OFFICIALS at the Agricultural Research Center in Beltsville arrived at work last Monday morning to find signs of a crime that is growing in familiarity: a raid by "animal liberationists." A group calling itself the Band of Mercy had broken into their laboratory and removed 37 cats and assorted other animals, leaving behind smashed windows, cut wires, graffiti and several thousand dollars worth of damage. Worse than the damage was the possible public health hazard: 11 of the released cats had been infected with toxoplasmosis as part of the scientific experiment that was the reason cited for "liberating" them.

Groups opposed to the use of animals in research make much of the unfairness of "trading off" animal pain for the relief of human suffering; it seems ironic that they would be willing to hold public health hostage in this manner. The group, People for the Ethical Treatment of Animals, acting as spokesmen for the vigilantes, made light of the danger: the cats, they said, would be treated by a vet and then placed in "safe, caring homes." But toxoplasmosis is not curable, and the cats cannot be made noninfectious. The disease can infect farm animals, in which it causes spontaneous abortion, and pregnant women, whose fetuses can be born blind or with brain damage. Is that transmission direct or likely? Nobody knows for sure; that happens to be what Dr. J. P. Dubey of the Agricultural Research Center had been working for 15 years to find out.

There are competing values and costs to be weighed in the debate over use and misuse of laboratory animals for research. The animal rights movement has forced useful debate and negotiation on some of them. People for the Ethical Treatment of Animals was itself involved in just these type of negotiations with the Beltsville center when the Band of Mercy made its strike; those negotiations will unavoidably be set back now. PETA nevertheless put its arm around the Band's action, holding a press conference in which it attempted to characterize Dr. Dubey's work as useless -- a difficult endeavor, since they had first heard of it only 48 hours before.

The insistence of some of these groups on violent acts that shun legal channels -- channels that have brought considerable results -- must necessarily impair scientists' ability to negotiate with them in good faith. The vigorous prosecution that the federal government intends in this case cannot undo this harm. But firm disciplinary measures may at least have a salutary restraining effect on the excesses of the movement at large.