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Full Research Article

Sedative Efficacy and Dose Sparing Effect of Butorphanol-acepromazine-glycopyrrolate in Dogs Induced with Propofol or Thiopentone and Maintained on Isoflurane Anaesthesia

K
K.K. Chauhan1,*
D
D.N. Suthar1
T
T.P. Patel2
B
B.K. Raygaur2
K
K.M. Sheth2
1Department of Veterinary Clinical Complex, College of Veterinary Science and Animal Husbandry, Sardarkrushinagar, Banaskantha-385 506, Gujarat, India.
2Department of Veterinary Surgery and Radiology, College of Veterinary Science and Animal Husbandry, Kamdhenu University, Himmatnagar-383 010, Gujarat, India.

ABSTRACT

Background: Premedication plays an important role in balanced anaesthesia by improving sedation, facilitating handling and reducing anaesthetic requirements. The present study evaluated the sedative efficacy and dose-sparing effect of butorphanol-acepromazine-glycopyrrolate premedication on propofol and thiopentone induction anaesthesia in dogs.

Methods: Twenty-four client-owned dogs undergoing various surgical procedures were randomly divided into two groups. All dogs received butorphanol (0.2 mg/kg IM), acepromazine (0.02 mg/kg IV) and glycopyrrolate (0.01 mg/kg IM). Anaesthesia was induced with propofol in Group I and thiopentone sodium in Group II and maintained with isoflurane in oxygen in both the groups. Sedation quality, induction dose, induction characteristics and recovery parameters were evaluated.

Result: Premedication produced good to excellent sedation in all dogs. Mean induction doses of propofol (2.89±0.21 mg/kg) and thiopentone sodium (8.16±0.71 mg/kg) were markedly lower than conventional doses. Propofol provided smoother induction and significantly faster recovery than thiopentone sodium.

INTRODUCTION

Canines (Canis lupus) have been domesticated for thousands of years primarily serving roles of companionship, protection, hunting and personal enjoyment (Serpell, 2016). The rising awareness of pet owners has created an imperative for veterinary clinicians to employ safer, effective and scientifically validated anaesthetic techniques tailored to small animals particularly canines (Snyder et al., 2019).

Safe and effective general anaesthesia in dogs relies heavily on appropriate pre-anaesthetic medication and balanced anaesthetic techniques (Thurmon and Short, 2007 and Nam et al., 2014). Premedication is an integral component of modern veterinary anaesthesia, aiming to reduce stress and anxiety, facilitate handling, improve induction quality, enhance analgesia and reduce the dose requirement of induction and maintenance agents (Duke-Novakovski et al., 2016 and Ko, 2018). The concept of balanced anaesthesia utilizes drugs with complementary pharmacological actions to achieve hypnosis, analgesia and muscle relaxation while minimising adverse effects associated with high doses of a single agent (Redondo et al., 2024).

Butorphanol is a synthetic opioid with k-agonist and μ-antagonist properties, widely used in dogs for its sedative and analgesic effects with minimal respiratory depression (Girard et al., 2010 and Crabtree et al., 2019). Acepromazine, a phenothiazine tranquilliser, produces central sedation through dopaminergic antagonism and contributes to muscle relaxation and anxiolysis. However, acepromazine lacks analgesic properties and may cause vasodilatation when used alone (Clarke et al., 2014 and Plumb, 2018). Glycopyrrolate, a quaternary anticholinergic agent, is commonly administered to counteract vagally mediated bradycardia and excessive salivary secretions without central nervous system penetration (Hall et al., 2014 and Chabicovsky et al., 2019).

Propofol and thiopentone sodium remain commonly employed intravenous induction agents in veterinary practice (Suthar, 2016). Propofol is characterised by rapid onset, smooth induction and short recovery due to rapid redistribution and metabolism, whereas thiopentone, a barbiturate, is economical and effective but associated with cumulative effects and comparatively prolonged recovery (Wolfe and Ehrenfeld, 2022). Both agents exhibit dose-dependent cardiovascular and respiratory depression by making dose reduction which is clinically desirable.

Although several studies have evaluated different pre-anaesthetic combinations but limited consolidated data are available on the sedative quality and dose-sparing efficacy of butorphanol-acepromazine-glycopyrrolate prior to propofol or thiopentone induction under clinical conditions.

Therefore, the present study was undertaken to evaluate the sedative efficacy and dose-sparing effect of butorphanol-acepromazine-glycopyrrolate premedication on propofol and thiopentone induction anaesthesia in dogs. 

MATERIALS AND METHODS

Present study was conducted on twenty-four client-owned dogs of either sex of various breeds presented for elective or therapeutic surgical procedures from January to October 2025 at the Veterinary Clinical Complex, Kamdhenu University, Rajpur, Himmatnagar (Gujarat). Animals included in the study ranged from 6 to 156 months of age and had body weights between 4.5 and 37.9 kg. Prior to inclusion, all dogs underwent a thorough clinical examination to assess their general health status and only those deemed fit for general anaesthesia were selected for the study.

For pre-anaesthetic preparation, all animals were withheld from food for 12 hours and water for 6 hours prior to induction of anaesthesia to reduce the risk of regurgitation and aspiration. An intravenous catheter was aseptically placed in each dog to facilitate administration of anaesthetic agents and intraoperative fluid therapy.

Experimental design involved random allocation of the dogs into two groups (Group I and II), comprising twelve animals in each. Both the groups received an identical balanced pre-anaesthetic medication protocol consisting of butorphanol administered @ 0.2 mg/kg intramuscularly, acepromazine at 0.02 mg/kg intravenously and glycopyrrolate @ 0.01 mg/kg intramuscularly. Following administration of the preanaesthetic and achievement of adequate sedation, anaesthesia was induced intravenously to effect with 1% propofol in Group I and 2.5 % thiopentone sodium in Group II.

After successful induction and endotracheal intubation, anaesthesia was maintained with isoflurane in oxygen in all dogs using a rebreathing system. Throughout the anaesthetic period, animals were continuously monitored to ensure an adequate depth of anaesthesia and physiological stability.

Various anaesthetic parameters were recorded during the study, including quality of sedation, induction dose requirement, quality of induction, duration of anaesthesia and recovery time. Quality of sedation, anaesthetic induction and recovery was assessed by standard numerical scoring systems. Analysis of variance (ANOVA) and Duncan’s new multiple range tests (DNMRT) were used to compare the mean values at different time intervals among both the groups. Paired t-test was used to compare the mean values at different time intervals with their respective base values in each group. The analysis was performed using IBM SPSS 30.0 statistical software.  P-value d 0.05 was considered indicative of statistical significance.

RESULTS AND DISCUSSION

Sedation quality
 
Premedication with butorphanol-acepromazine-glycopyrrolate produced consistent and clinically desirable sedation in all dogs. Animals exhibited calm behaviour, reduced responsiveness to handling and improved compliance during catheter placement and positioning. Present study demonstrated that butorphanol-acepromazine-glycopyrrolate provided reliable pre-anaesthetic sedation and produced a significant dose-sparing effect on both propofol and thiopentone induction anaesthetics in dogs. Synergistic sedative and analgesic actions of opioids combined with benzodiazepine or phenothiazine derivatives and anticholinergic agents are well recognised to enhance tranquillity and exert a pronounced dose-sparing effect on induction anaesthetics in dogs (Suthar, 2016 and Hareesh, 2016). Combination of acepromazine with butorphanol and glycopyrrolate has been shown to provide good to excellent sedation (Table 1), reduce anaesthetic risks and ensure balanced preanaesthetic preparations in dogs (Talekar et al., 2022; Manjusha et al., 2023 and Dewangan et al., 2024).

Table 1: Sedation quality scores.


 
Dose-sparing effect on induction anaesthesia
 
A marked reduction in induction dose requirement was observed in both the groups compared to conventionally recommended doses. Induction doses recorded in the present study were lower than the recommended post-premedication ranges of 4-6 mg/kg for propofol and 10-15 mg/kg for thiopentone sodium reported by Berry (2015). Premedication with butorphanol, acepromazine and glycopyrrolate in the present study markedly reduced the induction requirements of both propofol and thiopentone sodium in dogs (Table 2), highlighting the effectiveness of balanced preanaesthetic protocols for smooth, safe and efficient anaesthetic induction in dogs.

Table 2: Induction dose and dose-sparing effect.


 
Induction quality
 
Induction was smooth and rapid in most dogs. Propofol consistently produced excellent induction with rapid jaw relaxation and minimal excitation. Induction was rated as excellent in all animals except two dogs in Group II (Table 3) which showed fair scores due to moderate resistance to jaw opening, prolonged abolition of pharyngeal/laryngeal reflexes, vomiting and gagging requiring an additional one-third dose of thiopentone for smooth intubation. Difficulty in intubation observed in two dogs of Group II was due to tight jaw tone or strong pharyngeal reflexes consistent with previous findings (Ralh and Mohindroo, 2010 and Cakirgoz et al., 2025a).

Table 3: Induction quality scores.


 
Anaesthetic duration and recovery
 
The duration of anaesthetic maintenance and anaesthesia did not differ significantly between groups (Table 4); however, recovery time was significantly shorter in Group I. In the present study, short recovery time observed in both the groups can be primarily attributed to the use of isoflurane for the maintenance of inhalant anaesthetics. Good to excellent recovery quality was observed in both the groups, except for one dog in Group II, which exhibited a fair recovery score. Statistically significant difference was noted between the groups for which indicating comparatively smoother recovery in Group I. Similar recovery patterns have been documented by Arunkumar et al. (2017), Hampton et al. (2019), Dewangan et al. (2024), Zalavadiya et al. (2024) and Khutey et al. (2026).

Table 4: Anaesthetic duration and recovery parameters.

CONCLUSION

Premedication with butorphanol, acepromazine and glycopyrrolate produced effective sedation and significantly reduced the induction dose of propofol and thiopentone sodium in dogs. Propofol provided smoother induction and faster recovery than thiopentone sodium. The protocol may be recommended as an effective balanced anaesthetic regimen for canine surgical procedures

ACKNOWLEDGEMENT

The authors are thankful to the Dean, College of Veterinary Science and Animal Husbandry, Kamdhenu University, Himmatnagar, Gujarat, India for providing facilities to conduct the study.
 
Ethical approval
 
The study was conducted after approval of the Institutional Animal Ethics Committee and in accordance with CPCSEA guidelines.

CONFLICT OF INTEREST

The authors declare that there is no conflict of interest.

REFERENCES


  1. Arunkumar, S., Dilipkumar, D. and Shivaprakash, B.V. (2017). Clinical and physiological evaluation of dexmedetomidine, xylazine and triflupromazine as preanaesthetics with propofol- is oflurane anaesthesia for various surgeries in dogs. The Pharma Innovation Journal. 6(8): 100-105.

  2. Berry, S.H. (2015). Injectable Anaesthetics. In: Veterinary Anaesthesia and Analgesia. 5th Edn. (Grimm, K.A., Ed.). Wiley Blackwell, Iowa, USA. pp. 277-296.

  3. Cakirgoz, M., Demirel, I., Kar, A.A., Alaygut, E., Sarac, O., Karagoz, E., Demirel, O. and Akan, M. (2025a). Comparison of the effects of propofol-dexmedetomidine and thiopental- dexmedetomidine combinations on the success of classical laryngeal mask airway insertions, hemodynamic responses and pharyngolaryngeal morbidity. Medicina. 61(5): 783.

  4. Chabicovsky, M., Winkler, S., Soeberdt, M., Kilic, A., Masur, C. and Abels, C. (2019). Pharmacology, toxicology and clinical safety of glycopyrrolate. Toxicology and Applied Pharmacology. 380: 114123.

  5. Clarke, K.W., Trim, C.M. and Hall, L.W. (2014). Anaesthesia of dog. In: Veterinary Anaesthesia. 11th Edn. (Clarke, K.W., Trim, C.M. and Hall, L.W., Eds.). Saunders Elsevier, London. pp. 409-498.

  6. Crabtree, N.E., Mochal-King, C.A., Sloan, P.B., Eddy, A.L., Wills, R.W., Meredith, A.N. and Fontenot, R.L. (2019). Synovial butorphanol concentrations and mechanical nociceptive thresholds after intravenous regional limb perfusion in standing sedated horses. Veterinary Surgery. 48(8): 1473-1482.

  7. Dewangan, R., Pal, S., Sharda, R., Khutey, B.B., Kumar, I. and Kurrey, L. (2026). Sedative, analgesic and anaesthetic evaluation of propofol in combination with butorphanol, dexmedetomidine and acepromazine in clinically healthy dogs. Indian Journal of Animal Research. 60(3): 423- 432. doi: 10.18805/IJAR.B-5446. 

  8. Dewangan, R., Pal, S., Sharda, R., Tiwari, S.K., Chaurasia, D., Khutey, B.B. and Ratre, H.K. (2024). Clinico-physiological and haemodynamic alterations following propofol induction and premedication with butorphanol, dexmedetomidine or acepromazine in dogs. International Journal of Bio- resource and Stress Management. 15(2): 1-12.

  9. Duke-Novakovski, T., Vries, M.D. and Seymour, C. (2016). Pre- anaesthetic medication and sedation. In: BSAVA Manual of Canine and Feline Anaesthesia and Analgesia. BSAVA Publications. pp. 170-189.

  10. Girard, N.M., Leece, E.A., Cardwell, J.M., Adams, V.J. and Brearley, J.C. (2010). The sedative effects of low-dose medetomidine and butorphanol alone and in combination intravenously in dogs. Veterinary Anaesthesia and Analgesia. 37(1): 1-6.

  11. Hall, L.W., Clarke, K.W. and Trim, C.M. (2014). Veterinary Anaesthesia. 11th Edn. W.B. Saunders, London.

  12. Hampton, C.E., Riebold, T.W. and Mandsager, R.E. (2019). Recovery characteristics of dogs following anesthesia induced with tiletamine-zolazepam, alfaxalone, ketamine-diazepam, or propofol and maintained with isoflurane. Journal of the American Veterinary Medical Association. 254(12): 1421-1426.

  13. Hareesh, A.U. (2016). Clinical evaluation of etomidate and propofol anaesthesia following atropine, diazepam and fentanyl premedication in geriatric dogs. M.V.Sc. Thesis, Sri Venkateswara Veterinary University, Tirupati, India.

  14. Khutey B.B., Sharda, R., Dewangan, R., Pal, S., Kumar, I., Kurrey L., Sengar, M., Singh, J. and Singh, S. (2026). Comparative anaesthetic evaluation of butorphanol, dexmedetomidine or acepromazine in combination with thiopentone sodium for inducing general anaesthesia in healthy dogs. Indian Journal of Animal Research. 60(1): 92-99. doi: 10.18805/IJAR.B-5704. 

  15. Ko, J.C. (2018). Preanesthetic Medication: Drugs and Dosages. In: Small Animal Anesthesia and Pain Management. CRC Press. pp. 51-76.

  16. Manjusha, K.M., Kinjavdekar, P., Amarpal, Kumar, R., Sharun, K., Islam, A., Aakanksha, Pawde, A.M., Saxena, A.C. and De, U.K. (2023). Evaluation of dexmedetomidine with and without butorphanol in tiletamine-zolazepam anesthetized dogs for ovariohysterectomy. Indian Journal of Veterinary Surgery. 44(2): 95-99.

  17. Nam, Lu, D.Z., Jiang, S., Yu, S.M. and Fan, H.G. (2014). A comparison of anesthetic and cardiorespiratory effects of tiletamine- zolazepam/xylazine and tiletamine-zolazepam/xylazine/ tramadol in dogs. Pakistan Veterinary Journal. 34(1): 70-80.

  18. Plumb, D.C. (2018). Veterinary Drug Handbook. 8th Edn. Iowa State University Press, Ames, Iowa. pp. 1-3, 109-111, 380-382, 444-445, 575-577, 673-675.

  19. Ralh, P. and Mohindroo, J. (2010). Evaluation of butorphanol- acepromazine-glycopyrrolate and butorphanol-midazolam- glycopyrrolate as preanaesthetic to thiopentone anaesthesia in dogs. Indian Journal of Veterinary Surgery. 31(2): 123-126.

  20. Redondo, J.I., Otero, P.E., Martinez-Taboada, F., Domenech, L., Hernandez-Magana, E.Z. and Viscasillas, J. (2024). Anaesthetic mortality in dogs: A worldwide analysis and risk assessment. Veterinary Record. 195(1).

  21. Serpell, J. (2016). The Domestic Dog: Its Evolution, Behavior and Interactions with People. Cambridge University Press.

  22. Snyder, L.C., Snyder, C. and Beebe, D. (2019). Anesthesia and pain management. In: Wiggs’s Veterinary Dentistry: Principles and Practice. pp. 177-192.

  23. Suthar, D.N. (2016). Evaluation of balanced anaesthesia using different preanaesthetics followed by induction with propofol/thiopentone sodium and maintenance with isoflurane in dog. Ph.D. Thesis, Navsari Agricultural University, Navsari, Gujarat, India.

  24. Talekar, S.H., Tank, P.H., Sharma, A., Kalaria, V.A. and Chaudhary, M.P. (2022). Clinical studies on the effect of glycopyrrolate, xylazine, acepromazine, dexmedetomidine and butorphanol in different combinations on propofol-isoflurane anaesthesia in dogs. Indian Journal of Canine Practice. 14(2): 121- 124.

  25. Thurmon, J.C. and Short, C.E. (2007). History and Overview of Veterinary Anaesthesia. In: Lumb and Jones’ Veterinary Anaesthesia and Analgesia. 4th Edn. Blackwell Publishing Ltd., Oxford. pp. 3-6.

  26. Wolfe, J.W. and Ehrenfeld, J.M. (2022). Pharmacology of Intravenous Anesthetic Agents. In: Springer. [Anesthesia Student Survival Guide. (Ehrenfeld, J.M., Urman, R.D. and Segal, B.S., Eds.)]. Cham. pp. 41-53.

  27. Zalavadiya, S.H., Vadalia, J.V., Vagh, A.A., Kalaria, V.A., Padaliya, N.R., Bhesaniya, M.B. and Kumar, R.K. (2024). Clinico- physiological and haemato-biochemical effects of propofol and tiletamine-zolazepam anaesthesia in dogs. International Journal of Veterinary Science and Animal Husbandry. 9(2S): 120-123.
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    Full Research Article

    Sedative Efficacy and Dose Sparing Effect of Butorphanol-acepromazine-glycopyrrolate in Dogs Induced with Propofol or Thiopentone and Maintained on Isoflurane Anaesthesia

    K
    K.K. Chauhan1,*
    D
    D.N. Suthar1
    T
    T.P. Patel2
    B
    B.K. Raygaur2
    K
    K.M. Sheth2
    1Department of Veterinary Clinical Complex, College of Veterinary Science and Animal Husbandry, Sardarkrushinagar, Banaskantha-385 506, Gujarat, India.
    2Department of Veterinary Surgery and Radiology, College of Veterinary Science and Animal Husbandry, Kamdhenu University, Himmatnagar-383 010, Gujarat, India.

    ABSTRACT

    Background: Premedication plays an important role in balanced anaesthesia by improving sedation, facilitating handling and reducing anaesthetic requirements. The present study evaluated the sedative efficacy and dose-sparing effect of butorphanol-acepromazine-glycopyrrolate premedication on propofol and thiopentone induction anaesthesia in dogs.

    Methods: Twenty-four client-owned dogs undergoing various surgical procedures were randomly divided into two groups. All dogs received butorphanol (0.2 mg/kg IM), acepromazine (0.02 mg/kg IV) and glycopyrrolate (0.01 mg/kg IM). Anaesthesia was induced with propofol in Group I and thiopentone sodium in Group II and maintained with isoflurane in oxygen in both the groups. Sedation quality, induction dose, induction characteristics and recovery parameters were evaluated.

    Result: Premedication produced good to excellent sedation in all dogs. Mean induction doses of propofol (2.89±0.21 mg/kg) and thiopentone sodium (8.16±0.71 mg/kg) were markedly lower than conventional doses. Propofol provided smoother induction and significantly faster recovery than thiopentone sodium.

    INTRODUCTION

    Canines (Canis lupus) have been domesticated for thousands of years primarily serving roles of companionship, protection, hunting and personal enjoyment (Serpell, 2016). The rising awareness of pet owners has created an imperative for veterinary clinicians to employ safer, effective and scientifically validated anaesthetic techniques tailored to small animals particularly canines (Snyder et al., 2019).

    Safe and effective general anaesthesia in dogs relies heavily on appropriate pre-anaesthetic medication and balanced anaesthetic techniques (Thurmon and Short, 2007 and Nam et al., 2014). Premedication is an integral component of modern veterinary anaesthesia, aiming to reduce stress and anxiety, facilitate handling, improve induction quality, enhance analgesia and reduce the dose requirement of induction and maintenance agents (Duke-Novakovski et al., 2016 and Ko, 2018). The concept of balanced anaesthesia utilizes drugs with complementary pharmacological actions to achieve hypnosis, analgesia and muscle relaxation while minimising adverse effects associated with high doses of a single agent (Redondo et al., 2024).

    Butorphanol is a synthetic opioid with k-agonist and μ-antagonist properties, widely used in dogs for its sedative and analgesic effects with minimal respiratory depression (Girard et al., 2010 and Crabtree et al., 2019). Acepromazine, a phenothiazine tranquilliser, produces central sedation through dopaminergic antagonism and contributes to muscle relaxation and anxiolysis. However, acepromazine lacks analgesic properties and may cause vasodilatation when used alone (Clarke et al., 2014 and Plumb, 2018). Glycopyrrolate, a quaternary anticholinergic agent, is commonly administered to counteract vagally mediated bradycardia and excessive salivary secretions without central nervous system penetration (Hall et al., 2014 and Chabicovsky et al., 2019).

    Propofol and thiopentone sodium remain commonly employed intravenous induction agents in veterinary practice (Suthar, 2016). Propofol is characterised by rapid onset, smooth induction and short recovery due to rapid redistribution and metabolism, whereas thiopentone, a barbiturate, is economical and effective but associated with cumulative effects and comparatively prolonged recovery (Wolfe and Ehrenfeld, 2022). Both agents exhibit dose-dependent cardiovascular and respiratory depression by making dose reduction which is clinically desirable.

    Although several studies have evaluated different pre-anaesthetic combinations but limited consolidated data are available on the sedative quality and dose-sparing efficacy of butorphanol-acepromazine-glycopyrrolate prior to propofol or thiopentone induction under clinical conditions.

    Therefore, the present study was undertaken to evaluate the sedative efficacy and dose-sparing effect of butorphanol-acepromazine-glycopyrrolate premedication on propofol and thiopentone induction anaesthesia in dogs. 

    MATERIALS AND METHODS

    Present study was conducted on twenty-four client-owned dogs of either sex of various breeds presented for elective or therapeutic surgical procedures from January to October 2025 at the Veterinary Clinical Complex, Kamdhenu University, Rajpur, Himmatnagar (Gujarat). Animals included in the study ranged from 6 to 156 months of age and had body weights between 4.5 and 37.9 kg. Prior to inclusion, all dogs underwent a thorough clinical examination to assess their general health status and only those deemed fit for general anaesthesia were selected for the study.

    For pre-anaesthetic preparation, all animals were withheld from food for 12 hours and water for 6 hours prior to induction of anaesthesia to reduce the risk of regurgitation and aspiration. An intravenous catheter was aseptically placed in each dog to facilitate administration of anaesthetic agents and intraoperative fluid therapy.

    Experimental design involved random allocation of the dogs into two groups (Group I and II), comprising twelve animals in each. Both the groups received an identical balanced pre-anaesthetic medication protocol consisting of butorphanol administered @ 0.2 mg/kg intramuscularly, acepromazine at 0.02 mg/kg intravenously and glycopyrrolate @ 0.01 mg/kg intramuscularly. Following administration of the preanaesthetic and achievement of adequate sedation, anaesthesia was induced intravenously to effect with 1% propofol in Group I and 2.5 % thiopentone sodium in Group II.

    After successful induction and endotracheal intubation, anaesthesia was maintained with isoflurane in oxygen in all dogs using a rebreathing system. Throughout the anaesthetic period, animals were continuously monitored to ensure an adequate depth of anaesthesia and physiological stability.

    Various anaesthetic parameters were recorded during the study, including quality of sedation, induction dose requirement, quality of induction, duration of anaesthesia and recovery time. Quality of sedation, anaesthetic induction and recovery was assessed by standard numerical scoring systems. Analysis of variance (ANOVA) and Duncan’s new multiple range tests (DNMRT) were used to compare the mean values at different time intervals among both the groups. Paired t-test was used to compare the mean values at different time intervals with their respective base values in each group. The analysis was performed using IBM SPSS 30.0 statistical software.  P-value d 0.05 was considered indicative of statistical significance.

    RESULTS AND DISCUSSION

    Sedation quality
     
    Premedication with butorphanol-acepromazine-glycopyrrolate produced consistent and clinically desirable sedation in all dogs. Animals exhibited calm behaviour, reduced responsiveness to handling and improved compliance during catheter placement and positioning. Present study demonstrated that butorphanol-acepromazine-glycopyrrolate provided reliable pre-anaesthetic sedation and produced a significant dose-sparing effect on both propofol and thiopentone induction anaesthetics in dogs. Synergistic sedative and analgesic actions of opioids combined with benzodiazepine or phenothiazine derivatives and anticholinergic agents are well recognised to enhance tranquillity and exert a pronounced dose-sparing effect on induction anaesthetics in dogs (Suthar, 2016 and Hareesh, 2016). Combination of acepromazine with butorphanol and glycopyrrolate has been shown to provide good to excellent sedation (Table 1), reduce anaesthetic risks and ensure balanced preanaesthetic preparations in dogs (Talekar et al., 2022; Manjusha et al., 2023 and Dewangan et al., 2024).

    Table 1: Sedation quality scores.


     
    Dose-sparing effect on induction anaesthesia
     
    A marked reduction in induction dose requirement was observed in both the groups compared to conventionally recommended doses. Induction doses recorded in the present study were lower than the recommended post-premedication ranges of 4-6 mg/kg for propofol and 10-15 mg/kg for thiopentone sodium reported by Berry (2015). Premedication with butorphanol, acepromazine and glycopyrrolate in the present study markedly reduced the induction requirements of both propofol and thiopentone sodium in dogs (Table 2), highlighting the effectiveness of balanced preanaesthetic protocols for smooth, safe and efficient anaesthetic induction in dogs.

    Table 2: Induction dose and dose-sparing effect.


     
    Induction quality
     
    Induction was smooth and rapid in most dogs. Propofol consistently produced excellent induction with rapid jaw relaxation and minimal excitation. Induction was rated as excellent in all animals except two dogs in Group II (Table 3) which showed fair scores due to moderate resistance to jaw opening, prolonged abolition of pharyngeal/laryngeal reflexes, vomiting and gagging requiring an additional one-third dose of thiopentone for smooth intubation. Difficulty in intubation observed in two dogs of Group II was due to tight jaw tone or strong pharyngeal reflexes consistent with previous findings (Ralh and Mohindroo, 2010 and Cakirgoz et al., 2025a).

    Table 3: Induction quality scores.


     
    Anaesthetic duration and recovery
     
    The duration of anaesthetic maintenance and anaesthesia did not differ significantly between groups (Table 4); however, recovery time was significantly shorter in Group I. In the present study, short recovery time observed in both the groups can be primarily attributed to the use of isoflurane for the maintenance of inhalant anaesthetics. Good to excellent recovery quality was observed in both the groups, except for one dog in Group II, which exhibited a fair recovery score. Statistically significant difference was noted between the groups for which indicating comparatively smoother recovery in Group I. Similar recovery patterns have been documented by Arunkumar et al. (2017), Hampton et al. (2019), Dewangan et al. (2024), Zalavadiya et al. (2024) and Khutey et al. (2026).

    Table 4: Anaesthetic duration and recovery parameters.

    CONCLUSION

    Premedication with butorphanol, acepromazine and glycopyrrolate produced effective sedation and significantly reduced the induction dose of propofol and thiopentone sodium in dogs. Propofol provided smoother induction and faster recovery than thiopentone sodium. The protocol may be recommended as an effective balanced anaesthetic regimen for canine surgical procedures

    ACKNOWLEDGEMENT

    The authors are thankful to the Dean, College of Veterinary Science and Animal Husbandry, Kamdhenu University, Himmatnagar, Gujarat, India for providing facilities to conduct the study.
     
    Ethical approval
     
    The study was conducted after approval of the Institutional Animal Ethics Committee and in accordance with CPCSEA guidelines.

    CONFLICT OF INTEREST

    The authors declare that there is no conflict of interest.

    REFERENCES


    1. Arunkumar, S., Dilipkumar, D. and Shivaprakash, B.V. (2017). Clinical and physiological evaluation of dexmedetomidine, xylazine and triflupromazine as preanaesthetics with propofol- is oflurane anaesthesia for various surgeries in dogs. The Pharma Innovation Journal. 6(8): 100-105.

    2. Berry, S.H. (2015). Injectable Anaesthetics. In: Veterinary Anaesthesia and Analgesia. 5th Edn. (Grimm, K.A., Ed.). Wiley Blackwell, Iowa, USA. pp. 277-296.

    3. Cakirgoz, M., Demirel, I., Kar, A.A., Alaygut, E., Sarac, O., Karagoz, E., Demirel, O. and Akan, M. (2025a). Comparison of the effects of propofol-dexmedetomidine and thiopental- dexmedetomidine combinations on the success of classical laryngeal mask airway insertions, hemodynamic responses and pharyngolaryngeal morbidity. Medicina. 61(5): 783.

    4. Chabicovsky, M., Winkler, S., Soeberdt, M., Kilic, A., Masur, C. and Abels, C. (2019). Pharmacology, toxicology and clinical safety of glycopyrrolate. Toxicology and Applied Pharmacology. 380: 114123.

    5. Clarke, K.W., Trim, C.M. and Hall, L.W. (2014). Anaesthesia of dog. In: Veterinary Anaesthesia. 11th Edn. (Clarke, K.W., Trim, C.M. and Hall, L.W., Eds.). Saunders Elsevier, London. pp. 409-498.

    6. Crabtree, N.E., Mochal-King, C.A., Sloan, P.B., Eddy, A.L., Wills, R.W., Meredith, A.N. and Fontenot, R.L. (2019). Synovial butorphanol concentrations and mechanical nociceptive thresholds after intravenous regional limb perfusion in standing sedated horses. Veterinary Surgery. 48(8): 1473-1482.

    7. Dewangan, R., Pal, S., Sharda, R., Khutey, B.B., Kumar, I. and Kurrey, L. (2026). Sedative, analgesic and anaesthetic evaluation of propofol in combination with butorphanol, dexmedetomidine and acepromazine in clinically healthy dogs. Indian Journal of Animal Research. 60(3): 423- 432. doi: 10.18805/IJAR.B-5446. 

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