While reading the June issue of Nature, I saw an editorial piece called Last Rites which touched on a subject which interests me: humane euthanization of lab animals. Our lab does research on guinea pigs (we must be the last lab to *actually* use guinea pigs), and its of the utmost concern to all of us that they feel no pain when they are sacrificed (or “sacked” as we say). There exists two main ways of euthanization: inhaling carbon dioxide gas or by “cervical dislocation” (euphamism for breaking the animal’s neck). The former require little to no researcher interaction, but may be a slow panic-filled death, while the latter requires hands-on participation in the animal’s demise, but it instant and painless. (More below the fold!)
Despite this, the opinion piece states:
In the United States, the institutional animal use and care committees that oversee animal research are likely to demand a “scientific justification” for breaking rodents’ necks rather than gassing them. This is because most of them adhere to guidelines written by the American Veterinary Medical Association (AVMA), which requires such justification, noting that cervical dislocation may be “aesthetically displeasing to personnel” who have to carry it out. This piece of red tape often makes it simpler for US researchers to stick with carbon dioxide.
I find this “justification” requirement disturbing, in that it will require an extra effort on the part of the researcher to fufill the actual objective of the AVMA (assuming it is to oversee the humane care of animals). The fact that some personnel may be squeamish about performing a cervical dislocation is absolutely no excuse for an animal to have a more difficult death.
The issue of how humane carbon dioxide gas euthanasia is was explored in another Nature News piece called Bioethics: An Easy Way Out.
‘There is a strong suspicion that CO2 levels that in no way cause them pain do cause them distress,’ says [neurophysiologist Huw] Golledge. Given the choice, rats will rapidly get out of a chamber containing CO2 concentrations of about 15% or more — far below the concentration needed to knock them senseless.
Kathleen Conlee of the Humane Society, an animal-welfare organization based in Washington DC, doesn’t need any more evidence. She thinks killing rodents with CO2 alone is cruel, and prefers an anaesthetic gas — or, in cases where the anaesthetic would interfere with post-mortem measurements, the guillotine. “We say, if there is a small number of animals, and the person is well trained, use decapitation. If you are doing a large number, use halothane or isoflurane, and then blast them with however much CO2 you want.” “I feel strongly about it personally,” Conlee adds. “The number of animals is huge; the evidence is here; the alternatives are here. It is a no-brainer.”