Rachel Maines is a visiting scholar in science and technology studies at Cornell and author, most recently, of "Asbestos and Fire: Technological Tradeoffs and the Body at Risk." This article is abridged from the original, published in the Chronicle of Higher Education, May 25, 2007.

At Cornell, women comprised 88 percent of the College of Veterinary Medicine's graduating class this year and 26 percent of the Ph.D. engineers in 2005-06 (most recent statistics available). Nationwide, according to The Chronicle of Higher Education, women earned more than 74 percent of the professional degrees in veterinary medicine in 2004 but fewer than 18 percent of the doctorates in engineering.

Why has veterinary medicine been so much more successful than engineering in attracting women?

To be sure, puppies are cuter than microchips, but most of what veterinarians do isn't about cute. Veterinary medicine, despite its modern high-tech character, remains irreducibly bloody, messy and often hazardous -- especially to pregnant women, because the human fetus is at risk from animal-borne diseases and mutagens. It certainly requires a rigorous scientific education that is at least as difficult and daunting as the demands of engineering.

Moreover, despite the apparent stampede of women to the discipline since 1930, when fewer than 1 percent of practicing vets were women, few female role models exist in high-prestige positions in veterinary science. Most senior faculty members are still male, and men are still the majority among practicing vets, even though they have been a minority in veterinary-college classes since 1986.

No other profession in the United States has experienced as significant a gender shift as has veterinary medicine. Yet, a significant earnings gap persists between men and women, though this may diminish as female practitioners gain more years of experience. Women vets, though, are more likely than men to work part time, which would explain some of the gap.

However, men remain overrepresented in large-animal and food-supply (cows and chickens) veterinary medicine. While large-animal practice, on average, pays better than doctoring small animals, there are far fewer opportunities to work with large animals.

Just as astonishing as the gender shift in veterinary medicine is the fact that we have so little research on why it happened, or on why fields like engineering did not experience similar changes. There were no organized efforts in veterinary medicine, as there now are in engineering and the sciences, to recruit women.

Cornell, for example, recently received a $3.3 million grant from the National Science Foundation to build a "critical mass" of female faculty members in science and engineering, and the university plans to hire 75 new female professors during the next five years. The idea is that having more women as role models in those fields will make them more appealing to female students. No such inducements seem to have been necessary for women to enter veterinary medicine, however.

Although several hypotheses have been proposed to explain why women have flocked to veterinary medicine but not to engineering, they all fail to explain the trends.

The first suggests that the 1964 anti-discrimination legislation explains why more women are going into veterinary science; however, the same legislation, the Title VII of the Civil Rights Act of 1964, removed obstacles to women in engineering and the physical sciences, but women remain vastly underrepresented in those fields.

A second hypothesis suggests that popular books, such as James Herriot's "All Creatures Great and Small," attracted women to the field, but why not men? Why did a male role model have so much influence on women? Maybe fields like engineering need more charismatic ambassadors.

A third hypothesis suggests that low pay and expensive education -- to say nothing of the fact that full-time vets, both men and women, typically work about 50 hours a week -- have been driving men away recently. But why did the same conditions in earlier years not have the same effect?

Could the cause instead be that treating cats and dogs, now more common patients than in the past, is insufficiently macho?

Gender anomalies of this kind -- especially contrasts as stunning as that between veterinary medicine and fields like engineering and the physical sciences -- demand research that nobody appears to be doing, possibly because no federal agency is offering to support it. In our efforts to bring more women into male-dominated fields, we may have a lot to learn from veterinary medicine. But we won't learn much until somebody -- not just the vets -- starts asking the important questions about why this happened.