Effect of intravenous fentanyl on cough reflex and quality of endotracheal intubation in cats

Published:January 19, 2023DOI:



      To assess the effects of intravenous (IV) fentanyl on cough reflex and quality of endotracheal intubation (ETI) in cats.

      Study design

      Randomized, blinded, negative controlled clinical trial.


      A total of 30 client-owned cats undergoing general anaesthesia for diagnostic or surgical procedures.


      Cats were sedated with dexmedetomidine (2 μg kg-1 IV) and 5 minutes later either fentanyl (3 μg kg-1, group F) or saline (group C) was administered IV. After alfaxalone (1.5 mg kg-1 IV) administration and 2% lidocaine application to the larynx, ETI was attempted. If unsuccessful, alfaxalone (1 mg kg-1 IV) was administered and ETI re-attempted. This process was repeated until successful ETI. Sedation scores, the total number of ETI attempts, cough reflex, laryngeal response, and quality of ETI were scored. Post-induction apnoea was recorded. Heart rate (HR) was continuously recorded and oscillometric arterial blood pressure (ABP) was measured every minute. Changes (Δ) in HR and ABP between pre-intubation and intubation were calculated. Groups were compared using univariate analysis. Statistical significance was set as p < 0.05.


      The median and 95% Confidence Interval alfaxalone dose was 1.5 (1.5-1.5) and 2.5 (1.5-2.5) mg kg-1 in group F and C, respectively (p = 0.001). The cough reflex was 2.10 (1.10-4.41) times more likely to occur in group C. The overall quality of ETI was superior in group F (p = 0.001), with lower laryngeal response to ETI (p < 0.0001) and ETI attempts (p = 0.045). No differences in HR, ABP and PIA were found.


      and clinical relevance: In cats sedated with dexmedetomidine, fentanyl could be considered to reduce the alfaxalone induction dose, the cough reflex, and the laryngeal response to ETI and to improve the overall quality of ETI.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Veterinary Anaesthesia and Analgesia
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


      1. Alfaxan, Jurox. (2022) Last accessed February 07, 2022.

        • Bhalla R.J.
        • Trimble T.A.
        • Leece E.A.
        • Vettorato E.
        Comparison of intramuscular butorphanol and buprenorphine combined with dexmedetomidine for sedation in cats.
        J Feline Med Surg. 2018; 20: 325-331
        • Billard V.
        • Moulla F.
        • Bourgain J.L.
        • et al.
        Hemodynamic response to induction and intubation.
        Propofol/fentanyl Interaction. Anesth. 1994; 81: 1384-1393
        • Brodbelt D.C.
        • Pfeiffer D.U.
        • Young L.E.
        • Wood J.L.N.
        Risk factors for anaesthetic-related death in cats: results from the confidential enquiry into perioperative small animal fatalities (CEPSAF).
        Br J Anaesth. 2007; 99: 617-623
        • Bülow K.
        • Nielsen T.G.
        • Lund J.
        The effect of topical lignocaine on intubating conditions after propofol-alfentanil induction.
        Acta Anaesthesiol Scand. 1996; 40: 752-756
        • Burney R.G.
        • Winn R.
        Increased cerebrospinal fluid pressure during laryngoscopy and intubation for induction of anesthesia.
        Anesth Analg. 1975; 54: 687-690
        • Callaway J.K.
        • King R.G.
        • Boura A.L.
        Evidence for peripheral mechanisms mediating the antitussive actions of opioids in the guinea pig.
        Gen Pharmacol. 1991; 22: 1103-1108
        • Cerasoli I.
        • Nannarone S.
        • Schauvliege
        • et al.
        The effects of intravenous lidocaine before propofol induction in premedicated dogs.
        J Small Anim Pract. 2016; 57: 435-440
        • Colby E.D.
        • McCarthy L.E.
        • Borison H.L.
        Emetic action of xylazine on the chemoreceptor trigger zone for vomiting in cats.
        J Vet Pharmacol Ther. 1981; 4: 93-96
        • da Cunha A.F.
        • Saile K.
        • Beaufrère H.
        • et al.
        Measuring level of agreement between values obtained by directly measured blood pressure and ultrasonic Doppler flow detector in cats.
        J Vet Emerg Crit Care (San Antonio). 2014; 24: 272-278
        • Fisher J.
        Use of Xylocaine spray in cats.
        Vet Rec. 2010; 167: 500
        • Gurulingappa M.A.
        • Awati M.N.
        • Adarsh S.
        Attenuation of Cardiovascular Responses to Direct Laryngoscopy and Intubation-A Comparative Study Between iv Bolus Fentanyl, Lignocaine and Placebo (NS).
        J Clin Diagn Res. 2012; 6: 1749-1752
        • Jones T.L.
        • Boyer K.
        • Chapman K.
        • et al.
        Evaluation of the time to desensitization of the larynx of cats following topical lidocaine application.
        J Feline Med Surg. 2021; 23: 563-567
        • Kamata M.
        • Nagahama S.
        • Kakishima K.
        • et al.
        Comparison of behavioral effects of morphine and fentanyl in dogs and cats.
        J Vet Med Sci. 2012; 74: 231-234
        • Lagos-Carvajal A.
        • Queiroz-Williams P.
        • Cremer J.
        • et al.
        Effects of a priming dose of alfaxalone on the total anesthetic induction dose for and cardiorespiratory function of sedated healthy cats.
        Am J Vet Res. 2020; 81: 850-855
        • Martin-Flores M.
        • Sakai D.M.
        • Portela D.A.
        • et al.
        Prevention of laryngospasm with rocuronium in cats: a dose-finding study.
        Vet Anaesth Analg. 2016; 43: 511-518
        • Martin-Flores M.
        • Sakai D.M.
        • Learn M.M.
        • et al.
        Effects of maropitant in cats receiving dexmedetomidine and morphine.
        J Am Vet Med Assoc. 2016; 248: 1257-1261
        • Mathis A.
        • Pinelas R.
        • Brodbelt D.C.
        • Alibhai H.I.
        Comparison of quality of recovery from anaesthesia in cats induced with propofol or alfaxalone.
        Vet Anaesth Analg. 2012; 39: 282-290
        • McMillan M.
        • Darcy H.
        Adverse event surveillance in small animal anaesthesia: an intervention-based, voluntary reporting audit.
        Vet Anaesth Analg. 2016; 43: 128-135
        • Michalek-Sauberer A.
        • Gilly H.
        • Steinbereithner K.
        • Vizi E.S.
        Effects of vecuronium and rocuronium in antagonistic laryngeal muscles and the anterior tibial muscle in the cat.
        Acta Anaesthesiol Scand. 2000; 44: 503-510
        • Moreno-Sala A.
        • Ortiz-Martínez R.
        • Valdivia A.G.
        • et al.
        Use of neuromuscular blockade with rocuronium bromide for intubation in cats.
        Vet Anaesth Analg. 2013; 40: 351-358
        • Re Bravo V.
        • Palomba N.
        • Corletto F.
        • et al.
        Comparison between intravenous lidocaine and fentanyl on cough reflex and sympathetic response during endotracheal intubation in dogs.
        Vet Anaesth Analg. 2020; 47: 481-489
        • Rex M.A.
        Laryngospasm and respiratory changes in the cat produced by mechanical stimulation of the pharynx and respiratory tract: problems of intubation in the cat.
        Br J Anaesth. 1971; 43: 54-57
        • Rex M.A.
        • Sutton R.H.
        • Reilly J.S.
        The effects of lignocaine spray on the laryngeal mucosa of the cat.
        Anaesth Intensive Care. 1983; 11: 47-51
        • Robinson E.P.
        • Rex M.A.
        • Brown T.C.
        A comparison of different concentrations of lignocaine hydrochloride used for topical anaesthesia of the larynx of the cat.
        Anaesth Intensive Care. 1985; 13: 137-144
        • Robinson R.
        • White M.
        • McCann P.
        • et al.
        Effect of anaesthesia on intraocular blood flow.
        Br J Ophthalmol. 1991; 75: 92-93
        • Sakai D.M.
        • Zornow K.A.
        • Campoy L.
        • et al.
        Intravenous rocuronium 0.3 mg/kg improves the conditions for tracheal intubation in cats: a randomized, placebo-controlled trial.
        J Feline Med Surg. 2018; 20: 1124-1129
        • Santos L.C.
        • Ludders J.W.
        • Erb H.
        • et al.
        A randomized, blinded, controlled trial of the antiemetic effect of ondansetron on dexmedetomidine-induced emesis in cats.
        Vet Anaesth Analg. 2011; 38: 320-327
        • Sasaki C.T.
        • Suzuki M.
        Laryngeal reflexes in cat, dog, and man.
        Arch Otolaryngol. 1976; 102: 400-402
        • Shribman A.J.
        • Smith G.
        • Achola K.J.
        Cardiovascular and catecholamine responses to laryngoscopy with and without tracheal intubation.
        Br J Anaesth. 1987; 59: 295-299
        • Tagaito Y.
        • Isono S.
        • Nishino T.
        Upper airway reflexes during a combination of propofol and fentanyl anesthesia.
        Anesthesiology. 1998; 88: 1459-1466
        • Thawley V.J.
        • Drobatz K.J.
        Assessment of dexmedetomidine and other agents for emesis induction in cats: 43 cases (2009-2014).
        J Am Vet Med Assoc. 2015; 247: 1415-1418
        • Thompson K.R.
        • Rioja E.
        Effects of intravenous and topical laryngeal lidocaine on heart rate, mean arterial pressure and cough response to endotracheal intubation in dogs.
        Vet Anaesth Analg. 2016; 43: 371-378
        • Zavataro A.L.
        • Bonatto N.
        • Julião G.H.
        • et al.
        Comparison of coinduction adjuvants to propofol in healthy cats sedated with dexmedetomidine.
        Top Companion Anim Med. 2022; 48100634