Once the most common fate of pound animals, carbon monoxide gassing is now nearly history
by Merritt Clifton
RALEIGH, North Carolina––The last dogs and cats in North Carolina to be killed in animal shelter gas chambers died as anonymously toward the end of February 2015 as most of the 21 million or thereabouts before them.
Gassing dogs was experimentally introduced to North Carolina in 1935, in connection with debate over whether to gas convicted human criminals instead of hanging them.
Public outcry over the dogs’ suffering delayed the introduction of gas chambers to animal shelters for more than 15 years, but human convicts were gassed in North Carolina until 1983, when the condemned were allowed to opt for lethal injection instead. North Carolina abolished gassing convicts in 1998.
The use of carbon monoxide chambers to kill dogs and cats caught on in North Carolina, in response to recurring rabies outbreaks, between 1951 and 1956. By that time gassing was already widely used in other states.
At peak, between 20 and 30 years later, North Carolina shelters used carbon monoxide chambers to kill as many as 1.5 million dogs, cats, puppies, and kittens per year.
Use fell off sharply during the past 25 years, as total shelter killing in North Carolina dropped to fewer than 180,000 animals per year, while gassing as a killing method fell out of humane favor worldwide, replaced by lethal injection.
Gassing in North Carolina officially ended 90 days after the North Carolina Department of Agriculture & Consumer Affairs decreed toward the end of November 2014 that carbon monoxide would no longer be considered an acceptable method of disposing of homeless dogs and cats.
As of July 2014, according to Humane Society of the U.S. survey data, only eight North Carolina shelters still used gassing.
Where gassing continues
Twenty-two states have now legally abolished using carbon monoxide chambers to kill dogs and cats. Gassing remains legal in 18 states where no shelter uses the method, and continues in 10 other states.
Fourteen Missouri shelters still have gas chambers, according to Humane Society of the U.S. survey data, along with nine shelters in Utah, six in Oklahoma, four each in Kansas and Michigan, three each in Ohio and Wyoming, one each in West Virginia and Nevada, and an unknown number in Kentucky.
A state house bill to abolish gassing in Kansas was introduced in January 2015, but died in committee.
Ending carbon monoxide gassing in animal shelters has so far taken 52 years since the first American Veterinary Medical Association Panel on Euthanasia was convened in 1963 to produce the AVMA Guidelines for the Euthanasia of Animals. The AVMA panel gave carbon monoxide gassing with cooled, filtered bottled gas a positive recommendation. Strong criticisms of carbon monoxide gassing did not emerge for more than 40 years.
Updated approximately every five years, the AVMA Guidelines have been instrumental in abolishing killing shelter dogs and cats by decompression, drowning, gunshot, and lethal injections of magnesium sulfate and the paralytic drug T-61––all quite common in the U.S. in 1963, but now history in the U.S.
The AVMA Guidelines have also been influential in promoting the abolition of these methods abroad, where some of them are still widely used.
But, partly because the AVMA Panel on Euthanasia has seen abolishing other killing methods as a higher priority, the panel recommendations pertaining to carbon monoxide gassing shifted only very slowly toward the present “conditionally acceptable” rating, which requires that eight specific conditions must be met to use carbon monoxide.
One of those conditions is that use of pentobarbital injection be inaccessible to the shelter in question. This is now rarely true of any shelter in the U.S.
How gassing began
Succeeding the use of chloroform as the approved humane method, gassing pound animals with carbon monoxide gained acceptance after the American SPCA took over the New York City animal control contract in 1895 and introduced carbide gassing in lieu of drowning mass-caged strays in the Hudson River.
Drowning, denounced nearly 40 years earlier by ASPCA founder Henry Bergh, was nonetheless considered to be much more humane than bludgeoning, as practiced in St. Louis among other cities, and gruesomely exposed by the New York Times in 1877.
Carbon monoxide gassing prevailed over many attempts to introduce other killing methods, including electrocution and lethal injections of various sorts.
Electrocution, in the early days of widespread use of electricity, was considered particularly promising. Inventor Thomas Edison demonstrated electrocution on a variety of animals, including an elephant named Topsy whom Edison electrocuted at Luna Park on Coney Island in 1903, after Topsy killed three handlers in as many years. Edison distributed video of the Topsy electrocution to movie theatres, expecting to build public support for electrocuting pound animals as well as human prisoners. But the stunt backfired, and was perhaps the beginning of the end of electrocution as a popular method for killing animals in the U.S., though it was still approved by the American Humane Association for pound use as late as 1940.
The Royal SPCA of Great Britain meanwhile experimented with electrocuting animals from approximately 1885 until about 1928, before concluding that electrocution could never be considered humane by British standards.
The RSPCA exported their six electrocution machines to India during a rabies panic circa 1930. Dogs were legally electrocuted in several cities of India until the last of the RSPCA machines known to remain there was dismantled in 1997.
Ironically, electrocuting pound animals surfaced as a potential replacement for use of an antiquated carbon monoxide chamber in the Philippines in 2005. Manila Veterinary Inspection Board members Manuel Socorro and Condenio Panogan reportedly electrocuted approximately 100 dogs from mid-May 2005 to mid-July before word of their work leaked out and it was stopped.
Tambucho, or tailpipe gassing, is still used to kill about 331,000 impounded dogs per year in the Philippines, according to Philippine Animal Welfare Society president Anna Hashim-Cabrera. Tambucho gassing persists in the Philippines because––although selling dog meat is illegal––dogcatching there is often done by for-profit contractors who clandestinely double as dog meat dealers, or by corrupt government employees who sell dogs to meat dealers on the side. Dogs who have been gassed are considered safe to eat; the remains of dogs killed by pentobarbital injection are considered unsafe.
Carbon monoxide gassing caught on parallel to the rise in use of automotive transport in the U.S. partly because carbon monoxide gassing was inexpensive and easily done, and partly also because it used a familiar and accessible technology. Early custom-made animal control vans often included on-board gas chambers, sometimes jury-rigged by the animal control officers themselves, but later installed by the manufacturers as optional equipment, that could be used in the field to kill animals suspected of being rabid or suffering from severe injuries.
The most popular argument for carbon monoxide gassing, however, was the perception that it was painless, based largely on the experience of humans who died or just barely survived as result of home heating accidents that quietly flooded houses with carbon monoxide in the night.
Use of carbon monoxide chambers for shelter killing accelerated after longtime Humane Society of Rochester & Monroe County executive director Raymond Naramore in 1939 invented a lethal chamber that used cooled, filtered carbon monoxide from pressurized bottles, instead of tailpipe exhaust. Naramore was later instrumental in winning passage of the Humane Slaughter Act of 1958, which ended the use of sledgehammers to stun and kill livestock at U.S. slaughterhouses.
The most successful challenge to carbon monoxide as a shelter killing method came from the 1949 introduction of decompression chambers to kill animals. Then-Los Angeles animal control chief Richard Bonner deployed the first “high altitude chamber,” as he called it, after becoming familiar with the effects of lack of oxygen at high altitudes on military pilots.
The American Humane Association endorsed killing animals by decompression in 1950. The San Francisco SPCA soon developed a side business in purchasing and adapting to shelter use Navy surplus decompression chambers originally used to help divers who developed “the bends.” In 1954 and 1955, respectively, the San Francisco SPCA formed the Northern California SPCA and the Western Humane Education Society, both now long defunct, to help promote decompression.
Bonner, the AHA, the SF/SPCA, and the subsidiaries argued that decompression produced a quicker, cleaner death than gas, essentially the same argument used by the AHA since 2010 in favor of introducing decompression to kill chickens for human consumption.
Shelter workers and the public, however, became skeptical of the alleged painlessness of decompressing dogs and cats.
Berkeley, California, led the turn away from decompression, abolishing it in 1972. The San Francisco SPCA itself abandoned decompression in 1976, when then newly appointed executive director Richard Avanzino (president of Maddie’s Fund since 1998) scrapped the decompression chamber on his second day.
Portland, Oregon, ended decompression in 1979, other cities followed, and by 1985 decompression was no longer used to kill animals anywhere in the U.S.
Some shelters merely converted decompression chambers into gas chambers, a relatively simple retrofit, but the arguments against decompression had caused the humane community to rethink the whole idea of killing animals in any sort of chamber.
A landmark study of attitudes and occupational stress among slaughterhouse workers published in 1988 by Colorado State University psychologist and livestock management expert Temple Grandin had an impact. Grandin found that slaughterhouse personnel responded to killing in three distinctly different ways: some detached themselves, some became sadistic, and some ritualized the act of killing, convincing themselves that what they did was for the greater good.
While shelter workers typically resented being compared to employees of slaughterhouses, follow-up studies determined that they responded in the same ways, just in different proportions, with ritualizing predominant among those who killed animals by lethal injection, and distancing more common among those who used gas.
As to whether any killing method has ever been easier on shelter workers as measured by either psychological studies or job turnover rates, “There is not much evidence either way that I have seen,” says former Humane Society of the U.S. companion animal issues director John Snyder. “However, I have heard a number of shelter workers say even though it may be a little more work, they feel that sodium pentobarbital is more humane for the animal, and they feel better using sodium pentobarbital to end the animal’s life.”
Recalls shelter consultant and euthanasia instructor Doug Fakkema. “All of the distance killing methods,” including gassing, decompression, and electrocution, “were an attempt to improve the method of death as well as remove the operator from the actual killing. This is an absurd notion to be sure, as anyone who has pushed the button on a chamber full of animals knows full well that killing is going on.”
Lethal injection began to supersede gassing in animal shelters in the 1970s, but any different approaches to lethal injection were tried before sodium pentobarbital became the standard killing drug. Magnesium sulfate gained brief acceptance, and is still commonly used in India and eastern Europe, but was rejected in the U.S. because it visibly causes animals to suffer. The paralytic injectable drug T-61 was commonly used to kill mink on fur farms, and crossed over into shelter use, but also caused evident suffering, and was federally banned in 1986.
Sodium pentobarbital caught on slowly because it is a federally regulated barbiturate. “Euthanasia by [sodium pentobarbital] injection became legally difficult,” Fakkema remembers, “when Congress passed the 1970 Comprehensive Drug Abuse Prevention & Control Act, which permitted only mid-level practitioners such as physicians and veterinarians to have access to sodium pentobarbital. In 1972 the Commonwealth of Virginia passed the first of the direct registration laws to permit animal shelters to directly purchase sodium pentobarbital, now a C-II controlled substance. The Drug Enforcement Agency now allows between 27 and 31 states to purchase and administer sodium pentobarbital without using a veterinarian’s DEA license. The number varies depending on how one defines direct registration.
“The trend is toward euthanasia by injection,” Fakkema believes, calling ‘euthanasia by injection’ “the preferred terminology, as ‘lethal injection’ evokes human execution and does not involve the same drugs we use.”
Drugs & money
Carbon monoxide gassing persists in the U.S., where still used, and in many jurisdictions abroad, mostly because of the belief that killing animals by carbon monoxide instead of sodium pentobarbital is that carbon monoxide is less expensive––if only because most of the gas chambers now in use were installed and paid for decades ago
Fakkema has repeatedly debunked that claim. “As an 18-plus year shelter director, including serving as shelter supervisor at Multnomah County Animal Control in Portland,” among the larger shelters in the U.S., “and as a 27-year animal care and control consultant,” Fakkema says, “I am familiar with costing out programs.
“Fatal Plus [the top brand of sodium pentobarbital] costs $0.18 per milliliter. A syringe and needle costs $0.13, PreMix (ketamine/xylazine) $0.40 per milliliter. With doses calculated, the cost for euthanizing an 80-pound methadrine-fed pit bull would be $1.92 for 4.8 milliliters of PreMix, $0.13 for the syringe and needle, and $1.44 for eight milliliters of Fatal Plus, for a total of $3.49.”
Even allowing for recent price increases and regional variation in pricing, the cost would be less than $5.00.
“Yes, it costs money to train staff to perform euthanasia by injection,” Fakkema allows. “But these are one-time costs which are spread out over the number of animals euthanized. The amount of wages paid doesn’t make a whole lot of difference. My cost model shows that wage differences impact the cost per animal only a little.”
With North Carolina convinced, the end of carbon monoxide gassing in animal shelters appears to be in sight.