“…In response to physical or psychological stress, corticotrophin-releasing hormone (CRH) is released by the hypothalamus, stimulating the secretion of adrenocorticotrophic hormone (ACTH) from the anterior pituitary, which acts on the adrenal gland to produce cortisol. Studies have investigated cortisol/ACTH levels in pigs with and without (controls/shams) a painful condition (68, 70, 72, 88, 93, 94, 104, 156, 171, 172), before, during, or after (68, 173–175), with or without anesthesia or analgesia (72, 78, 111, 156, 168), and associated with the severity of the pain (68, 88, 101, 171, 176). …”