CHEYENNE -- State veterinarians from Wyoming, Montana and Idaho plan to meet next week in Denver to discuss brucellosis and their concerns over federal rules for handling the livestock disease.

Wyoming state veterinarian Walter Cook said the states will confer on how they'd like to see USDA's Animal Plant and Health Inspection Service change its rules for brucellosis, a bacterial infection that can cause pregnant cows to abort their calves.

The meeting, set for Wednesday and Thursday, comes as Wyoming investigates the possibility of a second brucellosis-infected herd within its borders this summer. If a second case is confirmed, the state would likely lose its federal brucellosis-free status.

Cook said he would like to see APHIS change at least two of its brucellosis rules. One is the requirement that a rancher with an infected herd must slaughter the herd for his state to maintain its brucellosis-free status. The second is the provision that a state loses its brucellosis-free status if two infected herds are discovered within two years, regardless whether the animals are slaughtered.

"The current regulations are based on a situation where cattle are transmitting the disease to other cattle," Cook said. "When that was the situation, those regulations worked quite well. But now the United States is essentially free of brucellosis, but wildlife still occasionally transmit to livestock."

APHIS spokeswoman Lyndsay Griffin said Jerry Diemer, assistant regional director for the western region of APHIS, will attend the state veterinarians' meeting in Denver.

"APHIS is looking at the rules and the effectiveness and the fact that that region specifically holds the last reservoir of brucellosis in the United States," Griffin said. "I think that APHIS as well as the three state veterinarians are trying to look at all the possibilities and determine what's best for the region and those states."

Brucellosis has been the target of a federal eradication program for more than 70 years, but it persists in bison, elk and other wildlife in the Yellowstone region, and is occasionally transmitted to cattle.

Montana lost its brucellosis-free status this summer after the disease was found twice in that state in the last two years. Idaho regained its brucellosis-free status last year.

Cook said the mandate that a herd be slaughtered, referred to as depopulation, doesn't make sense when a replacement herd would be just as likely to be infected by wildlife in the area.

"You haven't done anything to mitigate the risk by depopulating that herd," he said.

He said the two-year rule seems "arbitrary," considering the sophistication of state and federal disease monitoring systems.

"If you detect it early enough and prevent it from spreading to another cattle herd, then you've achieved your objective," Cook said. "If it spreads to another herd that's a problem, but as long as that doesn't happen then our surveillance system is working."

When a state loses its brucellosis-free status, ranchers must conduct blood tests on their cattle before they're sold or moved across state lines. Cook said the added layer of testing is expensive for ranchers because the cattle tend to lose weight when they're rounded up and put through the chutes for testing.

"On an individual animal basis that's probably not a huge deal, but if somebody's selling a hundred head and each one loses a few pounds, that turns out to be pretty significant," Cook said.

Montana Department of Livestock spokesman Steve Merritt said the meeting is being held in Denver because it's a relatively convenient location for the various livestock officials to reach by plane.