Unmitigated Surgical Castration in Calves of Different Ages: Cortisol Concentrations, Heart Rate Variability, and Infrared Thermography Findings

Abstract

The objective was to characterize physiological responses to unmitigated surgical castration in calves of varying ages. Thirty male Holstein calves of three ages [<6 w (6W); 3 m (3M); 6 m (6M); n = 10] underwent a simulated castration treatment (SHAM) followed 24 h later by castration (CAST). For both treatments, heart rate variability, eye temperature, and cortisol were measured over time from treatment to specified end points to capture the acute response period. Interactions between treatment and age (p = 0.035) and time and age (p < 0.001) were noted for cortisol. The 6W calves had lower cortisol compared to 6M calves at SHAM and CAST. Cortisol of 6W calves decreased from peak to pre-treatment levels faster than 6M calves. An interaction between time and age was reported in squared differences of inter-beat-intervals (RMSSD; p = 0.02) and high-frequency power (HFP; p = 0.05), whereby both responses decreased in 6W calves during the sampling period which was not seen in 3M and 6M calves. Average eye temperature (AET) differed by age (p = 0.0018) whereby 6W calves had lower AET than 6M calves (p = 0.0013) regardless of treatment and time. The findings suggest that responses to unmitigated surgical castration seem to be mediated by the autonomic nervous system in an age-related manner.

A nationwide survey on producer and veterinarian perceptions of the painfulness of procedures and disease states in dairy and beef cattle

“…Tshoner et al, ( 89 ) reported a greater frequency of use of both local and systemic analgesia by veterinarians as compared with producers for surgical castration in calves but also reported that surgical castration was rated as one of the most painful procedures out of the those included in the survey; although it is challenging to compare across studies due to differences in methodology, in the current study, the pain associated with surgical castration was not rated as high. Despite substantial evidence that surgical castration causes pain in cattle (e.g., 11 – 13 , 54 , 57 , 61 – 63 ) and some regulatory guidance existing in countries outside of the United States, the provision of pain mitigation for surgical castration, although increasing has not reached full adoption as a consistently implemented best management practice.…”

“…This result is also likely in part explained by the misleading notion that younger animals feel less pain. Research has established that young animals, i.e., calves, do feel pain ( 8 , 61 , 62 ) but the response is expressed differently both physiologically and behaviorally as compared with older animals ( 12 , 13 , 57 , 63 ). Additionally, research in rats and humans has demonstrated that pain and stress events experienced as infants can have long-lasting physiological impacts ( 64 ).…”

“…Significant research has been performed to identify repeatable indicators of pain in cattle that can subsequently be used to assess the effectiveness of various pain mitigation strategies (5)(6)(7)(8). It has been well-established that disease states, such as lameness (9,10), and husbandry procedures, such as castration (11)(12)(13) and disbudding (14)(15)(16) cause pain in cattle, yet adoption of pain mitigation practices for these procedures and conditions is not universal and is highly variable by management practice, disease, and industry sector (17)(18)(19).…”

Literature Review on Technological Applications to Monitor and Evaluate Calves’ Health and Welfare

“…Martin et al [ 103 ] did not find a decrease in the orbital temperature right after cautery disbudding, with cornual nerve blocking. Bergamasco et al [ 109 ] observed a drop in the mean temperature of the eye immediately after castration (without pain control) and sham castration. These results suggest that the decrease in the temperature of the ocular region can be related to both stress and pain responses.…”

“…HRMs are usually fitted with a belt tied up behind the calf’s foreleg. Shaving the application site and using ultrasound gel can be used to facilitate electrode contact with the thorax [ 109 ]. The HRM usually only stays fitted in the animal during a certain phase of the trial period, around 15 to 60 min [ 81 , 109 , 118 , 119 ], in order to record the intended measurement interval, from which data can be directly obtained (Bluetooth [ 118 ]) or downloaded after to a computer [ 109 ].…”