The objective of this study was to more fully define the surgical stress response to dehorning by heat cauterization in dairy calves by measuring behavioral, hormonal, inflammatory, and immunological markers of stress and to determine whether a nerve block of the surgical site with a concentrated solution of lidocaine (5%) reduces the degree of stress. Thirty-two 10- to 12-wk-old female Holstein calves were randomly allotted to 1 of 4 treatments: 5% lidocaine followed by dehorning, 2% lidocaine followed by dehorning, saline followed by dehorning, or 5% lidocaine followed by sham dehorning. Plasma cortisol concentration was measured in blood samples collected via a jugular catheter at -0.5, 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 6, 9, 12, 24, 48, and 72 h. Various other blood constituents were measured in samples collected at -0.5, 12, 24, 48, and 72 h. Feeding, drinking, scratching, grooming, rubbing, licking, and inactivity behaviors were observed in the standing and recumbent positions using a 10-min scan sampling method analyzed on a time period and daily basis for 72 h following the dehorning procedure. The frequency of vocalization, kicking, and lying in the chute during the dehorning procedure were also assessed. The overall plasma cortisol concentrations were higher in calves subjected to dehorning than in control calves. Compared with the control group, the saline-treated calves had a higher cortisol concentration at 30 and 60 min postdehorning. Plasma cortisol concentrations were higher in all groups at 30 min postdehorning than at other sampling times. The percentage of circulating neutrophils and the neutrophil:lymphocyte ratio were increased in the saline and 2% lidocaine group. Total plasma protein, fibrinogen, and alpha1-acid glycoprotein concentrations were similar among treatments. The behavioral response to dehorning, as manifested by kicking while in the chute, was greater in the saline and 2% lidocaine group than in the control or 5% lidocaine treatment groups. In the postdehorning period, the percentage of time calves spent performing various maintenance behaviors did not differ among treatments. Thus, injection of 5% lidocaine may not provide any added comfort after the dehorning but may decrease the overall stress response during the procedure.

The objective of this study was to document changes in plasma concentrations of total cortisol, porcine corticosteroid-binding globulin (pCBG), and the free cortisol index (FCI) in pigs over a 6-h period in response to adrenal stimulation or suppression. Twenty-four 8-week old pigs allotted in equal numbers were administered ACTH, dexamethasone or saline, and blood samples were collected every 15 min via an indwelling jugular catheter for 1 h prior to and 5 h following treatment. Total plasma cortisol increased in ACTH-treated pigs and decreased in dexamethasone-treated pigs within 0.25 and 0.5 h, respectively. In contrast, pCBG concentration was altered in an inverse fashion subsequent to the changes exhibited in total cortisol. FCI reflected the changes observed in total cortisol. These results further document the negative relationship that exists between circulating concentrations of plasma cortisol and pCBG, and illustrate that this association exists under conditions of acute stress in the pig.