Women studying veterinary medicine now outnumber men by four to one. It’s not just veterinary school. The number of women has surpassed the number of men in law school, medical school, pharmacy school, optometry school and dental school. Women in the United States now earn 40 percent more doctoral degrees overall, and nearly twice as many master’s degrees, as men, according to the U.S. Department of Education — a trend transforming high-end work.