Nelida Belle describes 11-year-old Tootsie as another daughter.

"Out of all the dogs I have had, she is just precious," said Nelida. "She is lovable. She is perky."

Looking at her, you'd never know Tootsie's body is fighting to live.

"If I had ever known that this could happen to a dog, I would have had her in a month earlier to have her checked," Nelida said.

Tootsie was having a hard time eating. Nelida thought it was a dental problem. It turned out to be a malignant melanoma tumor in the back of her mouth. Veterinarian oncologist Stacy Santoro says canine melanoma is an aggressive form of cancer. Dogs typically only survive one to five months. But a canine cancer vaccine could change that.

"Overall, it's been shown to significantly prolong survival in dogs with oral melanoma," said Dr. Santoro.

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Studies show dogs that get the vaccine, along with surgery or radiation, have lived three-times longer. Researchers hope for similar results in humans.

"The point of it is to stimulate their own immune system to recognize tumor cells and then kill those affected cells," Dr. Santoro said.

But lengthening Tootsie's life comes at a cost. Radiation and the vaccine will run four to five thousand dollars.

"My daughter is graduating from high school this year, and we were planning a cruise for her graduation, and she said, 'Mom, the treatment is rather expensive. We'd rather give this money for Tootsie,'" said Nelida.

Melanoma is the most common type of oral cancer in dogs. It mostly showing up in those with dark-pigmented skin and is usually not related to sun exposure. The vaccine is being studied in humans at Memorial Sloan-Kettering Cancer Center. Only a veterinarian oncologist can administer it to the dogs.