West Valley City installed a new gas chamber this month to kill unwanted pets, reigniting the debate over how Utah shelters should euthanize dogs and cats.

Many tax-funded shelters place animals in chambers that fill with carbon monoxide gas, while in Salt Lake County, the public shelter follows Humane Society suggestions to the letter, killing them only through injections of sodium pentobarbital.

The Deseret News obtained special permission to observe both methods in an effort to shed light on the debate. The newspaper agreed not to identify shelter employees involved in the euthanasia and not to take photographs.

Carbon monoxide

On a crisp September morning in the back room of Sandy's industrial pound, an animal control officer glanced at a pair of caged feral cats with a morose, discouraged sigh.

The shelter was stark and sterile, but alive with the sound of dog barks echoing against the cold concrete.

The cats, a young tabby and an older gray-blue beauty, moved as far from the man as possible. The officer, dressed in a crisp uniform and heavy boots, approached the cages and hurriedly lifted them inside an oven-like box, locking the creatures inside He then flipped a switch, sending poison gas hissing inside. He turned to his supervisor, chatting about the daily grind, as the animals inside began to howl. Their small bodies became stiff and started to jerk, letting out one final shriek before collapsing.

The limp bodies were left in the chamber until the poison gas was converted into carbon dioxide and safely released outdoors.

"I prefer the chamber here over injection," the Sandy officer said, ignoring the dying felines. "These animals, the feral cats, they're not going to be able to be adopted. This is obviously the best thing for the animal. That gives us peace of mind."

Death in the carbon monoxide chamber can be even more violent for dogs because of their size, said Sandy shelter director Rich Bergan.

The newest gas chamber was installed in the facility shared by West Valley and Taylorsville. Murray and West Jordan shelters also use carbon monoxide to euthanize strays.

Lethal injection

Miles away in the massive Salt Lake County animal shelter, an injured yellow lab named Roxy was brought in as a stray. The 10- to 12-year-old dog was fitted with a microchip, but her owners never tried to claim her.