FREE SHIPPING over $40
OVER 10000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Journal of veterinary internal medicine2015; 30(1); 289-303; doi: 10.1111/jvim.13813

Qualitative and Quantitative Characteristics of the Electroencephalogram in Normal Horses during Administration of Inhaled Anesthesia.

Abstract: The effects of anesthesia on the equine electroencephalogram (EEG) after administration of various drugs for sedation, induction, and maintenance are known, but not that the effect of inhaled anesthetics alone for EEG recording. Objective: To determine the effects of isoflurane and halothane, administered as single agents at multiple levels, on the EEG and quantitative EEG (qEEG) of normal horses. Methods: Six healthy horses. Methods: Prospective study. Digital EEG with video and quantitative EEG (qEEG) were recorded after the administration of one of the 2 anesthetics, isoflurane or halothane, at 3 alveolar doses (1.2, 1.4 and 1.6 MAC). Segments of EEG during controlled ventilation (CV), spontaneous ventilation (SV), and with peroneal nerve stimulation (ST) at each MAC multiple for each anesthetic were selected, analyzed, and compared. Multiple non-EEG measurements were also recorded. Results: Specific raw EEG findings were indicative of changes in the depth of anesthesia. However, there was considerable variability in EEG between horses at identical MAC multiples/conditions and within individual horses over segments of a given epoch. Statistical significance for qEEG variables differed between anesthetics with bispectral index (BIS) CV MAC and 95% spectral edge frequency (SEF95) SV MAC differences in isoflurane only and median frequency (MED) differences in SV MAC with halothane only. Conclusions: Unprocessed EEG features (background and transients) appear to be beneficial for monitoring the depth of a particular anesthetic, but offer little advantage over the use of changes in mean arterial pressure for this purpose.
Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.
Get Full Text
Publication Date: 2015-12-30 PubMed ID: 26714626PubMed Central: PMC4913671DOI: 10.1111/jvim.13813Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Clinical Trial
  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article discusses the effects of inhaled anesthetics on the brainwaves (EEG) of horses. It compares the impact of two common anesthetics, isoflurane and halothane, and finds that while they influence EEG, they may not provide a significant advantage when monitoring the depth of anesthesia over more traditional methods like checking arterial pressure.

Objective of the Study

The main goal of this research was to examine the effects of two inhaled anesthetics – isoflurane and halothane and how they impact a horse’s electroencephalogram (EEG). This is important as there is a need to monitor the depth of anesthesia during veterinary procedures, and EEG is one potential measure for this.

  • Isoflurane and halothane were chosen as they are commonly used in veterinary medicine for anesthesia.
  • The study specifically looked at how these anesthetics affected the EEG when administered at different concentrations (1.2, 1.4 and 1.6 MAC).
  • A digital EEG was recorded with video and quantitative EEG (qEEG) before and after anesthetic administration. The segments were then compared.

Research Methods

Six healthy horses underwent this study and various physiological measures were recorded alongside EEG data.

  • The anesthetics were administered in a controlled environment and the EEG changes were recorded under three different conditions – controlled ventilation (CV), spontaneous ventilation (SV), and during peroneal nerve stimulation (ST).
  • EEG variability was evaluated not only between different horses but also within individual horses over time.
  • Other measurements taken during the study included changes in mean arterial pressure and heart rate.

Results

The results indicated that changes in the raw EEG data were linked to the depth of anesthesia.

  • However, the study showed important variability in EEG readings not only between different horses but also within the same horse over time. This casts doubts on the accuracy of using EEG as a single measure of anesthesia depth.
  • Different anesthetics also produced different changes in the qEEG values. Isoflurane altered the bispectral index (BIS) under controlled ventilation and 95% spectral edge frequency (SEF95) during spontaneous ventilation. Halothane mainly affected the median frequency (MED) during spontaneous ventilation.

Conclusion

The study’s findings suggest that while EEG features might help monitor the depth of anesthesia, they don’t offer significant advantages over conventional methods such as monitoring arterial pressure. This potentially limits the utility of EEG as a standalone anesthetic depth monitor.

Cite This Article

APA
Williams DC, Brosnan RJ, Fletcher DJ, Aleman M, Holliday TA, Tharp B, Kass PH, LeCouteur RA, Steffey EP. (2015). Qualitative and Quantitative Characteristics of the Electroencephalogram in Normal Horses during Administration of Inhaled Anesthesia. J Vet Intern Med, 30(1), 289-303. https://doi.org/10.1111/jvim.13813

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 30
Issue: 1
Pages: 289-303

Researcher Affiliations

Williams, D C
  • William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA.
Brosnan, R J
  • Departments of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA.
Fletcher, D J
  • Section of Emergency and Critical Care, Cornell University, Ithaca, NY.
Aleman, M
  • Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA.
Holliday, T A
  • Departments of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA.
Tharp, B
  • Department of Neurology, University of California Davis Medical Center, Sacramento, CA.
Kass, P H
  • Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA.
LeCouteur, R A
  • Departments of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA.
Steffey, E P
  • Departments of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA.

MeSH Terms

  • Anesthesia, Inhalation / veterinary
  • Anesthetics, Inhalation / pharmacology
  • Animals
  • Cross-Over Studies
  • Electroencephalography / drug effects
  • Electroencephalography / veterinary
  • Halothane / pharmacology
  • Horses / surgery
  • Isoflurane / pharmacology

References

This article includes 46 references
  1. Otto K, Short CE. Cerebral responses in horses to halothane and isoflurane anesthesia: EEG power spectrum analysis and differences in arteriovenous oxygen content. Vet Anaesth Analg 1991;18(S1):85–99.
  2. Ekström PM, Short CE, Geimer TR. Electroencephalography of detomidine-ketamine-halothane and detomidine-ketamine-isoflurane anesthetized horses during orthopedic surgery. A comparison.. Vet Surg 1993 Sep-Oct;22(5):414-8.
    pubmed: 8236790doi: 10.1111/j.1532-950x.1993.tb00416.xgoogle scholar: lookup
  3. Johnson CB, Young SS, Taylor PM. Analysis of the frequency spectrum of the equine electroencephalogram during halothane anaesthesia.. Res Vet Sci 1994 May;56(3):373-8.
    pubmed: 8073190doi: 10.1016/0034-5288(94)90155-4google scholar: lookup
  4. Miller SM, Short CE, Ekström PM. Quantitative electroencephalographic evaluation to determine the quality of analgesia during anesthesia of horses for arthroscopic surgery.. Am J Vet Res 1995 Mar;56(3):374-9.
    pubmed: 7771707
  5. Otto KA, Voight S, Piepenbrock S, Deegen E, Short CE. Differences in quantitated electroencephalographic variables during surgical stimulation of horses anesthetized with isoflurane.. Vet Surg 1996 May-Jun;25(3):249-55.
    pubmed: 9012111doi: 10.1111/j.1532-950x.1996.tb01409.xgoogle scholar: lookup
  6. Johnson CB, Taylor PM. Effects of alfentanil on the equine electroencephalogram during anaesthesia with halothane in oxygen.. Res Vet Sci 1997 Mar-Apr;62(2):159-63.
    pubmed: 9243716doi: 10.1016/s0034-5288(97)90139-9google scholar: lookup
  7. Otto KA, Voigt S, Piepenbrock S. Effects of low dose ketamine on haemodynamic and electroencephalographic variables during surgery in isoflurane anaesthetised horses. J Vet Anaesth 1998;25:8–12.
  8. Johnson CB, Taylor PM. Comparison of the effects of halothane, isoflurane and methoxyflurane on the electroencephalogram of the horse.. Br J Anaesth 1998 Nov;81(5):748-53.
    pubmed: 10193288doi: 10.1093/bja/81.5.748google scholar: lookup
  9. Johnson CB, Bloomfield M, Taylor PM. Effects of ketamine on the equine electroencephalogram during anesthesia with halothane in oxygen.. Vet Surg 1999 Sep-Oct;28(5):380-5.
    pubmed: 10493643doi: 10.1111/j.1532-950x.1999.00380.xgoogle scholar: lookup
  10. Johnson CB, Bloomfield M, Taylor PM. Effects of guaiphenesin on the equine electroencephalogram during anaesthesia with halothane in oxygen.. Vet Anaesth Analg 2000 Jan;27(1):6-12.
    pubmed: 28404180doi: 10.1046/j.1467-2995.2000.00011.xgoogle scholar: lookup
  11. Johnson CB, Bloomfield M, Taylor PM. Effects of thiopentone on the equine electroencephalogram during anaesthesia with halothane in oxygen.. Vet Anaesth Analg 2000 Jul;27(2):82-88.
    pubmed: 28404058doi: 10.1046/j.1467-2995.2000.00022.xgoogle scholar: lookup
  12. Otto K, Short CE. Electroencephalographic power spectrum analysis as a monitor of anesthetic depth in horses.. Vet Surg 1991 Sep-Oct;20(5):362-71.
    pubmed: 1962420doi: 10.1111/j.1532-950x.1991.tb01284.xgoogle scholar: lookup
  13. Haga HA, Dolvik NI. Evaluation of the bispectral index as an indicator of degree of central nervous system depression in isoflurane-anesthetized horses.. Am J Vet Res 2002 Mar;63(3):438-42.
    pubmed: 11911581doi: 10.2460/ajvr.2002.63.438google scholar: lookup
  14. Murrell JC, Johnson CB, White KL, Taylor PM, Haberham ZL, Waterman-Pearson AE. Changes in the EEG during castration in horses and ponies anaesthetized with halothane.. Vet Anaesth Analg 2003 Jul;30(3):138-46.
    pubmed: 14498845doi: 10.1046/j.1467-2995.2003.00138.xgoogle scholar: lookup
  15. Johnson CB, Bloomfield M, Taylor PM. Effects of midazolam and sarmazenil on the equine electroencephalogram during anaesthesia with halothane in oxygen.. J Vet Pharmacol Ther 2003 Apr;26(2):105-12.
    pubmed: 12667179doi: 10.1046/j.1365-2885.2003.00459.xgoogle scholar: lookup
  16. Murrell JC, White KL, Johnson CB, Taylor PM, Doherty TJ, Waterman-Pearson AE. Investigation of the EEG effects of intravenous lidocaine during halothane anaesthesia in ponies.. Vet Anaesth Analg 2005 Jul;32(4):212-21.
    pubmed: 16008718doi: 10.1111/j.1467-2995.2005.00201.xgoogle scholar: lookup
  17. Haga HA, Dolvik NI. Electroencephalographic and cardiovascular variables as nociceptive indicators in isoflurane-anaesthetized horses.. Vet Anaesth Analg 2005 May;32(3):128-35.
    pubmed: 15877659doi: 10.1111/j.1467-2995.2005.00194.xgoogle scholar: lookup
  18. Auer JA, Amend JF, Garner HE. Electroencephalographic responses during volatile anesthesia in domestic ponies: A comparative study of isoflurane, enflurane, methoxyflurane, and halothane. J Equine Med Surg 1979;3:130–134.
  19. Lacombe VA, Podell M, Furr M, Reed SM, Oglesbee MJ, Hinchcliff KW, Kohn CW. Diagnostic validity of electroencephalography in equine intracranial disorders.. J Vet Intern Med 2001 Jul-Aug;15(4):385-93.
    pubmed: 11467598
  20. March PA, Muir WW. Bispectral analysis of the electroencephalogram: a review of its development and use in anesthesia.. Vet Anaesth Analg 2005 Sep;32(5):241-55.
    pubmed: 16135205doi: 10.1111/j.1467-2995.2005.00221.xgoogle scholar: lookup
  21. Rampil IJ. A primer for EEG signal processing in anesthesia.. Anesthesiology 1998 Oct;89(4):980-1002.
    pubmed: 9778016doi: 10.1097/00000542-199810000-00023google scholar: lookup
  22. Williams DC, Aleman M, Holliday TA, Fletcher DJ, Tharp B, Kass PH, Steffey EP, LeCouteur RA. Qualitative and quantitative characteristics of the electroencephalogram in normal horses during spontaneous drowsiness and sleep.. J Vet Intern Med 2008 May-Jun;22(3):630-8.
    pubmed: 18466241doi: 10.1111/j.1939-1676.2008.0096.xgoogle scholar: lookup
  23. Williams DC, Aleman M, Tharp B, Fletcher DJ, Kass PH, Steffey EP, LeCouteur RA, Holliday TA. Qualitative and quantitative characteristics of the electroencephalogram in normal horses after sedation.. J Vet Intern Med 2012 May-Jun;26(3):645-53.
    pubmed: 22489924doi: 10.1111/j.1939-1676.2012.00921.xgoogle scholar: lookup
  24. Steffey EP, Howland D Jr. Comparison of circulatory and respiratory effects of isoflurane and halothane anesthesia in horses.. Am J Vet Res 1980 May;41(5):821-5.
    pubmed: 7406305
  25. Steffey EP, Howland D Jr, Giri S, Eger EI 2nd. Enflurane, halothane, and isoflurane potency in horses.. Am J Vet Res 1977 Jul;38(7):1037-9.
    pubmed: 883711
  26. Grandy JL, Steffey EP, Miller M. Arterial blood PO2 and PCO2 in horses during early halothane-oxygen anaesthesia.. Equine Vet J 1987 Jul;19(4):314-8.
    pubmed: 3113935doi: 10.1111/j.2042-3306.1987.tb01419.xgoogle scholar: lookup
  27. Steffey EP, Howland D Jr. Cardiovascular effects of halothane in the horse.. Am J Vet Res 1978 Apr;39(4):611-5.
    pubmed: 646195
  28. Brosnan RJ, Steffey EP, LeCouteur RA, Farver TB, Imai A. Effects of duration of isoflurane anesthesia and mode of ventilation on intracranial and cerebral perfusion pressures in horses.. Am J Vet Res 2003 Nov;64(11):1444-8.
    pubmed: 14620783doi: 10.2460/ajvr.2003.64.1444google scholar: lookup
  29. Aleman M, Brosnan RJ, Williams DC, LeCouteur RA, Imai A, Tharp BR, Steffey EP. Malignant hyperthermia in a horse anesthetized with halothane.. J Vet Intern Med 2005 May-Jun;19(3):363-6.
    pubmed: 15954554doi: 10.1892/0891-6640(2005)19[363:mhiaha]2.0.co;2google scholar: lookup
  30. Keifer JC, Baghdoyan HA, Lydic R. Pontine cholinergic mechanisms modulate the cortical electroencephalographic spindles of halothane anesthesia.. Anesthesiology 1996 Apr;84(4):945-54.
    pubmed: 8638850doi: 10.1097/00000542-199604000-00023google scholar: lookup
  31. MERKEL G, EGER EI 2nd. A comparative study of halothane and halopropane anesthesia including method for determining equipotency.. Anesthesiology 1963 May-Jun;24:346-57.
    pubmed: 13935000doi: 10.1097/00000542-196305000-00016google scholar: lookup
  32. Sigl JC, Chamoun NG. An introduction to bispectral analysis for the electroencephalogram.. J Clin Monit 1994 Nov;10(6):392-404.
    pubmed: 7836975doi: 10.1007/bf01618421google scholar: lookup
  33. Todd MM. EEGs, EEG processing, and the bispectral index.. Anesthesiology 1998 Oct;89(4):815-7.
    pubmed: 9777995doi: 10.1097/00000542-199810000-00002google scholar: lookup
  34. . Bispectral index monitor: an evidence-based analysis.. Ont Health Technol Assess Ser 2004;4(9):1-70.
    pmc: PMC3387745pubmed: 23074459
  35. Schuller PJ, Newell S, Strickland PA, Barry JJ. Response of bispectral index to neuromuscular block in awake volunteers.. Br J Anaesth 2015 Jul;115 Suppl 1:i95-i103.
    pubmed: 26174308doi: 10.1093/bja/aev072google scholar: lookup
  36. Avidan MS, Zhang L, Burnside BA, Finkel KJ, Searleman AC, Selvidge JA, Saager L, Turner MS, Rao S, Bottros M, Hantler C, Jacobsohn E, Evers AS. Anesthesia awareness and the bispectral index.. N Engl J Med 2008 Mar 13;358(11):1097-108.
    pubmed: 18337600doi: 10.1056/nejmoa0707361google scholar: lookup
  37. Romanov A, Moon RS, Wang M, Joshi S. Paradoxical increase in the bispectral index during deep anesthesia in New Zealand white rabbits.. J Am Assoc Lab Anim Sci 2014 Jan;53(1):74-80.
    pmc: PMC3894651pubmed: 24411783
  38. Bleijenberg EH, van Oostrom H, Akkerdaas LC, Doornenbal A, Hellebrekers LJ. Bispectral index and the clinically evaluated anaesthetic depth in dogs.. Vet Anaesth Analg 2011 Nov;38(6):536-43.
    pubmed: 21988808doi: 10.1111/j.1467-2995.2011.00651.xgoogle scholar: lookup
  39. Lamont LA, Greene SA, Grimm KA, Tranquilli WJ. Relationship of feline bispectral index to multiples of isoflurane minimum alveolar concentration.. Comp Med 2005 Jun;55(3):269-74.
    pubmed: 16089176
  40. Kruluc P, Nemec A. Electroencephalographic and electromyographic changes during the use of detomidine and detomidine-butorphanol combination in standing horses.. Acta Vet Hung 2006 Mar;54(1):35-42.
    pubmed: 16613024doi: 10.1556/avet.54.2006.1.4google scholar: lookup
  41. Sleigh JW, Andrzejowski J, Steyn-Ross A, Steyn-Ross M. The bispectral index: a measure of depth of sleep?. Anesth Analg 1999 Mar;88(3):659-61.
    pubmed: 10072023doi: 10.1097/00000539-199903000-00035google scholar: lookup
  42. Tung A, Mendelson WB. Anesthesia and sleep.. Sleep Med Rev 2004 Jun;8(3):213-25.
    pubmed: 15144963doi: 10.1016/j.smrv.2004.01.003google scholar: lookup
  43. Brown EN, Lydic R, Schiff ND. General anesthesia, sleep, and coma.. N Engl J Med 2010 Dec 30;363(27):2638-50.
    pmc: PMC3162622pubmed: 21190458doi: 10.1056/nejmra0808281google scholar: lookup
  44. Nelson AB, Faraguna U, Tononi G, Cirelli C. Effects of anesthesia on the response to sleep deprivation.. Sleep 2010 Dec;33(12):1659-67.
    pmc: PMC2982736pubmed: 21120128doi: 10.1093/sleep/33.12.1659google scholar: lookup
  45. Tung A, Bergmann BM, Herrera S, Cao D, Mendelson WB. Recovery from sleep deprivation occurs during propofol anesthesia.. Anesthesiology 2004 Jun;100(6):1419-26.
    pubmed: 15166561doi: 10.1097/00000542-200406000-00014google scholar: lookup
  46. Grabow JD, Anslow RO, Spalatin J. Electroencephalographic recordings with multicontact depth probes in a horse.. Am J Vet Res 1969 Jul;30(7):1239-43.
    pubmed: 5815928

Citations

This article has been cited 8 times.
  1. Vinardell T, Elestwani S, Jamieson C, Karim E, Robin M, Glynn S, Benini R, Aleman M. Electroencephalographic evaluation under standing sedation using sublingual detomidine hydrochloride in Egyptian Arabian foals for investigation of epilepsy. J Vet Intern Med 2023 May-Jun;37(3):1209-1215.
    doi: 10.1111/jvim.16695pubmed: 37029498google scholar: lookup
  2. Baker-Cook BI, Moritz AL, Zwueste D, Schwean-Lardner K, Machin KL. Evaluation of intravenous T-61 as a euthanasia method for birds. Can Vet J 2021 Apr;62(4):367-373.
    pubmed: 33867548
  3. Öterkuş M, Dönmez İ, Nadir AH, Rencüzoğulları İ, Karabağ Y, Binnetoğlu K. The effect of low flow anesthesia on hemodynamic and peripheral oxygenation parameters in obesity surgery. Saudi Med J 2021 Mar;42(3):264-269.
    doi: 10.15537/smj.2021.42.3.20200575pubmed: 33632904google scholar: lookup
  4. Aleman M, Finno CJ, Weich K, Penedo MCT. Investigation of Known Genetic Mutations of Arabian Horses in Egyptian Arabian Foals with Juvenile Idiopathic Epilepsy. J Vet Intern Med 2018 Jan;32(1):465-468.
    doi: 10.1111/jvim.14873pubmed: 29171123google scholar: lookup
  5. Cousillas H, Oger M, Rochais C, Pettoello C, Ménoret M, Henry S, Hausberger M. An Ambulatory Electroencephalography System for Freely Moving Horses: An Innovating Approach. Front Vet Sci 2017;4:57.
    doi: 10.3389/fvets.2017.00057pubmed: 28512633google scholar: lookup
  6. Williams DC, Aleman MR, Brosnan RJ, Fletcher DJ, Holliday TA, Tharp B, Kass PH, Steffey EP, LeCouteur RA. Electroencephalogram of Healthy Horses During Inhaled Anesthesia. J Vet Intern Med 2016 Jan-Feb;30(1):304-8.
    doi: 10.1111/jvim.13613pubmed: 26376458google scholar: lookup
  7. Figueroa S, Levionnois OL, Mirra A. Quantitative Variables Derived from the Electroencephalographic Signal to Assess Depth of Anaesthesia in Animals: A Narrative Review. Animals (Basel) 2025 Aug 5;15(15).
    doi: 10.3390/ani15152285pubmed: 40805076google scholar: lookup
  8. Aleman M, Benini R, Elestwani S, Vinardell T. Juvenile idiopathic epilepsy in Egyptian Arabian foals, a potential animal model of self-limited epilepsy in children. J Vet Intern Med 2024 Jan-Feb;38(1):449-459.
    doi: 10.1111/jvim.16965pubmed: 38041837google scholar: lookup
Subscribe to our newsletter
Join 100,151 horse owners like you who receive our email updates on horse health and nutrition.