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

•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.

Infrared 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 m from where the subjects spent most of the time. Temperature was measured from selected regions of both ear pinnae simultaneously. Temperatures 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.