[ Post a Response | Catahouligans ]
Posted by Suz on November 2, 2009, 5:35 am
http://www.gpmcf. org/respectovari es.html
A Healthier Respect for Ovaries
David J. Waters, DVM, PhD, Diplomate ACVS
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.
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.
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