Summary: Dairy cattle are handled frequently, and broken tails can result from improper handling. The aim of this crosssectional study was to determine cow-level factors that may be associated with the occurrence of broken tails in dairy cattle. Multiparous cows had a greater prevalence of broken tails than primiparous cows. Cows who were treated for mastitis twice or more had a greater prevalence of broken tails than cows treated once or never. These findings suggest that the longer a cow was present on the farm and the more times a cow was treated for an intramammary infection, the more likely she was to experience a broken tail.

Three penetrating captive bolt (PCB) placements were tested on cadaver heads from swine with estimated body weight (BW) >200 kg (sows = 232.9 ± 4.1 kg; boars = 229.3 ± 2.6 kg). The objectives were to determine tissue depth, cross-sectional brain area, visible brain damage (BD), regions of BD, and bolt-brain contact; and determine relationships between external head dimensions and tissue depth at each placement. A Jarvis PAS – Type P 0.25R PCB with a Long Stunning Rod Nosepiece Assembly and 3.5 gr power loads was used at the following placements on heads from 111 sows and 46 boars after storage at 2-4° C for approximately 62 h before treatment: FRONTAL (F) – 3.5 cm superior to the optic orbits at midline, TEMPORAL (T) – at the depression posterior to the lateral canthus of the eye within the plane between the lateral canthus and the base of the ear, or BEHIND EAR (BE) – directly caudal to the pinna of the ear on the same plane as the eyes and targeting the middle of the opposite eye. For sows, the bolt path was in the plane of the brain for 42/42 (100%, 95% CI: 91.6-100.0%) F heads, 39/40 (97.5%, 95% CI: 86.8-99.9%) T heads, and 34/39 (87.5%, 95% CI: 72.6-95.7%) BE heads; for the heads that could reliably be assessed for BD damage was detected in 25/26 (96.2%, 95% CI: 80.4-99.9%) F heads, 24/35 (68.6%, 95% CI: 50.7-83.2%) T heads, and 5/40 (12.5%, 95% CI: 4.2-26.8%) BE heads. For boars, the bolt path was in the plane of the brain for 17/17 (100.0%, 95% CI: 80.5-100.0%) F heads, 18/18 (100.0%, 95% CI: 81.5-100.0%) T heads, and 14/14 (100.0%, 95% CI: 76.8-100.0%) BE heads; damage was detected in 11/12 (91.7%, 95% CI: 61.5-99.8%) F heads, 2/15 (13.3%, 95% CI: 1.7-40.5%) T heads, and 7/14 (50.0%, 95% CI: 23.0-77.0%) BE heads. Tissue depth was reported as mean ± standard error followed by 95% one-sided upper reference limit (URL). For sows, total tissue thickness was different (P < 0.05) between placements (F: 52.7 ± 1.0 mm, URL: 64.1 mm; T: 69.8 ± 1.4 mm, URL: 83.9 mm; BE: 89.3 ± 1.5 mm, URL: 103.4 mm). In boars, total tissue thickness was different (P < 0.05) between placements (F: 41.2 ± 2.1 mm, URL: 56.3 mm; T: 73.2 ± 1.5 mm, URL: 83.4 mm; BE: 90.9 ± 3.5 mm, URL: 113.5 mm). For swine > 200 kg BW, F placement may be more effective than T or BE due to less soft tissue thickness, which may reduce concussive force. The brain was within the plane of bolt travel for 100% of F heads with brain damage for 96.2% and 91.7% of F sow and boar heads, respectively.

The main objective of this study was to describe tissue thicknesses of cadaver heads from physically castrated market barrows (PC MARKET BARROWS) and immunocastrated boars (IC BOARS) at the frontal penetrating captive bolt (PCB) placement. Other objectives were to describe differences in bolt force and energy requirements to penetrate and describe potential for bolt-thalamus contact. Forty-four heads were obtained from PC MARKET BARROWS (n = 22) and IC BOARS (n = 22) of similar age and size that were rendered insensible with CO₂. Mean HCW was 117.32 ± 3.52 kg. Snout to poll distance (cm) and maximum deflection distance (cm) were collected in duplicate. Heads were split at midline with a bandsaw and soft tissue and cranial thicknesses were measured with a digital caliper. Images of each cut surface were collected to evaluate the potential for thalamic damage. Tissue samples were retained from each half of each head and a universal tester was used to determine maximum force and energy of bolt penetration. There was no evidence to support a significant difference (P > 0.05) in tissue thicknesses between PC MARKET BARROWS and IC BOARS. Maximum deflection distance (maximum distance from a straight edge that was placed from the tip of the snout to the poll of the head) was not different (P = 0.10) between PC MARKET BARROWS (3.31 ± 0.10 cm) and IC BOARS (3.08 ± 0.10 cm). There was no evidence to support a difference (P = 0.77) in maximum force between PC MARKET BARROWS (7130.32 ± 483.23 N) and IC BOARS (6974.60 ± 463.70 N). There was also no evidence to support a difference (P = 0.62) in maximum energy between PC MARKET BARROWS (33.37 ± 2.77 J) and IC BOARS (32.04 ± 2.50 J). For PC MARKET BARROWS, there was a difference (P = 0.05) between the number of heads where the thalamus was located within the theoretical plane of bolt travel for market placement (21/21) versus mature placement (16/21). For IC BOARS, the number of heads where the thalamus was located within the plane of theoretical bolt path was not different between the two PCB placements (19/21 each). Overall, the data suggest that tissue profiles of PC MARKET BARROWS and IC BOARS do not differ at the frontal PCB placement site and the mechanical tools that are effective for PC MARKET BARROWS should also be effective for IC BOARS. Euthanasia is a procedure that cannot be avoided on swine farms. One common method for euthanizing swine is penetrating captive bolt (PCB); this involves passing a metal bolt through the skull and into the brain, resulting in immediate unconsciousness. PCB use has been evaluated for market hogs and breeding sows and boars, but not for immunocastrated boars. It is unknown whether the skull thickness of immunocastrated boars is similar to that of market hogs, or if it increases and resembles that of mature breeding swine. Immunocastrated boars are becoming more common in US swine production because the painful procedure of castration is eliminated, the expression of sexual characteristics and associated meat quality defects are prevented. Evaluating the tissue profile at the common PCB application site on the front of the head allows for caretakers to select appropriate PCB devices for euthanasia of immunocastrated boars. We found that there was no evidence to support a difference between soft tissue thickness, cranial thickness, total tissue thickness, captive bolt penetration force and energy, and potential for bolt-thalamus contact between market hogs and immunocastrated boars. This finding suggests that PCB devices that are effective for market hogs should also be effective for immunocastrated boars.

The definition of animal welfare includes how an animal dies. As such, euthanasia is intrinsically linked to animal welfare, and ensuring a good death through effective, safe, and validated practices is a critical piece of promoting positive animal welfare. The objective of this review is to provide a better understanding of the literature on the euthanasia of swine via penetrating captive bolt (PCB) and nonpenetrating captive bolt (NPCB), as well as a history of captive bolt use, and indicators of sensibility and insensibility. To do this, we performed a systematic review that included 30 peer-reviewed articles and 17 other publications. NPCB devices have been validated as an effective single-step euthanasia method for neonatal and preweaning swine, as well as a two-step euthanasia method for nursery swine. PCB devices have been validated as an effective euthanasia method for nursery and market swine up to 120 kg, but further investigation is required for the use of captive bolt devices on mature breeding sows and boars.

Penetrating captive bolt (PCB) is a common method of euthanasia for swine but has not been evaluated for mature swine < 200 kg body weight (BW). The objectives were to determine tissue depth, brain contact plane, and visible brain tissue damage (brain damage[BD]) for the common FRONTAL (F) and alternative TEMPORAL (T) and BEHIND EAR (BE) placements for PCB use on sows and boars weighing < 200 kg. Cadaver heads were obtained from 30 sows and 30 boars (estimated BW, mean ± SD; sows: 165.8 ± 22.4 kg; boars: 173.6 ± 21.4 kg) from a slaughter establishment after electrical stunning and exsanguination. Heads were cooled at 2 to 4 °C for approximately 64 h. A Jarvis PAS-Type P 0.25R PCB with a Long Stunning Rod Nosepiece Assembly and a 3.5 GR power load was used for all PCB applications at the following placements: F–3.5 cm superior to the optic orbits at midline, T–at the depression posterior to the lateral canthus of the eye within the plane between the lateral canthus and the base of the ear, or BE–directly caudal to the pinna of the ear on the same plane as the eyes and targeting the middle of the opposite eye. For sows, the bolt path was in the brain for 10/10 (100.0%, 95% CI: 69.2% to 100.0%) F, T, and BE heads. In heads that could reliably be assessed for BD, BD was detected in 10/10 (100.0%, 95% CI: 69.2% to 100.0%) F heads, 9/9 (100.0%, 95% CI: 66.4% to 100.0%) T heads, and 0/10 (0.0%, 95% CI: 0.0% to 30.1%) BE heads. For boars, the bolt path was in the plane of the brain for 8/9 (88.9%, 95% CI: 51.8% to 99.7%) F heads, 9/10 (90.0%, 95% CI: 55.5% to 99.7%) T heads, and 11/11 (100.0%, 95% CI: 71.5% to 100.0%) BE heads. In heads that could reliably be assessed for BD, BD was detected in 8/9 (88.9%, 95% CI: 51.7% to 99.7%) F heads, 7/10 (70.0%, 95% CI: 34.8% to 93.3%) T heads, and 4/11 (36.4%, 95% CI: 10.9% to 69.2%) BE heads. Tissue depth was reported as mean ± SE followed by 95% one-sided upper reference limit (URL). For sows, total tissue thickness differed (P < 0.05) between placements (F: 49.41 ± 2.74 mm, URL: 70.0 mm; T: 62.83 ± 1.83 mm, URL: 76.6 mm; BE: 84.63 ± 3.67 mm; URL: 112.3 mm). Total tissue thickness differed (P < 0.05) between placements for boars (F: 54.73 ± 3.23 mm, URL: 77.6 mm; T: 70.72 ± 3.60 mm, URL: 96.3 mm; BE: 92.81 ± 5.50 mm; URL: 135.3 mm). For swine between 120 and 200 kg BW, the F placement may have the greatest likelihood for successful euthanasia due to the least total tissue thickness and may present less risk for failure than the T and BE placements. Euthanasia is an important procedure to protect animal welfare and cannot be avoided on swine farms. A common method of euthanasia for swine is penetrating captive bolt (PCB), which involves passing a metal bolt through the skull into the brain. This process should result in an immediate loss of consciousness. The use of PCB has been evaluated for market hogs and heavier sows and boars, but not for sows and boars weighing < 200 kg. As pigs mature, the cranial thickness at the common frontal PCB placement increases due to the expansion of sinus cavities. This makes PCB euthanasia more challenging for sows and boars. As a result, alternative PCB application sites, including behind the ear and at a temporal location, have been proposed. This study evaluated frontal, temporal, and behind-ear placements for PCB application to cadaver heads from sows and boars weighing < 200 kg. The frontal placement appeared to be more reliable than the temporal or behind ear placements due to the least tissue for the bolt to travel through to reach the brain, the greatest potential target area, and prevalent brain damage.

Penetrating captive bolt (PCB) is the primary method of preslaughter stunning for cattle and is also used for on-farm euthanasia. The objective of this study was to quantify the impact of cooling on the soft tissue thickness, cranial thickness, total tissue thickness, and cross-sectional brain area of cadaver heads collected from mature (> 30 mo of age) dairy cows following the application of a PCB stun in a frontal placement. Hide-on cadaver heads were obtained from culled dairy cows (N = 37) stunned in a frontal location using a handheld PCB device (Jarvis Model PAS—Type C 0.25R Caliber Captive Bolt, Long Bolt) at a commercial slaughter establishment. Following transport to the University of Wisconsin—River Falls, heads were split at midline along the bolt path by a bandsaw and then underwent FRESH, CHILL24, CHILL48, and CHILL72 refrigeration treatments. The FRESH treatment involved images collected immediately after splitting each head, the CHILL24 treatment involved images collected after 24 h of refrigeration, the CHIL48 treatment involved images collected after 48 h of refrigeration, and the CHILL72 treatment involved images collected after 72 h of refrigeration. Measurements of soft tissue thickness, cranial thickness, total tissue thickness, and cross-sectional brain area were recorded for each refrigeration treatment. Soft tissue thickness did not differ caudal to (P = 0.3751) or rostral to (P = 0.2555) the bolt path. Cranial thickness did not differ caudal to (P = 0.9281) or rostral to (P = 0.9051) the bolt path. Total tissue thickness did not differ caudal to (P = 0.9225; FRESH: 24.77 mm, CHILL24: 23.93 mm, CHILL48: 24.27 mm, CHILL72: 42.30, SE: 0.86) or rostral to (P = 0.8931; FRESH: 24.09 mm, CHILL24: 23.99, CHILL48: 24.26, CHILL72: 24.43 mm, SE: 0.79 mm) the bolt path. Cross-sectional brain area was not different (P = 0.0971) between refrigeration treatments (FRESH: 9,829.65 ± 163.87 mm², CHILL24: 10,012.00 ± 163.87 mm², CHILL48: 9,672.43 ± 163.87 mm², CHILL72: 10,235.00 ± 166.34 mm²). This study demonstrated that FRESH tissue parameters can be determined from cattle cadaver heads refrigerated for 24, 48, or 72 h. Euthanasia and preslaughter stunning are important to animal welfare. Penetrating captive bolt (PCB) is the primary method of preslaughter stunning for cattle and is also used for euthanasia. PCB causes severe brain damage by passing a metal bolt through the skull and into the brain of the animal. An immediate loss of consciousness should result from this process. There has been a growing interest in understanding various aspects of PCB stunning and euthanasia for cattle, including the impacts of bolt length and PCB placement. Much of the literature in this space includes the assessment of brain damage. The brain is a semifluid structure, which makes it difficult to assess brain damage after splitting cadaver heads with a bandsaw without refrigeration. It is unknown whether refrigerated cow heads can be used as a model for fresh heads, or if refrigeration significantly modifies the tissues. This study evaluated the impact of four refrigeration periods (0, 24, 48, and 72 h) on tissue parameters associated with the frontal PCB placement using cadaver heads from culled dairy cows. Refrigeration time did not change the tissue parameters, suggesting that a refrigeration period can be used to improve brain rigidity without mathematical adjustments to tissue parameters.