Journal of Thermal Biology 92 (2020) 102677 Available online 29 July 2020 0306-4565/© 2020 Elsevier Ltd. All rights reserved. Infrared methodologies for the assessment of skin temperature daily rhythm in two domestic mammalian species Claudia Giannetto a, * , Francesca Arfuso a , Elisabetta Giudice a , Matteo Gianesella b , Francesco Fazio a , Michele Panzera a , Giuseppe Piccione a a Department of Veterinary Sciences, University of Messina, Polo Universitario Dell’Annunziata, 98168, Messina, Italy b Department of Animal Medicine, Production and Health, University of Padova, Viale Dell’ Universit� a 16, 35020, Legnaro, PD, Italy A R T I C L E INFO Keywords: Daily rhythm Cutaneous temperature Rectal temperature Digital infrared camera Infrared thermometer Horses Goats ABSTRACT To assess the accuracy of infrared methodologies for daily rhythm monitoring of skin temperature, fve clinically healthy Italian Saddle gelding horses, and fve not pregnant and not lactating Camosciata goats, were monitored every 4 h over a 48 h period. The horses were housed in individual boxes, while the goats in two indoor pens, under natural photoperiod and natural environmental temperature. In each animal, skin temperature was recorded with the use of a digital infrared camera and a non-contact infrared thermometer, in fve regions: neck, shoulder, ribs, fank and croup. Recorded values were compared with the well-established daily rhythm of rectal temperature. Rectal temperature was recorded at the same time by means of a digital thermometer. In horses, a lower value of skin temperature was recorded using the infrared thermometer for the croup region compared to shoulder and fank; a lower value of skin temperature was recorded using thermography for the croup region compared to the shoulder. In goats, a lower value of skin temperature was recorded using the infrared ther- mometer for the croup region compared to the fank. In both species, higher values of rectal temperature were observed, compared to the temperature recorded at the skin regions using the other two methodologies. Cosinor rhythmometry showed a daily rhythm of rectal and skin temperature recorded using both methodologies in all the examined regions. General linear model (GLM) showed statistically signifcant effect of breed on all rhythmic parameters; of day of monitoring on amplitude; of site of recording (rectal vs skin regions) on mesor, amplitude and acrophase; and no effect of methodologies used. The results of this study show the differences in rhythmicity of various body regions temperature and their differences in comparison with daily rhythm rectal temperature. The use of infrared methodologies was inaccurate in assessing body core temperature, but its use could be considered for the evaluation of infammation in the different body sites. 1. Introduction The homeothermic animal is able to maintain a balance between heat production and heat loss in order to keep its temperature constant (Arfuso et al., 2016). The body produces continuously heat that is dissipated through the surface in several ways (Piccione et al., 2005a). The evaluation of body temperature represents a valuable tool to monitor the physiologic status, the welfare and the stress responses of animals. Temperature monitoring is an important part of clinical med- icine that enables early detection of changes in the patient clinical condition associated with infection, systemic infammatory response syndrome, immune-mediate diseases, neoplasia and shock (Battersby et al., 2006). In mammals, core temperature is homeostatically regulated at around 37-39 � C despite large variations in the environment temperature. Daily oscillations of up to 2 or 3 � C above and below the thermoregulatory set point area are typical of mammalian physiology (Refnetti and Menaker, 1992), showing an endogenous daily cycle (Refnetti and Piccione, 2003). Measuring body temperature in animals includes the use of rectal thermometers, tympanic infrared thermome- ters and thermal microchips (Goodwin, 1998). Rectal temperature measurement requires the patient to be restrained. This invasive pro- cedure, in reactive animals, might alter the result of the measurement, therefore compromising its interpretation, and the consequent diag- nostic and therapeutic measures. Moreover, this procedure may cause a danger for the operator and alternative ways of temperature measuring could be useful and practical for the clinician. Infrared thermography * Corresponding author. E-mail address: clgiannetto@unime.it (C. Giannetto). Contents lists available at ScienceDirect Journal of Thermal Biology journal homepage: http://www.elsevier.com/locate/jtherbio https://doi.org/10.1016/j.jtherbio.2020.102677 Received 5 May 2020; Received in revised form 15 July 2020; Accepted 15 July 2020