Sutherland, M. A., Dowling, S. K., Schütz, K. E. et al. 2019. Behavioral and physiological assessment of liquid nitrogen cryoablation to prevent horn development in dairy calves. Journal of Veterinary Behavior 31, 74-81.

The aim of this series of studies was to evaluate the behavioral and physiological responses (experiment 1), the electroencephalographic response (experiment 2), and the efficacy (experiment 3) of cryoablation to determine if it could provide an alternative to cautery disbudding (DB) for calves. In experiment 1, at approximately 3 d of age, 58 female Friesian dairy calves were allocated to one of five treatments: (1) control handling (CON, n = 11), (2) cautery DB (n = 11), DB plus local anesthetic (n = 12), DB using cryoablation (CR, n = 12), and CR plus local anesthetic (n = 12). Behavioral and physiological (complete blood cell counts and plasma cortisol concentrations) measures were recorded for up to 4 and 72 h post-treatment, respectively. In experiment 2, at approximately 4 d of age, the electroencephalographic response was recorded in 20 male and female Friesian-cross dairy calves disbudded using cautery (DB, n = 10) or cryoablation (CR, n = 10). In experiment 3, at approximately 4 d of age, 274 female Friesian-cross dairy calves were enrolled from two dairy farms and each calf had one of two treatments randomly assigned to each horn bud: cryoablation applied for 10 s (CR-10, n = 274 buds) or 15 s (CR-15, n = 274 buds). At approximately 6 months of age, calves were checked for scur or horn growth. In experiment 1, DB calves spent less (P < 0.05) time lying than DB plus local anesthetic, CR, and CR plus local anesthetic calves. At 3 h post-treatment, the total white blood cell counts and neutrophil:lymphocyte ratio were higher (P < 0.05) in CR than DB and CON calves. Plasma cortisol concentrations were greater (P < 0.05) 30 min after DB and CR compared with CON; however, concentrations did not differ between DB and CR calves. Cortisol concentrations were greater (P < 0.05) in CR calves 90 min post-treatment compared with all other treatments. In experiment 2, cryoablation elicited increases in median frequency and 95% spectral edge frequency and a decrease in total power, whereas cautery elicited an increase in 95% spectral edge frequency only. In experiment 3, cryoablation successfully prevented horn growth in only 19% and 33% of CR-10 and CR-15 calves, respectively. Spraying liquid nitrogen directly onto the horn bud region appeared to cause more acute pain than cautery DB and did not effectively prevent horn growth.

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