A wealthy, retired orthopedic surgeon is dangling a $75-million carrot in front of anyone who can curb pet overpopulation by inventing a non-surgical and safe means to sterilize animals.

Retired orthopedic surgeon Gary Michelson made his initial fortune by inventing spinal implants and now holds 185 patents, earning him a spot on Forbe’s 2007 list of world billionaires. According to reports, he donated $10 million last year to saving unwanted animals in Los Angeles.

Now the 59-year-old animal lover has launched the Michelson Prize in Reproductive Biology to see if researchers can solve pet overpopulation. The international competition involves granting $25 million to the first person or group to invent a safe, one-time non-surgical means to sterilize companion animals. An additional $50 million is being offered to support the research of those who present reasonable approaches.

“We’re killing millions of pets annually in the U.S. for the simple lack of a home, and sterilization programs are the only viable solution,” Michelson says. “Animal-welfare experts have long recognized sterilization as the most important component in the fight against pet overpopulation.”

He speculates that a lack of funding has stood in the way of researchers on the verge of discovering pet contraceptives and non-surgical sterilants. Surgical spay and neuter is not ideal, he says, because it requires anesthesia and adequately equipped facilities, both of which create cost obstacles for those who rescue homeless pets.