Two female Labrador retrievers trained to sniff out the plastic used to make pirated CDs and DVDs have gotten so good at their jobs that Malaysian bootleggers are spraying chemicals on their ill-made wares — and have placed a bounty on the dogs' heads.

Local authorities moved the imperiled pooches, named Lucky and Flo, to a safe house after being notified of the threat.

Since going into action for the first time two weeks ago, the dogs, on loan for at least a month from the Motion Picture Association of America, have uncovered nearly 1 million illegal discs, a Malaysian official said Monday.

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The black Labs are trained to detect the polycarbonate chemicals used in manufacturing discs, but officials received a tip-off that bootleggers are using sprays to throw them off the scent, said Fahmi Kassim, the Domestic Trade Ministry's enforcement chief in southern Johor state.

"The pirates are believed to be desperate because the dogs were so successful," Fahmi told The Associated Press.

The dogs, which began sniffing out disc shipments at Malaysia's main airport on March 13, won acclaim when they traveled south to Johor, helping officials uncover 1 million pirated DVDs, CDs and computer game discs worth $2.8 million in an office complex on March 19.

Fahmi declined to say whether Lucky and Flo were still in Johor, citing security reasons. However, the dogs have not taken part in any raids in Johor since last week's effort, he said.

The large seizure has not crippled pirates, Fahmi said, noting that authorities in Johor, which borders Singapore, found several retail outlets selling pirated discs over the weekend.

"We believe the pirates wanted to show off their strength, to show that they managed to reorganize and reopen their business even after we confiscated so many discs," Fahmi said.

Malaysia is among the world's main producers and exporters of pirated discs, the U.S. government and the MPAA have said.

According to the Malaysian government, 5 million discs were seized in more than 2,000 raids nationwide last year, and 780 people were arrested.

The MPAA says Lucky and Flo's work in this Southeast Asian country is the first time authorities anywhere in the world have used dogs to detect contraband discs. Malaysian officials have said they will consider training their own canines to perform similar tasks.

The Associated Press contributed to this report.