How gassing came & went

From ANIMAL PEOPLE, October 2006:
Gassing pound animals with carbon monoxide gained acceptance
across the U.S. 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.
Carbon monoxide gassing prevailed over many attempts to
introduce other killing methods partly because it was inexpensive and
easily done, but perhaps mostly because it was perceived as painless.
The most successful challenge to carbon monoxide came from
the introduction of decompression chambers to kill animals, after
World War II, when the San Francisco SPCA developed a side business
in purchasing and adapting to shelter use Navy surplus decompression
chambers originally used to help divers who developed “the bends.”

The SF/SPCA in 1954 and 1955, respectively, formed the
Northern California SPCA and the Western Humane Education Society to
help promote decompression. The SF/SPCA and the subsidiaries argued
that decompression produced a quicker, cleaner death than gas, but
shelter workers and the public became skeptical.
Across San Francisco Bay, the city of Berkeley abolished
decompression in 1972. The SF/SPCA itself abandoned decompression in
1976, when newly appointed executive director Richard Avanzino (now
president of Maddie’s Fund) scrapped the decompression chamber on his
second day. Portland, Oregon, banned decompression in 1977, 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 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,” Humane Society of the U.S. companion animal issues director
John Snyder told ANIMAL PEOPLE. “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.”
“Electrocution, hypoxic gasses such as carbon monoxide,
carbon dioxide, nitrogen and argon, and decompression became the
predominant methods of animal shelter killing by 1970,” recalls
shelter consultanent and euthanasia instructor Doug Fakkema. “All of
the distance killing methods 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,” Fakkema told ANIMAL
PEOPLE, “as anyone who has pushed the button on a chamber full
of animals knows full well that killing is going on. A similar
movement in human executions has been taking place since the 19th
century, with the invention of the guillotine to replace hanging or
clubbing, then electrocution, gassing, and finally lethal
injection,” by a series of methods that are still evolving and often
challenged in court.
“In animal shelters,” Fakkema continued, “carbon monoxide
by gasoline engine was replaced by decompression,” as the purported
best method, if not the method most widely used. “Then
decompression was replaced by nitrogen gassing, then [back to] carbon monoxide using compressed, bottled gas,” which has the
advantages of being relatively quietly administered and not burning
animals’ nasal passages and lungs, as exhaust fumes do if not
properly cooled before introduction into the lethal chamber.
Many different approaches to lethal injection were tried
before sodium pentobarbital became the standard killing drug.
Magnesium sulphate 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. A paralytic injectible
drug called 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 barbituate. “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 Virginal 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.”
But critics of high-volume shelter killing, including Nathan
Winograd of No Kill Solutions, argue that the term “euthanasia”
itself is inappropriately used to describe killing healthy animals,
and that people should take it as seriously as executing human
convicts.