Technical note : applicability of infrared thermography as a non invasive measurements of stress in rabbit

Among the main physiological stress indicators, the temperature evaluation is very important and innovative because it may be monitored without directly interacting with the animal. The use of a thermographic system, which is based on the detection of infrared radiation emitted by a subject, is a suitable method in order to measure temperature without any contact. In this research, a thermographic system was employed in order to single out the rabbit skin's zones most suitable for the temperature monitoring during stress challenges. Six hybrid rabbits were observed during induced stress; the areas selected as reference were: the ocular area (globe and periocular area), the internal auricle pavilion, and a shaved area of the head. The results of this pilot study show that the thermographic technique is a suitable method for the evaluation of temperature on rabbit. The best areas singled out were the eye bulb, the periocular area and the ear skin. The results concerning the effect of stress on cutaneous temperature showed that during stress condition a decrease in temperature occurs with respect to the basal condition (Delta T similar or equal to 1 degrees C) and this trend is more evident for the auricle pavillion. In fact, this reaction is more evidenced in the ear skin, where a vasoconstriction process occurs. Moreover, corticosterone levels slightly increase (P=0.08) following the stressor's challenge due to tonic immobility test. In this research, both temperature and the change in corticosterone level show that the stress reaction induced by tonic immobility test is stronger than the one due to the other stressors applied to rabbits.