A Comparison of Intravenous and Oral Transmucosal Administration of Pentobarbital Sodium for Humane Euthanasia in White Leghorn Chickens (Gallus gallus domesticus)

Euthanasia is a common veterinary medical procedure performed on terminally ill backyard chickens (<i>Gallus gallus domesticus</i>). To reduce stress for these animals, it is important to develop a euthanasia protocol that provides a rapid and humane death. For this prospective research investigation, we evaluated 2 different methods of euthanasia in chickens. Twenty-two adult female leghorn chickens were administered an intravenous (IV, n = 11) or oral transmucosal (OTM, n = 11) 602 mg/kg dose of pentobarbital sodium solution for humane euthanasia. Loss of consciousness (LOC) occurred in 95.4% (21/22) of the birds within 5 minutes. Both apnea and asystole were achieved in 100% (11/11) of the birds in the IV group and 54.5% (6/11) of the birds in the OTM group after 5 minutes; 45.5% (5/11) of the chickens in the OTM group had to be rescued. Birds administered the euthanasia solution IV were found to have faster times to LOC (Mann-Whitney <i>U</i> [MW]=110.5, <i>P</i> < 0.001), asystole (MW: 121, <i>P</i> < 0.001), and apnea (MW: 121, <i>P</i> < 0.001) compared with the OTM chickens. Overall, the OTM route for administering pentobarbital sodium in chickens resulted in a reliable LOC in all but 1 bird; however, it did not result in apnea and asystole for all birds within 5 minutes. Based on the results of this study, the OTM administration of pentobarbital sodium is not a reliable method to euthanize chickens.