Women’s Health Initiative warning on estrogen therapy may help horses
From ANIMAL PEOPLE, September 2002:
ATLANTA, WASHINGTON D.C., WINNIPEG–The beginning of the
end of keeping pregnant mares standing from October to March of each
year on urine production lines, and auctioning their foals to
slaughter, may have come with a July 9 scientific warning that, on
balance, estrogen supplements made from pregnant mare’s urine do
menopausal women more harm than good.
The Women’s Health Initiative, an unprecedentedly large
scientific investigation of the effects of taking hormonal
supplements, monitored the health of 16,000 women for nine years,
beginning in 1993.
The study found that for each 10,000 women who take the Wyeth
Pharmaceuticals estrogen-plus-progestin drug Prempro for one year,
there are eight more cases of invasive breast cancer than among women
of the same age range and state of health who do not take the drug,
along with seven more heart attacks, eight more strokes, and eight
more cases of blood clots forming in the lungs.
There are six fewer colorectal cancers and five fewer hip fractures.
Funded directly by Congress, through a special allocation to
the National Institutes of Health requested by then-HIH director
Bernadine Healy, the Women’s Health Initiative study of Prempro
concluded by advising each of the participants by mail that their
health would be safer if they quit taking it.
The study was to have continued for longer, but lead
researcher Nanette K. Wenger, M.D., and team decided that the risks
to the participants of continuing to take Prempro were too high to
allow them to go on unawares. Wenger is chief of cardiology at Grady
Memorial Hospital in Atlanta.
A part of the Women’s Health Initiative monitoring the health
of women who have had hysterectomies and are taking estrogen without
progestin is still underway, producing as yet inconclusive findings.
The trading price of Wyeth stock fell 24% within 24 hours of
the Women’s Health Initiative warning, but investment advisors
suggested that it would rebound from the initial panic even if the
longterm trend is downward due to decreased Prempro sales. The
health care information company IMS Health said the retail value of
Prempro sold in 2001 was approximately $732 million. Wyeth also sold
$1.3 billion worth of Premarin, the estrogen supplement without
progestin which was the original form of the drug, and is reputedly
still the top-selling prescription drug worldwide.
Including estrogen supplements produced from sources other
than pregnant mares’ urine, the total retail value of the estrogen
replacement industry in the U.S. alone was $2.75 billion in 2001.
Retail sales trends will take longer to become apparent than
the effect of the Women’s Health Initiative on stocks.
As the Women’s Health Initiative focused on longterm effects,
short-term use of estrogen drugs to ease severe symptoms of menopause
may still be widely recommended by physicians. Use by women who have
had hysterectomies may also still be recommended –though perhaps
only until the results of the ongoing portions of the study are in.
The July 9 warning to the study participants confirmed
reports circulating since the April 2002 preliminary release of
findings as part of an International Position Paper on Women’s Health
and Menopause. Women’s Health Initiative lead researcher Nanette K.
Wenger, M.D., edited the paper, to which an international panel of
28 scientists contributed.
Rating front-page coverage by The New York Times, but
lightly covered–if at all–by other news media, the position paper
was jointly funded by the U.S. National Institutes of Health and the
Giovanni Loren Zini Medical Science Foundation of Italy.
Ups and downs
Wyeth has managed to keep the pregnant mare’s urine industry
profitable through bad-news cycles before, and may yet find another
way to do so.
“The use of horse urine in hormone replacement therapy for
menopausal women was first introduced in 1930 when the German
newspaper Zondeck published a study showing that equine urine was a
rich source of estrogen,” summarized Robin Gaby Fisher of the
Winnipeg Star-Ledger. “Two years later, scientists at Ayerst
Pharmaceutical in Montreal began to develop a hormone replacement
drug. Early research had relied on the urine of nuns and pregnant
women, but the supplies were limited, so the scientists at Ayerst
began testing the urine of livestock. Ten years later, in 1942,
Premarin was approved by the U.S. Food and Drug Administration.”
The major market for estrogen supplements during the next
three decades was in connection with making birth control drugs.
Ayerst Pharmaceutical became Wyeth-Ayerst, and cashed in.
The pregnant mare’s urine industry of that era was centered
in Quebec and Ontario, with other producers scattered about New
England. The product was refined in Montreal, trucked in bulk to
Rouse’s Point, Vermont, and packaged there for global distribution.
The surplus foals produced by keeping tens of thousands of
mares almost continuously pregnant made Quebec the center of the
North American horsemeat export industry, as well, selling mainly
to customers in continental Europe.
As other estrogen formulations gained ascendence in the birth
control field, Wyeth-Ayerst found a new profit center in menopausal
symptomatic relief. In 1966 Wyeth-Ayerst funded Robert Wilson,
M.D., to write and extensively promote a book called Feminine
Forever, extolling the benefits of estrogen therapy in keeping women
physically youthful. The book became a bestseller, Wilson developed
a fashionable private practice on Park Avenue in Manhattan, and by
1975 Premarin was the fifth best-selling prescription drug in the U.S.
In 1975, however, the U.S. Food and Drug Administration
ordered that women taking estrogen supplements must be warned that
the supplements may be linked to a higher risk of uterine cancer.
The NIH dealt another blow to the estrogen supplement industry in
1979 by reporting that the supplements were demonstrably medically
useful only in treating hot flashes and vaginal dryness.
But Wyeth rallied during the 1980s after additional studies
indicated that combining Progestin with Premarin offset the uterine
cancer risk. Then in 1984 the National Institutes of Health added to
previous findings the observation that women taking estrogen
supplements seemed to have less bone loss and fewer fractures
associated with osteoporosis.
Premarin sales accelerated despite a 1990 Nurses Health Study
report that women using estrogen for a prolonged time appeared to
have a 36% greater chance of developing breast cancer. The same
year, the FDA denied Wyeth-Ayerst permission to advertise that
Premarin could help post-menopausal women to avoid heart disease.
Aging production facilities, investor anxieties about Quebec
nationalism, and the rise of concern about the treatment and fate of
the horses meanwhile combined to push the pregnant mares’ urine
Of the 419 ranches currently keeping urine-producing mares
under contract to Wyeth, as the firm is now called, 248 are in
Manitoba, 93 in Saskatchewan, 56 in Alberta, and 22 in North
Humane organizations have scant presence in most of the
region. After the pregnant mares’ urine industry left Quebec,
Ontario, and New England, the plight of the horses was almost
entirely overlooked until in early 1993 Canadian Farm Animal Care
Trust founder Tom Hughes shared with ANIMAL PEOPLE his findings from
visits to Manitoba pregnant mares’ urine farms in 1991 and 1992.
Hughes, of Barrie, Ontario, was among the Ontario Humane
Society inspectors whose earlier reports drove the pregnant mares’
urine industry west, after producers failed to meet basic horse care
standards. Hughes found that the western producers were somewhat
less inhumane than their eastern predecessors of a generation
earlier, but argued that their methods could still use improvement.
ANIMAL PEOPLE put a summary of the Hughes findings on page
one in April 1993, along with more critical commentary by other
At that time, pregnant mares’ urine producers were sending
an estimated 70,000 foals and “retired” mares to slaughter each year,
and the industry was expanding production facilities, anticipating a
surge of demand as the Baby Boom generation hit menopause.
The ANIMAL PEOPLE coverage was amplified within the next
several months by three of the five biggest newspapers in New York
City, received the International Generic Horse Association/ HorseAid
“Equine Awareness in Media” award, and was amplified again through
special mailings of the coverage to lists of potentially concerned
People for the Ethical Treatment of Animals, Friends of
Animals, the Animal Protection Institute, the World Society for the
Protection of Animals, and Animal Rights Mobilization all started
anti-Premarin campaigns that fall.
Other animal advocacy groups followed. The number of
pregnant mares’ urine producers–485 as of 1990–began to decline.
Countering boycotts eventually called by more than 50 national and
international animal advocacy organizations, Wyeth funded formation
of the North American Equine Ranching Information Council, based in
Lexington, Kentucky. NAERIC pushed the idea that there might be
destinations for the foals of urine-producing mares other than
slaughter and/or replacing their mothers on the production lines.
Currently, NAERIC claims, mares bred to produce
estrogen-rich urine under contract to Wyeth give birth to about
35,000 foals per year–half the estimated volume in 1990.
“Last year, in Manitoba alone, 21,000 Premarin foals were
born, based on statistics collected by the Manitoba government from
Wyeth’s Ayerst Organics Division,” wrote Robin Gaby Fisher of the
Winnipeg Star-Ledger. “Of those foals, 30% to 40% were sentenced to
slaughter, said Janet Honey, manager of market analysis and
statistics for the Manitoba agricultural and food division.”
Other industry observers including longtime horse rescuer Ray
Kello-salmi, M.D., of British Columbia, International Generic
Horse Association/ HorseAid cofounders Enzo Giobe and Stacy Wilson,
and Robin Duxbury of Project Equus believe from their personal
investigations in western Canada that at least twice as many foals
“The lowest number that I have ever seen sold to slaughter”
at auction “was 52%,” Kellosalmi told Fisher. “The highest was 99%.
At least 70% to 80% go to slaughter” overall.
Said Equine Advocates president and founder Susan Wagner,
“We have always hoped that the treatment of the horses in the
pregnant mares’ urine industry would stop people from taking these
drugs, but the reality has always been that medical consequences
would be the thing to do it. Now, with these new studies, we think
we may finally see an end to a 60-year catastrophe for horses.”
But even if Wagner is right, the catastrophe may get worse,
in the short run, United Pegasus Foundation president Helen Meredith
told ANIMAL PEOPLE. Preparing to make her annual pilgrimage of
recent years to the Manitoba foal auctions to buy Premarin foals for
adoption and sanctuary placement in southern California, Meredith
anticipated that ranchers may breed fewer mares for urine production
after this year, but will also retire more mares.
The full-grown mares, mostly of big draft breeds, will
fetch a higher price from slaughter buyers at auction, and will be
much more expensive and difficult to try to reroute to any other fate.
“The good news,” Meredith agreed, “is that once the
ranchers sell their mares, they won’t be breeding any longer.”