From ANIMAL PEOPLE, April 2006:

Leo L. Lieberman, 91, DVM, died on February 15, 2006,
in Swampscott, Massachusetts. A 1935 graduate of the Ohio State
University School of Veterinary Medicine, Lieberman joined the U.S.
Army after graduation, became the youngest lieutentant in the
Veterinary Corps., and served in Europe during World War II.
Leaving the Army as a lieutenant colonel, after 13 years of service,
Lieberman practiced veterinary medicine for more than 30 years in
Waterford, Connecticut. “In the 1940s and 1950s,” recalls Marcia
Hess in The History of Spay/Neuter Surgery, “anesthetics were not
terribly safe, especially for young animals. Surgical instruments
now used to find a tiny uterus did not exist. Vets were mainly men.
They had big hands, and had to find that uterus with their fingers.
Since a uterus is bigger and much easier to find after an estrus, or
after having a litter, the advice of waiting until after the first
estrus or after a litter began and persists.” Lieberman began to
question the conventional wisdom after noting that early-age
sterilizing prevents mammary tumors in dogs, and that the few vets
who did early-age sterilizing had gotten good results for as long as
20 years–including a Dr. Flynn of Chicago, who developed the basic
technique in 1925, but could not convince other vets to try it. “I
did a literature search and found nothing on why the ages were set at
what they were,” Lieberman recalled. He began doing early-age
sterilization in 1970. As then-president of the Connecticut
Veterinary Medical Association, Lieberman set an influential
example. The American SPCA in 1972 became the first major humane
society to endorse early-age sterilization. Lieberman’s 1987 Journal
of the American Veterinary Medical Association article “A case for
neutering pups and kittens at two months of age” turned veterinary
opinion in favor of early-age sterilization by explaining that
guardians of dogs and cats who were spayed or castrated young
reported less aggressive behavior, less obesity, and fewer medical
problems. Lieberman followed up in JAVMA in 1988 and 1991. Research
funded by the Winn Feline Foundation, conducted by Thomas J. Lane,
DVM, of the College of Veterinary Medicine at the University of
Florida, Gainesville, in 1991 and 1992 supported Lieberman, as did
a major study of early-age sterilization done by the Massachusetts
SPCA at Angell Memorial Hospital in Boston. In March 1993 Lieberman
faced off in ANIMAL PEOPLE against early-age sterilization critic
Leslie N. John-ston, DVM, of Tulsa, Oklahoma; defended early-age
sterilization before a gallery of critics at the World Veterinary
Congress in Berlin, Germany; and in July 1993 won endorsement of
early-age sterilization from the AVMA. Lieberman in 1993 received
the Alex Lewyt Veterinary Medical Center Award of Achievement for
exceptional innovation, and in 2001 received a Lifetime Achievement
Award from Spay/USA.

Read more