Lee Morgan, DVM

When Lee Morgan, DVM, heard about a police dog that was euthanized because the officers couldn't pay for his surgery, he knew he'd found his mission. The officers "were devastated," says Morgan, 48, who owns Georgetown Veterinary Hospital in Washington, D.C. "I vowed then that no service dog should die for lack of money."

In 2008, Morgan's foundation raised $20,000 for a mobile veterinary unit for the D.C. police department's K-9 unit, so injured police dogs could be treated in the field. He also provides no-cost care to guide dogs. "The relationship between working dogs and their owners exemplifies the potential of the human-animal bond," Morgan says. "It is humbling to be able to support that."

Morgan also famously treated a Marine Corps bomb-sniffing dog named Lex, who survived a grenade blast in Iraq that killed his handler, Cpl. Dustin Lee. Lex's war injuries led to severe arthritis and other mobility problems. In 2010, Morgan's groundbreaking stem cell treatment helped to regenerate some of Lex's cartilage and nerve function, which allowed him to "walk, play, everything," Morgan says. Lex spent his remaining years with Lee's parents in Mississippi, where he died in 2012.

"It was so rewarding to help this dog get some good years," Morgan says, "and to help the parents maintain this last bond with their son."