The 8th (2011) edition of the Guide for the Care and Use of Laboratory Animals(1) , published by the National Research Council of the National Academies, discusses issues related to the speed, rate and supply of air in individually ventilated cage systems ( IVCs). The possible impact of the direct exposure of animals to air moving at high velocity (=0.3m/sec) is a specific concern. The Guide states on page 46 “ ..direct exposure to air moving at high velocity should be avoided as the speed of the air to which animals are exposed affects the rate at which heat and moisture are removed from an animal”.
This issue has been raised by a number of authors who cited the high turnover of air as a possible cause of a stressful, dry, micro-environment (2, 3, 4, 5).In 2002, Baumans et al (6), in a study of commercial IVC systems, concluded “we found that mice prefer having large cages and an air supply in the cover, at least in the studies systems, and nesting material should be supplied whenever possible”. Discussing the effects of draughts ,Krohn &Hansen(7) concluded that:”the point of air entrance into the cage can be responsible (due to the high air speed directed at the animal) of welfare problems in mice and consequently the air should not be blown into the cage at animal level, irrespective of the number of air changes”.
1. Guide for the care and use of laboratory animals; National Research Council,8thedition, National Academies Press Washington D.C; 2011.
2. Clough, G., J. Wallace, M. R. Gamble, E. R. Merryweather, and E. Bailey. 1995. A positive, individually ventilated caging system: a local barrier system to protect both animals and personnel. Lab. Anim. 29:139-151.
3. Keller, G. L. 1983. A forced air individually ventilated caging system for rodents. Lab. Anim. Sci. 33:580-582.
4. Perkins, S. E., and N. S. Lipman. 1996. Evaluation of microenvironmental conditions and noise generation in three individually ventilated rodent caging systems and static isolator cages. Contemp.
Top. Lab. Anim. Sci. 35:61-65.
5. Reeb, C. K., R. B. Jones, D. W. Bearg, H. Bedigian, D. D. Meyers, and B. Paigen. 1998. Microenvironment in ventilated animal cages with differing ventilation rates, mice populations, and frequency of bedding changes. Contemp. Top. Lab. Anim. Sci. 37:43-49.
6. Baumanns V.,Schlingmann F., Vonk M., Van Lith A.H. Individually Ventilated Cages: Beneficial for Mice and Men? Contemp. Top. Lab Anim. Sci. 41:13-19 2002
7. Krohn T.C. and Hansen A K. Mice prefer draught-free housing. Laboratory Animals, 44: 370-372:2002