Infrared Thermography (IRT) in nude mice : an alternative method for body temperature measurement

Researchers at Milan University and Mario Negri Institute in Italy have developed an alternative method for body temperature measurement, using infrared thermography (IRT) in nude mice. At the 2010 Scand FELASA meeting, Fornasier et Al., showed that baseline recordings (5 min) of Tmax (the time after administration of a drug where maximum plasma concentration is achieved) showed an acceptable variability within the same animal with a coefficient of variability (CV%) ranging between 0.8–1.21. Tmax (39.0°C) was always located in the intrascapular region, in the area of brown adipose deposits (IBAT) which is normally involved in thermogenesis in rodents. In another trial2,3, researchers studied stress in C57BL/6j and BALB / c mice housed in different individually ventilated cages (IVCs). To ensure the highest state of welfare of laboratory animals, they evaluated the behavioural and physiological (surface temperature) response of mice maintained in two different IVCsystems characterised by different points of air injection (cover or animal level) to determine any possible difference in the anxiety levels of the animals. 64 C57Bl6/J and 64 BALB/c 6 weeks old SPF, female mice were used; the animals were maintained at 22± 2 °C and 55± 10% RH with food and water provided ad-libitum. The animals were housed four per cage in two different IVC cages with different air inlet solutions at cover (75 ACH) or animal (50 ACH) level and observed for seven weeks. They found significant differences in anxiety-related behaviour between strain and housing systems. These results suggest that, in addition to influencing mouse choice4, different IVC housing systems can influence mouse behaviour, with mice of both strains, exhibiting more anxiety-related behaviour when housing in cage systems where the air entry is at “animal” level at 50 ACH. The same Milan University team2 showed the use of IRT analysis in immunodeficient mice’s nest (Figures 1 and 2). Through the use of IRT, they evaluated the temperature of the nest during the cage change, showing a decrease of about 3°C, as shown in Figure 3. The thermographic technique ensured a strict SPF status and limited operator intervention and invasiveness, improving animal welfare. CONCLUSION InfraRed thermography is a non-invasive method to monitor the health status of laboratory animals. In the future, the thermographic technique could be optimised in order to detect temperature of the animals in the least invasive way possible. This technique has to be further investigated to determine the correlation between superficial (as measured by thermography) and internal body temperatures in different species and in different physiological conditions. REFERENCES Fornasier M., Redaelli V., Tarantino A., Luzi F., Verga M. “Infrared Thermography (IRT) in nude mice: alternative method for body temperature measurement. SCAND FELASA 2010, Helsinki, June 14-17 2010. Freschi M. Thermographic analysis of immunodeficient mice’s nest. Degree Thesis Diss (2012). Medicine Veterinary Faculty. Università di Milano. Italy. Burman O., Buccarello L., Redaelli V., Cervo L. The effect of two different Individually Ventilated Cages systems on anxiety-related behavior and welfare in two strains of laboratory mouse. 12nd FELASA SECAL Congress, Barcelona, 10-13 June 2013. Baumans, V., Schlingmann, F., Vonck, M., Van Lith, H.A., 2002. Individually ventilated cages: Beneficial for mice and man? Contemporary Topics 41, 13–19.