A woman with a history of drug abuse says she woke up from a nap to find her miniature dachshund had torn off her baby boy's genitals. Authorities have doubts about her story, but exactly how the newborn was maimed is still a mystery.

Holden Gothia, now 7 weeks old, was found on a bed in his mother's suburban Houston apartment March 13, covered in blood. His genitals were severed and there was a deep cut in his upper leg.

He has been in critical condition ever since. He may never regain the use of his leg and faces years of operations, according to the boy's father, Camden Gothia.

Police, doctors and Child Protective Service officials told the baby's father that the injuries were not consistent with dog bites — the lacerations were too neat.

But Holden's mother, the only person who might have the answers, has checked into a treatment program and refuses to cooperate with police. No charges have been filed.

"In this case, all the investigators can do is go over photographs, trying to make determination based on what experts are telling us," said Houston police spokesman John Cannon.

Child-protection authorities said the 25-year-old woman had a history of prescription drug abuse and tested positive for cocaine and methadone the day after Holden was mutilated.

The mother's name has not been released, and the boy's father would not disclose it. The couple were living together but were not married.

Gothia, a 36-year-old assistant supervisor at a chemical plant, said Holden was born healthy and drug-free, and for the first month of his life, the mother "was just glowing. She was head-over-heels in love with Holden."

But in the week before Holden was injured, Gothia, said he saw nagging signs that his girlfriend was once again taking painkillers, an addiction he thought she had conquered. Her doctor had prescribed methadone to keep her off other drugs during her pregnancy.

She admitted taking Xanax, but assured Gothia it had been a misstep.

Then, the day before the attack, Holden's mother said she was going to Wal-Mart and came back apparently high, Gothia said.

"I called her mother and said, she either gets help or I will remove Holden permanently. I was not going to take a risk with Holden," he said.

The couple made plans to talk about their future when Gothia came home from work on March 13. Instead, he got a call from Holden's mother that afternoon telling him to rush home.

He arrived at the couple's apartment to find an animal control van outside, Holden's mother in an apparent drug-induced stupor and blood covering the bed where the baby had been sleeping. The baby's mother told him that their dog had bitten Holden in the stomach and the infant was in surgery.

Gothia did not learn the extent of Holden's injuries until he arrived at the hospital.

"At that point, your world or what's left of it starts going to chaos," he said. "Every emotion starts shooting through you — guilt that I wasn't there, thinking what I could have done differently every day prior to that."

The 8-pound dachshund named Shorty, which he bought as a gift for Holden's mother, had never shown any aggressive behavior and often slept nestled to the newborn. He said he has been given permission by animal control to take the dog home.

Gothia says he has not had any further contact with Holden's mother since the attack, and that he tries not to let his mind center on what might have happened that day. "It can drive you mad," said Gothia, who spends as much time as possible at his son's side.

"It's me and Holden now," said Gothia, who brought a stuffed toy puppy to place in Holden's hospital crib. "I am going to spend the rest of my life making sure he is safe and happy and held."