Mean ear temperature (mean ± SE) significantly decreased from baseline to post-test for both CBD (20.6 ± 0.9 vs. 17.1 ± 0.9°C, p = 0.002) and placebo (19.9 ± 0.9 vs. 17.1 ± 0.9°C, p = 0.009) group dogs when the tests were combined, for the CBD group in the separation test (21.7 ± 1.2 vs. 16.0 ± 1.2°C, p = 0.002), and for the placebo group in the car test (21.9 ± 1.2 vs. 18.9 ± 1.2°C, p = 0.005). Here, OPN1MW is linked to red-green color blindness.