Aging gas chambers in places like Eureka, a southeast Kansas town of about 2,600 residents, are seen as much cheaper than paying a veterinarian to administer a shot to an animal that needs to be put down, The Topeka Capital-Journal reported.

Animal-rights advocates condemn the chambers as cruel to the animals, which are forced into a tight box where they wait alone in the darkness before fans pump in carbon monoxide to end their lives.

The American Veterinary Medical Association — whose rules provide direction for Kansas animal care standards — has listed injections as the preferred form of euthanasia since 1986. Its 2013 guidelines made the use of gas chambers acceptable only if eight conditions are met that Kansas’ aging chambers likely can’t meet, said Michael Faurot, director of the Kansas Department of Agriculture’s animal facilities inspections.

Three Kansas shelters — in Liberal, Burlington and Emporia — have closed their gas chambers in the past few years, said Midge Grinstead, director of the Humane Society branch in Kansas. Eureka, Humboldt, Norton and Chanute remain the last known Kansas pounds to have operating gas chambers, she said, noting that Humboldt hasn’t used its chamber in at least a year.

Eureka and Chanute started working with the Humane Society of the United States last month to end the practice.

About 50 shelters and pounds in 11 states still use gas chambers, according to Humane Society statistics.

For cash-strapped communities with little access to veterinary services, transitioning away from gas chambers is neither easy nor inexpensive.

It costs $37.50 to have a veterinarian put down a single feral cat, Humboldt police Lt. Jeff Collins said, while a bottle of carbon monoxide that can be used 200 times costs $13.

“The chamber seemed pretty humane to me,” said Collins, who has been present for both methods. “I turned gas on, and it looks like they slowly go to sleep.”

Burlington animal control officer Jessica Stice sees it differently.

“It’s selfish of the human race to think that (animals) don’t have emotions and they don’t have feelings,” she said.

Humboldt stopped using its chamber last year after the pound heard from its Kansas Department of Agriculture inspector that limitations on gas chambers were coming. The costs of euthanizing were absorbed into the police department’s budget, with other areas cut to avoid a tax increase.

In some towns, veterinarians are too far away, or the local vet won’t provide the injections. That’s the case in Eureka, which is seeking a grant to pay for its sole animal control officer to become certified to administer euthanasia injections because the local veterinarian refuses to provide the service.

The local veterinarian claims his job is to heal animals, not kill them, Eureka City Administrator Ian Martell said.