Can we make our pets live longer?

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We are all attracted to sites like this one because we are inherently interested in the health and well-being of our pets.  The question is how much of the control of our pet’s health lies in our hands.   We are bombarded with premium pet foods and supplements, all of which purport “better health” for our pets.  Which diets do we choose?    Many of us are vehement advocates of feeding our dogs raw, and avoid commercial diets altogether.  We angst over whether to vaccinate.  Which vaccines are necessary, how many doses of those necessary vaccines bestow immunity,  and for how long does immunity last?  Is neutering really the “healthy” choice for our pets?  If so, when?

We think about these topics because we want our pets to achieve optimal health.  There are clearly examples where making the right choices with vaccination, spay and neuter, and diet can clearly bestow benefits.  For example, by keeping male dogs intact we can help prevent obesity, cranial cruciate rupture, and debatably, certain types of cancer.   Nutrition clearly can help to control food allergy, obesity, dental disease.  Limiting over-vaccination can lessen the chances of certain immune-mediated disorders and vaccine related sarcomas.  But is it in our power to actually bestow longevity upon our pets?  Can we make our pets live longer?  At the end of the day, shouldn’t that be the ultimate goal?  The answer may surprise and perhaps disappoint you.

First, it is helpful to reflect on some of the factors that determine longevity.  How do our pets die?  We can divide up causes of death into categories.  Congenital malformations, dystocia (trouble with birthing),  poor nursing and fading syndromes, exposure to infectious disease in unvaccinated puppies and kittens with under-developed immune systems, and inherited breed-related disorders, all contribute to early death, and thus lower overall species life expectancy.  Most of these aforementioned causes of early death are not that common, and we have made great strides to lessen their occurrence.  Proper vaccination against diseases like parvovirus and panleukopenia, proper nutrition for puppies who won’t suckle, identifying and not breeding animals with known genetic diseases, are all examples where we have made strides to lessen the incidence of infant mortality.

Accidental deaths also occur and thus lower overall species life expectancy.  Anesthetic deaths, vaccine-related deaths, hit by cars (HBC), cats with high rise syndrome (cats jumping out of windows) are all examples of this.  These too, are fortunately, rare.  We can have a limited role in preventing accidents and have done so.  Removing harmful toys from the market, not over-vaccinating, recognizing common household and dietary toxins (xylitol gum, chocolate, grapes, certain household plants etc.) all can help minimize these incidences.  Proponents of spay and neuter would argue that spaying and neutering will cut down on wandering, dog fights, and HBC’s.  The pros and cons of spaying and neutering are discussed in many articles on this site.

Metabolic disease, including cancer,  are common causes of death amongst geriatric patients.  Suffice it to say that we have made some strides over the years in treating these diseases.  I think that it is also fair to say that while we have made great strides in treating and managing metabolic disease, we do face challenges.  Simple economics limits both the research and development of various treatments used in humans, and access to some of the treatments that are currently available.

When we are discussing species life expectancy, we are not simply looking at all of the diseases that eventually kill us, but we are also examining the programmed life expectancy of a particular species.  Why is it that elephants live 60-70 years, tortoises, 100 years, and gerbils, 7 years?  What is it that programs us to age, and to subsequently die of old age?  This process of deterioration with age is called senescence.

Cellular senescence is the process where cells in the body stop dividing.  This occurs due to telomere (the end caps of genes) shortening.  The telomere is responsible for repairing damaged DNA;  and when it is shortened, cells lose their ability to repair themselves.  Subsequently, they become more susceptible to oxidative damage and cancer expression.  Organismal senescence is the aging of the whole animal.  To what degree the two are related is an area of intense research.  In organismal senescence, there is a disruption in the body’s ability to maintain homeostasis.  Homeostasis is the animal’s ability to main stable internal conditions for things like pH and temperature when faced with varying external conditions.  There becomes a general susceptibility to age-related diseases.  There is always a cause of death.  We don’t simply “die of old age”, but we become susceptible to organ dysfunction, lose our ability to deal with harsh environments,  repair mutations and  to  fight cancer.  There is an abundance of research into drugs and other therapies that focus on delaying senescence.  A recent 60 Minutes special featured one scientist who predicted that within 30 years, we will be able to manipulate the genome’s ability to repair itself,  and increase life expectancy in humans to 200 years!  This obviously is a bold statement; but if true, it raises a host of ethical dilemmas.

What is also interesting is that there is variation in life expectancy, not just between species, but also within the same species.  For example, within nature there is, in general, a correlation between size and life expectancy.  Larger animals, in general, live longer (compare an elephant to an ant, for example).  Why is this same phenomenon not true within the canine species?   Smaller dogs have a longer life expectancy than larger dogs.  Dr. Cornelia Kraus studied a host of different possible explanations including onset of senescence, faster aging, susceptibility to various types of diseases, etc.  She concluded that once larger dogs hit senescence, they age faster and thus die sooner. One potential cause may be the higher levels of growth hormone and IGF-1 during growth in larger dogs.1. Manipulation of these hormones could be worthy of study in promoting longevity, but more research is warranted.

While we are certainly some time away from manipulating genes to alter longevity, are there any things that we can do to increase longevity?  How about nutrition? Are there any diets or supplements that have been shown definitively to increase lifespan?   Sadly, the only study in veterinary medicine involving diet and longevity was one that demonstrated that calorie restriction led to an increased lifespan in dogs 2.  . Perhaps we should worry less about what to feed our dogs, but more on how much to feed them.

What effects does spaying and neutering have on life-expectancy.   The benefits of keeping animals intact or of at least delaying spaying  and neutering have been described throughout other posts on this blog. Does keeping animals intact increase life expectancy?  As of now, there is conflicting data.  A study involving 119 Rottweillers with exceptional longevity demonstrated that females that maintained their ovaries, for at least the first 4 years of their life, lived an average of 30% longer than their spayed cohorts.  This phenomenon is also seen in humans, where women live longer than men and are more likely to reach 100 years old by a factor of more than 4:1. Possible explanations could include a protective effect of estrogen against oxidative stress and an enhanced immune response. 3.  Interestingly, the study also demonstrated that spayed female Rottweilers were more likely to die of cancers like osteosarcoma (bone cancer).  While this is another reason to consider not spaying, especially young pups, once these dogs were removed from the study, the  association between ovaries and exceptional longevity persisted.  Critics of this study cite that there was only one breed represented in the study. Furthermore, there was no indication of whether or not the intact females were bred, and if so how often; there was no indication of genetics or whether the participants in the study were related to each other; and that there was a small sample size of dogs in the study.

In contrast, a retrospective study examined over 40,000 causes of death among sterilized and reproductively intact dogs at American teaching hospitals.  They were able to demonstrate that reproduction comes with a cost to the mother.  This effect has been demonstrated in a wide range of animal species.  The theory is that the energy expended by a mother to create, carry and nurture offspring, in order to pass on her DNA, comes with the cost of shortening her lifespan.   They found in this study that sterilization was strongly correlated with increased lifespan.  While it decreased risk of death from some causes like infectious disease, it actually increased the risk of death from cancer. 4.  While the increased cancer risk was in sterilized animals, it was also supported in the Rottweiler study. The authors of this retrospective study concluded that the increased risk of cancer was simply a reflection of sterilized animals living longer, and thus being more likely to develop cancer.  Critics of this study point to the fact that these data were collected at referral hospitals, which are often not reflective of the general population. There was no data as to whether or not the females in the study were bred or not.  It is difficult to prove cause and effect through retrospective studies; moreover, the study didn’t specify at what age the sterilized dogs that were sterilized.

As we start to really understand the aging process at the cellular level, moral hazards surface.  Would you directly manipulate your pets DNA or supplement him with hormones to make him live longer?  At what point are we “playing GOD”?  If it were feasible to manipulate your dog to live 50 years, would you do it?  Why is that not ethical if tortoises live a lot longer than that?  Are there already too many unwanted pets out there at current life expectancies?  Certainly increasing life expectancy would exacerbate that problem.  Your thoughts and comments below would be appreciated.

1. Kraus, Cornelia, Parvard, Samuel, Promislow, Daniel E.L. The Size-Life Span Trade-off Decomposed: Why Large Dogs Die Young. Am. Nat 2013. Vol 181. 492-505.

2. Kealy, Richard d., Lawler, Dennis F., Ballam, Joan M. Effects of Diet Restriction and lifespan and Age-related Changes in Dogs. Javma Vol 220 (9). 1315-20.

3. Waters, David. Kengeri, Seema. Clever, Beth. Exploring Mechanisms in Sex Differences in Longevity: Lifetime Ovary Exposure and Exceptional Longevity in Dogs. Aging Cell. 2009 December 8 (6): 752-5.

4. Hoffman, Jessica M. Creevy, Kate E., Promislow, Daniel E. Reproductive Capability is Associated With Lifespan and Cause of Death in Companion Dogs. PLOS One April 17, 2013.

 

Questions

Comments

  1. Kathy says:

    Great article that offers insight into how and why dogs age…and ethical questions as well. TY!

  2. Mare says:

    There are so many factors that complicate the discussion about life expectancy, I think it will be many years before we have a true picture of the complex situation. In the meantime, we owners gather information from trusted sources and make the best decision we can with the help of our veterinarian. Thank you as always for your thought-provoking blogs.

  3. Jodi says:

    I think I agree with my grandmother that, “life is a crapshoot.” You can do everything right medically, physically, and emotionally for your dog and still not have an optimum outcome. Genetics play a huge part in quality of life and life expectancy. So food choices, neutering choices, and vaccination choices may not have much, if any, effect on a dog’s life span. The one commonality is that we all wish our dogs could live forever.

    • Patricia Kimbell says:

      Jodi,
      Your last sentence says it all. No matter what the causes, choices, life styles, talents, we all just wish they could live forever…..

    • Angry Vet says:

      life is a crapshoot, but compare our lifespan now to 25, 50, and 100 years ago and you will quickly realize that we can make HUGE differences…still doesn’t mean you won’t get hit by a bus tomorrow but…

  4. Marilyn Frese says:

    Not a question, but a review of care at South Bellmore Vet Group:
    Dear Dr. Foley, I just read your latest article here about ‘can the lifespan of your dog actually be enhanced with some of todays options’. I felt like you were speaking to ME! You have been so great helping me find just WHAT is wrong with Mickey, (Yorkie, age 7). I brought him to you because his belly was filling with fluids every few weeks and needed constant needle draining… and you did an amazing amount of research to help him. Although we are not in the clear yet, you seem to be on the right track!! His Albumin levels are better, he no longer fills with FLUIDS- yet his belly is still getting bloated. He seems to be enjoying life a lot more, and for that I am so grateful! I know he is not OUT OF THE WOODS, but you have made him look and feel better with the use of both HUMAN and Pet meds you found through your research. And you FIRST had me change his diet of nothing but ‘just low fat baked or boiled white chicken meat’ that his last vet had him on for years!! Only to find out that CHICKEN was probably the WORST food choice for what he was suffering from. (But boy, does he still miss that!!) I pray that he will recover and live a full life- even if it’s on the yucky play dough like RX dog food that he is now tolerating!! But he’s eating it and it sure seems to be helping. It’s been a costly process, but well worth the returns! Anyone reading this… TAKE OUT PET INSURANCE ON YOUR ANIMALS!! It has saved us a few THOUSAND dollars in Mickey’s last couple of years! I also appreciate your decisions to not do anything drastic without trying other more simple and common sense methods first. I completely TRUST any procedure or meds that you recommend. I totally trust your expertise! Thank you for saving Mickey… and trying to give him a longer life with comfort and meaning. I know you’ve warned me that things could go bad at any time, but so far you have been doing an amazing job in controlling his well being. Marilyn Frese, Mickey’s Mom!

  5. Joanne says:

    I recently lost a 7 yr Aussie to Hemangiosarcoma. Unknown to me when I bought him as a puppy he was VERY linebred. I have learned from other Aussie owners/breeders that Hemangiosarcoma is “just in the lines”. It seems as if people have not made an effort to try to lessen the cancer in the breed. I have learned entire litters have died of this around 10 yrs of age. It seems as if breeders are breeding longevity right out of the breed!

    • Jodi says:

      Joanne, my boy died of Hemangiosarcoma before he reached 10 years of age. I know for a fact that others in his litter had the same lifelong health issues he had (epilepsy and allegies) and died of the same cancer. And this was a dog from “AKC champion” lines. Makes me so angry that the breeder is still in service and they are still turning out dogs with a high likelihood of illness.

  6. Kathy says:

    The 2007 Rutgers University study (Long-Term Health Risks and Benefits Associated with Spay / Neuter in Dogs by Laura J. Sanborn, M.S., May 14, 2007) also supports later neutering and spaying, which I have always recommended as a breeder. I think, however, environmental carcinogens such as chlorinated water, chemicals used on food ingredients, GMOs, etc may also be helping to shorten the lives of our pets. We should try to keep our pets as “green” as possible to help avoid shortening their lives and I believe that every little bit helps. Thank you for exploring this subject – it is certainly one that should be revisited regularly.

  7. Madeleine says:

    Oddly, your long article on pet health dealt only with dogs though it dealt with diseases that also affected cats. And yet there was not a mention of the species. Cats are the second most popular pet, die in shelters far more than dogs and often because of illness and suffer many of the same diseases and yet you didn’t mention them once. For cat parents like me this is not a mere oversight but an ignorant speciesism that is observed more and more and is less and less acceptable.

    • robert foley says:

      All of the studies that were cited in the study were for dogs only. It is inappropriate to extrapolate from one species to another until they are studied.

  8. LisaT says:

    I think it all matters, and it all affects how our genes are expressed. And I also think that sometimes you can’t beat your genes, but you can optimize what you have.

    Using a few well-known examples – IgA deficiencies in GSDs, even if minor, can affect the dog’s ability to fight disease, particularly as it ages. The human Lyme disease vaccine was thought to make roughly 30% of the population susceptible to debilitating arthritis because of some type of genetic halytope (not sure if I have the right word there), having had a dog that had lifetime illness from one of the original Lyme vaccines, I can tell you it was only “fringe” medicine that gave her an almost normal life span. In people, there is a fairly significant population that has problems with folate metabolism, and cannot utilize folic acid. What you eat makes a huge in how many of these genes expresss themselves and whether you get the right nutrients for some very important process in the body. Just as there is an mdr1 mutation for processing some meds, in people (and I’m sure in dogs), there are similar mutations that can affect processing some pesticides, etc. So what they are exposed to matters a lot. I don’t think studies will pick this up unless it’s specifically looked for.

    And then there are people with the longevity gene, which might through off a lot of the statistical analysis in some studies. I don’t know a lot about having the gene vs having the gene expressed, but I think what we are trying to do, in general, with good food and a varied diet, with minimal exposures to destructive chemicals etc., is to try to optimize our pets good genes, and minimize the bad ones, even if we don’t think of it in those terms. But if we do think of it in those terms, I think the studies will continue to be conflicting, to some degree, if they don’t control for major genetic types. I guess we try to do that by controlling for breed sometimes, but I don’t think it’s exactly the same.

  9. Carol Minot says:

    My Mom always said we all have some form of cancer inside us & it takes something to trigger it. It’s clearly obvious this is also true for dogs too. Owning golden retrievers I’ve lost 2 to HSA, 1 to suspected lymphoma & do everything possible to protect my 2 girls now with healthcare, diet, exercise & research to keep them healthy as possible. My breeder is meticulous with breeding, so I have to cross my fingers & do what I can.

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  11. Amelia says:

    Pet parents become overwhelmed with information overload and can feel anxious about the choices that they make for their dogs. Do they listen to their vet, their breeder, or their friends when it comes to certain issues? What about using the latest drugs? Pet parents should take a well-balanced approach to living with a pet and rely on trusted sources when needed for those hard choices. Excellent article…we do want our pets to live as long and as healthy as possible.

  12. Susan says:

    I will be picking up my 12cweek old puppy from the breeder in 2 weeks.She cooks for her dogs and I decided to do the same.I need a lot of guidance with this as I do not know what to do about supplements
    Everything I read says to go to my vet or pet nutrionist.I am very confused and need guidance

    • Janey Darnell says:

      Read Pukka’s Promise: The Quest for Longer-Lived Pets. Dr. Marty Becker has great info on dog foods (video and articles). Dr. Michael Fox’s dog food recipes helped when I started cooking dog food, later FB groups helped me when I switched to a primarily raw diet. DogFoodAdvisor.com helped me choose canned options (and rarely kibble) for convenience.

  13. Janey Darnell says:

    I just want to say THANK YOU for the “balanced approach” information you have provided through this website. I am a fan of Ted Kerasote’s books, esp “Pukka’s Promise: The Quest for Longer-Lived Dogs”, Drs. Marty Becker, Jean Dodds, Robert Schultz, Michael Fox, and now I can add you to my list! Found your site while trying to decide whether or not to neuter new adult shelter rescue that is fearfully reactive to men and most dogs in strange places. (Teeth cleaning next Tues. Back teeth nasty. Could combine procedures to save money and stress.) Prob gonna try training first. Lotsa variables and food for thought brought to awareness here!

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