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

Abstract

Highlights• Pet dogs were tested in a brief separation test and filmed remotely using thermography• Temperature was analyzed from selected patches of both ear pinnae simultaneously• Social isolation was associated with a significant decrease in ear pinnae temperature• Temperature of the two ears did not differ significantly from each other• Long distance thermography is a useful tool in non-invasive stress monitoring AbstractInfrared thermography can visualize changes in body surface temperature that result from stress-induced physiological changes and alterations of blood flow patterns. Here we explored its use for remote stress monitoring (i.e. removing need for human presence) in a sample of six pet dogs. Dogs were tested in a brief separation test involving contact with their owner, a stranger, and social isolation for two one-minute-periods. Tests were filmed using a thermographic camera set up in a corner of the room, around 7 metres from where the subjects spent most of the time. Temperature was measured from selected regions of both ear pinnae simultaneously. Temperature of both ear pinnae showed a pattern of decrease during separation and increase when a person (either the owner or a stranger) was present, with no lateralized temperature differences between the two ears. Long distance thermographic measurement is a promising technique for non-invasive remote stress assessment, although there are some limitations related to dogs' hair structure over the ears, making it unsuitable for some subjects.

Assessing the welfare of kennelled dogs—A review of animal-based measures

“…Some dogs may also show aversive behaviour toward camera. Ogata et al, 2006;Part et al, 2014;Vainionpää, 2014;Nääs et al, 2014;Redaelli et al, 2014;Travain et al, 2015;Proctor and Carder, 2015;Telkänranta et al, 2016;Whitham and Miller, 2016;Riemer et al, 2016 Immune function (IgA/ antibody and WBC levels)…”

“…In contrast, Part et al (2014) found that dogs who were moved to kennels from a home environment had no difference in their core temperatures (measured with a thermometer in the ear canal), but they did have significantly lower surface temperatures, as measured using an infrared camera recording nose temperature. Similarly, Riemer et al (2016) used an infrared camera to measure surface temperature, specifically the temperature of the ear pinnae from long distances (6-8 m). Although this was a small sample (six dogs), the results showed that peripheral temperature decreased in response to separation and increased again upon reunion with the owner.…”

“…With the advance of technology, thermal imaging can now be used as a noninvasive measure of temperature, which greatly reduces the stresses involved. This is because thermal imaging requires no restraint and, in some cases, does not even require a person to be present, meaning that the animal is not even necessarily aware that the measurements are being taken (Riemer et al, 2016). Thermal imaging is a useful measure of welfare across a variety of species for both core and peripheral temperatures (for reviews, see: Nääs et al, 2014 andRedaelli et al, 2014), however few studies have used it to assess canine welfare specifically, as a standard methodology has not yet been developed and validated.…”

“…Polgár, et al Applied Animal Behaviour Science 213 (2019) 1-13 camera (Travain et al, 2015), suggesting that camera itself could be a source of distress for the animals. This could clearly influence the measures taken, however other studies have developed methods where the dogs are completely unaware of the camera, with measurements being taken from five to eight metres away (Riemer et al, 2016) or where the animals are habituated to the camera over time (Proctor and Carder, 2015). Even in these cases however, there is still the possible confounding effect of the environment that needs to be taken into consideration, as the temperature, material, dimensions, and heat-reflecting ability of the animal's surroundings could all influence the measurements (Telkänranta et al, 2016;Whitham and Miller, 2016).…”

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“…29 Infrared thermal imaging (IRT) has emerged as a promising tool for studying animal behaviour. 30 For instance, research employing this methodology has helped cast light on affective processing 31 in a variety of species, including macaques (Macaca mulatta) (Nakayama et al 2005;Kuraoka 32 and Nakamura 2011; Ioannou et al 2015), chimpanzees (Pan troglodytes) (Kano et al 2016; 33 Dezecache et al 2017) or dogs (Canis lupus familiaris) (Travain et al 2015;Riemer et al 2016; 34 Travain et al 2016). In these studies, IRT was deployed to detect changes in emissivity of the 35 skin caused by shifts in blood flow at body surface, a physiological process controlled by the 36 autonomic nervous system (see Ioannou et al 2014 for a comprehensive review).…”