Abstract
The study investigated the role of subclinical respiratory tract infection in producing an abnormality of lung function assessed by measuring an index of the permeability of the blood-gas barrier to 99mTcDTPA. Pasteurella pneumotropica was grown from throat swabs taken from 9 female rats age 10 weeks at the time of the experiment and housed under conventional husbandry conditions for 4 weeks previously. There was a significant association between the amount of bacteriological growth and an abnormality of the index of permeability. In contrast to this finding, there was no bacterial growth and no abnormality of function found in 12 female rats age 6 weeks, kept under strict barrier-maintained conditions. This finding emphasises the need for great care to be taken in the husbandry of animals used in scientific research.