This study, evaluated as a whole, suggests that although there are different results in each part, the increase in body weight and body temperature in mice housed in IVC cages, the low levels of leptin relative to body weight, the increase in ghrelin, ACTH, and CORT levels, the high level of thigmotaxis in the OFT of anxiety tests, and the delayed response to stimuli in the hot‐plate suggest that the stress‐related welfare of the animals is low. The gene discussed is GHRL; the disease is Anxiety.