We used eye-surface temperature and heart rate as simple, noninvasive physiological indices to evaluate dogs' responses to an approaching person. Thirteen healthy pet dogs (49.62 ± 31.42 months; 19.28 ± 11.46 kg) were recruited as subjects to investigate physiological responses to approach. We set up two types of approach (smiling and expressionless) by familiar or unfamiliar people of either sex, and all tests were recorded by video cameras. Eye temperature was measured with an infrared

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... camera image, and the dog was equipped with a heart-rate monitor during testing. There were temporal changes in heart rate, and response time differed between HR and eye temperature. Although it may be the one which has to control both a background of the dogs or observational environment, and the response time of each parameter needs to be considered, these two parameters should be useful for non-invasive monitoring of physiological states in dogs in various practical animal situations.