Carbon dioxide as a short-term restraint anaesthetic in rats with subclinical respiratory disease

Abstract

SummaryThe use of carbon dioxide (C0 2 ) with, and without, oxygen (0 2 ) as a short-term restraint anaesthetic for Wistar rats in which subclinical respiratory disease was endemic, was assessed in 3 separate experiments. In the first, rats were placed in a CO 2 atmosphere generated from solid CO 2 chips in a 70 Iplastic bin, and removed at time intervals ranging from 0 to 120 s after disappearance of the pedal reflex. Eight of 25 rats died, including 2 which were removed immediately the pedal reflex disappeared; it was concluded that CO 2 without O 2 was not a suitable short-term anaesthetic for rats. In a second study, rats were anaesthetized in atmospheres of 50 : 50 and 80 : 20 (C0 2 : O 2 ) provided from commercially available cylinders, in 2 different environments -a 3, 41 glass jar and a 171 plastic bin. Rats became excited in the plastic bin but not the glass jar. Rats in the glass jar displayed visible depression and cessation of whiskers movement significantly more quickly in the 80: 20 (C0 2 : O 2 ) than in the SO: 50 mixture (4'2±0'98s, n=6, and 66·0±4·9s, n=6 vs 13·8±2·77s, n=5 and 152·0±20·8s, n=5, respectively). Rats in the 171 plastic bin lost their pedal reflexes in a mean 41· 5 ± 4· 55 s (n = 11) in the SO : SO mixture and in a mean 30·9 ± 6·38 s (n = 11) in the 80: 20 (C02: O 2 ) group. Those left in the 50 : 50 mixture for 60 sand 180 s after disappearance of their pedal reflexes, recovered these reflexes in 20· 2 ± 0,44 sand 21·5 ± 7· 23 s respectively after removal from the gas. Respiration and heart beat ceased in one rat remaining in the SO : 50 mixture after 13 min 10 s. Received 12 March 1987. Accepted 25 November 1988 No untoward effects occurred in rats left in the 50 : 50 mixture for 180 s after disappearance of the pedal reflex, but 2 died when left for an equivalent period in the 80: 20 mixture. In the third study, examples of the practical use of a 50 : 50 mixture as a short term restraint anaesthetic are described. It was concluded that this mixture was a cheap, safe, and effective means of short-term restraint for rats with subclinical respiratory disease, when the minimal time of exposure to the gases was employed.

Is carbon dioxide (CO2) a useful short acting anaesthetic for small laboratory animals?

“…1986, Blackshaw et a1. 1988, Fenwick & Blackshaw 1989, Urbanski & Kelly 1991, Dannemann et a1. 1994, Fodor 1995.…”

Blood Sampling in the Rat: Current Practices and Limitations

“…There are contra- dictory reports on pain or distress in animals being anaesthetised or euthanised with CO 2 (Mikeska and Klemm 1975;Feldman and Gupta 1976;Fenwick and Blackshaw 1989;Urbanski and Kelley 1991;Hewett et al 1993;Berger-Sweeney et al 1994;Coenen et al 1995;Danneman et al 1997). Danneman et al (1997) have reported that the concentrations that are least likely to cause pain and distress are associated with histological changes in the lungs.…”

“…This CO 2 mixture is volatile, non-£ammable, odourless, and colourless. Fenwick and Blackshaw (1989) described a method for short-term anaesthesia in rats with subclinical respiratory disease using CO 2 /O 2 (80:20). Lukas (1994) reported the use of a 60:40 mixture to produce light anaesthesia for blood sampling in rodents.…”

Opinion of the Scientific Panel on Animal Health and Welfare (AHAW) on a request from the Commission related to welfare aspects of the main systems of stunning and killing the main commercial species of animals

“…Concerning carbon dioxide / oxygen mixtures, a different opinion can be found in a paper by Hoenderken et al (1994). The authors refer to AVMA (1986), van den Bogaard, Dam andWeekers (1985), van Luytelaar et al (1993), and Fenwick and Blackshaw (1989), who claim that adding oxygen to carbon dioxide , in contrast to using carbon dioxide in air, reduces signs of asphyxia and excitation in rats and can therefore be beneficial for anaesthetising rats (see papers by Leach et al that showed that in choice tests, rats found levels of carbon dioxide more than 20% aversive). In the other series of experiments with chickens, the conclusion drawn was that adding oxygen to carbon dioxide atmospheres and moistening the very dry technical gases are beneficial for animal welfare.…”