Simple Summary Pig farmers are forced to euthanize a significant number of pigs due to injuries, hernias, or unthriftiness. The majority of pigs are euthanized using carbon dioxide gas asphyxiation. However, the humaneness of carbon dioxide is being increasingly questioned. An alternative is the use of nitrous oxide gas. We conducted this study to compare the euthanasia of young pigs using nitrous oxide or carbon dioxide. In addition, we tested the administration of a pain relief drug prior to carbon dioxide exposure to determine if we could eliminate behaviors indicative of pain. Pigs became unable to control their muscle movement, breathed heavily, and lost posture at the same time regardless of treatment. Pigs exposed to both gases showed heavy breathing and open-mouth breathing prior to losing posture. However, pigs exposed to carbon dioxide made more escape attempts but fewer squeals than pigs exposed to nitrous oxide. Administration of pain relief prior to exposure to carbon dioxide did not alter behaviors indicative of pain. The findings are inconclusive as to whether using nitrous oxide is significantly better than using carbon dioxide, but the results show that its use is just as effective, and possibly more humane.