For a while, it looked like a progressive new policy for pet lovers. To cynics, it was a gigantic public relations ploy. But by week's end, it looked more like a bureaucratic blunder that left Pentagon officials scrambling for an explanation.

The Defense Department announced Friday that it had no new policy regarding the use of animals in research -- despite announcements by the Army and Air Force that, in line with new Pentagon guidelines, they would ban the use of dogs and cats in all biomedical and clinical experiments.

"I've been as confused as you are," said Capt. James Vorosmarti, a spokesman in the office of the assistant secretary of defense for research and engineering.

The confusion apparently arose out of a late September meeting between Defense Secretary Caspar W. Weinberger and the service secretaries, when the subject of dogs and cats came up, DOD spokesman Jan Bodanyi said. "There was no new policy," she said. "He Weinberger restated and emphasized the current guidelines."

Current Pentagon policy bans the use of dogs and cats only in weapons development and in experiments ways of treating bullet wounds. However, after the meeting, the Army and Air Force issued directives that went considerably further, banning use of the animals in all biomedical experiments.

"I can't tell you the reason for that," said Vorosmarti. "There is no new policy. Secretary Weinberger did not initiate any new policy."

After meetings Friday, the Air Force issued a statement that the new dog and cat ban "will be in effect while we ascertain that we are complying with Department of Defense guidance on this research.

"Once the Air Force has ascertained that our research programs are in full compliance," the statement read, "appropriate programs may continue."

An Army spokesman said that as of Friday, its new policy was still in effect. But animal-welfare advocates didn't expect the new policy to survive for long.

John McArdle, of the Humane Society of the United States, said, "I'm sure the medical research community put a tremendous amount of pressure on them . . . .

Added Don Barnes, director of the National Anti-Vivisection Society: "Here we are in Washington, D.C., the city I often call Dis- neyland East, trying hard to differentiate between illusion and reality."