Cell biologist Bonnie Dunbar was trying to develop a contraceptive shot for humans, but her initial work yielded a sterilization shot instead. So she thought, why not take that and market it for pets, as an alternative to surgical spaying? Zonagen Inc., in The Woodlands, Tex., hopes to make a sterilization vaccine available to veterinarians in 1992. Among the backers: The Perot Group.

-- Leslie Brokaw