Raleigh, N.C. — New rules approved by the North Carolina Board of Agriculture would allow animal shelters to continue using gas chambers for euthanasia, but with some guidelines.

The board said Wednesday that the shelters that euthanize with gas must use commercial carbon monoxide and commercially made chambers. Shelters must stop using practices such as connecting a hose to an automobile exhaust pipe.

The shelters may continue using lethal injection. In addition, shelter workers must have specialized training in both areas.

"They have to receive further training on that particular method from somebody that's knowledgeable and somebody that's approved by our office," said Dr. Lee Hunter with the state Department of Agriculture & Consumer Services. "Then, they have to be able to demonstrate to that person that they can do it appropriately and humanely."

The board declined to approve a proposal to outlaw gas chambers at all shelters by Jan. 1, 2012, saying it is necessary to put down some aggressive animals.

In 2005, legislators ordered the Agriculture Department to come up with rules for humanely euthanizing shelter animals.

The state Rules Review Commission must still sign off on the Board of Agriculture's proposal. If it does, the guidelines could be in place by April 1.