Scientific Abstract

Three penetrating captive bolt (PCB) application sites were tested on cadaver heads from sows and boars with estimated BW > 200 kg. The objectives were to determine the tissue depth, cross-sectional brain area (CSBA), regions of brain damage, and visible brain damage (BD) for each of the sites; and to determine the relationship between external dimensional head measurements and tissue depth, CSBA, regions of brain damage, and BD associated with each of the sites. The PCB device was a Jarvis Model PAS – Type P 0.25R equipped with Long Stunning Rod Nosepiece Assembly and 3.5 grain powder cartridges. The three treatments were: FRONTAL – shot placed 3.5 cm superior to a line drawn across the top of the eyes at midline, TEMPORAL – shot placed 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 – shot placed directly caudal to the pinna of the ear on the same plane as the eyes and targeting the middle of the opposite eye. Heads were obtained from 111 sows and 46 boars that were slaughtered at a regional abattoir and stored in a walk-in cooler for approximately 62 h at 2-4° C prior to treatment. BD was detected in digital images from 96.26% (95% CI: 87.43 – 99.95%) of sows and boars combined in the FRONTAL treatment, 47.27% (95% CI: 33.65 – 61.20%) in the TEMPORAL treatment, and 27.78% (95% CI: 16.46 – 41.64%) in the BEHIND EAR treatment. Soft tissue thickness was greatest (P < 0.0001) for BEHIND EAR (59.2 ± 1.4 mm), followed by TEMPORAL (51.7 ± 1.4 mm), and was least for FRONTAL (6.0 ± 0.05 mm). Cranial thickness was greatest (P < 0.0001) for FRONTAL (41.0 ± 1.5 mm), followed by BEHIND EAR (30.9 ± mm), and was least for TEMPORAL (19.8 ± 1.5 mm). Total tissue thickness was greatest (P < 0.0001) in BEHIND EAR (90.1 ± 1.3 mm), followed by TEMPORAL (71.5 ± 1.3 mm), and was least for FRONTAL (47.0 ± 1.3 mm). CSBA was greatest (P < 0.0001) for FRONTAL (4194.4 ± 160.3 mm2), followed by BEHIND EAR (2618.7 ± 160.3 mm2), and least for TEMPORAL (1546.2 ± 160.3 mm2). Positive linear relationships were identified regarding the impacts of maximum deflection distance of the frontal profile of the head and head weight on cranial thickness and total tissue thickness in the FRONTAL position in a subset of 19 sow heads (P < 0.0001). FRONTAL placement of the PCB used in this study may present the least risk of euthanasia failure in sows and boars > 200 kg BW.