Evaluation of Stress Response under a Standard Euthanasia Protocol in Horses Using Analysis of Heart Rate Variability.
Authors: Gehlen Heidrun, Loschelder Johanna, Merle Roswitha, Walther Maike
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Heart Rate Variability as an Indicator of Stress During Equine Euthanasia German researchers examined whether heart rate variability (HRV) could reliably detect stress responses during euthanasia in 40 horses across varied settings, using telemetric electrocardiography to measure low-frequency (LF) and high-frequency (HF) components alongside the sympathovagal balance ratio (LF/HF) at three distinct protocol phases: initial sedation (xylazine ± butorphanol), anaesthetic induction (diazepam and ketamine), and the period from anaesthetic induction through pentobarbital administration. The analysis revealed statistically significant shifts in all HRV parameters across the three phases (p < 0.001), with pronounced sympathetic dominance evident during both the preparation phase and pentobarbital injection—suggesting heightened physiological stress at these critical junctures. Notably, neither the euthanasia location, owner presence, nor the horse's primary diagnosis influenced these stress markers; however, colicky horses demonstrated a concerning tendency towards resumed respiratory effort post-euthanasia, warranting investigation of modified protocols for this population. For practitioners involved in end-of-life care, these findings validate HRV as a sensitive, non-invasive tool for objectively assessing the horse's physiological state during euthanasia and suggest that further research into tailored anaesthetic approaches for colic cases may improve the humaneness of the procedure.
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Practical Takeaways
- •Heart rate variability analysis provides a sensitive, noninvasive method to assess stress during equine euthanasia procedures, potentially helping refine protocols
- •Environmental factors (location, owner presence) do not significantly affect the physiological stress response during euthanasia, so standardization of these conditions is not necessary
- •Colic cases may require modified euthanasia protocols to prevent breathing reoccurrence; further research is needed to optimize euthanasia in this population
Key Findings
- •Significant differences in heart rate variability (LF, HF, and LF/HF ratio) were found between the three euthanasia phases (sedation, anesthesia, anesthesia until death; p < 0.001)
- •Dominating sympathetic activity occurred during the preparation phase and pentobarbital injection, indicating stress response
- •Location of euthanasia, owner presence, and primary disease type had no influence on HRV stress parameters
- •Horses with colic were more likely to show reoccurrence of breathing during euthanasia despite similar HRV patterns