It is inevitable in every swine production system young pigs not recovering from disease, weakness, or trauma will need to be euthanized in a timely, humane, and safe manner. The industry continues to be scrutinized about how euthanasia can be effectively accomplished. This can be especially problematic with suckling pigs. Currently approved methodologies such as blunt force trauma, non-penetrating captive bolt, and carbon dioxide receive heavy criticism from consumers and animal rights organizations. Additionally, these methods may impact the caregivers’ well-being and psychology.
Electrocution induces a loss of consciousness in a rapid, timely manner, and requires little training3. Electrocution, if effectively administered will render the brain insensible and initiate cardiac fibrillation and death1. Traditionally, electrocution has not been used on young pigs under 10 pounds because the resistance around the skin can be less than that across the body causing the electrical current to flow on the skin’s surface rather than through the body. Preliminary trials of the electrode design of S & R Resources, LLC appear to overcome the previous disadvantage. In addition, this novel device is equipped with user safety features that limit the chance of electrical exposure to the user. The focus of this research was to validate that this novel electrocution device provides a safe, humane alternative to current euthanasia methods available for young pigs from birth to 15 pounds.
The first consideration with euthanasia via electrocution is validating that the method causes a rapid loss of consciousness (Phase I). Initially, a minimal time to loss of consciousness was determined for 2 different times of electrocution in 3 different age and weight groups: Pigs less than 3 days of age and less than 5 pounds (n=10), pigs greater than 3 days of age and less than 5 pounds (n=10), and pigs greater than 3 days of age and greater than 5 pounds (n=10). Thirty commercial pigs ranging from birth to 15 pounds were identified as being ill, unthrifty, or fallouts. These animals were lightly anesthetized to Stage 3 Plane 1 (palpebral responses present) prior to electrocution5. They were then placed in the electrocution device and a 110-120 voltage alternating current (VAC) was applied for 3 or 5 seconds. Parameters measured included tong placement relative to weight, voltage, and amperage. Cardiac and brain electrical activity were monitored using an electrocardiogram and an electroencephalogram, respectively. All electrocutions were videotaped and motor activities such as kicks, paddling, gasps or vocalization were recorded. Additionally, the pigs were evaluated for dilation of pupils, absence of corneal reflexes, and absence of nociceptive reflexes to determine unconsciousness to the level of Stage 3 Plane 2 (surgical loss of consciousness)5. If this level of loss of consciousness was confirmed in a specific age/weight group, that cohort was allowed to remain in the study. The electrocution device was successful in inducing a loss of consciousness in all pigs at 5 seconds and 3 second duration for the groups >3 days of age, <5 pounds and >3 days of age, > 5 pounds. However, the <3 days, < 5 pound cohort was eliminated from Phase II of the trial due to a poor stunning success rate (70% success) at the 5 second electrocution interval. Any pigs that did not lose consciousness by electrocution were immediately and humanely euthanized via Pentobarbitol injection. If a pig started to regain consciousness after loss of consciousness, these pigs were also humanely euthanized.
In Phase II of the trial, 66 commercial sick pigs (>3 days of age, <5 pounds; and >3 days of age, > 5 pounds) were sedated and euthanized via electrocution at time intervals of 5, 10, and 15 seconds. The same monitoring equipment and data collection parameters were used as in Phase I. Successful death events were recorded in 98.5% of pigs. The one unsuccessful euthanasia occurred in the >3 days of age and <5 pound group at 15 seconds.
Caregiver well being during implementation and emotional response to the perception of the quality of death is an important consideration of the euthanasia method and design of this novel device. One of the disadvantages of electrocution euthanasia is that there is sudden stiffening and extension of the limbs, head, and neck2. This device is designed with a door that will block the caregiver’s view of the pig during the electrocution and is also a safety feature. The other most common involuntary reflex observed was occasional pig gasps (53%) or singular kicks (9.1%) after Stage 3 Level 2 unconsciousness and during and/or after death.
This study indicates that electrocution using this novel device is a humane form of euthanasia when carried out in piglets greater than 3 days of age. Electrocution reliably induced unconsciousness at less than or equal to 3 seconds after the application of current. Additionally, electrocution repeatedly induced death in piglets greater than 3 days of age at time periods equal to or greater than 5 seconds of current application.
This research was funded by the National Pork Checkoff. Any questions may directed to: Sarah Probst Miller, DVM at [email protected] A special thanks goes to project co-investigators: Aaron Lower, DVM, Carthage Veterinary Service;, Sherrie Clark, DVM, PhD, University of Illinois; and student intern Jessica McKinney, University of Illinois College of Veterinary Medicine. We also thank the other student interns who assisted with the trial.
