A group of veterinarians and horseowners in the Potomac area, eager to find a cure for a mystery disease killing expensive thoroughbreds in Maryland and Virginia, are proposing to bring in healthy horses from outside the area and expose them to conditions they think may lead the horses to contract the often-fatal disease.

According to veterinarians drawing up the program, the horses would be quartered at Saxon Field in Potomac, stables owned by the family of former unsuccessful gubernatorial candidate Louise Gore, where seven horses have died of the disease, called Potomac Fever, this summer.

"I'm an animal lover, but they have to do something," said Sandra Hudson, manager of Saxon Fields. "The real humane question is to see a little kid watch a pony die and watch the vet not be able to do anything."

The veterinarians say they need a test group of animals to study before and after they contract the disease, which so far this year has killed 47 horses in Maryland and Virginia. But humane organization members and Montgomery County officials who have put up money for Potomac Fever research have expressed deep reservations.

"I can understand the distress of the horseowners," says Janet Huling, spokeswoman for the Humane Society of the United States, "but it sounds like they're grasping at straws. From what I understand, they have enough samples from horses who died of the disease to analyze all winter long."

Says Charles Maier, spokesman for Montgomery County Executive Charles Gilchrist, "The government would think twice about spending money on the program."

The veterinarians themselves are at odds over how to proceed.

"As a practicing vet, does it look good for me to take horses out and put them in this field?" asks Chester Anderson, a veterinarian who has treated most of the local cases of Potomac Fever. "For a clinician to take horses out and basically hope they get sick? Even though I think that's the type of research that has to be done."

The horses, preferably ones on their "last legs," would be bought at auction in the northern and western parts of the state, Anderson said.

But Ralph Knowles, assistant state veterinarian, said the horses would have to be healthy, since "older horses come with influenza and all sorts of problems." He said they would be bought for about $600 each from private farms.

Both Knowles and Anderson expressed doubts that the program could be implemented this year, since the fever occurs only in hot, humid weather, from mid-June through mid-September.

"It would be a darn good program for next June," Anderson said.

This year, the fifth summer the illness has been systematically studied, there have been 95 cases of acute equine diarrhea syndrome, the formal name for the fever, in Maryland. Thirty-seven of those horses have died.

This was the first year the fever spread to the Virginia side of the Potomac River.

The Virginia state veterinarian's office reports about 30 cases this summer, 10 of them fatal.

Montgomery County horseowners, trainers and equine organizations have raised over $15,000 to support research to find a cure, including $4,000 in county funds.

According to horseowners who met recently to discuss the research, about $4,000 would be spent to buy the horses.

The American Horse Protection Association in Washington favors any project that may lead to a cure. "We don't go along with research using live animals like in the Taub case with the monkeys," says Susan West, AHPA administrative assistant. "But when they're trying to isolate this virus, they have to infect healthy horses."

Matthew MacKay-Smith, a practicing veterinarian and medical editor of the horse magazine Equus, also supports the program providing it uses older horses.

"If an animal has no future . . . , I don't think it makes any difference to the horse whether it gets ill from Potomac Fever or from an attack of pneumonia," he says. "There's a whole lot worse things that can happen to a horse than die."