Low welfare impact of noise: assessment in an experimental model of mice infected by Herpes simplex-1

The breeding practices adopted and the equipment typically found in animal facilities produce sounds at frequencies within the auditory range of the mice (1 to 100 kHz), which can cause hearing and other non-hearing effects. Another aspect that could potentially affects the welfare of experimental animals would be their impaired health condition, since in addition to all the variables present in the environment, some of them are deliberately infected with pathogens. This study aimed to evaluate the possible effects of the chronic exposure of C57BL/6 and Tlr2/Tlr9(−/−) mice, uninfected and infected, with a low m.o.i. of Herpes simplex-1, at different noise levels present in the “Quiet” and “Noisy” rooms. Considering all procedures, a total of 51 male mice were used, 27 of the C57BL/6 and 24 of the Tlr2/Tlr9(−/−) strains. Physiological parameters such as weight gain, hemogram, cholesterol, glucose,corticosterone and cytokines involved in the immune response were evaluated together with the animals’ behavioral responses in Open Field and Light/Dark tests. In relation to the physiological parameters in C57BL/6, there was infection x noise interaction (P