SPAY & NEUTER ADVERSE EFFECTS

Several studies released over the past number of years have documented the adverse affects on the development of both male and female dogs resulting from spay and neuter.  The American Veterinary Medical Association official policy now states “Mandatory spay-neuter is a bad idea.”

The AVMA policy statement goes on to say:  “… potential health problems associated with spaying and neutering have also been identified, including an increased risk of prostatic cancer in males; increased risks of bone cancer and hip dysplasia in large-breed dogs associated with sterilization before maturity; and increased incidences of obesity, diabetes, urinary tract infections, urinary incontinence, and hypothyroidism.” (Reference: AVMA.org)

It is our desire that all of our puppies be given the utmost advantage to grow and develop into healthy, long lived adults.  It is with this in mind that we share the following articles with you.

New Research That Raises Questions About Current Neutering Recommendations

Nancy Kay, DVM

Results from a hot-off-the-press study published by the Journal of the American Veterinary Medical Association, raise questions about traditional neutering recommendations within the United States where most veterinarians advise that dogs be neutered at a young age in order to induce sterility and eliminate behavioral issues before they have a chance to begin. This new information along with data from other recent studies are a prompt for all of us to reconsider current neutering dogma.

The title of the newest study is, “Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas.” The word “gonadectomized” is medical jargon for “neutered”. The research included 2,505 dogs and was supported by the Vizsla Club of America Welfare Foundation.

Effect of neutering on the incidence of cancer

Here is what the researchers learned about the prevalence of cancer as it relates to neutering:

Mast cell cancer: 3.5 times higher incidence in neutered male and female dogs, independent of age at the time of neutering.

Hemangiosarcoma: 9.0 times higher incidence in neutered females compared to nonneutered females, independent of age at the time spaying was performed. No difference in incidence of this disease was found for neutered versus nonneutered males.

Lymphoma (lymphosarcoma): 4.3 times higher incidence in neutered male and female dogs, independent of age at the time of neutering.

Other types of cancer: 5.0 times higher incidence in neutered male and female dogs. The younger a dog was at the time of neutering the younger the age of the dog at the time the cancer was diagnosed.

All cancers combined: 6.5 times higher incidence of cancer in neutered females compared to nonneutered females; 3.6 times higher incidence of cancer in neutered males compared to nonneutered males.

Effect of neutering on the incidence of behavioral issues

The research documented that dogs neutered at or before 6 months of age were at greater risk for developing a variety of behavioral issues including: separation anxiety, fear of noises, fear of gunfire, timidity, excitability, submissive urination, aggression, hyperactivity, and fear biting. Neutering after 6 months of age did not create increased risk. Fear of storms was the behavioral exception. Regardless of age at the time of neutering, neutered Vizslas were at greater risk for developing fear of storms than their nonneutered cohorts.

What does all this mean?

Interesting stuff, eh? From my perspective, I think this is a good wakeup call for anyone still clinging to the notion that all dogs not used for breeding purposes should be neutered at a young age. The recent studies that challenge traditional neutering recommendations seemingly raise more questions than they answer. All have studied large breed dogs (Rottweilers, Golden Retrievers, and now Vizslas). Do these results translate to small and medium sized dog breeds as well? Would similar studies within every breed produce differing results? Should males and females be spayed at a different ages? Are the effects of neutering on behavior breed-specific?

Clearly, there is much more research to be done before determining exactly how current neutering recommendations should be altered (pun intended). For now, what makes the most sense is one-on-one discussion between family veterinarians and their clients to determine how factors such as current knowledge about the effects of neutering, intended use of the dog, breed, temperament, and the way in which the dog will be housed and cared for influence the decision of whether or not to neuter and, if so, at what age.

Would recent research results influence your decision of whether or not to neuter your dog?

Best wishes,

Nancy Kay, DVM

Spay-Neuter Adverse Effects  AVMA on resulting urinary, ligament, bone, obesity, cancer, thyroid, etc.

SPAY & NEUTER MEDICAL FACTS

The American Veterinary Medical Association official policy says

“Mandatory spay-neuter is a bad idea.”

The AVMA has taken this stance in direct contradiction to the Humane Society (HSUS) stated goals.

http://www.thedogplace.org/Veterinary/09051-Spay-Neuter_Andrews.asp

Barbara (BJ) Andrews © TheDogPlace May 2009 - AVMA policy is particularly brave because the AVMA is under assault by the newest of the Humane Society’s creations, the HSVA. The AVMA boasts over 70,000 members. No one knows how many members the Humane Society Veterinary Assoc. actually has but with millions of non-taxable HSUS dollars behind it, the Humane Society Vets will probably prevail.

Even so, the AVMA deals HSUS a blow in its straightforward policy statement “potential health problems associated with spaying and neutering have also been identified, including an increased risk of prostatic cancer in males; increased risks of bone cancer and hip dysplasia in large-breed dogs associated with sterilization before maturity; and increased incidences of obesity, diabetes, urinary tract infections, urinary incontinence, and hypothyroidism.” Ref: AVMA.org

Whether/when to spay or neuter has been studied by various veterinary groups. Linda Witouski, TheDogPress Legislative Editor, compiled this 2008 summary report:

In a study of well over a million dogs, information on breed, sex, and age was collected and reported to the Veterinary Medical Database between 1964 and 2003. Results—Castrated male dogs were significantly more likely than other dogs to have hip dysplasia (CHD) than other dogs and spayed females were significantly more likely to have cranial cruciate ligament deficiency (CCLD).

Dogs up to 4 years old were significantly more likely to have HD whereas dogs over 4 years old were significantly more likely to have CCLD. In general, large- and giant-breed dogs were more likely than other dogs to have HD, CCLD, or both.

Prevalence of HD and CCLD increased significantly over the 4 decades for which data were examined. There was no data reflecting the decade-by-decade increase but one might suspect that the significantly increased rate of spay and castration procedures may be a factor in the overall forty-year increase. ref: June 15, 2008 Journal of the American Veterinary Medical Association

There is unquestioned benefit to spay and castration but it may be a human benefit rather than of any tangible benefit to the canine.

There are other adverse effects of surgical neutering, particularly when the surgery is performed on puppies, obliquely referred to as “early-age” spay/neuter, pediatric spay/neuter, or juvenile spay/neuter, presumably depending on age at which ovariohysterectomy or orchietomy is performed on the puppy. A study published in the Journal of Am. Veterinary Medicine, noted an “increased rate of cystitis and decreasing age at gonadectomy was associated with increased rate of urinary incontinence. Among male and female dogs with early-age gonadectomy, hip dysplasia, noise phobias, and sexual behaviors were increased, whereas obesity, separation anxiety, escaping behaviors, inappropriate elimination when frightened…”

These are not insignificant problems. Urinary incontinence and uncontrolled elimination will banish a dog to the outdoors and more often than not, to the “shelter.” Hip dysplasia, worsened by obesity, will bring valued family dogs in to the veterinary office where costly hip surgery may be performed. Other dogs, owned by families of lesser means or smaller hearts, will be dumped at the pound. The same can be said of dogs with noise phobias, separation anxieties, and embarrassing sexual behaviors. Dogs that habitually escape will inevitably be run over or taken to the local shelter.

While all agree that surgical castration and hysterectomy are the only viable options for sterilization, Chris Zink DVM, PhD, DACVP explains risks for the canine athlete, covering the subject in an easy to read format.

In summary, our Health Editors and knowledgeable breeders agree; pets should be spayed or neutered but not until growth plates have closed and then only if their behavior becomes an annoyance to the family. Note that age of puberty varies depending on breed growth rate.

Thanks to the Animal Rights Extremist (ARE) and the Humane Society of the U.S. (HSUS), none of which rescue, adopt, or shelter unwanted dogs, it is almost impossible to adopt a shelter pet that isn’t already spayed or castrated. Like the surgery itself, that situation has benefits and drawbacks for adoptive owners. The spay/neuter policy has virtually no benefit to the cat or dog other than to prevent pregnancy. Unwanted pregnancy can be prevented by keeping the animal inside the home or a secure fence.

By the way, an electric fence does not prevent other dogs from getting to your dog!

Whether and When to have surgical sterilization performed should be up to the owner, not the government or local bureaucrats. Who knows more about your dog’s health than your veterinarian? Even though promoting early spay and neuter profits vets in the long run; honest, knowledgeable vets who learn from clinical experience and vet school instead of animal “rights” activists will veto early spay/neuter.

So talk to your vet. Then contact a responsible breeder who is as knowledgeable as your good vet. Breeders have been a little bit brainwashed but if you convince them that you want only to delay premature, risky removal of sex hormone organs, they will listen.  By far, your best best is a purebred puppy or retired adult from a knowledgeable breeder.

Your choice should not be limited to a shelter mongrel with unpredictable size and personality, one that may or may not fit your family; one that has been subjected to surgical sterilization resulting in serious side effects.  The choice should be yours and it should be an informed choice, not an automatic compliance of something you don't understand, the results of which could keep you in and out of the vet's office for a lifetime!

Early Spay/Neuter warns of adverse physical effects when sterilized before 6 months of age.

 SPAY & NEUTER COMMON SENSE

Early Spay-Neuter Considerations for the Canine Athlete

 http://www.thedogplace.org/Veterinary/0603-SpayNeuter_Zink.asp

Rethinking Spay & Neuter, 2011 spay/neuter study reveals shorter life span, higher vet bills, hormone & health problems, contradicting pet sterilization campaign!

http://www.thedogplace.org/Veterinary/Spay-Neuter-1101_Coats.asp

RETHINKING SPAY & NEUTER

By Geneva Coats R.N., TheDogPlace.org Genetics Editor / January 2011

Is Pet sterilization a purely beneficial routine procedure? Most breeders today sell companion puppies under contracts requiring spay or neuter as a condition of sale. [6]

Ingrained in current culture is the notion of pet overpopulation and to prevent the deaths of animals in shelters all pets should be sterilized. To bolster that campaign, we are told that a sterilized pet is happier, healthier and longer-lived than one who remains intact. What are the facts?

"PET OVERPOPULATION"

In the mid-twentieth century, there was an abundance of pets; many were available “free to good home” via newspaper ads. Few pets were sterilized, and many people unwisely allowed their dogs to roam the neighborhood, producing unplanned litters.

According to “Maddie’s Fund” president Richard Avanzino, in the 1970s, our country’s animal control agencies were killing, on average, about 115 dogs and cats annually for every 1000 human residents. This amounted to about 24 million shelter deaths every year.² Avanzino is also the former executive director of the San Francisco SPCA, and is regarded by many as the founder of the modern no-kill movement in the US.

"The Problem" of too many pets and not enough homes to go around began a huge campaign based on spaying and neutering pets. Vets began to routinely urge clients to sterilize their pets as an integral part of being a “responsible owner”. Planned breeding became a politically incorrect activity. A popular slogan today is “Don’t breed or buy, while shelter dogs die.”

The crusade for spaying and neutering pets has been very successful. A 2009-2010 national pet owners’ survey by the American Pet Products Manufacturers Association reveals that the vast majority of owned pets...75% of dogs and 87% of cats... are spayed or neutered. (As reported by the HSUS in Dec. 2009):

In recent years, according to Avanzino, annual shelter death numbers have dramatically declined to about 12 per thousand human residents, or about 3.6 million deaths each year. This amounts to a staggering 85% reduction in killing since the 1970s.²  We have reached a nationwide pet shelter death rate averaging just 1.2% per population, effectively a “no kill” rate.

Feral cats and kittens account for the majority of shelter numbers⁹ but many areas have actual shortages of adoptable dogs, particularly purebreds and puppies, and must import from other regions to fill the need. Dogs are being smuggled into the US by the thousands with rescue groups importing small dogs from Mexico, Brazil, the Caribbean, Taiwan and Romania, to name some of the most popular points of origin. The conservative estimate is that 300,000 dogs are imported into the US each year to meet the demand for pets.³

According to shelter expert Nathan Winograd, every year in this country, approximately 3 million adoptable pets die in shelters.* At the same time, around 17 million US households are looking for a new pet. That is 17 million households above and beyond those who already will adopt a shelter or rescue pet. There are nearly six times as many homes opening up every year as the number of adoptable pets killed in shelters!⁸ It seems the greatest challenge these days is to find ways to match up the adoptable pets with the homes that are waiting for them. Breed rescues fill this niche admirably, but are privately funded and desperately in need of assistance in order to be able to effectively perform this service. Perhaps some of the public funds budgeted for shelters to kill animals could be better spent helping rescue groups who are proactive in matching adoptable pets to suitable homes.

SPAY/NEUTER AND HEALTH

Now that we have addressed the issue of pet overpopulation, let’s examine the claim that sterilization surgery promotes better health. While there are some benefits to sterilization, there are some drawbacks as well.

Sterilization will naturally serve to prevent any unwanted litters. In bitches, spaying will greatly reduce the risk of breast cancer, pyometra, perianal fistula and cancers of the reproductive organs.⁵

Spay surgery itself carries a somewhat high rate (around 20%) of complications such as infection, hemorrhage and even death.5 Spaying significantly increases the rate of urinary incontinence in bitches….about 20-30% of all spayed bitches will eventually develop this problem. This is believed to be most likely caused by the lack of estrogen that results from being spayed.¹

Sterilization of males may reduce some unwanted sexual behaviors, but there are few other proven benefits to neutering a male dog. Testicular cancer is prevented, but the actual risk of that cancer is extremely low (<1%) among intact dogs. Contrary to popular belief, studies show that the risk of prostate cancer is actually HIGHER in neutered dogs than in their intact counterparts.⁵

Several studies prove significant health risks associated with sterilization, particularly when done at an early age. The most problematic is a delayed closure of the bony growth plates. This results in an abnormal, “weedy” skeletal development that increases the incidence of orthopedic problems like hip dysplasia and patellar luxation. Working and performance dogs, if neutered before maturity, risk the inability to perform the jobs they were bred for.¹⁰

But by far the most startling news to surface this year is the result of a study that shows that keeping ovaries to the age of six years or later is associated with a greater than 30% increase of lifespan in female Rottweilers.⁴ Similar studies in humans reinforce this finding.^7,11

A 30% longer lifespan means that you could have many additional years with your bitch simply by delaying spay surgery until middle-age or later.

Behavioral studies show that sterilization increases fearfulness, noise phobias and aggression. Other well-documented adverse health effects of de-sexing include increased risk of bone cancer, hemangiosarcoma, hypothyroidism, and cognitive dysfunction in older pets. Sterilization confers an increased susceptibility to infectious disease, and also a higher incidence of adverse reactions to vaccines.¹⁰

So there is no need to feel obligated to sterilize for health or welfare reasons. But what about the need to protect the puppies that we sell from unethical breeders?

PUPPY SALES CONTRACTS

Many breeders are justifiably very concerned about their dogs being subjected to neglect or abuse by falling into disreputable hands. To help prevent such situations, it has become commonplace for breeders to include spay/neuter requirements in their pet sales contract, and/or to sell the dog on a limited registration. Another common stipulation, particularly for a show/breeding dog, is requiring that the dog be returned to the seller in the event the buyer no longer wishes to keep him.⁶

Such contracts are highly effective when selling a puppy to someone who is honest and ethical. However, contracts are easily skirted by the unscrupulous, particularly if the buyer lives in a different region. Someone intent on breeding may do so regardless of contract language, and then sell the puppies without registration. And without personal knowledge of the living conditions at your puppy’s new home, it is impossible to predict what sort of care and attention he or she will receive. Even some show breeders may have very different ideas on what constitutes proper care. There is no substitute for a home check to follow up that initial puppy application!

Bottom line, the best insurance for your puppies is making sure that you get to know the buyer personally. If something about the buyer or his attitude doesn’t seem right, then it’s probably best to cancel the sale. If you want to sell puppies on spay-neuter agreements you might consider advising the buyer to wait until the puppy reaches maturity before having sterilization surgery performed. Another idea is to ask your vet if vasectomy would be a viable alternative to castration for your male. This would preserve sex hormones and possibly prevent some of the adverse health effects of castration.
 

PUREBRED GENE POOLS

Sterilization of all dogs sold as companions may have some unintended adverse effects. The nature of breeding for the show ring involves intense selection that severely narrows the gene pool in many, if not most, breeds. Some breeds started with just a small pool of founders. Through the years, overuse of only a few popular sires further reduced the genetic variety available in the breed. When troublesome health problems surface and become widespread, where can we turn for “new blood”?

The show-bred population of a breed may have become too small as a result of intense inbreeding or the genetic bottleneck created by overuse of popular sires; or the breed gene pool may have become genetically depleted because of unwise selection for specific, sometimes unhealthy physical traits favored in the show ring. As a result, dogs from the “pet” population may actually be the salvation of the breed gene pool.

Trying to guess which dogs are the "best" to keep intact for showing and breeding can be hit-or-miss. Imagine the scenario where a successful show dog eventually develops a heritable health issue, while his brother is much healthier...but brother was neutered long ago, thereby eliminating those good genes forever. What about that Champion's non-show quality sister, who has good health, great mothering instincts and the genetic ability produce exceptional offspring? If sold as a spayed companion, her genes are effectively lost.

And what about the very future of the dog fancy? Many people (myself included) bought an intact dog as a pet, and only later sparked an interest in showing and breeding. Developing new breeders is critical to the survival of our sport, but if we sell all companions on spay/neuter agreements, we will lose many fanciers before they have the chance to discover the joy of dog breeding and showing!

Sadly, mandatory sterilization laws are sweeping the nation and may further compromise the future of the dog fancy. AKC registrations continue to decline and the push to legally and/or contractually require spay and neuter of most every dog will only worsen that situation.

Regardless, there is a huge demand in society for healthy pets; a demand which the responsible breeders could not come close to meeting even if they wanted to...and sometimes, they do not want to. The choice we have as a society is how that demand will be filled. Many believe that only responsible people should be allowed to keep intact dogs and breed on a limited basis. However, the attempt to legally force well-regulated and inspected commercial breeders and the casual small home breeders out of the picture leaves only the unregulated, less visible "underground" producers and smugglers to fill the need for pets. Perhaps it is time to re-think our preconceived notions about who should and shouldn't possess intact dogs!

As a dog owner, one must weigh the risks of sterilization against the benefits in order to make that very personal decision. Popular culture and many veterinarians downplay or even ignore the risks involved with spay/neuter because of their own belief in the need to reduce dog breeding in general. Many people still believe that overpopulation remains a pressing concern and that sterilization always promotes better health. Some even believe that breeding a female is abusive. It seems the animal rights groups have done an excellent job of brainwashing the public on these matters!

As breeders, we may be wise to re-examine the routine request to have all our companion puppies spayed or neutered. The future availability of pets, the perpetuation of the dog fancy, the health of the individual dogs and the gene pools of the breeds that we love may all depend on keeping a few more dogs intact!

*An adoptable pet is one that does not have insurmountable health or temperament issues. Per California’s Hayden law: The California Legislature Defines No-Kill Terms ■ California Law, SB 1785 Statutes of 1998, also known as "The Hayden Law" has defined no-kill terms.

What is Adoptable? 1834.4. (a) "No adoptable animal should be euthanized if it can be adopted into a suitable home. Adoptable animals include only those animals eight weeks of age or older that, at or subsequent to the time the animal is impounded or otherwise taken into possession, have manifested no sign of a behavioral or temperamental defect that could pose a health or safety risk or otherwise make the animal unsuitable for placement as a pet, and have manifested no sign of disease, injury, or congenital or hereditary condition that adversely affects the health of the animal or that is likely to adversely affect the animal's health in the future."

Adoptable dogs may be old, deaf, blind, disfigured or disabled.

http://www.thedogplace.org/Veterinary/Spay-Neuter-1101_Coats.asp

REFERENCES AND FURTHER READING
¹ Bovsun, Mara; "Puddle Jumping; Canine Urinary Incontinence"; AKC Gazette April 2009
barkingbulletin.com/newsletter/2009/q4/Puddle-Jumping--Canine-Urinary-Incontinence/

² Fry, Mike, "Reflections from the No Kill Conference in Washington DC":
animalarkshelter.org/animal/ArkArticles.nsf/AllArticles/3A078C33CD079D17862575AD00471A9B

³ James, Susan Donaldson (ABC News) "300,000 Imported Puppies Prompt Rabies Concerns"
October 24, 2007 petpac.net/news/headlines/importedpuppies/

⁴ Nolen, R. Scott "Rottweiler Study Links Ovaries With Exceptional Longevity"
JAVMA March 2010 avma.org/onlnews/javma/mar10/100301g.asp

⁵ Sanborn, Laura J., MS
"Long-Term Health Risks and Benefits Associated with Spay/Neuter in Dogs"; May 14,2007
naiaonline.org/pdfs/longtermhealtheffectsofspayneuterindogs.pdf

⁶ Thoms, Joy "The Importance of Spay-Neuter Contracts" The Orient Express, Nov, 2009

⁷ Waters, David J., DVM, PhD, Diplomate ACVS "A Healthier Respect for Ovaries"
gpmcf.org/respectovaries.html

⁸ Winograd, Nathan J. "Debunking Pet Overpopulation" June 29, 2009
nathanwinograd.com/?p=1390

⁹ Winograd, Nathan, “Redemption: The Myth of Pet Overpopulation and the No Kill Revolution in America” Almaden Books, 2nd edition, Feb 25, 2009.

¹⁰ Zink, Christine, DVM, PhD, DACVP
"Early Spay-Neuter Considerations for the Canine Athlete"; 2005
http://www.thedogplace.org/Veterinary/0603-SpayNeuter_Zink.asp

¹¹ “Retaining ovaries may be a key to prolonged life in women and dogs”; DVM Newsmagazine; Dec 5, 2009. veterinarynews.dvm360.com/dvm/ArticleStandard/Article/detail/646838

SPAY & NEUTER CONSIDERATIONS

Removal of Ovaries affects life span, how long dogs keep their ovaries determines how long they live! Early spay may be ill advised. 

A Healthier Respect For Ovaries

by David J. Waters, DVM, PhD, Diplomate ACVS - TheDogPlace June 2011

A recent study by my research group appearing next month in Aging Cell reveals shortened longevity as a possible complication associated with ovary removal in dogs (1). This work represents the first investigation testing the strength of association between lifetime duration of ovary exposure and exceptional longevity in mammals. To accomplish this, we constructed lifetime medical histories for two cohorts of Rottweiler dogs living in 29 states and Canada: Exceptional Longevity Cohort = a group of exceptionally long-lived dogs that lived at least 13 years; and Usual Longevity Cohort = a comparison group of dogs that lived 8.0 to 10.8 years (average age at death for Rottweilers is 9.4 years). A female survival advantage in humans is well-documented; women are 4 times more likely than men to live to 100. We found that, like women, female Rottweilers were more likely than males to achieve exceptional longevity (Odds Ratio, 95% confidence interval = 2.0, 1.2 - 3.3; p = .006). However, removal of ovaries during the first 4 years of life erased the female survival advantage. In females, this strong positive association between ovaries and longevity persisted in multivariate analysis that considered other factors, such as height, adult body weight, and mother with exceptional longevity.

In summary, we found female Rottweilers who kept their ovaries for at least 6 years were 4.6 times more likely to reach exceptional longevity (i.e. live >30 % longer than average) than females with the shortest ovary exposure. Our results support the notion that how long females keep their ovaries determines how long they live.

In the pages that follow, I have attempted to frame these new findings in a way that will encourage veterinarians to venture beyond the peer-reviewed scientific text and data-filled tables of Aging Cell to consider the pragmatic, yet sometimes emotionally charged implications of this work. Call it a primer for the dynamic discussions that will undoubtedly take place, not only between practitioners and pet owners, but also within the veterinary profession. Call it a wake-up call for how little veterinarians have been schooled in the mechanistic nuts and bolts underlying the aging process. Call it an ovary story.

Do ovaries really promote longevity? Observed associations between exposures and outcomes may not necessarily be causal, so we explored alternative, non-causal explanations for the association between ovaries and exceptional longevity in our study. But we found no evidence that factors which may influence a pet owner's decision on age at ovary removal — for example, earlier ovariectomy in dogs with substandard conformation or delayed ovariectomy to obtain more offspring in daughters of long-lived mothers — could adequately account for the strong association.

There is another aspect of our data pattern that gives us further confidence that ovaries really do matter when it comes to successful aging. A simple explanation for the observation that ovaries promote longevity would be that taking away ovaries increases the risk for a major lethal disease. In Rottweilers, cancer is the major killer. We found, however, that by conducting a subgroup analysis that excluded all dogs that died of cancer, the strong association between intact ovaries and exceptional longevity persisted. After excluding all cancer deaths, females that kept their ovaries the longest were 9 times more likely to reach exceptional longevity than females with shortest ovary exposure. Thus, we observed a robust ovarian association with longevity that was independent of cause of death, suggesting that a network of processes regulating the intrinsic rate of aging is under ovarian control. This work positions pet dogs, with their broad range of lifetime ovary exposure, to become biogerontology&apos;s new workhorse for identifying ovary-sensitive physiological processes that promote healthy longevity.

Interestingly, our findings in dogs surface just as data from women are calling into question whether those who undergo hysterectomy should have ovary removal or ovary sparing. In fact, our results mirror the findings from more than 29,000 women in the Nurses’ Health Study who underwent hysterectomy for benign uterine disease (2). In that study, the upside of ovariectomy — protection against ovarian, uterine, and breast cancer — was outweighed by increased mortality from other causes. As a result, longevity was cut short in women who lost their ovaries before the age of 50 compared with those who kept their ovaries for at least 50 years. Taken together, the emerging message for dogs and women seems to be that when it comes to longevity, it pays to keep your ovaries.

But before we all go out and buy T-shirts with some romantic imperative like “Save the Ovaries”, perhaps we should step back and consider the following question: Why haven’t previous dog studies called our attention to this potential downside of ovariectomy? Reviewing the literature, an answer quickly bubbles up. No previous studies in pet dogs have rigorously evaluated the association between ovaries and longevity. Two frequently cited reports (3,4) provide limited guidance because: (1) longevity data are presented as combined mean age at death for a relatively small number of individuals of more than 50 breeds of different body size and life expectancy; and (2) ovarian status is reported as “intact” or “spayed”, rather than as number of years of lifetime ovary exposure. Comparing female dogs binned into the categories of “intact” versus “spayed” introduces a methodological bias that might lead one to conclude that ovaries adversely influence longevity, i.e. ovary removal promotes longevity. Because the reasons for ovariectomy (e.g., uterine infection, mammary cancer) increase with increasing age, it is expected that a large percentage of the oldest-dogs are binned as “spayed” despite having many years of ovary exposure. For example, a dog who at age 12 undergoes ovariohysterectomy for pyometra would be binned as “spayed”, despite 12 years of ovary exposure. In our study, we employed a more stringent study design — restricting the study population to AKC registered, pure-bred dogs of one breed, carefully quantitating the lifetime duration of ovarian exposure — in order to lessen the likelihood of such bias. And we reasoned that studying veterinary teaching hospital-based populations of dogs with artifactually low life expectancies (for example, 3.5 years is median age at death for Rottweilers in the Veterinary Medical Data Base)(5) was an inappropriate vehicle to describe the influence that ovaries have on aging. So we cast a wider net and collected data from Rottweiler owners nationwide, focusing our attention on exceptional longevity, not average age at death, as our study endpoint.

Why study exceptional longevity? Why not average longevity? We thought studying the most exceptionally long-lived individuals would tell us something about what it takes to age successfully. It’s the same rationale used by Thomas Perls and investigators of the New England Centenarian Study (6) and by other scientists who study long-lived humans in other parts of the world (7). The approach even garners support from the mathematical field. In a seminal book on the origins of creative genius, the mathematician Jacques Hadamard wrote: “In conformity with a rule which seems applicable to every science of observation, it is the exceptional phenomenon which is likely to explain the usual one.” (8) Hadamard was trying to understand how the brain gets creative so he studied people with extreme creativity. When it comes to studying aging, we’re solidly in the Hadamard camp. That is why in 2005 we established the Exceptional Longevity Data Base, launching the first systematic study of the oldest-old pet dogs (9). But folks in the opposing camp might justifiably fire back: “Don’t study extreme longevity. Extreme longevity is much more about luck than it is about genes, or environment, or ovaries.”

So to address the possibility that the “strangeness” or outlier nature of dogs with exceptional longevity could be forging a misleading link between ovaries and longevity, we studied a separate cohort of Rottweiler dogs. This data set was comprised of 237 female Rottweilers living in North America that died at ages 1.2 to 12.9 years — none were exceptionally long-lived. Information on medical history, age at death, and cause of death was collected by questionnaire and telephone interviews with pet owners and local veterinary practitioners. In this population, we found females that kept their ovaries for at least 4.5 years had a statistically significant 37% reduction in mortality rate (1). This translated into a median survival of 10.4 years for females with more than 4.5 years of ovary exposure — 1.4 years longer than the median survival of only 9.0 years in females with shorter ovary exposure (p < 0.0001). Taken together, if you take out ovaries before 4 years of age you cut longevity short an average of 1.4 years and decrease the likelihood of reaching exceptional longevity by 3-fold.

Up to this point, my ovary story has centered around a summarizing of methodologies and results. The reader has been given opportunity to see the gist of our findings within the context of previous dog studies and late-breaking studies in women. Now, let us pivot our attention a bit away from the results to focus on the recipients of these results — DVMs and pet owners.

We can start by tackling the question: Just how receptive will DVMs be to these new research findings? It’s hard for old dogs to learn new tricks. But one thing is sure — blossoming change is rooted in real communication. The anthropologist Gregory Bateson wrote: “The pre-instructed state of the recipient of every message is a necessary condition for all communication. A book can tell you nothing unless you know 9/10ths of it already.” (10). I call this “Bateson’s Rule of the 9/10ths”. If Bateson is right, then we will want to do something about the pre-instructed state of veterinarians. Because when it comes to the biology of aging, the state is virtually a blank slate. None of us received training in the biology of aging as part of our DVM curriculum — whether we graduated 30 years ago or last summer. Therefore, most DVMs are ill-prepared to receive messages examining the mechanistic underpinnings of the aging process. A Batesonian prescription for positive change would be to ratchet up the biology of aging IQ of practicing veterinarians. We agree. That is why we established the first gerontology training program for veterinarians in 2007 (11). We believe that by helping veterinarians “know” more about aging, they will be more able and more receptive to communicating the things that promote healthy longevity in their patients — things like preserving ovaries.

For certain, DVMs will be asked by pet owners to help them make their decision about age at spay in light of this new information. The question will be asked: Just how generalizable are these findings in Rottweilers to other segments of the pet dog population? It is impossible to say at this time. It will demand further study. Alas, 10 years from now, we might just find out that a longevity-promoting effect of ovaries in dogs is limited — limited to large breeds, urban but not rural dogs, or only those individuals with particular polymorphisms in insulin-like growth factor-1. These restrictions should not only be expected, they should be celebrated. It will mean that we have looked more deeply into how ovaries might influence healthy longevity. It will mean that our initial findings have been contextualized. And it is this contextualization of information that marks scientific progress — the kind of progress that guides sound clinical decision making. For it is context that determines meaning (12).

Our provocative findings in Aging Cell mean that it’s time to re-think the notion that taking away ovaries has no significant downside to a dog’s healthy longevity. Perhaps it would help us if we thought of lifetime ovary exposure as information — information that instructs the organism. Just how long and how healthy a female lives reflects what her cells, tissues, and organs thought they heard from the message received. Of course in biology, there is no single message but a symphony of messages, enabling each individual to successfully respond to environmental challenges. Our findings suggest that ovaries orchestrate that symphony. Taking away ovaries in early or mid-life makes for muddled information, less than perfect music.

Information muddling can ensnarl decision-making. Our research takes an important first step toward disentangling the thinking about ovaries and longevity. We must never be paralyzed by the incompleteness of our knowledge. Our knowledge will always be incomplete — subject to revision, primed for further inquiry. This uncertainty, although invigorating for the investigator, is often painful for the practitioner who seeks simple, fact-driven algorithms to guide his action. Just as scientists will be called upon to forge ahead with their scientific inquiries, so too will practitioners be counted on to master the uncertainty. Together, we must navigate what the Danish philosopher-theologian Soren Kierkegaard called the gap “between the understanding and the willing.” That is, we must ask the right questions and make smart choices so that our action (the willing) is in synch with our knowledge (the understanding). Under just what circumstances will a particular individual benefit from specific lifestyle decisions? This is perhaps the most prescient, overarching question in the wellness and preventive medicine fields facing both human and veterinary health professionals today. How can we promote healthy longevity? Antioxidant supplementation or calorie restriction? Ovary removal or ovary sparing?

Undoubtedly, there will be protagonists and antagonists in this ovary story. The protagonists will be open-minded to following a new script. They will embrace the idea of ovary sparing for critical periods of time to maximize longevity. They might even recognize the need for some sort of “ovarian mimetic” in spayed dogs to optimize healthy aging. The antagonists in this story — the defenders of the old script — will dismiss as trivial the notion that ovaries regulate the rate of aging and influence healthy longevity. Lines will be drawn and opinions will fly. But that's what healthy debate is — antagonists and protagonists keeping a high priority issue front and center, not allowing it to fade into the woodwork. It would seem that, in light of the new scientific findings, a contemporary dialogue should balance the potential benefits of elective ovary removal (13) with its possible detrimental effects on longevity.

http://www.thedogplace.org/HEALTH/Respect-Ovaries_Waters(Jordan)-1106.asp #1106

References:

1. Waters DJ, Kengeri SS, Clever B, et al: "Exploring the mechanisms of sex differences in longevity: lifetime ovary exposure and exceptional longevity in dogs." Aging Cell October 26, 2009

2. Parker WH, Broder MS, Chang E et al: "Ovarian conservation at the time of hysterectomy and long-term health outcomes in the Nurses' Health Study." Obstet Gynecol 113: 1027-1037, 2009

3. Bronson RT: "Variation in age at death of dogs of different sexes and breeds." Am J Vet Res 43: 2057-9, 1982

4. Michell AR: "Longevity of British breeds of dog and its relationships with sex, size, cardiovascular variables and disease." Vet Rec 145: 625-629, 1999

5. Patronek GJ, Waters DJ, Glickman LT et al: "Comparative longevity of pet dogs and humans: implications for gerontology research." J Gerontol A Biol Sci Med Sci 52: B171-8, 1997

6. Perls TT, Hutter Silver M, Lauerman JF: Living to 100: Lessons in Living to Your Maximum Potential at Any Age, New York, NY, Basic Books, 1999

7. Franceschi C, Motta L, Valensin S et al: "Do men and women follow different trajectories to reach extreme longevity?" Aging (Milano) 12: 77-84, 2000

8. Hadamard J: The Psychology of Invention in the Mathematical Field. New York, NY, Oxford Univ Press, 1945, p. 136

9. Waters DJ, Wildasin K: "Cancer clues from pet dogs." Sci Am 295: 94-101, 2006

10. Bateson G, Bateson MC: Angels Fear: Towards an Epistemology of the Sacred. New York, NY, Bantam, 1988, p 163

11. Gerontology Program for DVMs co-sponsored and organized by Gerald P. Murphy Cancer Foundation, Purdue University Center on Aging and the Life Course, P&G Pet Care; for more information go to www.gpmcf.org

12. Waters DJ, Chiang EC, Bostwick DG: "The art of casting nets: fishing for the prize of personalized cancer prevention." Nutr Cancer 60: 1-6, 2008

13. Kustritz MV: "Determining the optimal age for gonadectomy of dogs and cats." J Am Vet Med Assoc 231: 1665-75, 2007

http://www.gpmcf.org/respectovaries.html