BAD FOR HORSES AND FOR PEOPLE

by Andrew G. Lang D.V.M.

Out of a tragic combination of misguided notions about women's health, thousands of horses in jeopardy, and an incredible marketing machine trumped by medical research comes the latest chapter in the story of Premarin. Premarin, which contains estrogens from the urine of pregnant mares, has long ruled the Hormone Replacement Therapy (HRT) market, with more than $1 billion in sales last year. Players in this drama include the pharmaceutical giant Wyeth; millions of postmenopausal women and their doctors, who have been assured for decades that Premarin and its variations are save and effective for long-term use; and tens of thousands of horses carrying foals while producing the drug industry's liquid gold.

Although conditions on pregnant mare's urine (PMU) ranches have improved over the last 20 years as a result of the increased attention of animal welfare groups, pregnant mares are still tethered in stalls with urine collection funnels attached to their bodies for six months out of each year. Their foals, often taken from them at four months of age or younger, must find adoptive homes - or end up at feedlots to be prepared for the slaughterhouse. It is impossible to know exactly how many "premarin foals" end up slaughtered for overseas horsemeat markets, but even conservation industry estimated suggest that more than 10,000 meet that fate each year. This tragedy is compounded by the fact that many humane alternatives exist to the HRT drugs that are made from mares' urine.

Tragic for women and their doctors is the fact that drugs that combine estrogens with progestin are not safe for long-term use after all. Prempro, one so called "combination" drug that contains Premarin plus progestin, was used in the federal Women's Health Initiative (WHI) study of 16,000 postmenopausal women aged 50-79. Participants were abruptly taken off the drug in the summer of 2002, when data showed that they had developed significant higher rates of breast cancer, stroke, heart attack and other cardiovascular diseases. In addition, the breast cancers discovered in women taking Prempro were harder to detect and were diagnosed at a more advanced stage than in women given placebo. It was later discovered that combination HRT drugs nearly double the risk of dementia, including Alzheimer's Disease, for women aged 65 and older. Estrogens alone have long been known to cause uterine cancer; research shows that estrogen-only HRT drugs may increase the risk of breast cancer, as well.

Opposition to the mistreatment of mares and foals wasn't enough to make a dent in Premarin sales. Not so with research documenting the drug's health risks, at least for long-term users. Wyeth stock plummeted last summer when the WHI study was halted, and sales of Premarin and Prempro in the second quarter of 2003 were down to less than two-thirds of last year's. Wyeth has bought less urine from ranchers this year, which is at least a start. However, there are sobering realities to consider. Wyeth will hold onto whatever share of the market that it can. The company is currently producing a lower-strength version of Prempro for short-term use, while looking to increase sales in developing nations. In addition, even as the PMU industry shrinks, horses are still in danger. For years to come, as ranches reduce stock or close completely, more and more mares and their foals will need help finding good homes.