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Study Links Ovaries and Longevity

By Marissa Heflin

Female dogs that keep their ovaries longer also live longer, according to a study led by David Waters, DVM, executive director of the Gerald P. Murphy Cancer Foundation.

The findings, according to researchers at Purdue Research Park in West Lafayette, Ind., challenge almost four decades of standard operating procedures used in female pets as well as humans. It was the first investigation to look for a link between retained ovaries and exceptional longevity in mammals, the researchers said.

“A female survival advantage in humans is well-documented—women outnumber men by 4-to-1 among those who reach 100,” said Dr. Waters, associate director of Purdue University’s Center on Aging and the Life Course.

“Like women, female dogs in our study had a distinct survival advantage over males. But taking away ovaries during the first four years of life completely erased the female survival advantage. We found that female Rottweilers that kept their ovaries for at least six years were four times more likely to reach exceptional longevity compared to females who had the shortest lifetime ovary exposure.”

The researchers collected and analyzed lifetime medical histories, ages and causes of death for 119 canine “centenarians”—Rottweilers living in the U.S. and Canada that survived to 13 years, about 30 percent longer than the average Rottweiler. These dogs were compared to 186 Rottweilers that had usual longevity, about nine years.

“Clearly we have tapped into a unique resource with our Exceptional Longevity Database,” said Waters, a professor in Purdue’s Department of Veterinary Clinical Sciences. “We like to think of it as the pet dog equivalent of the New England Centenarian Study. We want to better understand the biology of aging. Our quest to validate pet dogs as a model for the study of healthy human aging is at the core of this research.”

The dog study mirrors research from the Nurses’ Health Study, which evaluated more than 29,000 women who underwent a hysterectomy for benign uterine disease. The findings showed that the upside of ovary removal—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 age 50 compared with those who kept their ovaries for at least 50 years.

“For the last 35 years most doctors have been routinely advising women undergoing hysterectomy to have their ovaries removed to prevent ovarian cancer,” said William Parker, MD, of the John Wayne Cancer Institute, who published the study. “We believe that such an automatic recommendation is no longer warranted.”

Taken together, the emerging message for dogs and women seems to be that when it comes to longevity, it pays to keep your ovaries, according to Purdue Research Park.

“What we have here is a compelling convergence,” Waters said. “The data from women and dogs, together with reported longevity benefits from ovary transplants in mice, are pointing in the same direction: the notion that a network of processes regulating longevity is under ovarian control.”

The dog study was published in Aging Cell.

The Gerald P. Murphy Cancer Foundation, based at Purdue Research Park, is home to the Center for Exceptional Longevity Studies, which tracks the oldest living pet dogs in the U.S. <HOME>

This article first appeared in the February 2010 issue of Veterinary Practice News

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Study Links Ovaries and Longevity

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1. The study itself appears to be a rehash of a study that was published back in 2003 - the same data was used but the emphasis in that study was on canine cancer. "Exceptional longevity in pet dogs is accompanied by cancer resistance and delayed onset of major diseases." No mention was made of ovary exposure as related to longevity even though the same Rottweiler data was used. 2. The dogs studied died between 1995-2000 - further indicating this was an old study - first used for a different purpose. 3. The major flaw in the 2009 study is the control groups of dogs used. They used one group aged 9-10 yrs. - and another group aged 13.3-14.3. The study only included 183 Rottweiler dogs in healthy home environments. We already know that the benefits of spaying include greatly decreased risk of breast & ovarian cancer. The average age of onset for breast & ovarian cancers in Rottweilers is generally younger than the control groups studied, thus all Rottweilers that died of breast or ovarian cancer at a younger age would have been excluded from the study. This would compare to taking a group of female smokers 90 years old and over - and concluding that cigarette smoking has no effect on women's health since they are still alive at 90. All the women who died of smoking related diseases at younger than 90 years of age (common) would not have been considered in the study. 4. There appears to be other factors that contributed to the longevity of the Rottweilers in the 13.3-14.3 age group. As a group they weighed less at 79-90 lbs. - versus the younger group that weighed 90-100 lbs. Also the older dogs were shorter. Studies have long shown smaller, thinner dogs live longer by two years on average. 5. The oldest Rottweiler group - 13.3-14.3 - had a considerably larger number of mothers that achieved exceptional longevity - showing a genetic link to their longevity. 6. The 2009 study greatly contradicts much broader previous studies on ALL breeds and MIXED breeds - in reputable journals that show unequivocally the spaying prolongs female dog's lives and that breeding shortens their lives. 7. The study is flawed also because he states that the average life expectancy of a Rottweiller is 9-10 yrs., when the majority of resources indicate it is actually 10-12 years - thus the "exceptional longevity" of 13 is not that extraordinary. Even more notable is the major cause of death he shows for in Rottweillers in the 9-10 yr. group is indeed cancer - 73% dying from it. 8. The study was originally completed to show that Rottweilers that lived past the age of 10 had a reduced risk for cancer. 73% died from it in his 9-10 year group and only 25% died from it in his 13.3 to 14.3 age group. This is the REAL information the study revealed - and the main thrust of the 2003 paper. Brent, LA, CA Posted: 3/23/2010 3:06:07 PM