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About Premarin

For decades, Premarin was the most popular drug in the United States, with an estimated 22 million women taking the drug to treat menopausal symptoms in 2002. Because Premarin is made with estrogens extracted from pregnant mares’ urine (PMU), thousands of mares are used to produce this bitter pill, contributing to the unnecessary overbreeding of horses.

Premarin is made from pregnant mare urine

What happens to PMU mares?

For approximately six months from Fall through Spring, the pregnant mares live in the "pee barns," forced to remain in stalls with urine collection devices strapped to them. The stalls are deliberately narrow to prevent pregnant mares from turning around and detaching the collection cups. In the last month of their eleven-month pregnancy, the mares are put out to pasture to have their foals. The mares are put in a herd with a stallion, so they quickly become pregnant again. In September, their foals are taken away from them to be sold, whether or not they are fully weaned. The next month, the mares area back in the barns and the cycle starts again. 

The organization that represents the interests of the PMU ranchers, the North American Equine Ranching Information Council (NAERIC), considers it "a testament to her health and strength" if a mare can have a foal each year. Groups that are concerned with horses' well-being disagree with using breeding success as a mark of welfare. Check out this screen shot from NAERIC's own FAQ page for how they like to tell the story:

Currently, approximately 2,000 PMU mares live on 26 contracted ranches in Saskatchewan and Manitoba, Canada, within proximity of Brandon, Manitoba, where the sole urine processing plant is located. The minimum stall width specified in the regulations­ -- even for the largest draft breeds so commonly used -- is a mere five feet. A typical PMU ranch consists of a small family and one hired ranch hand responsible for feeding, cleaning and exercising nearly 100 pregnant mares at a time.

View and share our short video about Premarin


What about the foals who are born every year?

The manufacturers of PMU drugs would like us to believe that every single foal born as a result of these pregnancies is sold to be used for companionship, recreation, ranching, shows and competitions – what they call “productive markets.” The fillies sometimes grow up to replace their worn-out mothers, too. But the horse market is oversaturated as it is, and there just aren’t enough homes for another estimated 2,000 foals born from this industry each year. According to the industry's own statistics, only half of foals are sold privately, leaving the other half to be sold at auction and "breeder production sales". As a result, PMU foals may be at risk for slaughter, their meat shipped to Europe and Japan for human consumption. Read more about the horse slaughter industry here.

What has the pharmaceutical company done to help?

One pharmaceutical company alone, Wyeth Pharmaceuticals (which was purchased by Pfizer in 2009), produces the hormone therapy drugs that use pregnant mares' urine: Premarin, Prempro, Premphase and other like-sounding drugs. To date, Wyeth/Pfizer has contributed $6.75 million dollars to an industry-run "Equine Placement Fund," a paltry amount in comparison to the approximately one billion dollars in revenue in 2006 from this drug family, and the tens of billions more these drugs have earned Wyeth in past years. And to make matters worse, they've prohibited currently contracted ranchers from working with rescue groups, since they want to avoid the image that any of these horses are in need of rescue.

What about the health risks to women?

Women’s Health Initiative study revealed that taking PMU drugs like Premarin and Prempro may lead to serious health problems such as heart attack, stroke, dementia and breast cancer. In 2007, studies linked a drop in breast cancer rates with the reduced use of PMU drugs. At least six lawsuits have gone to trial alleging that Premarin or Prempro caused illness, and 5,000 lawsuits are pending. Yet the manufacturer of Premarin continues to market lower-dose versions of the drugs aggressively. 

What makes this issue with the horses more complicated?

At the PMU industry's peak in the late 1990s and early 2000s, there were reports of as many as 70,000 mares involved in the production of hormone drugs, and as many as 422 contracted ranches. But in 2003, everything changed. Wyeth, the company that manufactured Premain and related drugs, won a lawsuit against Natural Biologics, a company that was poised to bring a generic version of Premarin to the market. This left many ranches that contracted with Natural Biologics with pregnant, out-of-work PMU mares. Most of these ranches were in the U.S., in North Dakota, South Dakota and nearby states. Around the same time, the Women's Health Initiative suddently stopped a study of PMU drugs after it found an increase of significant health problems with their use. Prescriptions plummeted, and Wyeth cut many contracts with ranches in response to decreased demand. This left the former ranchers with thousands of unwanted pregnant mares, many of which had received little training and handling, and were difficult to sell. Some of the ranching families had held PMU contracts for generations, and Wyeth didn't do enough to transition these ranchers to new careers. Without other options and training, many former ranchers continue to breed their mares and sell the foals to the slaughter market when they can't find other buyers. Often, rescue or placement groups step in to help ranchers find homes for these horses instead of selling them for meat. Thousands of foals are born each year at these former ranches.

In 2003, in response to the flood of pregnant out-of-work PMU mares from both Natural Biologics and Wyeth-contracted ranches, RedRover created a searachable database of adoptable PMU horses called to assist with the placement of these horses. Over the site's six-year existence, it helped facilitate the adoptions of more than 3,000 PMU horses, and more than 80 different rescue organizations participated in advertising and placing horses through the database. RedRover also contributed cash rebates totaling nearly $40,000 to assist adopters with the costs of rescuing a PMU horse. Read more about in the Winter, 2010 issue of RedRover's quarterly member magazine (PDF).

What can women do?

1. Talk to your doctor about ways to alleviate menopausal symptoms through lifestyle and diet changes, or discuss synthetic or plant-derived HRT alternatives. And if you decide not to take Premarin or switch from Premarin to an alternative, let RedRover know by joining our I've Switched Campaign. Here are some alternatives to Premarin:

  • Cenestin
  • Estrace
  • Estraderm
  • Ogen
  • OrthoEst
  • Estratab
  • Enjuvia
  • Menest
  • Estinyl
  • OrthoDienestrol
  • Climara

2. Spread the word about the PMU industry and the dangers these drugs pose to women. Our Premarin: The Bitter Truth brochure contains valuable information and is great to leave behind at your doctor's office. Dowload a PDF

3. Contact your legislators to ban horse slaughter for human consumption. Horse slaughter provides a profitable economic incentive to overbreed horses, which enables the PMU industry to operate the way it does. Find more information about efforts to stop horse slaughter through the Homes for Horse Coalition, of which RedRover was a founding steering committee member. For information on Canadian efforts, visit the Canadian Horse Defence Coalition