The value of a static mouse cage is partially determined by the cage's ability to dissipate carbon dioxide and ammonia. The authors compared the concentrations of ammonia and carbon dioxide produced by mice housed in two types of static isolator cages: a newly introduced disposable cage and a conventional reusable cage. Female mice were housed in three disposable and three reusable cages (n = 5 per cage). After 7 d, groups that were housed in disposable cages were rehoused in fresh reusable cages and vice versa. Intracage carbon dioxide, ammonia, temperature and relative humidity were measured daily. Overall, there were no significant differences in carbon dioxide or ammonia concentrations between the cage types. Within 30 min of placing mice in cages, carbon dioxide concentrations rose to more than 10,000 ppm in both cage types and rarely dropped below 8,000 ppm during both phases of the study. Ammonia concentrations rose slowly until day 4 and then began to rise rapidly. The maximum average ammonia concentration was 710 ppm. There was a highly significant relationship between increasing levels of humidity and ammonia production in the disposable cages (r = 0.88). For the reusable cages, the correlation was not as strong (r = 0.68). Both cage types were similar in their ability to dissipate carbon dioxide and ammonia. The suggested frequency of cage changing can only be estimated; on the basis of existing literature, it seems prudent to change cages when the ammonia concentration reaches 50 ppm.

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Decisions about the appropriate use of animals in research are largely made by Institutional Animal Care and Use Committees (IACUCs). Several commentators claim that scientists exert excessive influence on IACUC decisions. We studied 87 protocol reviews from 10 IACUCs to assess if any group of participants appeared to dominate the protocol discussions. Audio recordings of the meetings were coded to capture the topics of the discussions. We found that animal research scientists made the largest total number of topic mentions while community members made the fewest. On a per person basis, chairpersons and attending veterinarians made the most mentions. Scientists presented the largest number of protocols and the subsequent discussions tended to contain the same topics mentioned in the presentations. The large number of protocols presented by scientists and their total number of comments made during protocol discussions suggest that scientists may significantly influence IACUC decision making.

Nearly half of all external grants from the US National Institutes of Health require approval by the recipient organization's Institutional Animal Care and Use Committee (IACUC) before the funds can be used for research with animals. Given that large sums of money are spent annually on research involving animals, studies evaluating the strengths, weaknesses and overall effectiveness of IACUCs and similar animal welfare committees are needed. The authors designed and carried out a self-assessment survey on IACUC function and effectiveness. They found that 98% of all respondents believed that their IACUCs advanced animal welfare, but in many instances, veterinarians' responses to individual survey items were significantly different from those of other IACUC members. Protocol compliance, protocol review training and better understanding among non-committee members of the need for regulatory oversight are some areas where improvements could be made. Less than 50% of respondents stated that literature searches to find alternatives to animal use or painful or distressful procedures were helpful.

When animals are used in a biomedical research activity that may result in more than mild or momentary pain or distress, humanity, federal regulations and common sense direct us to use the least sentient species that can fulfill the aims of the research. The use of a less-sentient species is in line with the concept of Replacement, one of the well-known 3Rs of laboratory animal use. But what is a less-sentient species? Is a chimpanzee less sentient than a human; is a dog less sentient than a chimpanzee; and is a mouse less sentient than a dog? Does 'less sentient' imply that a species is less able to experience pain, is less intelligent or has less self-awareness? This essay will explore some of the relationships between sentience, pain and vertebrate phylogeny.

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SummaryTotal fatty acids and the proportions of methyl esters of individual fatty acids were measured in mouse milk. Pregnant mice were fed either a high fat (OF) diet or a low fat (LF) diet from 14 days of gestation. After parturition, each dam was milked once a day for a period of 18 days. The mean total fatty acid concentration over the entire study period was 110 mg/g of milk (approximately 11,70/0 fat as triglyceride) for both dietary treatment groups. During days 2 to 6 postpartum, the mean total fatty acid concentration for dams fed OF diet was lower than for the LF group.Although the concentration of total fatty acids of mouse milk was not affected by the level of dietary fat fed to the dam, several variations in the proportions of individual fatty acids were observed.

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