title: Effectiveness of a nonpenetrating captive bolt for euthanasia of 3 kg to 9 kg pigs.
abstract: The objective of this study was to determine the effectiveness of a nonpenetrating captive bolt, Zephyr-E, for euthanasia of suckling and weaned pigs from 3 to 9 kg (5-49 d of age) using signs of insensibility and death as well as postmortem assessment of traumatic brain injury (TBI). The Zephyr-E was used by 15 stock people to euthanize 150 compromised pigs from 4 farrowing and nursery units from commercial farms and 2 research stations. Brainstem reflexes, convulsions, and heartbeat were used to assess insensibility, time of brain death, and cardiac arrest following Zephyr-E application. Skull fracture displacement (FD) was quantified from computed tomography (CT) scans (n = 24), macroscopic scoring was used to assess brain hemorrhage and skull fracture severity (n = 150), and microscopic scoring was used to assess subdural hemorrhage (SDH) and parenchymal hemorrhage within specific brain regions that are responsible for consciousness and vital function (n = 32). The Zephyr-E caused immediate, sustained insensibility until death in 98.6% of pigs. On average, clonic convulsions (CC) ceased in 82.2 s (± 3.4 SE), brain death was achieved in 144.9 s (± 5.4 SE), and cardiac arrest occurred in 226.5 s (± 8.7 SE). Time of brain death and cardiac arrest differed significantly among stock people (P = 0.0225 and P = 0.0369). Age was positively related to the duration of CC (P = 0.0092), time of brain death (P = 0.0025), and cardiac arrest (P = 0.0068) with shorter durations seen in younger pigs. Average FD was 8.3 mm (± 1.0 SE). Macroscopic scores were significantly different among weight classes for subcutaneous (P = 0.0402) and subdural-ventral (P = 0.0037) hemorrhage with the lowest severity hemorrhage found in the 9-kg weight category. Microscopic scores differed among brain sections (P = 0.0070) for SDH with lower scores found in the brainstem compared to the cerebral cortex and midbrain. Parenchymal hemorrhage differed among brain sections (P = 0.0052) and weight categories (P = 0.0128) with the lowest scores in the midbrain and brainstem and the 7- and 9-kg weight categories. The Zephyr-E was highly effective for the euthanasia of pigs up to 9 kg (49 d) based on immediate insensibility sustained until death. Postmortem results confirmed that severe skull fracture and widespread brain hemorrhage were caused by the Zephyr-E nonpenetrating captive bolt.
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Guelph, ON, Canada N1G 2W1.
authors.forename: T M
authors.initials: TM
authors.lastname: Casey-Trott
authors.affiliation: Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames 50011-1250.
authors.forename: S T
authors.initials: ST
authors.lastname: Millman
authors.affiliation: Department of Pathobiology, University of Guelph, Guelph, ON, Canada N1G 2W1.
authors.forename: P V
authors.initials: PV
authors.lastname: Turner
authors.affiliation: Ontario Veterinary College, Health Sciences Centre, Primary Healthcare Centre, Guelph, ON, Canada N1G 2W1.
authors.forename: S G
authors.initials: SG
authors.lastname: Nykamp
authors.affiliation: Ontario Ministry of Agriculture and Food, Guelph, ON, Canada N1G 4Y2.
authors.forename: P C
authors.initials: PC
authors.lastname: Lawlis
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Guelph, ON, Canada N1G 2W1 twidowsk@uoguelph.ca.
authors.forename: T M
authors.initials: TM
authors.lastname: Widowski
mesh_terms: D000367:Age Factors; D000827:Animal Welfare / Q000592:standards*; D000818:Animals; D000831:Animals, Newborn / Q000293:injuries*; D001835:Body Weight; D020201:Brain Hemorrhage, Traumatic / Q000175:diagnosis / Q000453:epidemiology / Q000662:veterinary; D004867:Equipment Design; D004864:Equipment and Supplies / Q000592:standards / Q000662:veterinary*; D037901:Euthanasia, Animal / Q000379:methods*; D006323:Heart Arrest / Q000175:diagnosis / Q000453:epidemiology / Q000662:veterinary; D015994:Incidence; D012640:Seizures / Q000175:diagnosis / Q000453:epidemiology / Q000662:veterinary; D012887:Skull Fractures / Q000175:diagnosis / Q000453:epidemiology / Q000662:veterinary; D013552:Swine / Q000293:injuries*
keywords: animal welfare; captive bolt; euthanasia; insensibility; nursery; pig