Research Summary - 4
Evaluation of Clinical and Electrophysiological Changes During Intrathecal Lidocaine Euthanasia in Anesthetized Sheep
| Date/Time: |
8/29/2026
15:30
|
| Author: |
Jenna E Bayne |
| Clinic: |
Auburn University College of Veterinary Medicine |
| City, State, ZIP: |
Auburn, AL 36849 |
J.E. Bayne , DVM, PhD, DACVIM
1
;
R.C. Cole , DVM, DACVR, DACVR-EDI
1
;
J.E. Stockler , DVM, DACVIM
1
;
A.B. Yanke , DVM, MS, DACVIM
1
;
A. Michael , DVM, PhD, DACVP
2
;
R. Dewell , DVM, MS
3
;
1Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL
2Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL
3Center for Food Security and Public Health, College of Veterinary Medicine, Iowa State University, Ames, IA
Introduction:
Livestock euthanasia methods must be efficacious, safe, and minimize environmental risks. Concerns regarding barbiturate residues and limited appropriateness of physical methods in certain situations have prompted interest in alternative approaches. Intrathecal lidocaine is an AVMA-approved method in horses and may address these concerns; however, data in small ruminants remain limited.
The objectives of this study were to characterize clinical and electrophysiological changes during euthanasia of anesthetized sheep using intrathecal lidocaine, including time to respiratory and cardiovascular arrest and loss of brainstem activity, assessed via clinical parameters, electrocardiography (ECG), and electroencephalography (EEG).
Materials and methods:
Twelve mature sheep were anesthetized and positioned in lateral recumbency. Cranial nerve reflexes, cardiorespiratory parameters (heart rate, respiratory rate, pulses), and electrophysiological activity (ECG, EEG) were continuously monitored. Lidocaine (4 mg/kg) was administered into the intrathecal space under ultrasound guidance. Monitoring continued until cessation of all activity, with confirmation of cardiac and respiratory arrest and brain death.
Results:
Brainstem reflexes were abolished within 30–60 seconds of the end of lidocaine administration in most animals. Respiratory arrest occurred within <60 seconds and consistently preceded loss of an audible heartbeat and palpable pulses (3–11 minutes). Agonal muscular activity was typically observed within 2 minutes. EEG inactivity across all leads occurred within <60 seconds to 5 minutes; however, transient spontaneous return of activity in 1–2 leads was observed in 7/12 sheep, with complete, sustained inactivity achieved by 11 minutes. ECG activity persisted longest (3–19 minutes), with cessation between 9 and 11 minutes in most animals.
Significance:
Intrathecal lidocaine effectively achieved euthanasia in anesthetized sheep. Clinical parameters typically used to confirm death were reliably established within 11 minutes post-infusion.
