Understanding and assessing animal emotions via non-invasive methods has become a key point for improving animal welfare. Previous studies have shown how emotional contexts affect the emotional status and the physiological response in dogs. The aim of this study was to investigate the influence of an emotional context in the eye temperature of dogs, measured via a non-invasive method, the infrared thermal imaging (IRT), in a separation-reunion experiment. Additionally, validation tests for testing the IRT equipment were conducted.