I have nothing against homemade diets. There needs to be more research done on them, certainly, and they are probably not harmful, but I get so tired of hearing ridiculous unfounded claims and anecdotes and people touting them as panaceas. The comment about someone's dog's not having fleas on one of these diets -- animals in the wild eat mostly prey that they have killed, so why are they covered with fleas in this case?

      For anyone wanting something balanced to read, Brennan McKenzie has an article on sciencebasedmedicine http://www.sciencebasedmedicine.org/index.php/raw-meat-and-bone-diets-for-dogs-its-enough-to-make-you-barf/ I tried to find the Dodds study again, but Google got clogged up with the writings of silly people claiming that the study means Dodds endorses these diets and that they prove they are healthier than conventional commercial ones (which they don't, and which was not Dodds's conclusion -- the measurements were all within the normal range).

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    10. Anon 14:39: My comment about my dogs rarely getting fleas on a raw diet is exactly how it is for me; my dogs now rarely get fleas. This is something I have observed in my own dogs, not something I've plucked out of thin air.

      Wild canids live in the cruel, natural world, where their health is affected by the harsh environment and frequently having to subsist on inferior rations.

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    11. Beth, Dodds' study:

      http://www.apdt.co.uk/documents/KennelClubNutrition.pdf

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    12. Jean Dodds on raw fed dogs:

      "Many of us in the veterinary community, including myself, have seen first-hand the health and vigor of dogs and cats fed raw diets. These animals just ‘shine’ in all respects. While these observations are shared by a growing number of animal health care professionals as well as experienced dog and cat fanciers, they could be considered as merely anecdotal. Perhaps so, but I consider them experiential findings based on years of observations by many dedicated professionals in the holistic veterinary field."

      http://drjeandoddspethealthresource.tumblr.com/post/34362052572/raw-dog-food-versus-cooked

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  11. Is there a test to see if Mast cell cancer was likely then? I ask as a human with Mast Cell degranulation/activation disorder which causes anaphylactic reactions without allergies.

    2 of our friends have died because of it, it is one of the most difficult to diagnose due to no mis shaped/excessive production of Mast cells, with all allergy and bone marrow tests turning up normal

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  12. Fran, horse people have had extensive studies (TONS of them) done on different types of hay, none of which come from commercial producers-- hay is grown at the farm most of the time. That whole line of "of course there are no studies on raw because only pet food companies fund studies" is bull. A feeding study is not that expensive to run. Solicit some well-off dog-owners for donations, contact a teaching hospital, and go at it.

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    1. Beth, I didn't know about hay studies. Are you American, because maybe that kind of thing is more common in the US? One problem I do foresee is that disease and deficiencies can often take years to materialise. For example, in humans, Vitamin B12 deficiency in vegans can take up to a decade for symptoms to appear, but that doesn't mean the diet isn't deficient. Short-term feeding trials, like those done by dog food companies, don't strike me as being particularly effective and I can't see dog owners being willing to fund a 10-year study, which is why the VetCompass study would be so useful.

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  13. Does the "year one" peak for deaths represent very young puppies or dogs approaching their first birthday? It would be interesting to know whether it follows the same breed pattern as deaths at the old age end of life.

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  14. Annie Macfarlane9 June 2012 22:42

    Thank you for your response Dan. A very interesting study which I'm sure will develop in years to come.

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  15. Thanks for Dan's response. It is interesting research, but I still don't believe it justifies the sweeping statement that 'cross-bred dogs live longer than pure-bred dogs'. Lifespans for particular breeds can be averaged out and compared, but you simply can't do this meaningfully with cross-bred dogs as a category as they can be composed of any combination of any breeds, long-lived or short-lived. Most crossbreed dogs I know have at least one parent of a healthy and popular breed, such as a terrier or Labrador. I have never met a mongrel dog who I understood to have one of the notoriously unhealthy breeds in its ancestry, such as the Neopolitan Mastiff or Bulldog. Have you considered looking into the composition of mongrels and factoring this in, perhaps to compare their lifespan to that of related breeds?

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    1. You can find X breeds from breeds with health problems.
      Pugalier: Pug x Cavalier
      Bandogge: Mastiff x (often pit bull, sometimes English bulldog or boxer)
      It would be interesting to know the longevity of these crosses, though bandogges are often used for dangerous sports like pig hunting, so may have lifespans foreshortened.

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    2. Any kind of cross is possible, and anyone can give a 'fake breed' name to a mutt, but I would argue that this is not comparable to the composition of most mutts. I went to the Battersea Dogs Home website and looked at the dogs available page, which gave me three dogs at random. They were a Border Collie cross, a terrier cross, and a GSD cross. If the studies show that most mutts have DNA from long-lived breeds in them, that's still a worthwhile conclusion, but it doesn't mean cross-bred dogs in general live longer than dogs of named breeds.

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    3. That's not the point. Generalizations about X-breeds simply don't make sense. It's like assuming green, purple, and orange look alike because they are blends, as opposed to primary colours. The behaviour of a blend depends on its constituents. Much as I dislike breeding dogs for aggression, I'd guess that a Neo x pit bull would have a longer life expectancy than a Neo, though not necessarily than a pit bull. Whether a Goldie x Labrador has a longer life expectancy than a Golden or Labrador is going to depend on the individuals . . . the health differences withing the two breeds are probably greater than the differences between the breeds. To the extent that pedigree dogs are inbred and suffer from the consequences of homozygosity, any breeding that increases diversity should increase life expectancy, whether it is within the breed or outcrossing.
      btw. mutt mixes vary with geography. Where I live most pound mutts, and there are loads of them, are pit bull, chihuahua, or mixtures containing pit or chi. They have low life expectancies cause they often get pts or run over, but if well cared for, they are long lived. But the street pits and chis from which they are derived are a hardy, scrappy lot with no recorded pedigrees.

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  16. Will the data collected by VetCompass be analysed 'blind'? This is to prevent fudging of the results to make them favourable to whomever is funding this project. Ben Goldacre would call this 'bad science'. In most research, there is a subtle pressure on the researchers to give the funders the results they desire, it's subtle, but it's still there, otherwise how else do universities etc., keep securing their funding?

    One thing that concerns me is that vets and rescues, for very good reasons, support neutering. However, if Vetcompass's research found that neutering had a detrimental effect on the longterm health of the dogs (e.g. a significantly increased risk of cancer), would this be reported, or would these results not be disclosed to the general public? Would they point out the (small) number of dogs prevented from getting testicular cancer, whilst ignoring the significantly increased risk of urinary bladder cancer, prostrate cancer, hemangiosarcomas and osteosarcomas, as suggested by other research?

    If neutering is found to be detrimental to the dogs, would VetCompass recommend further research on alternatives? At the moment, dog population control has a one-size-fits-every-dog, procedure, even though neutering may not be in the best interests of that individual dog.

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  17. It wouldn't just be Ben Goldacre who would call it "bad science", Fran.

    Funding bias is an issue in research but I am persuaded of VetCompass's integrity. There's an interesting test of this on the way, btw as the KC has (rather bravely I think) funded VC to look at health difference between KC registered purebreds and non-KC purebreds. One might assume, then, that there would be some subtle pressure to give the KC the answer it is looking for.

    Knowing how VC operates, however, I am pretty convinced that we will get the real answer, come what may.

    Jemima

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  18. And here is the response from Vet Compass's Dan O'Neill: "...this perception of science being in the pocket of funders is a difficult one to allay because the ‘methinks he doth protest too much’ syndrome is likely to come into play. All I can ever do is to assure that we will publish any important findings that we identify, regardless of who does or does not like the results. The sole objective of VetCompass is to shed light that will improve animal welfare and that requires the unadulterated truth. If we identified an association of poor health with neutering or any other prophylactic procedure, it would be reported."

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    1. Will the findings be breed-specific? For example, from what I've read, spaying reduces the risk of mammary tumours, but increases the risk of osteosarcoma. If this is valid, whilst it seems sensible to spay breeds prone to mammary tumours (certain spaniels, I think), on the other hand, spaying breeds already prone to osteosarcoma (Greyhounds, Rottweilers), strikes me as madness.

      Yet I have not come across research into alternative forms of sterilisation, apart from removal of just the ovaries, which also eliminates the protective hormones. From what I understand in people, a hysterectomy that leaves the ovaries intact, frequently results in the ovaries atrophying over time.

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  19. Only just seen this. Thank you both for taking the time to reply.

    Hopefully we're in for exciting times ahead!

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  20. I can't help but wonder if one reason for uninsured dogs living longer, is down to them being recommended for conservative treatment rather than risky and expensive surgery?

    I experienced this with my own dog. She fractured her neck (C2), an uncommon fracture site the orthopaedic surgeon at the veterinary hospital we were referred to, had never seen before. Despite this, he recommended surgery at a cost of £3.5K, with a recovery rate estimated at 60%. As we weren't insured, we opted for the conservative treatment of a cast, which cost a fifth of the price. We later found a cohort study from 1999, which showed dogs with this exact same fracture site that were put in a cast, had an 80-90% chance of recovery. The faster the dogs received treatment, the more likely they were to recover. Therefore, by not being insured, we increased our dog's odds of recovery by a further 30%. This study did not recommend surgery as a cast had such a high success rate. Whilst I can appreciate that surgery has improved since 1999, there was still no reason for this vet to recommend surgery for my dog. He should have been aware of this study, or if he wasn't, it was very easy to find on Google.

    The success rate of a cast over surgery, was later confirmed by a sports injury vet. He sees a couple of cases of C2 fractures a year. He always puts them in a cast; they always recover.

    Needless to say, I know which vet I will see in the future and which vet I now know to avoid! Additionally, I recommend the sports injury vet to my friends and other dog walkers, but not the vet hospital. The former is also far cheaper!

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    1. I want to add that we were put under a LOT of pressure to have the operation. It was reiterated several times that the referral vet thought surgery was the best option for her recovery and that a cast was a very poor second. I did get the impression we were viewed as bad owners for opting for the cast.

      This means that if we'd been insured with a high-enough policy, we would have gone for the surgery.

      In future, I will always see a Greyhound vet - cheaper and more experienced.

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