Meeting Abstract

38.11  Tuesday, Jan. 5  Science based criteria for assessing humane euthanasia BRYER, PJ*; DAVIS, BL; SUTHERLAND, MA; Lamar University, Beaumont TX; Texas Tech University, Lubbock TX; AgResearch, Hamilton NZ pamela.bryer@lamar.edu

Humane methods of on-farm euthanasia are currently a topic of interest both for producers and the public. There are many different views on what is considered humane euthanasia. Clear, objective, and measurable assessment endpoints that indicate distress and pain are needed to compare and contrast existing and developing euthanasia methods. The AVMA says inhalation of gases is one of the most humane euthanasia methods and is used extensively in laboratory animals. We euthanized piglets ranging from 1 to 6 weeks old using a 100% CO₂ gradual-fill protocol (n=5/ wk). An additional group of 3 week old pigs (n=5) were euthanized via a 100% CO₂ pre-fill protocol. Behaviors associated with asphyxiation, escape, and consciousness were recorded. Blood was collected before and after death for plasma cortisol. Older pigs took longer to sense the CO₂ gas due to their taller height. After the initial gas sensing however, age did not influence the onset of any behaviors or timing of death. Pre-fill pigs showed consistently shorter intervals to unconsciousness and death. Cortisol concentrations rose dramatically in all pigs following euthanasia (t=1.69, df=34, p<0.0001). Age did not effect the cortisol response to euthanasia (p= 0.08, r²= 0.10). Pre-fill pigs had a lower cortisol increase than similarly aged gradual-fill pigs (t=2.78, df=4, p=0.049). Age did not appear to affect pigs’ responses to 100% CO₂ gas. Pre-filling the chamber decreased the amount of time to unconsciousness and to death; this in turn may have contributed to lower cortisol levels. These results indicate that the more intense pre-fill chamber experience may ultimately be more humane because of the shorter period of suffering.