ATLANTA -- They were the "worst of the worst." They were caged, tortured, beaten, and trained to kill. Of the dozens of dogs seized from the Michael Vick dogfighting ring, these four animals seemed destined for euthanization.

SLIDESHOW: Michael Vick's Fighting Dogs

The pit bulls, all of whom were taken from Vick's Virginia property during a police raid in April 2007, underwent a year-long, $800,000 therapy program at the Best Friends Animal Sanctuary in Kanab, Utah. The sanctuary helped the dogs overcome serious health problems and their deadly fighting instincts.

Cherry

Cherry was believed to be a "bait dog", a sparring partner upon which the ring's other fighting dogs trained. At first, he was so scared and shy, he was frightened by his own leash. He refused to walk and needed to be carried by sanctuary staffers.

After months of training and socialization, Cherry overcame his shyness. His scars and wounds are healing. Best Friends Animal Society staffers believe he'll ultimately be prepared for adoption.

VIDEO: "Cherry" Encounters Another Dog

Georgia

Georgia was believed to be a former champion fighter. The experts at Best Friends Animal Sanctuary suspect Georgia was forced to breed with other dogs, perhaps through use of the "rape stand" seized from Vick's property. All of Georgia's teeth had been pulled from her head, likely to prevent her from injuring the other dogs in the breeding process.

Her jaw had been broken, her ears had been cropped, and her tail had been broken several times.

The sanctuary provided dental care and behavioral training. She has been transformed, the sanctuary said, into a "cutie-pie who snores, plays, always carries a bone in her mouth, and is even fighting to pass the Canine Good Citizen test."

VIDEO: "Georgia" Health Problem | VIDEO: "Georgia" Dental Exam

Denzel

Denzel arrived at the sanctuary in 2007 with a deadly blood illness, which veterinarians suspect he contracted during a bloody fight. He'd undergo a transfusion and extensive testing at the facility. Though the initial prognosis was grim, Denzel's health rebounded. A sanctuary statement said of Denzel, "For the first time, has a life worth living." His appetite, which was nonexistent last year, has returned. He's sociable and a future candidate for adoption now.

VIDEO: "Denzel" Deadly Blood Disease

Meryl

Meryl was among the fiercest of all the dogs rescued from Vick's property. A court ordered Meryl be restricted to a sanctuary and prohibited from adoption. Shortly after her arrival at the sanctuary, Meryl made a frightening lunge at her caregivers.

Behavioral therapy has helped Meryl overcome most of her aggressiveness. The sanctuary's statement about Meryl's current condition said, "Meryl is a plaful dog wh enjoys people once she gets to know them."

VIDEO: "Meryl" Lashes Out at Sanctuary Staffers

Rehabilitation is rarely provided for dogs seized from animal fighting ventures, said John Goodwin, an animal fighting investigator for the Humane Society of the United States. Goodwin said the Vick dogs are a "special case" because a court ordered the former NFL star to set aside $1 million to rehab the animals.

VIDEO: Humane Society Fighting Investigator Talks About Rehab for Dogs

To see more images of the four Vick dogs, click on the links to the right.

To watch National Geographic's two-hour feature documentary on the dogs' rehabilitation, watch "DogTown: Saving the Michael Vick Dogs" on the National Geographic Channel Friday at 9 p.m. Eastern Time.

VIDEO: Scott MacFarlane Reports - Michael Vick Dogs' Rehab