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

Abstract

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 (ΔT~1°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.

Dynamic changes in ear temperature in relation to separation distress in dogs

“…This is in line with the prediction that the stress response through activation of the sympathetic nervous system results in peripheral vasoconstriction [46,47] leading to a decrease in surface temperature of the extremities. The findings add to previous studies demonstrating a reduction in the ear temperature of other species in stressful situations (macaques [19]; rabbits [11]) and support the notion that dogs are disturbed by isolation, at least in an unfamiliar environment [44].…”

“…[6,7]) and thermoregulation analysis [5]. In animal welfare science, its applicability in the measurement of physiological stress responses has been explored, such as via eye temperature in cattle [8,9] and horses [10], ear temperature in rabbits [11], and temperature of the comb and wattle in chickens [12], adding to the more conventional methods of stress monitoring in non-human animals (including body posture, heart rate, heart rate variability, and cortisol concentrations in saliva, plasma and urine [13][14][15]). Recently, thermography has also been used in the assessment of positive affective states in animals [16,17].…”

“…Fear and distress have been associated with a cooling of the extremities: tail and paw in rats [18], nose, nasal mucosa, ears, hands, feet, and tail in pigtail monkeys [19], nasal skin in rhesus macaques [20], and ear pinnae in sheep and rabbits [11,21]. Changes in eye temperature in relation to stressful or painful procedures were found in horses [3,10], cattle [8,9,21,22], and elk [23], although changes were not always in the same direction.…”

Validation of a fear test in sport horses using infrared thermography

“…Stewart et al (2007) measured an increase in eye temperature in cows after intramuscular injection of adrenocorticotropic hormone, corticotropin-releasing hormone, and epinephrine. Research carried out on different species correlated increased eye temperature with cortisol concentrations in response to pain (Stewart et al, 2008b(Stewart et al, , 2008c, stress (Ludwig et al, 2007;Stewart et al, 2007;Valera et al, 2012), and fear (Stewart et al, 2008a). In a study on horses undergoing stressful situations, Valera et al (2012) found that the eye temperature increased as a consequence of stress.…”

Using eye temperature and heart rate for stress assessment in young horses competing in jumping competitions and its possible influence on sport performance

“…ET has been shown to be a more consistent measure of temperature changes in response to stress than other anatomical areas such as the nose (Nakayama et al, 2005), ear (Ludwig et al, 2007), head (McGreevy et al, 2012) or body surfaces (McCafferty, 2007) and it has been also used for detection of inflammatory processes in extremities in horses (Eddy et al, 2001). Furthermore, as the temperature of the eye and surrounding area are less affected by coat variations (colour, thickness, etc.)…”