Inside PMU: Urine factories and the menopause horse industry

A paint filly and her mother, a young mare rescued from a Canadian Premarin farm.
A paint filly and her mother, a young mare rescued from a Canadian Premarin farm.
© Marianne Banes McNamee

In generations past, horses were abandoned or shipped off to slaughter once it was decided that they had worn out their usefulness in pulling wagons or plows and in carrying loads or people: think of poor Boxer, carried away by a van marked “Alfred Simmonds, Horse Slaughterer and Glue Boiler” toward the end of George Orwell’s Animal Farm.

Today, some horses are sentenced to die because they are of no more use to pharmaceutical companies that make fortunes dispensing medicines to consumers, most notably the drug Premarin.

In the 1940s, researchers at one drug firm discovered that estrogen taken from the urine of pregnant mares helped to relieve some of the effects of menopause in women. Overnight, an industry sprang up in the northern United States and Canada as hundreds of farms were placed under contract to deliver this urine.

More than sixty years later, it remains an industry. As if on an assembly line, mares are impregnated and placed in narrow stalls; the industry-mandated stall width is 3.5 feet (about 1.1 meters) for horses weighing less than 900 pounds (410 kg) and 5 feet (1.5 meters) for those exceeding 1,700 pounds (770 kg), whereas the usual dimension of a stall at a regular stable is at least twice that size.

Fitted with collection bags, the mares are regularly deprived of water in order to concentrate their urine. Or so it is believed, in any event; there is no way of telling whether the 1940s-era practice continues, since the industry stonewalls such inquiries. The Humane Society of the United States reported in 2007, “The pharmaceutical company now claims that the water restriction policy has been modified; however, they remain unwilling to allow humane organizations access to the farms to verify such changes.”

After giving birth to their foals, the mares are impregnated again and returned to the stalls, while most of the foals are slaughtered for meat. So, too, are the mares once their bearing years have passed.

© Gail Eisnitz/Humane Farming Association

In most particulars, in other words, and in more than half a century since its inception, little has changed in the Premarin industry – for the horses, that is. In 2002 a study by the Women’s Health Initiative, part of the National Institutes of Health (NIH), linked the long-term use of Premarin to an increased risk of stroke and blood clots, and the use of the related drug Prempro to elevated rates of heart disease and breast cancer. The NIH advised physicians to cease prescribing the drugs;sales fell, and some 350 PMU (pregnant mares’ urine) farms lost their contracts over the next two years, while thousands of lawsuits were filed against the manufacturer.

Yet the drug is still made and sold; indeed, the FDA recently gave the manufacturer permission to market a new Premarin-based drug meant to treat osteoporosis as well as menopause. Says the Pharmaceutical Business Review, “This would open up bazedoxofine/Premarin therapy to the whole postmenopausal market while providing a continuum of care throughout the menopausal period.” Even with the health scare, the market for Premarin and allied PMU-based drugs is estimated to exceed $1.2 billion; the market for the new combined product, the article continues, is expected to exceed $550 million by 2010.

An unknown number of farms, most in the Canadian province of Manitoba, continue to serve as urine factories – halfway houses to the slaughterhouse or an early grave in all events. A study in the Canadian Veterinary Journal, for instance, reports that nearly one in four of the foals born on PMU farms in western Manitoba in a single year died of starvation or exposure.

Opposition to the PMU industry has been strong since the 1990s, spearheaded by the American Society for the Prevention of Cruelty to Animals (ASPCA), which decried it as “unthinkable and unforgivable.” Mere outrage has not proved particularly effective, however. What has brought exposure to the problem is the work of PMU rescue groups and adoption agencies such as Crooked Pine Animal Rescue of Dudley, N.C.; Equine Voices, headquartered in southern Arizona; and Canyon Creek Farm of Acton, Calif. Says Karen Pomroy of Equine Voices, “We have so much to do. In 2005 we rescued 43 horses at one time from PMU farms that were closing down. Now the manufacturer forbids anyone who signs a contract to produce PMU from dealing with rescue groups, so we’ll probably have to start bidding against the slaughter industry to get the mares and foals out.”

Another strategy – one that is gathering momentum – is to emphasize that Premarin is not the only remedy for troublesome menopausal symptoms. The FDA has approved several plant-derived and synthetic estrogens as safe and effective, and some are thought to be superior to Premarin in both performance and patient tolerance. Some patients who have made the switch, advocates report, have encountered initial resistance from insurance companies, but others have made converts of their doctors in the process, helping to slowly spread the word about the unnecessary suffering of the Premarin-industry horses.


Article first published on in October, 2007, and as Menopause, Horses, and the Industry of Death by Encyclopaedia Britannica, in October 2007.

Premarin: Hormone therapy hurts women and horses

Premarin – Just what’s in those menopause pills?


Gregory McNamee
Gregory McNamee

Gregory McNamee is a writer, journalist, editor, photographer, and consultant in publishing, film, and other media. He is the author or title-page editor of twenty-six books and more than three thousand periodical publications, including articles, essays, reviews, interviews, editorials, poems, and short stories.
He is a consultant, contributor, and contributing editor to the Encyclopaedia Britannica and its blog. He is also a contributing editor to Kirkus Reviews and The Bloomsbury Review. He is also a correspondent for, a London-based travel syndicate.
McNamee operates Sonora Wordworks, an editorial and publishing service, and has been involved in the publication of more than five hundred books.
He publishes the occasional Weblogs InfoStacks and Tools for Readers, as well as a site devoted to his photography.
McNamee is a research associate at the Southwest Center of the University of Arizona, and adjunct curator of literature at the Sharlot Hall Museum in Prescott, Arizona. He is a member of the Speakers Bureau of the Arizona Humanities Council, and he also gives courses and talks on writing, publishing, journalism, and cultural and environmental issues.


This article has been written by a contributor to

6 thoughts on “Inside PMU: Urine factories and the menopause horse industry

  • February 16, 2017 at 12:33 am

    There are 20 family-owned equine ranches that are members of NAERIC and contracted by Pfizer to collect pregnant mares’ urine (PMU). These equine ranches are located in the Canadian provinces of Manitoba (16) and Saskatchewan (4). All ranches are within reasonable proximity to Pfizer, in Brandon, Manitoba, where the initial PMU processing occurs.

  • February 25, 2020 at 4:50 pm

    What a terrible thing to treat and abuse theses poor horses and starving and killing their foals. What heartless POS people doing this to the poor horses and their babies all for money for this pharmaceutical company. All they care about is making money not about all the suffering being done to the animals. Don’t know how you people could sleep at night. Shame on all of you

  • April 18, 2020 at 11:52 am

    I had to search for this to see for myself, I couldn’t believe it was true. How can these people who do this for a ‘living’ look themselves in the mirror each day? And think they are a good person?

  • February 16, 2021 at 5:07 am

    Yes cry over horses being killed for slaughter but most of the same cry babies are in favor of abortions

  • September 10, 2021 at 9:12 am

    Absolutely disgusted in you Canada for allowing these PMU farms to be in your country – you also accept horses – including once wild Iconic stunning healthy MUSTANGS and slaughter them in your coutry – disgusted beyond belief. Thought you were a cool country and civilised :):):) Extremely disappointed in you Canada

  • September 10, 2021 at 9:39 am

    WHO CAN WE WRITE TO ? WHAT CAN WE DO TO GET THESE PMU FARMS SHUT DOWN IN CANADA? I know they will just got to China instead but …it’s just inhumane and unacceptable


Leave a Reply

Your email address will not be published. Required fields are marked *