More health findings hit PMU industry
From ANIMAL PEOPLE, October 2010:
(Actual press date November 3.)
LOS ANGELES, DALLAS–The fast-falling numbers of horses bred
to produce estrogen supplements made from pregnant mares’ urine are
expected to drop further after publication of new findings from the
U.S. government-funded Women’s Health Initiative linking estrogen
supplements to elevated rates of death from breast cancer and risk of
developing kidney stones.
The new findings came eight years after the Women’s Health
Initiative in July 2002 reported thatestrogen supplements appear to
be linked to increased risk of women suffering heart attacks,
strokes, and blood clots in their lungs.
Based on the Women’s Health Initiative study results, the
U.S. Food & Drug Administration in February 2003 began requiring all
estrogen product labels to carry warnings that the products “may
slightly increase the risk of heart attack, stroke, breast cancer,
and blood clots.” The FDA and most leading medical organizations
believe these risks pertain to estrogens from all sources, not just
PMU, but since the PMU-based products Primarin and Prempro had by
far the largest estrogen supplement market share, their sales
decline was steepest.
The Women’s Health Initiative breast cancer study looked at
women who took the PMU-based estrogen drug Premarin in combination
with progestin, a formula sold as Prempro. “Women taking estrogen
plus progestin are at greater risk from dying from the two leading
causes of cancer death in women,” concluded study team leader Rowan
T. Chlebowski of the Los Angeles Biomedical Research Institute at
Harbor-UCLA Medical Center. Among the the 15,387 women who
participated in the second phase of the Women’s Health Initiative,
the death rate from breast cancer among those who did not take
estrogen plus progestin was 3.4 per 10,000; the rate among those who
did was 5.3, or 40% higher.
The findings appeared in the October 20, 2010 edition of the
Journal of the American Medical Association, published nearly two
years after Chlebowski presented the research to the San Antonio
Breast Cancer Symposium in December 2008. The January/February 2009
edition of ANIMAL PEOPLE summarized the data.
Confirmation of the elevated risk of death from breast cancer
associated with taking estrogen supplements came two weeks after the
October 11, 2010 edition of Archives of Internal Medicine reported
the link to risk of developing kidney stones. “Among more than
24,000 postmenopausal women taking either hormones or dummy pills,
those using hormones were 21% more likely to develop kidney stones
over about five years,” summarized Associated Press medical writer
Lindsay Tanner. “Those results suggest that over a year’s time,”
assessed Tanner, “among 10,000 postmenopausal women taking
hormones, five would develop kidney stones who wouldn’t have if they
hadn’t used the pills. The risks were similar for women taking
either Prempro, containing estrogen plus progestin, or Premarin,”
which contains only estrogen.
Prempro has in recent years been the most popular drug based
on Premarin, the longtime top-selling estrogen supplement. Both
products were made by Wyeth Inc. until 2009, when Wyeth was sold to
Since publication of the 2002 Women’s Health Initiative
findings, the volume of prescriptions filled for PMU-based drugs has
reportedly fallen from more than 110 million to about 40 million,
producing a parallel drop in the numbers of horses kept on PMU farms,
and the numbers of PMU farms remaining in business. This trend is
expected to continue as PMU product sales further decline.
Along with falling hormone use since 2002, “Breast cancer
diagnoses started to drop,” summarized Washington Post medical
writer Rob Stein of the latest Women’s Health Initiative findings.
“That appeared to help explain one of the biggest mysteries about
breast cancer–why the number of cases rose steadily for decades.
Hormone use probably played a key role,” the study results suggest,
” along with better detection by mammography and other factors.”
PMU was the active ingredient of the first birth control
pills for humans, marketed in the late 1940s. The humane community
voiced two major concerns about the PMU industry from inception. One
was that it involves keeping pregnant mares artificially closely
confined, to collect their urine. The other was that impregnating
the mares year after year to collect their urine creates a surplus of
foals, most of whom were and are sold to slaughter after a few
months at pasture.