Evaluation of individually ventilated cage systems for laboratory rodents:cage environment and animal health aspects

The use of individually ventilated cage (IVC) systems has become an attract ive housing regime of laboratory rodents. The benefits of IVC systems are, reportedly, a high degree of containment combined with relative ease of han dling, and a high degree of protection from allergenes. In the present study we tested whether two IVC systems (BioZone VentiRack, IVC1 and Techniplast SealSafe, IVC2S), in which we held mature male NMRI mi ce, were constructed to maintain a constant differential pressure, positive or negative, during a prolonged period of time. We also measured ammonia ( NH3) concentrations after about 2 weeks of use, and CO2 build-up during a 6 0 min simulated power failure situation. In addition, animal weight develop ment and bite-wound frequency were recorded (Renstrom et al. 2000). From the present study it is concluded that the IVC1 air handling system pr ovides a more uniform and balanced differential pressure than the IVC2S. Bo th systems effectively scavenge NH3 when bedding material is not soaked by urine. Although the IVCs are dependent on the continual function of the fan s to work properly, it seems unlikely that CO2 concentrations increase to h azardous levels, as a result of a one hour power failure, with the type of cages used in this study. Differences in weight development and bite-wound occurrence were noted between the two IVC systems. Causes for these differe nces could not be established and need more investigation.