In 2002, the American College of Obstetricians and Gynecologists revised their 1994 guidelines to recommend that pregnant women without medical or obstetric complications follow exercise guidelines for nonpregnant women. In spite of these guidelines, the optimal dose of recreational physical activity (i.e., total volume of energy expenditure, and specific frequency, duration and intensity) for a pregnant woman remains to be determined. Identification of this dose has been hampered by the complexity of assessing recreational physical activity in general, and particularly during pregnancy, a demanding period characterized by changing physiology. Therefore, we reviewed the measurement methods in the epidemiologic studies that examined the association between recreational physical activity and two specific pregnancy outcomes of primary public health importance, birthweight and length of gestation. From a review of the medical literature, we identified 20 published journal articles between 1966 and 2005. Study designs, participants, and physical activity assessment measures varied widely across studies. The majority of these studies did not consistently assess type, frequency, intensity, and duration of activity and did not measure these variables during each trimester of pregnancy. Because the effect of recreational physical activity on birth outcomes is likely to be modest, measurement must be highly accurate to minimize the possibility that an effect will not be observed because of measurement error. Recommendations are made for the future assessment of recreational physical activity in epidemiologic studies of these major birth outcomes.

To move closer to understanding the mechanistic underpinnings of sex differences in human longevity, we studied pet dogs to determine whether lifetime duration of ovary exposure was associated with exceptional longevity. This hypothesis was tested by collecting and analyzing lifetime medical histories, age at death, and cause of death for a cohort of canine ‘centenarians’– exceptionally long-lived Rottweiler dogs that lived more than 30% longer than average life expectancy for the breed. Sex and lifetime ovary exposure in the oldest-old Rottweilers (age at death, ≥ 13 years) were compared to a cohort of Rottweilers that had usual longevity (age at death, 8.0–10.8 years). Like women, female dogs were more likely than males to achieve exceptional longevity (OR, 95% CI = 2.0, 1.2–3.3; P= 0.006). However, removal of ovaries during the first 4 years of life erased the female survival advantage. In females, a strong positive association between ovaries and longevity persisted in multivariate analysis that considered other factors, such as height, body weight, and mother with exceptional longevity. A beneficial effect of ovaries on longevity in females could not be attributed to resistance against a particular disease or major cause of death. Our results document in dogs a female sex advantage for achieving exceptional longevity and show that lifetime ovary exposure, a factor not previously evaluated in women, is associated with exceptional longevity. This work introduces a conceptual framework for designing additional studies in pet dogs to define the ovary-sensitive biological processes that promote healthy human longevity.

The vast majority of dogs with cervical disk herniation experience cervical pain and only mild motor deficits; therefore, not much is known about the factors that predict recovery in dogs with nonambulatory tetraparesis (NAT) secondary to cervical disk herniation. In this retrospective study, we tested the hypothesis that two previously reported prognostic factors, site of disk herniation and severity of neurological deficits, are useful predictors of complete recovery. Overall, 20 (62%) of 32 dogs with cervical disk herniation-associated NAT had complete recovery. Site of disk herniation was not a significant predictor of complete recovery; dogs with high cervical lesions (C2 to C3, C3 to C4) did not have a higher likelihood of complete recovery than other dogs. Likewise, severity of neurological deficits (i.e., intact voluntary motor function versus absent voluntary motor function) was not a significant predictor of complete recovery. Using stepwise logistic regression, two significant predictors of complete recovery were identified. Small dogs (delta15 kg body weight) were six times more likely to achieve complete recovery than larger dogs. Dogs that regained the ability to walk within 96 hours after surgery were seven times more likely to completely recover than dogs not walking 96 hours after surgery. We conclude that neither the site of disk herniation nor severity of neurological deficits assists the clinician in predicting postoperative outcome in dogs with cervical disk herniation-associated NAT. Reliable preoperative predictors of complete recovery are needed to advance current diagnostic and treatment protocols to improve overall prognosis.

ᮀ Our work in dogs has revealed a U-shaped dose response between selenium status and prostatic DNA damage that remarkably parallels the relationship between dietary selenium and prostate cancer risk in men, suggesting that more selenium is not necessarily better. Herein, we extend this canine work to show that the selenium dose that minimizes prostatic DNA damage also maximizes apoptosis-a cancer-suppressing death switch used by prostatic epithelial cells. These provocative findings suggest a new line of thinking about how selenium can reduce cancer risk. Mid-range selenium status (.67-.92 ppm in toenails) favors a process we call "homeostatic housecleaning"-an upregulated apoptosis that preferentially purges damaged prostatic cells. Also, the U-shaped relationship provides valuable insight into stratifying individuals as selenium-responsive or seleniumrefractory, based upon the likelihood of reducing their cancer risk by additional selenium. By studying elderly dogs, the only non-human animal model of spontaneous prostate cancer, we have established a robust experimental approach bridging the gap between laboratory and human studies that can help to define the optimal doses of cancer preventives for large-scale human trials. Moreover, our observations bring much needed clarity to the null results of the Selenium and Vitamin E Cancer Prevention Trial (SELECT) and set a new research priority: testing whether men with low, suboptimal selenium levels less than 0.8 ppm in toenails can achieve cancer risk reduction through daily supplementation.