Tatum O'Neal, arrested for buying cocaine, has blamed the bust on her dog's death.

The actress, who was nabbed by New York police on Sunday night, said losing her pet drove her to seek cocaine.

The 44-year-old, who was the youngest Oscar winner ever, previously battled heroin addiction, as chronicled in her 2004 autobiography 'A Paper Life'.

When arrested O'Neal claimed she was "doing research" for a role. Now she claims the death of her dog three weeks ago pushed her over the edge.

"There's no excuse for what I did. (But) I lost my Scottish terrier, Lena. That seemed to set me off," she told the New York Post.

"She got old. She got cancer. She was the fabric of our family. We had to let her go to heaven. My daughter and I had to put her down. It was too horrible for words," said the woman who won an Academy Award for 'Paper Moon' in 1974, aged 10.

"I couldn't get out of it. I was going to my psychiatrist. I was doing everything I could do. I have the disease of alcoholism. It's lifelong. I treat it every day by going to my 12-step program."

She thanked the New York police force for saving her.

"I'm still sober! Just when I was about to change that and wreck my life, the cops came and saved me!

"I was saved by the bell, by the guys in the Seventh Precinct."

The daughter of actor Ryan O'Neal is due to appear in court on 28 July.