ATLANTA -- A pit bull was rushed to the Atlanta Humane Society Wednesday, with a knife in its skull.

Pit bulls often have a bad reputation as being aggressive dogs, but Mama, the injured dog, is very sweet, said the dog's owner.

Mama's owner found the injured pit bull in the front yard of his southwest Atlanta home with the knife protruding out of her head.

The owner rushed Mama to the Atlanta Humane Society in midtown, and turned custody of the dog over to the agency.

Humane Society workers took X-rays of the dog, which clearly show the blade of the knife embedded in the dog's skull, stopping just short of her brain.

The owner told workers he did not know how the knife got into the Mama's skull.

"I've seen my share of cruelty cases, but nothing like this," said worker P.J. Smith. But the story appears to have a happy ending.

Dr. Paula Murray performed surgey on Mama to get the blade out. Within minutes after the operation, Mama was up and alert.

"We were finally able to get it out, which is good," Murray said. "We kind of feel like most of it is just in the bone and maybe in the sinuses."

Mama is now in stable condition recovering at the clinic.

Workers said she will survive the injury.

"On a scale of 1 to 10, I would say she's 10 on the scale of being lucky," Murray said. "There is the possibility of swelling, but hopeful we'll be able to combat that and she'll do OK."

Humane workers said that Mama doesn't seem to know what happened or how she wound up at the clinic. They said they hope she never remembers.

Now, the knife is a key piece of evidence as investigators search for the person who stabbed the dog.

The Humane Society is offering a $1,000 reward for information.

"If anyone knows anything about this we just hope that they come forward," Murray said. "Whoever inflicted this horrible act on this poor helpless animal hopefully they'll be caught."