Antivivisection gains momentum in Switzerland

''At least 80 percent of all animal experiments could be stopped without any harm to medical research,'' exclaimed Valerie Baiter, her tiny Zurich office drowning in antivivisectionist pamphlets and books. Dozens of letters from supporters were piled on a packed desk. On the floor, a peacefully sleeping shepherd dog clutched a green pillow covered in white hearts.

The lively Swiss is typical of a growing movement across Central Europe that is bent on keeping animals out of laboratories. They do not send letter bombs as a militant group calling itself the ''Animal Rights Militia'' claims to have done to British Prime Minister Margaret Thatcher recently. But they are in peaceful earnest slogging away each day at getting support for the animal cause.

This month Zurich's antivivisectionists managed the extraordinary feat of penetrating the opposition camp by publishing pages on gruesome animal experiments in Switzerland's leading business magazine, proving that when it comes to animals, support can come from the most surprising places.

More than 150,000 Swiss are forcing a nationwide people's referendum to ban vivisection throughout the country along with other ''cruel animal experiments.'' If passed, it could effectively kill pharmaceutical research in Switzerland. A recent demonstration in Bern supporting such a move drew sympathizers from West Germany, France and Austria.

For the Swiss chemical industry, ''animal experiments are indispensable,'' says Alfred Hartmann, the chemical industry association's president.

Switzerland's three major chemical companies - Ciba-Geigy, Hoffmann-La Roche, and Sandoz - are among the world industry's top researchers. Some 2 million animals are used annually in their laboratories, according to industry figures. Some 90 percent are mice and rats, the rest primarily guinea pigs, rabbits, cats , and dogs.

''If you do not use animals, what are you going to use - humans? You cannot do that,'' Mr. Hartmann points out.

The antivivisectionists accuse the chemical industry of using the easy way out and challenge it to use alternate means of experimenting. Miss Baiter ticks off isolated organs, cell and tissue cultures, bacteria cultures, insects, and computers.

''I feel sorry for the insects, but it is better than animals,'' she quickly adds.

Sandoz research executive Heinz Weber jumps to the industry's defense: ''We do not make animals suffer unnecessarily.''

The industry insists that it is using alternaitive methods where possible. However, its spokesman say in most cases a total living body is needed.