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Brosnan RJ, Pypendop BH, Cenani A. Effects of trazodone and dexmedetomidine on fentanyl-mediated reduction of isoflurane minimum alveolar concentration in cats. Vet Anaesth Analg 2024; 51:80-89. [PMID: 37926586 DOI: 10.1016/j.vaa.2023.09.130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 09/16/2023] [Accepted: 09/30/2023] [Indexed: 11/07/2023]
Abstract
OBJECTIVE To screen modulators of biogenic amine (BA) neurotransmission for the ability to cause fentanyl to decrease isoflurane minimum alveolar concentration (MAC) in cats, and to test whether fentanyl plus a combination of modulators decreases isoflurane MAC more than fentanyl alone. STUDY DESIGN Prospective, experimental study. ANIMALS A total of six adult male Domestic Short Hair cats. METHODS Each cat was anesthetized in three phases with a 1 week washout between studies. In phase 1, anesthesia was induced and maintained with isoflurane, and MAC was measured in duplicate using a tail clamp stimulus and standard bracketing technique. A 21 ng mL-1 fentanyl target-controlled infusion was then administered and MAC measured again. In phase 2, a single cat was administered a single BA modulator (buspirone, haloperidol, dexmedetomidine, pregabalin, ramelteon or trazodone) in a pilot drug screen, and isoflurane MAC was measured before and after fentanyl administration. In phase 3, isoflurane MAC was measured before and after fentanyl administration in cats co-administered trazodone and dexmedetomidine, the two BA modulator drugs associated with fentanyl MAC-sparing in the screen. Isoflurane MAC-sparing by fentanyl alone, trazodone-dexmedetomidine and trazodone-dexmedetomidine-fentanyl was evaluated using paired t tests with p < 0.05 denoting significant effects. RESULTS The MAC of isoflurane was 1.87% ± 0.09 and was not significantly affected by fentanyl administration (p = 0.09). In the BA screen, cats administered trazodone or dexmedetomidine exhibited 26% and 22% fentanyl MAC-sparing, respectively. Trazodone-dexmedetomidine co-administration decreased isoflurane MAC to 1.50% ± 0.14 (p < 0.001), and the addition of fentanyl further decreased MAC to 0.95% ± 0.16 (p < 0.001). CONCLUSIONS AND CLINICAL RELEVANCE Fentanyl alone does not affect isoflurane MAC in cats, but co-administration of trazodone and dexmedetomidine causes fentanyl to significantly decrease isoflurane requirement.
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Affiliation(s)
- Robert J Brosnan
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
| | - Bruno H Pypendop
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - Alessia Cenani
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
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Effects of remifentanil on the noxiously stimulated somatosensory evoked potentials recorded at the spinal cord in dogs and cats. Res Vet Sci 2023; 158:13-16. [PMID: 36898954 DOI: 10.1016/j.rvsc.2023.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 11/10/2022] [Accepted: 03/01/2023] [Indexed: 03/07/2023]
Abstract
This study assessed the somatosensory evoked potentials (SEPs) in dogs and cats to compare the effect of remifentanil on the action potentials evoked by peripheral noxious stimulation in the spinal cord. Five healthy dogs and five healthy cats underwent general anaesthesia induced with propofol and maintained with isoflurane. Each animals received all dosage of a constant-rate infusion of remifentanil at 0 (control), 0.25, 0.5, 1.0 or 2.0 μg/kg/min. The hair of the dorsal foot of a hind limb was clipped and an intraepidermal stimulation electrode that could selectively stimulate the nociceptive Aδ and C fibres was attached. An electrical stimulus was generated by a portable peripheral nerve testing device. The evoked potentials were recorded by two needle electrodes inserted subcutaneously in the dorsal midline between the lumbar vertebra: L3-L4 and L4-L5. Bimodal waveforms were obtained by electrical stimulation in control dogs and cats. The inhibitory effect of remifentanil was evaluated by comparing the changes in the N1P2 and P2N2 amplitudes. The N1P2 amplitude was depressed by remifentanil in a dose-dependent manner in dogs, but it showed no remifentanil-induced changes in cats. While the P2N2 amplitude was also depressed in a dose-dependent manner in dogs, it showed milder remifentanil-induced effects in cats. The N1P2 and P2N2 amplitudes observed herein are assumed to represent the evoked potentials derived from the Aδ and C fibres, respectively. Thus, the inhibitory effect of remifentanil on nociceptive transmission at the spinal cord was much weaker in cats, especially for transmissions possibly derived from Aδ fibres.
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Sevoflurane sparing effect of morphine in tegus (Salvator merianae) – a preliminary study. Top Companion Anim Med 2022; 50:100678. [DOI: 10.1016/j.tcam.2022.100678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 04/14/2022] [Accepted: 06/01/2022] [Indexed: 11/24/2022]
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Steagall PV, Robertson S, Simon B, Warne LN, Shilo-Benjamini Y, Taylor S. 2022 ISFM Consensus Guidelines on the Management of Acute Pain in Cats. J Feline Med Surg 2022; 24:4-30. [PMID: 34937455 PMCID: PMC10845386 DOI: 10.1177/1098612x211066268] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PRACTICAL RELEVANCE Increases in cat ownership worldwide mean more cats are requiring veterinary care. Illness, trauma and surgery can result in acute pain, and effective management of pain is required for optimal feline welfare (ie, physical health and mental wellbeing). Validated pain assessment tools are available and pain management plans for the individual patient should incorporate pharmacological and non-pharmacological therapy. Preventive and multimodal analgesia, including local anaesthesia, are important principles of pain management, and the choice of analgesic drugs should take into account the type, severity and duration of pain, presence of comorbidities and avoidance of adverse effects. Nursing care, environmental modifications and cat friendly handling are likewise pivotal to the pain management plan, as is a team approach, involving the cat carer. CLINICAL CHALLENGES Pain has traditionally been under-recognised in cats. Pain assessment tools are not widely implemented, and signs of pain in this species may be subtle. The unique challenges of feline metabolism and comorbidities may lead to undertreatment of pain and the development of peripheral and central sensitisation. Lack of availability or experience with various analgesic drugs may compromise effective pain management. EVIDENCE BASE These Guidelines have been created by a panel of experts and the International Society of Feline Medicine (ISFM) based on the available literature and the authors' experience. They are aimed at general practitioners to assist in the assessment, prevention and management of acute pain in feline patients, and to provide a practical guide to selection and dosing of effective analgesic agents.
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Affiliation(s)
- Paulo V Steagall
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Universite de Montréal, Saint-Hyacinthe, Canada; and Department of Veterinary Clinical Sciences and Centre for Companion Animal Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China
| | | | - Bradley Simon
- Department of Small Animal Clinical Sciences, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, Texas, USA
| | - Leon N Warne
- Veterinary Anaesthesia & Pain Management Australia, Perth, Western Australia; and Veterinary Cannabis Medicines Australia, Perth, Western Australia, Australia
| | - Yael Shilo-Benjamini
- Koret School of Veterinary Medicine, The Robert H Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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Pypendop BH, Goich M, Shilo-Benjamini Y. Effect of intravenous butorphanol infusion on the minimum alveolar concentration of isoflurane in cats. Vet Anaesth Analg 2021; 49:165-172. [PMID: 35033447 DOI: 10.1016/j.vaa.2021.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 12/06/2021] [Accepted: 12/14/2021] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To determine the effect of butorphanol, administered by intravenous (IV) infusion, on the minimum alveolar concentration of isoflurane (MACISO) in cats and to examine the dosage dependence of this effect. STUDY DESIGN Randomized, placebo-controlled, crossover experimental study. ANIMALS A group of six healthy adult male neutered cats. METHODS Cats were anesthetized with isoflurane in oxygen. A venous catheter was placed for fluid and drug administration, and an arterial catheter was placed for measurement of arterial pressure and blood sampling. Four treatments were administered at random with at least 2 week interval between treatments: saline (control), butorphanol low dosage (treatment LD; 0.25 mg kg-1 IV bolus followed by 85 μg kg-1 minute-1 for 20 minutes, then 43 μg kg-1 minute-1 for 40 minutes, then 19 μg kg-1 minute-1), medium dosage (treatment MD, double the dosages in LD) and high dosage (treatment HD, quadruple the dosages in LD). MACISO was determined in duplicate using the bracketing technique and tail clamping. Pulse rate, arterial pressure, hemoglobin oxygen saturation, end-tidal partial pressure of carbon dioxide and arterial blood gas and pH were measured. RESULTS Butorphanol reduced MACISO in a dosage-dependent manner, by 23 ± 8%, 37 ± 12% and 68 ± 10% (mean ± standard deviation) in treatments LD, MD and HD, respectively. The main cardiopulmonary effect observed was a decrease in pulse rate, significant in treatment HD compared with control. CONCLUSIONS AND CLINICAL RELEVANCE Butorphanol caused a dosage-dependent MACISO reduction in cats. IV infusion of butorphanol may be of interest for partial IV anesthesia in cats.
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Affiliation(s)
- Bruno H Pypendop
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
| | - Mariela Goich
- School of Veterinary Medicine, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Yael Shilo-Benjamini
- Koret School of Veterinary Medicine, The Robert H Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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Molter C, Escobar A, Schroeder C. Backyard Poultry and Waterfowl Sedation and Anesthesia. Vet Clin North Am Exot Anim Pract 2021; 25:163-180. [PMID: 34823690 DOI: 10.1016/j.cvex.2021.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The popularity of backyard poultry (chickens, turkey, guinea fowl) and waterfowl (ducks and geese) is increasing in the United States, and these animals frequently present for veterinary care. Like other birds, these species have unique anatomy that should be clinically considered before anesthesia. A balanced approach to an injectable, inhalational, or combination anesthesia protocol must be taken to ensure a safe outcome for the patient and to achieve the procedural needs. A well-informed clinician may use both sedation and general anesthesia to care for backyard bird patients in practice.
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Affiliation(s)
- Christine Molter
- Animal Health Department, Houston Zoo, Inc., 1513 Cambridge Street, Houston, TX 77030, USA.
| | - André Escobar
- Department of Clinical Sciences, Ross University School of Veterinary Medicine, PO Box 334, Basseterre, St. Kitts, West Indies
| | - Carrie Schroeder
- Department of Surgical Sciences, University of Wisconsin School of Veterinary Medicine, 2015 Linden Drive, Madison, WI 53706, USA
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Brosnan RJ, Pypendop BH. Evaluation of whether acepromazine maleate causes fentanyl to decrease the minimum alveolar concentration of isoflurane in cats. Am J Vet Res 2021; 82:352-357. [PMID: 33904805 DOI: 10.2460/ajvr.82.5.352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine whether isoflurane-anesthetized cats with demonstrated resistance to the immobilizing effects of fentanyl would exhibit naltrexone-reversible sparing of the minimum alveolar concentration (MAC) of isoflurane when fentanyl was coadministered with the centrally acting catecholamine receptor antagonist acepromazine. ANIMALS 5 healthy male purpose-bred cats. PROCEDURES Anesthesia was induced and maintained with isoflurane in oxygen. Baseline isoflurane MAC was measured by use of a standard tail clamp stimulus and bracketing study design. Afterward, fentanyl was administered IV to achieve a plasma concentration of 100 ng/mL by means of target-controlled infusion, and isoflurane MAC was remeasured. Next, acepromazine maleate (0.1 mg/kg) was administered IV, and isoflurane MAC was remeasured. Finally, isoflurane concentration was equilibrated at 70% of the baseline MAC. Movement of cats in response to tail clamping was tested before and after IV bolus administration of naltrexone. Physiologic responses were compared among treatment conditions. RESULTS Isoflurane MAC did not differ significantly between baseline and fentanyl infusion (mean ± SD, 1.944 ± 0.111% and 1.982 ± 0.126%, respectively). Acepromazine with fentanyl significantly decreased isoflurane MAC to 1.002 ± 0.056% of 1 atm pressure. When isoflurane was increased to 70% of the baseline MAC, no cats moved in response to tail clamping before naltrexone administration, but all cats moved after naltrexone administration. CONCLUSIONS AND CLINICAL RELEVANCE Acepromazine caused fentanyl to decrease the isoflurane MAC in cats that otherwise did not exhibit altered isoflurane requirements with fentanyl alone. Results suggested that opioid-mediated increases in brain catecholamine concentrations in cats counteract the opioid MAC-sparing effect.
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Keating SCJ, Kerr CL. Cardiopulmonary effects of an intravenous infusion of fentanyl in cats during isoflurane anesthesia and with concurrent acepromazine or dexmedetomidine administration during anesthetic recovery. Am J Vet Res 2021; 82:261-267. [PMID: 33764830 DOI: 10.2460/ajvr.82.4.261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine the cardiopulmonary effects of IV administration of fentanyl to cats anesthetized with isoflurane and during anesthetic recovery with concurrent administration of acepromazine or dexmedetomidine. ANIMALS 6 healthy adult cats. PROCEDURES Cats received an IV bolus (5 μg/kg) followed by an IV infusion (5 μg/kg/h) of fentanyl for 120 minutes during isoflurane anesthesia and for 30 minutes after discontinuing isoflurane. Cats were randomly assigned in a crossover study to receive acepromazine (0.05 mg/kg) or dexmedetomidine (2.5 μg/kg), IV, when isoflurane was discontinued. Cardiopulmonary data were obtained during anesthesia and for 30 minutes during the anesthetic recovery period. RESULTS The administration of fentanyl during isoflurane anesthesia resulted in a transient increase in arterial blood pressure, mean pulmonary artery pressure, and oxygen delivery. Compared with values during isoflurane anesthesia, administration of dexmedetomidine during anesthetic recovery resulted in significant decreases in cardiac index, stroke index, and oxygen delivery and significant increases in arterial, central venous, and mean pulmonary artery pressures; systemic vascular resistance index; and oxygen extraction ratio. Administration of acepromazine resulted in increases in heart rate, cardiac index, oxygen uptake, and oxygen extraction ratio. Oxygen extraction ratio did not differ between acepromazine and dexmedetomidine. CONCLUSIONS AND CLINICAL RELEVANCE Fentanyl transiently improved indices of cardiopulmonary performance when administered to healthy cats anesthetized with isoflurane. The cardiovascular effects of acepromazine and dexmedetomidine in healthy cats receiving fentanyl during recovery from isoflurane anesthesia differed, but measured cardiopulmonary parameters remained within acceptable limits.
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Escobar A, Barletta M, Pypendop BH, Sakai DM, Gordon J, Quandt JE. Pharmacokinetics and pharmacodynamics of methadone administered intravenously and intramuscularly to isoflurane-anesthetized chickens. Am J Vet Res 2021; 82:181-188. [PMID: 33629899 DOI: 10.2460/ajvr.82.3.181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine the pharmacokinetics and pharmacodynamics of methadone after IV or IM administration to isoflurane-anesthetized chickens. ANIMALS 6 healthy adult Hy-Line hens. PROCEDURES In a randomized crossover-design study, methadone (6 mg/kg) was administered IV and IM to isoflurane-anesthetized chickens with a 1-week washout period between experiments. Blood samples were collected immediately before and at predetermined time points up to 480 minutes after methadone administration. Plasma concentrations were determined by liquid chromatography-mass spectrometry, and appropriate compartmental models were fit to the plasma concentration-versus-time data. Cardiorespiratory variables were compared between treatments and over time with mixed-effect repeated-measures analysis. RESULTS A 3-compartment model best described the changes in plasma methadone concentration after IV or IM administration. Estimated typical values for volumes of distribution were 692 mL/kg for the central compartment and 2,439 and 2,293 mL/kg for the first and second peripheral compartments, respectively, with metabolic clearance of 23.3 mL/kg/min and first and second distributional clearances of 556.4 and 51.8 mL/kg/min, respectively. Typical bioavailability after IM administration was 79%. Elimination half-life was 177 minutes, and maximum plasma concentration after IM administration was 950 ng/mL. Heart rate was mildly decreased at most time points beginning 5 minutes after IV or IM drug administration. CONCLUSIONS AND CLINICAL RELEVANCE Disposition of methadone in isoflurane-anesthetized chickens was characterized by a large volume of distribution and moderate clearance, with high bioavailability after IM administration. Additional studies are warranted to assess pharmacokinetics and pharmacodynamics of methadone in awake chickens.
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Amon T, Kästner SBR, Kietzmann M, Tünsmeyer J. Plasma levels of a methadone constant rate infusion and their corresponding effects on thermal and mechanical nociceptive thresholds in dogs. BMC Vet Res 2021; 17:35. [PMID: 33461553 PMCID: PMC7814539 DOI: 10.1186/s12917-020-02735-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 09/20/2020] [Indexed: 11/22/2022] Open
Abstract
Background The present study aimed to collect pharmacokinetic data of a methadone continuous rate infusion (CRI) and to investigate its effect on mechanical and thermal nociceptive thresholds. Seven, 47 to 54 months old beagle dogs, weighing 9.8 to 21.2 kg, were used in this experimental, randomized, blinded, placebo-controlled crossover study. Each dog was treated twice with either a methadone bolus of 0.2 mg kg− 1 followed by a 0.1 mg kg− 1 h− 1 methadone CRI (group M) or an equivalent volume of isotonic saline solution (group P) for 72 h. Mechanical and thermal thresholds, as well as vital parameters and sedation were measured during CRI and for further 24 h. Blood samples for methadone plasma concentrations were collected during this 96 h period. Results Percentage thermal excursion (%TE) increased significantly from baseline (BL) until 3 h after discontinuation of CRI in M. Within P and between treatment groups differences were not significant. Mechanical threshold (MT) increased in M until 2 h after CRI discontinuation. Bradycardia and hypothermia occurred in M during drug administration and dogs were mildly sedated for the first 47 h. Decreased food intake and regurgitation were observed in M in five and four dogs, respectively. For methadone a volume of distribution of 10.26 l kg− 1 and a terminal half-life of 2.4 h were detected and a clearance of 51.44 ml kg− 1 min− 1 was calculated. Effective methadone plasma concentrations for thermal and mechanical antinociception were above 17 ng ml− 1. Conclusion A methadone CRI of 0.1 mg kg− 1 h− 1 for 3 days after a loading dose results in steady anti-nociceptive effects in an acute pain model in healthy dogs. Main side effects were related to gastrointestinal tract, hypothermia, bradycardia and sedation.
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Affiliation(s)
- T Amon
- Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany.
| | - S B R Kästner
- Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany
| | - M Kietzmann
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany
| | - J Tünsmeyer
- Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany
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Raue JF, Tünsmeyer J, Kästner SBR. Effects of isoflurane, remifentanil and dexmedetomidine on selected EEG parameters derived from a Narcotrend Monitor before and after nociceptive stimulation at different MAC multiples in cats. BMC Vet Res 2020; 16:332. [PMID: 32928231 PMCID: PMC7489203 DOI: 10.1186/s12917-020-02532-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/19/2020] [Indexed: 11/19/2022] Open
Abstract
Background The aim of this prospective and complete cross-over study was to evaluate the effects of isoflurane, remifentanil and dexmedetomidine on EEG parameters derived from the Narcotrend® Monitor before and after nociceptive stimulation at different isoflurane MAC (minimal alveolar concentration) multiples. Seven adult European Domestic Short Hair cats were used. Each cat went through 3 experimental treatments. Group I received isoflurane, group IR received isoflurane and a constant rate infusion (CRI) of remifentanil (18 μg/kg/h IV), and group ID received isoflurane and a CRI of dexmedetomidine (3 μg/kg/h IV). The isoflurane MAC in each group was determined via supramaximal electrical stimulation. The EEG parameters were derived by a Narcotrend Monitor at specific time points before and after nociceptive stimulation at 0.75, 1.0 and 1.5 MAC. The depth of anaesthesia was also assessed by a clinical score. Results The mean MAC sparing effects in group IR and group ID were 9.8 and 55.2%, respectively. The best correlation of EEG and MAC multiples was found for the Narcotrend Index (NI) in group I (r = − 0.67). The NI was also able to differentiate between 0.75 MAC and 1.5 MAC in group IR. Spectral edge frequency had a lower correlation with MAC multiples in group I (r = − 0.62) but was able to differentiate between 0.75 MAC and 1.5 MAC in groups I and IR, and between 1.0 MAC and 1.5 MAC in group IR. Narcotrend Index, SEF 95 and MF increased significantly after nociceptive stimulation at 1.0 MAC in group I, and SEF 95 increased significantly at 0.75 MAC in group ID. The clinical score correlated closer than any of the EEG parameters with MAC in all groups, with highest correlation values in group I (r = − 0.89). Noxious stimulation led to a significant increase of the clinical score at 0.75 MAC and 1.0 MAC in group I. Conclusions The EEG parameters derived from the Narcotrend Monitor show correlation to isoflurane MAC multiples in cats, but the anaesthetic protocol and especially the addition of dexmedetomidine have great influence on the reliability. The Narcotrend Monitor can be used as an additional tool to assess anesthetic depth in cats.
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Affiliation(s)
- Jonathan F Raue
- Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany.
| | - Julia Tünsmeyer
- Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany
| | - Sabine B R Kästner
- Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany.,Center for Systems Neuroscience Hannover, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany
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Brosnan RJ, Pypendop BH, Stanley SD. Phenylpiperidine opioid effects on isoflurane minimum alveolar concentration in cats. J Vet Pharmacol Ther 2020; 43:533-537. [PMID: 32557697 DOI: 10.1111/jvp.12886] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/12/2020] [Accepted: 05/27/2020] [Indexed: 12/01/2022]
Abstract
Different structurally related phenylpiperidine opioids exhibit different isoflurane-sparing effects in cats. Because minimum alveolar concentration (MAC) in cats is affected only by very high plasma concentrations of some phenylpiperidine opioids, we hypothesized these effects are caused by actions on nonopioid receptors. Using a prospective, randomized, crossover design, six cats were anesthetized with isoflurane, intubated, ventilated, and instrumented. Isoflurane MAC was measured in triplicate using a tail-clamp and bracketing technique. A computer-controlled intravenous infusion using prior pharmacokinetic models targeted plasma concentrations of 60 ng/ml fentanyl, 10 ng/ml sufentanil, or 500 ng/ml alfentanil, and isoflurane MAC was measured in duplicate. Next, naltrexone 0.6 mg/kg was administered to cats hourly during the opioid infusion, and isoflurane MAC was measured in duplicate. Blood was collected during MAC determinations to measure opioid concentrations. Responses were analyzed using repeated measures ANOVA with significance at p < .05. Alfentanil and sufentanil decreased isoflurane MAC by 16.4% and 6.4%, respectively, and these effects were completely reversed by naltrexone. Fentanyl had no significant effect on isoflurane MAC. Alfentanil and sufentanil modestly reduce isoflurane MAC via agonist effects on opioid receptors. However, these effects are too small to justify clinical use of phenylpiperidine opioids as single agents to reduce MAC in cats.
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Affiliation(s)
- Robert J Brosnan
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, USA
| | - Bruno H Pypendop
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, USA
| | - Scott D Stanley
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, USA
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Santos EA, Monteiro ER, Herrera JR, Mombach VS, Boos MZ, Gutierrez LG, Alievi MM. Total intravenous anesthesia in domestic chicken (Gallus gallus domesticus) with propofol alone or in combination with methadone, nalbuphine or fentanyl for ulna osteotomy. Vet Anaesth Analg 2020; 47:347-355. [PMID: 32222345 DOI: 10.1016/j.vaa.2020.01.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 01/24/2020] [Accepted: 01/25/2020] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To compare the propofol infusion rate and cardiopulmonary effects during total intravenous anesthesia with propofol alone and propofol combined with methadone, fentanyl or nalbuphine in domestic chickens undergoing ulna osteotomy. STUDY DESIGN Prospective, randomized, experiment trial. ANIMALS A total of 59 healthy Hissex Brown chickens weighing 1.5 ± 0.2 kg. METHODS Anesthesia was induced with propofol (9 mg kg-1) administered intravenously (IV) and maintained with propofol (1.2 mg kg-1 minute-1) for 30 minutes. Birds were intubated and supplemented with 100% oxygen through a nonrebreathing circuit under spontaneous ventilation. Thereafter, each animal was randomly assigned to one of four groups: group P, no treatment; group PM, methadone (6 mg kg-1) intramuscularly (IM); group PN, nalbuphine IM (12.5 mg kg-1); and group PF, fentanyl IV (30 μg kg-1 loading dose, 30 μg kg-1 hour-1 constant rate infusion). During the osteotomy surgery, the propofol infusion rate was adjusted to avoid movement of birds and provide adequate anesthesia. Pulse rate, invasive blood pressure, respiratory frequency, end-tidal carbon dioxide partial pressure (Pe'CO2) and hemoglobin oxygen saturation (SpO2) were recorded. RESULTS Data were available from 58 chickens. The mean ± standard deviation propofol infusion rate (mg kg-1 minute-1) for the duration of anesthesia was: group P, 0.81 ± 0.15; group PM, 0.66 ± 0.11; group PN, 0.60 ± 0.14; and group PF, 0.80 ± 0.07. Significant differences were P versus PM (p = 0.042), P versus PN (p = 0.002) and PF versus PN (p = 0.004). Pulse rate, blood pressure and SpO2 remained acceptable for anesthetized birds with minor differences among groups. Values of Pe'CO2 >60 mmHg (8 kPa) were observed in all groups. CONCLUSIONS AND CLINICAL RELEVANCE Methadone and nalbuphine, but not fentanyl, decreased the propofol infusion rate required for anesthesia maintenance, but resulted in no obvious benefit in physiological variables.
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Affiliation(s)
- Eduardo Ar Santos
- Department of Animal Medicine, Faculty of Veterinary Medicine, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Eduardo R Monteiro
- Department of Animal Medicine, Faculty of Veterinary Medicine, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
| | - José R Herrera
- Department of Animal Medicine, Faculty of Veterinary Medicine, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Verônica S Mombach
- Department of Animal Medicine, Faculty of Veterinary Medicine, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Mariana Z Boos
- Department of Animal Medicine, Faculty of Veterinary Medicine, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Letícia G Gutierrez
- Department of Animal Medicine, Faculty of Veterinary Medicine, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Marcelo M Alievi
- Department of Animal Medicine, Faculty of Veterinary Medicine, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
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Williams CJA, James LE, Bertelsen MF, Wang T. Analgesia for non-mammalian vertebrates. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Experimental study on the effects of isoflurane with and without remifentanil or dexmedetomidine on heart rate variability before and after nociceptive stimulation at different MAC multiples in cats. BMC Vet Res 2019; 15:258. [PMID: 31340857 PMCID: PMC6657164 DOI: 10.1186/s12917-019-2004-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 07/15/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Heart rate variability (HRV) provides information about autonomic nervous system (ANS) activity and is therefore a possible tool with which to assess anaesthetic depth. The aim of the present study was to evaluate the effects of isoflurane, remifentanil and dexmedetomidine on HRV before and after nociceptive stimulation at different anaesthetic depths. Seven healthy domestic short-hair cats were used, and each cat was anaesthetized three times - group I with isoflurane alone, group IR with isoflurane and a constant rate infusion (CRI) of remifentanil (18 μg/kg/h), and group ID with isoflurane and a CRI of dexmedetomidine (3 μg/kg/h). Minimum alveolar concentration (MAC) values were determined via electrical supramaximal nociceptive stimulation for each treatment group. Nociceptive stimulation was repeated at 3 different MAC multiples (0.75, 1.0 and 1.5 MAC), and electrocardiographic recordings were performed for 3 min before and after stimulation. Only the 1 min epochs were used for further statistical analysis. Electrocardiographic data were exported for offline HRV analysis. RESULTS The mean isoflurane MAC ± standard deviation (SD) was 1.83 ± 0.22 vol% in group I, 1.65 ± 0.13 vol% in group IR and 0.82 ± 0.20 vol% in group ID. Nociception was indicated by several HRV parameters, however, with high variability between treatments. The best correlation with MAC was found for the SD of heart rate (STD HR) in group I (rs = - 0.76, p = 0.0001, r2 = 0.46). STD HR was also able to distinguish 0.75 MAC from 1.5 MAC and 1.0 MAC from 1.5 MAC in group I, as well as 0.75 MAC from 1.5 MAC in group ID. CONCLUSIONS The choice of anaesthetic protocol influences the HRV parameters in cats. Frequency domain parameters respond to nociception at lower MAC levels. The STD HR has the potential to provide additional information for the assessment of anaesthetic depth in isoflurane-anaesthetized cats. The utility of HRV analysis for the assessment of anaesthetic depth in cats is still questionable.
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Effect of fentanyl on thermal and mechanical nociceptive thresholds in horses and estimation of anti-nociceptive plasma concentration. Vet J 2019; 249:82-88. [PMID: 31239171 DOI: 10.1016/j.tvjl.2019.05.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 05/12/2019] [Accepted: 05/29/2019] [Indexed: 11/23/2022]
Abstract
There are few investigations relating anti-nociception to plasma concentrations of fentanyl in horses. The study objective was to evaluate analgesic efficacy and duration in horses and determine the minimum anti-nociceptive plasma concentrations. Eight horses were treated with saline (P) and fentanyl (F2.5=2.5μg/kg; F5=5μg/kg; F10=10μg/kg) given IV over 5min, with a wash-out period of 10 days. To evaluate thermal (°C) and mechanical (N) nociceptive threshold single stimulations were applied prior to (baseline) and 10, 30, 60, 90, 120, 180, 240, 300, 360, 420, 540min and 22.5h after treatment. Plasma fentanyl concentrations were measured at specific time points. Locomotor activity, heart rate, respiratory rate and gastrointestinal sounds were recorded. Two-way repeated measures ANOVA and pairwise comparisons were used for data analysis (P<0.05). With treatment F10, there was a significant increase in thermal threshold above baseline (47.2ö4.1°C) at t10 (53.7ö4.2°C) and t30 (52.1ö5.6°C), whereas mechanical threshold increased considerably above baseline (3.7ö1.3N) only at t10 (6.6ö3.6N). Estimated mean minimum anti-nociceptive plasma concentration determined by thermal stimulation was 6.1-6.8ng/mL. Dose-dependent increased locomotion occurred, but no significant changes in heart rate, respiratory rate and gastrointestinal sounds were observed. Fentanyl IV at 10μg/kg produced anti-nociception for 10-30min and fentanyl plasma concentrations of ≥6.1-6.8ng/mL appear necessary to induce thermal anti-nociception. Dose-dependent increased locomotion was the main side effect observed.
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Machado ML, Soares JHN, Kuster de Albuquerque Gress MA, dos Santos e Castro D, Teodoro Rosa K, Bauer de Araujo Doria P, Otero Ascoli F. Dose-finding study comparing three treatments of remifentanil in cats anesthetized with isoflurane undergoing ovariohysterectomy. J Feline Med Surg 2018; 20:164-171. [PMID: 28391757 PMCID: PMC11129268 DOI: 10.1177/1098612x17703010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Objectives Three infusion rates of remifentanil were used in isoflurane-anesthetized cats undergoing ovariohysterectomy. The aim of this study was to identify a dosage regimen that would provide optimal anesthetic and surgical conditions, as well as to compare cardiovascular response to surgical stimulation, postoperative analgesia, anesthetic duration and quality of recovery among the tested remifentanil infusion rates. Methods Twenty-seven client-owned, mixed-breed adult healthy female cats were randomized to receive remifentanil 0.1 µg/kg/min (REMI01), remifentanil 0.2 µg/kg/min (REMI02) or remifentanil 0.4 µg/kg/min (REMI04). After premedication with acepromazine and induction of anesthesia with propofol, cats were mechanically ventilated and anesthesia was maintained at approximately 1.0 minimum alveolar concentration (MAC) of isoflurane (1.63% end-tidal isoflurane [ETISO]). Remifentanil infusion rate was increased or decreased by 20% if blood pressure had increased or decreased by 20% from previous values. Pulse rate (PR), systolic arterial pressure (SAP), esophageal temperature, pulse oximetry, end-tidal partial pressure of CO2 and ETISO were recorded at different time points during surgery. Meloxicam was administered before the end of surgery. Data within each treatment group were analyzed using a mixed-model ANOVA and Friedman's test followed by the Wilcoxon signed rank test. Bonferroni or Dunnett's post-hoc tests were used. The Kruskal-Wallis test followed by Dunn's post-hoc test were used to compare data between groups; significance was set at P <0.05. Results Time to sternal recumbency and time to standing were significantly longer in REMI04 than in the other groups. SAP was higher when compared with baseline in REMI01 and REMI02 groups than in REMI04. No significant difference in PR among groups was observed. One cat in REMI01 and another in REMI02 required postoperative rescue analgesia. Conclusion and relevance The dosage regimen of 0.4 µg/kg/min seemed to be the most appropriate to be used in cats undergoing ovariohysterectomy and anesthetized with 1.0 MAC of isoflurane.
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Affiliation(s)
- Marcela L Machado
- Graduate Program in Cardiovascular Sciences, College of Medicine, Fluminense Federal University (UFF), Niterói, RJ, Brazil
| | - João Henrique N Soares
- Department of Small Animal Clinical Sciences, Virginia–Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | | | | | - Kaleizu Teodoro Rosa
- Department of Large Animal Clinical Sciences. Anesthesia and Pain Management Service, University of Florida, Gainesville, FL, USA
| | - Phillipe Bauer de Araujo Doria
- Department of Pathology and Clinical Sciences, College of Veterinary Medicine, Fluminense Federal University, Niterói, RJ, Brazil
| | - Fabio Otero Ascoli
- Graduate Program in Cardiovascular Sciences, College of Medicine, Fluminense Federal University (UFF), Niterói, RJ, Brazil
- Department of Physiology and Pharmacology, Biomedical Institute, Fluminense Federal University, Niterói, RJ, Brazil
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Reed R, Doherty T. Minimum alveolar concentration: Key concepts and a review of its pharmacological reduction in dogs. Part 1. Res Vet Sci 2018; 117:266-270. [PMID: 29331922 DOI: 10.1016/j.rvsc.2018.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 11/25/2017] [Accepted: 01/08/2018] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To outline the major components of the minimum alveolar concentration (MAC) and review the literature in regard to pharmacological manipulation of the MAC of halothane, isoflurane, sevoflurane, enflurane, and desflurane in dogs. The pharmacologic agents included are alpha-2 agonists, benzodiazepines, propofol, maropitant, opioids, lidocaine, acepromazine, non-steroidal anti-inflammatory agents, and NMDA antagonists. Part 1 will focus on summarizing the relevance, measurement, and mechanisms of MAC and review the effects of alpha-2 agonists, benzodiazepines, and propofol on MAC. DATABASES USED PubMed, Google Scholar, CAB Abstracts. Search terms used: minimum alveolar concentration, MAC, dog, canine, inhaled anesthetic potency, isoflurane, sevoflurane, desflurane, enflurane, and halothane. CONCLUSIONS Many drugs reduce the MAC of inhaled anesthetics in dogs, and allow for a clinically important decrease in inhalant anesthetic use. A decrease in MAC may decrease the adverse cardiovascular and pulmonary effects associated with the use of high concentrations of inhaled anesthetics.
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Affiliation(s)
- Rachel Reed
- University of Georgia College of Veterinary Medicine, 2200 College Station Rd., Athens, GA 30605, USA.
| | - Thomas Doherty
- University of Tennessee College of Veterinary Medicine, 2407 River Dr., Knoxville, TN 37996, USA.
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Pekkola V, Braun C, Larenza Menzies MP. Anaesthetising a cat with tetralogy of Fallot for non‐cardiac surgery. VETERINARY RECORD CASE REPORTS 2017. [DOI: 10.1136/vetreccr-2017-000508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Vuokko Pekkola
- Veterinary Teaching HospitalUniversity of HelsinkiFinland
| | - Christina Braun
- Department for Companion Animals and HorsesUniversity of Veterinary Medicine ViennaAustria
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Nagakubo D, Hamamoto Y, Hasegawa D, Kamata M, Iizuka T, Muta K, Fujita N, Nakagawa T, Nishimura R. Functional MRI-based identification of brain regions activated by mechanical noxious stimulation and modulatory effect of remifentanil in cats. Res Vet Sci 2017; 114:444-449. [PMID: 28772233 DOI: 10.1016/j.rvsc.2017.07.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 06/10/2017] [Accepted: 07/21/2017] [Indexed: 12/18/2022]
Abstract
This study was conducted to identify the brain regions corresponding to mechanical noxious stimulation in cats using functional magnetic resonance imaging (fMRI) and to investigate the modulatory effect of remifentanil on the activation of these regions. Six healthy cats were anesthetized using a constant-rate infusion of alfaxalone. Cats were allocated to one of three treatment groups: remifentanil 0 (saline), 0.25, and 0.5μg/kg/min. A 3.0-T MRI unit was used to collect fMRI data. During the fMRI scanning, mechanical noxious stimulation was applied by tail clamping. The brain regions activated by the stimulation were identified based on blood oxygenation level-dependent (BOLD) responses. The modulatory effects of remifentanil were evaluated using a region of interest (ROI) analysis comparing signal changes in each brain region. Increased activity from noxious stimulation was observed in the somatosensory area (the postcruciatus gyrus, the anterior part of the marginalis gyrus, and the anterior part of the ectomarginalis gyrus), the parietal association area (the middle part of the marginalis gyrus and the middle part of the ectomarginalis gyrus), the cingulate cortex, the hippocampus, and the cerebellum. The results of the ROI analysis indicated that activations in the somatosensory area, the cingulate cortex, the hippocampus, and the cerebellum were significantly modulated (P<0.05) by remifentanil. In cats, activation patterns evoked by mechanical noxious stimulation were observed in several brain regions thought to be involved in various aspects of pain processing, including sensory discrimination and integration, affect, and motor response. These brain responses were modulated by remifentanil.
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Affiliation(s)
- Dai Nagakubo
- Laboratory of Veterinary Surgery, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yuji Hamamoto
- Department of Clinical Veterinary Medicine, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino-shi, Tokyo 180-8602, Japan
| | - Daisuke Hasegawa
- Department of Clinical Veterinary Medicine, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino-shi, Tokyo 180-8602, Japan
| | - Masatoshi Kamata
- Veterinary Medical Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tomoya Iizuka
- Veterinary Medical Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kanako Muta
- Laboratory of Veterinary Surgery, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Naoki Fujita
- Laboratory of Veterinary Surgery, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takayuki Nakagawa
- Laboratory of Veterinary Surgery, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Ryohei Nishimura
- Laboratory of Veterinary Surgery, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
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EFFECTS OF TRAMADOL ON THE MINIMUM ANESTHETIC CONCENTRATION OF ISOFLURANE IN WHITE-EYED PARAKEETS (PSITTACARA LEUCOPHTHALMUS). J Zoo Wildl Med 2017; 48:380-387. [DOI: 10.1638/2016-0180r1.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Dönselmann Im Sande P, Hopster K, Kästner S. [Effects of morphine, butorphanol and levomethadone in different doses on thermal nociceptive thresholds in horses]. Tierarztl Prax Ausg G Grosstiere Nutztiere 2017; 45:98-106. [PMID: 28075433 DOI: 10.15653/tpg-160655] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 10/14/2016] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Various opioids are available for use in equine medicine. Studies directly comparing their analgesic effects and side effects are rare. Therefore, the aim of this study was to compare the antinociceptive effect and the duration of analgesia of two different doses of morphine, butorphanol and levomethadone in horses. MATERIAL AND METHODS Eight adult, healthy horses were used for this randomized, placebo-controlled, blinded cross-over trail. Each horse received placebo (P = 0.9% saline) and morphine (M0.1 = 0.1 mg/kg; M0.2 = 0.2 mg/kg), butorphanol (B0.1 = 0.1 mg/kg; B0.2 = 0.2 mg/kg) and levomethadone (L0.1 = 0.1 mg/kg; L0.2 = 0.2 mg/kg) in a low and a high dose and with a wash-out period of 14 days. Thermal thresholds were determined by incremental contact heat applied to the skin at the withers. Single stimulations were performed 15 minutes prior and 10, 30, 60, 90, 120, 180, 240, 300, 360, 420, 540 and 1350 minutes after treatment. Threshold values, gastrointestinal auscultation score and horses' behavior were recorded. Data were analyzed with analysis of variance for repeated measurements (p < 0.05). RESULTS In group M0.1, changes in thermal thresholds did not reach significance. Thermal threshold increased significantly in the groups M0.2, B0.1, B0.2, L0.1 and L0.2 for 240, 90, 90, 60 and 300 minutes, respectively. Behavioural changes, increased locomotion and decreased bowel sounds as well as delayed time until defecation were noticed in all groups. CONCLUSIONS Levomethadone induced a dose-dependent increase and prolongation of analgesia, whereas with butorphanol there was no difference between dosages regarding duration and intensity of analgesia. Morphine provided detectable analgesia only in the high dose of 0.2 mg/kg. CLINICAL RELEVANCE Levomethadone and morphine in the low dose (0.1 mg/kg) produced only minor and short lived anti-nociception and further studies are necessary to give a profound dose recommendation for the use of these drugs in horses.
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Affiliation(s)
| | | | - Sabine Kästner
- Prof. Dr. Sabine Kästner, Klinik für Pferde, Tierärztliche Hochschule Hannover, Bünteweg 9, 30559 Hannover, E-Mail:
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Schütter AF, Tünsmeyer J, Kästner SBR. Influence of tramadol on acute thermal and mechanical cutaneous nociception in dogs. Vet Anaesth Analg 2017; 44:309-316. [PMID: 28215815 DOI: 10.1016/j.vaa.2016.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 12/19/2015] [Accepted: 02/02/2016] [Indexed: 10/20/2022]
Abstract
OBJECTIVE The aim of the study was to evaluate the influence of tramadol on acute nociception in dogs. STUDY DESIGN Experimental, blinded, randomized, crossover study. ANIMALS Six healthy laboratory Beagle dogs. METHODS Dogs received three treatments intravenously (IV): isotonic saline placebo (P), tramadol 1 mg kg-1 (T1) and tramadol 4 mg kg-1 (T4). Thermal thresholds were determined by ramped contact heat stimulation (0.6 °C second-1) at the lateral thoracic wall. Mechanical thresholds (MT) were measured using a probe containing three blunted pins which were constantly advanced over the radial bone, using a rate of force increase of 0.8 N second-1. Stimulation end points were defined responses (e.g. skin twitch, head turn, repositioning, vocalization) or pre-set cut-out values (55 °C, 20 N). Thresholds were determined before treatment and at predetermined time points up to 24 hours after treatment. At each measurement point, blood was collected for determination of O-desmethyltramadol concentrations. The degree of sedation and behavioural side effects were recorded. Data were analysed by one-way anova and two-way anova for repeated measurements. RESULTS Thermal nociception was not influenced by drug treatment. Mechanical nociception was significantly increased between P and T1 at 120 and 240 minutes, and between P and T4 at 30, 60, 240 and 420 minutes. T1 and T4 did not differ. O-desmethyltramadol (M1) maximum plasma concentrations (Cmax) were 4.2±0.8 ng mL-1 and 14.3±2.8 ng mL-1 for T1 and T4, respectively. Times to reach maximum plasma concentrations (Tmax) were 27.6±6.3 minutes for T1 and 32.1±7.8 minutes for T4. No sedation occurred. There were signs of nausea and mild to moderate salivation in both groups. CONCLUSION AND CLINICAL RELEVANCE Tramadol was metabolized marginally to O-desmethyltramadol and failed to produce clinically relevant acute antinociception. Therefore, the use of tramadol for acute nociceptive pain is questionable in dogs.
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Affiliation(s)
- Alexandra F Schütter
- Clinic for Small Animals, University of Veterinary Medicine, Hannover Foundation, Germany.
| | - Julia Tünsmeyer
- Clinic for Small Animals, University of Veterinary Medicine, Hannover Foundation, Germany
| | - Sabine B R Kästner
- Clinic for Small Animals, University of Veterinary Medicine, Hannover Foundation, Germany
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Amitriptyline, minocycline and maropitant reduce the sevoflurane minimum alveolar concentration and potentiate remifentanil but do not prevent acute opioid tolerance and hyperalgesia in the rat: a randomised laboratory study. Eur J Anaesthesiol 2016; 32:248-54. [PMID: 24849503 DOI: 10.1097/eja.0000000000000098] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The antidepressant amitriptyline, the inhibitor of microglia activation minocycline, and the neurokinin-1 antagonist maropitant have all been used to prevent or treat hyperalgesia and opioid tolerance. OBJECTIVES To determine the effect of amitriptyline, minocycline, maropitant, independently or with remifentanil, on the sevoflurane minimum alveolar concentration in rats and whether these drugs may block opioid-induced hyperalgesia and acute opioid tolerance under inhalational anaesthesia. DESIGN A randomised, laboratory study. SETTING Experimental Unit, La Paz University Hospital, Madrid, Spain. ANIMALS One hundred and fourteen adult male Wistar rats. INTERVENTIONS Intraperitoneal administration of amitriptyline (10 and 50 mg kg-1), minocycline (30 and 100 mg kg-1), maropitant (10 and 30 mg kg-1) or isotonic saline, combined with a constant rate intravenous infusion of remifentanil (240 μg kg-1 h-1) or saline. MAIN OUTCOME MEASURES Sevoflurane minimum alveolar concentration was determined before and after administration of the drugs; acute opioid tolerance was defined as a decreased ability of remifentanil to reduce the minimum alveolar concentration in the short term. In addition, mechanical nociceptive thresholds were determined before and after these treatments. Opioid-induced hyperalgesia was defined as an increase in mechanical nociceptive thresholds after opioid administration. RESULTS Amitriptyline, minocycline and maropitant reduced minimum alveolar concentration up to 24 (8)%, 23 (6)% and 15 (5)%, respectively (P <0.001). Remifentanil alone reduced minimum alveolar concentration by 36 (6)% (P <0.001), and in combination with amitriptyline, minocycline and maropitant, the reduction was 76 (9)%, 75 (16)% and 59 (5)%, respectively (P <0.001). An acute tolerance effect (P < 0.01) and a decrease in the mechanical nociceptive thresholds were observed with remifentanil in all groups. CONCLUSION Amitriptyline, minocycline and maropitant reduced the minimum alveolar concentration and potentiated the remifentanil minimum alveolar concentration reduction but failed to block opioid-induced hyperalgesia and acute opioid tolerance.
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Effects of Methadone on the Minimum Anesthetic Concentration of Isoflurane, and Its Effects on Heart Rate, Blood Pressure and Ventilation during Isoflurane Anesthesia in Hens (Gallus gallus domesticus). PLoS One 2016; 11:e0152546. [PMID: 27018890 PMCID: PMC4809615 DOI: 10.1371/journal.pone.0152546] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 03/16/2016] [Indexed: 11/24/2022] Open
Abstract
The aim of this study was to measure the temporal effects of intramuscular methadone administration on the minimum anesthetic concentration (MAC) of isoflurane in hens, and to evaluate the effects of the isoflurane-methadone combination on heart rate and rhythm, blood pressure and ventilation. Thirteen healthy adult hens weighing 1.7 ± 0.2 kg were used. The MAC of isoflurane was determined in each individual using the bracketing method. Subsequently, the reduction in isoflurane MAC produced by methadone (3 or 6 mg kg-1, IM) was determined by the up-and-down method. Stimulation was applied at 15 and 30 minutes, and at 45 minutes if the bird had not moved at 30 minutes. Isoflurane MAC reduction was calculated at each time point using logistic regression. After a washout period, birds were anesthetized with isoflurane and methadone, 6 mg kg-1 IM was administered. Heart rate and rhythm, respiratory rate, blood gas values and invasive blood pressure were measured at 1.0 and 0.7 isoflurane MAC, and during 45 minutes after administration of methadone once birds were anesthetized with 0.7 isoflurane MAC. Fifteen minutes after administration of 3 mg kg-1 of methadone, isoflurane MAC was reduced by 2 (-9 to 13)% [logistic regression estimate (95% Wald confidence interval)]. Administration of 6 mg kg-1 of methadone decreased isoflurane MAC by 29 (11 to 46)%, 27 (-3 to 56)% and 10 (-8 to 28)% after 15, 30 and 45 minutes, respectively. Methadone (6 mg kg-1) induced atrioventricular block in three animals and ventricular premature contractions in two. Methadone caused an increase in arterial blood pressure and arterial partial pressure of carbon dioxide, while heart rate and pH decreased. Methadone, 6 mg kg-1 IM significantly reduced isoflurane MAC by 30% in hens 15 minutes after administration. At this dose, methadone caused mild respiratory acidosis and increase in systemic blood pressure.
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Schütter AF, Tünsmeyer J, Kästner SBR. Influence of metamizole on 1) minimal alveolar concentration of sevoflurane in dogs and 2) on thermal and mechanical nociception in conscious dogs. Vet Anaesth Analg 2016; 43:215-26. [DOI: 10.1111/vaa.12289] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Accepted: 03/25/2015] [Indexed: 01/15/2023]
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Sayre RS, Lepiz MA, Horsley KT, Pashmakova MB, Barr JW, Washburn SE. Effects of oxymorphone hydrochloride or hydromorphone hydrochloride on minimal alveolar concentration of desflurane in sheep. Am J Vet Res 2016; 76:583-90. [PMID: 26111087 DOI: 10.2460/ajvr.76.7.583] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To establish the minimum alveolar concentration (MAC) of desflurane and evaluate the effects of 2 opioids on MAC in sheep. ANIMALS 8 adult nulliparous mixed-breed sheep. PROCEDURES A randomized crossover design was used. Each sheep was evaluated individually on 2 occasions (to allow assessment of the effects of each of 2 opioids), separated by a minimum of 10 days. On each occasion, sheep were anesthetized with desflurane in 100% oxygen, MAC of desflurane was determined, oxymorphone (0.05 mg/kg) or hydromorphone (0.10 mg/kg) was administered IV, and MAC was redetermined. Physiologic variables and arterial blood gas and electrolyte concentrations were measured at baseline (before MAC determination, with end-tidal desflurane concentration maintained at 10%) and each time MAC was determined. Timing of various stages of anesthesia was recorded for both occasions. RESULTS Mean ± SEM MAC of desflurane was 8.6 ± 0.2%. Oxymorphone or hydromorphone administration resulted in significantly lower MAC (7.6 ± 0.4% and 7.9 ± 0.2%, respectively). Cardiac output at MAC determination for desflurane alone and for desflurane with opioid administration was higher than that at baseline. No difference was identified among hematologic values at any point. Effects of oxymorphone and hydromorphone on durations of various stages of anesthesia did not differ significantly. CONCLUSIONS AND CLINICAL RELEVANCE MAC of desflurane in nulliparous adult sheep was established. Intravenous administration of oxymorphone or hydromorphone led to a decrease in MAC; however, the clinical importance of that decrease was minor relative to the effect in other species.
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Steagall PVM, Aucoin M, Monteiro BP, Moreau M, Simon BT, Burns PM. Clinical effects of a constant rate infusion of remifentanil, alone or in combination with ketamine, in cats anesthetized with isoflurane. J Am Vet Med Assoc 2016; 246:976-81. [PMID: 25875668 DOI: 10.2460/javma.246.9.976] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate the effects of a constant rate infusion of remifentanil, alone or in combination with ketamine, in healthy cats anesthetized with isoflurane. DESIGN Randomized, controlled, clinical trial. ANIMALS 23 cats undergoing elective ovariohysterectomy. PROCEDURES Cats were premedicated with acepromazine and morphine; anesthesia was induced with propofol and maintained with isoflurane. Cats were given constant rate infusions of remifentanil (20 μg/kg/h [9 μg/lb/h], IV; n = 8), remifentanil and ketamine (0.5 mg/kg [0.23 mg/lb], then 1.8 mg/kg/h [0.82 mg/lb/h], IV; 7), or crystalloid fluids (8). The anesthesiologist was blinded to treatment group, end-tidal isoflurane concentration, and vaporizer setting. Heart rate, systolic arterial blood pressure, respiratory rate, end-tidal partial pressure of CO2, temperature, and end-tidal isoflurane concentration were monitored; recovery scores were assigned. RESULTS There were no significant differences among treatment groups with respect to age, body weight, surgery time, anesthesia time, time to extubation, recovery score, or cardiorespiratory variables. End-tidal isoflurane concentration was significantly reduced in cats given remifentanil and ketamine (mean ± SD, 0.63 ± 0.4%), compared with concentration in cats given crystalloid fluids (1.22 ± 0.5%) but not compared with concentration in cats given remifentanil alone (1.03 ± 0.4%). Compared with cats given crystalloid fluids, mean isoflurane requirement was reduced by 48.3% in cats given remifentanil-ketamine and 15.6% in cats given remifentanil alone. CONCLUSIONS AND CLINICAL RELEVANCE At the dosages administered, a constant rate infusion of remifentanil-ketamine resulted in a significant decrease in the isoflurane requirement in healthy cats undergoing ovariohysterectomy. However, significant differences in cardiovascular variables were not observed among treatment groups.
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Affiliation(s)
- Paulo V M Steagall
- Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC J2S 2M2, Canada
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Bortolami E, Love EJ. Practical use of opioids in cats: a state-of-the-art, evidence-based review. J Feline Med Surg 2015; 17:283-311. [PMID: 25832586 PMCID: PMC11104155 DOI: 10.1177/1098612x15572970] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
RATIONALE Recent recognition of the need to improve pain management in cats has led to the investigation of the pharmacokinetics and efficacy of opioid analgesic drugs in this species. The results of these studies may be difficult to interpret because the effect of these drugs varies with dose, route of administration and the method used to assess them. As equipotency of different opioids is not known, it is hard to compare their effects. Animals do not verbalise the pain they feel and, in cats, it may be more difficult to recognise signs of pain in comparison with other species such as dogs. AIM This article reviews the use of opioid analgesics in cats. It must be remembered that not all drugs are licensed for use in cats, and that marketing authorisations vary between different countries.
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Affiliation(s)
- Elisa Bortolami
- Department of Animal Medicine, Production and Health, University of Padua, Italy
| | - Emma J Love
- School of Veterinary Sciences, University of Bristol, Langford, UK
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Shaughnessy MR, Hofmeister EH. A systematic review of sevoflurane and isoflurane minimum alveolar concentration in domestic cats. Vet Anaesth Analg 2014; 41:1-13. [DOI: 10.1111/vaa.12083] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 03/13/2013] [Indexed: 10/26/2022]
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Hedges AR, Pypendop BH, Shilo-Benjamini Y, Stanley SD, Ilkiw JE. Pharmacokinetics of buprenorphine following intravenous and buccal administration in cats, and effects on thermal threshold. J Vet Pharmacol Ther 2013; 37:252-9. [DOI: 10.1111/jvp.12084] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 09/19/2013] [Indexed: 11/28/2022]
Affiliation(s)
- A. R. Hedges
- Department of Surgical and Radiological Sciences; School of Veterinary Medicine; University of California; Davis CA USA
| | - B. H. Pypendop
- Department of Surgical and Radiological Sciences; School of Veterinary Medicine; University of California; Davis CA USA
| | - Y. Shilo-Benjamini
- Department of Surgical and Radiological Sciences; School of Veterinary Medicine; University of California; Davis CA USA
| | - S. D. Stanley
- California Animal Health and Food Safety Laboratory System; School of Veterinary Medicine; University of California; Davis CA USA
| | - J. E. Ilkiw
- Department of Surgical and Radiological Sciences; School of Veterinary Medicine; University of California; Davis CA USA
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Poller C, Hopster K, Rohn K, Kästner SBR. Nociceptive thermal threshold testing in horses - effect of neuroleptic sedation and neuroleptanalgesia at different stimulation sites. BMC Vet Res 2013; 9:135. [PMID: 23837730 PMCID: PMC3708779 DOI: 10.1186/1746-6148-9-135] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 07/01/2013] [Indexed: 11/15/2022] Open
Abstract
Background Aim of the study was to compare the effect of neuroleptic sedation with acepromazine and neuroleptanalgesia with acepromazine and buprenorphine on thermal thresholds (TT) obtained at the nostrils and at the withers. The study was carried out as a randomized, blinded, controlled trial with cross-over design. Thermal thresholds were determined by incremental contact heat applied to the skin above the nostril (N) or the withers (W). Eleven horses were treated with saline (S), acepromazine (0.05 mg/kg) (ACE) or acepromazine and buprenorphine (0.0075 mg/kg) (AB) intravenously (IV). Single stimulations were performed 15 minutes prior and 15, 45, 75, 105, 165, 225, 285, 405 and 525 minutes after treatment. Sedation score, gastrointestinal auscultation score and occurrence of skin lesions were recorded. Data were analysed with analysis of variance for repeated measurements. Results There were no significant differences in TT between N and W with all treatments. The TT remained constant after S and there was no difference in TT between S and ACE. After AB there was a significant increase above baseline in TT until 405 minutes after treatment. Restlessness occurred 30–90 minutes after AB in 7 horses. All horses had reduced to absent borborygmi after AB administration for 165 to 495 minutes. Conclusion Thermal stimulation at both described body areas gives comparable results in the assessment of cutaneous anti-nociception in horses. There is no differential influence of neuroleptic sedation or neuroleptanalgesia on TTs obtained at N or W. Buprenorphine combined with acepromazine has a long lasting anti-nociceptive effect associated with the typical opioid induced side effects in horses.
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Quandt J. Analgesia, Anesthesia, and Chemical Restraint in the Emergent Small Animal Patient. Vet Clin North Am Small Anim Pract 2013; 43:941-53. [DOI: 10.1016/j.cvsm.2013.03.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Aguado D, Abreu M, Benito J, Garcia-Fernandez J, Gómez de Segura IA. Effects of Naloxone on Opioid-induced Hyperalgesia and Tolerance to Remifentanil under Sevoflurane Anesthesia in Rats. Anesthesiology 2013; 118:1160-9. [DOI: 10.1097/aln.0b013e3182887526] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Abstract
Background:
Opioid antagonists at ultra-low doses have been used with opioid agonists to prevent or limit opioid tolerance. The aim of this study was to evaluate whether an ultra-low dose of naloxone combined with remifentanil could block opioid-induced hyperalgesia and tolerance under sevoflurane anesthesia in rats.
Methods:
Male adult Wistar rats were allocated into one of four treatment groups (n = 7), receiving remifentanil (4 µg·kg−1·min−1) combined with naloxone (0.17 ng·kg−1·min−1), remifentanil alone, naloxone alone, or saline. Animals were evaluated for mechanical nociceptive thresholds (von Frey) and subsequently anesthetized with sevoflurane to determine the baseline minimum alveolar concentration (MAC). Next, treatments were administered, and the MAC was redetermined twice during the infusion. The experiment was performed three times on nonconsecutive days (0, 2, and 4). Hyperalgesia was considered to be a decrease in mechanical thresholds, whereas opioid tolerance was considered to be a decrease in sevoflurane MAC reduction by remifentanil.
Results:
Remifentanil produced a significant decrease in mechanical thresholds compared with baseline values at days 2 and 4 (mean ± SD, 30.7 ± 5.5, 22.1 ± 6.4, and 20.7 ± 3.7g at days 0, 2, and 4, respectively) and an increase in MAC baseline values (2.5 ± 0.3, 3.0 ± 0.3, and 3.1 ± 0.3 vol% at days 0, 2, and 4, respectively). Both effects were blocked by naloxone coadministration. However, both remifentanil-treated groups (with or without naloxone) developed opioid tolerance determined by their decrease in MAC reduction.
Conclusions:
An ultra-low dose of naloxone blocked remifentanil-induced hyperalgesia but did not change opioid tolerance under inhalant anesthesia. Moreover, the MAC increase associated with hyperalgesia was also blocked by naloxone.
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Affiliation(s)
| | - Mariana Abreu
- Research Assistant, Department of Experimental Surgery, La Paz University Hospital, Madrid, Spain
| | - Javier Benito
- Research Assistant, Comparative Pain Research Laboratory, Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - Javier Garcia-Fernandez
- Chairman, Department of Anesthesiology and Intensive Care, Puerta de Hierro University Hospital, Madrid, Spain
| | - Ignacio A. Gómez de Segura
- Professor, Department of Animal Medicine and Surgery, Veterinary Faculty, University Complutense, Madrid, Spain
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Evaluation of contact heat thermal threshold testing for standardized assessment of cutaneous nociception in horses - comparison of different locations and environmental conditions. BMC Vet Res 2013; 9:4. [PMID: 23298405 PMCID: PMC3551666 DOI: 10.1186/1746-6148-9-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 01/02/2013] [Indexed: 11/13/2022] Open
Abstract
Background The aim of the study was to evaluate the performance of contact heat thermal stimulation in horses at different body sites and under different environmental conditions and different test situations. Five warm-blood horses were equipped with the thermal probe located on the skin of nostril (N), withers (W) or coronary band (C). Skin temperature and reaction temperature (thermal threshold) at each location were measured and percent thermal excursion (% TE = 100 * (threshold temperature - skin temperature)/(cut-out temperature - skin temperature) was calculated. Environmental conditions were changed in partial random order for all locations, so each horse was tested in its familiar box stall and stocks, in the morning and evening and at warm and cold ambient temperatures. Type of reaction to the stimulus and horse’s general behaviour during stimulation were recorded. The stimulation sites were examined for the occurrence of possible skin lesions. Results Skin temperatures were significantly different during warm and cold ambient temperatures at all three locations, but remained constant over repeated stimulation. An obvious response to stimulation before reaching cut-out temperature could be detected most frequently at N and W in boxes during warm ambient temperatures. The most frequent type of reaction to thermal stimulation at the nostril was headshaking (64.6%), skin twitching at the withers (82.9%) and hoof withdrawal at the coronary band (79.2%). Conclusion The outcome of thermal threshold testing depended on ambient temperature, stimulation site and environment. Best results with the WTT2 in horses were obtained at the nostrils or withers in a familiar environment at warm ambient temperatures.
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Brosnan RJ, Pypendop BH, Majewski-Tiedeken CR, Shilo-Benjamini Y, Ilkiw JE. Naltrexone does not affect isoflurane minimum alveolar concentration in cats. Vet Anaesth Analg 2012; 40:225-8. [PMID: 23279646 DOI: 10.1111/vaa.12004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 09/23/2011] [Indexed: 12/20/2022]
Abstract
OBJECTIVE To test whether naltrexone, an opioid receptor antagonist, affects the minimum alveolar concentration (MAC) of isoflurane in cats, a species that is relatively resistant to the general anesthetic sparing effects of most opioids. STUDY DESIGN Randomized, crossover, placebo-controlled, blinded experimental design. ANIMALS Six healthy adult cats weighing 4.9 ± 0.7 kg. METHODS The cats were studied twice. In the first study, baseline isoflurane MAC was measured in duplicate. The drug (saline control or 0.6 mg kg(-1) naltrexone) was administered IV every 40-60 minutes, and isoflurane MAC was re-measured. In the second study, cats received the second drug treatment using identical methods 2 weeks later. RESULTS Isoflurane MAC was 2.03 ± 0.12% and was unchanged from baseline following saline or naltrexone administration. CONCLUSION AND CLINICAL RELEVANCE Minimum alveolar concentration was unaffected by naltrexone. Because MAC in cats is unaffected by at least some mu-opioid agonists and antagonists, spinal neurons that are directly modulated by mu-opioid receptors in this species cannot be the neuroanatomic sites responsible for immobility from inhaled anesthetics.
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Affiliation(s)
- Robert J Brosnan
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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Fleming GJ, Robertson SA. Assessments of thermal antinociceptive effects of butorphanol and human observer effect on quantitative evaluation of analgesia in green iguanas (Iguana iguana). Am J Vet Res 2012; 73:1507-11. [DOI: 10.2460/ajvr.73.10.1507] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abreu M, Aguado D, Benito J, Gómez de Segura IA. Reduction of the sevoflurane minimum alveolar concentration induced by methadone, tramadol, butorphanol and morphine in rats. Lab Anim 2012; 46:200-6. [DOI: 10.1258/la.2012.010066] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study aimed to estimate the reduction in the minimum alveolar concentration (MAC) of sevoflurane induced by low and high doses of methadone (5 and 10 mg/kg), tramadol (25 and 50 mg/kg), butorphanol (5 and 10 mg/kg) or morphine (5 and 10 mg/kg) in the rat. A control group received normal saline. Sixty-three adult male Sprague-Dawley rats were anaesthetized with sevoflurane ( n = 7 per group). Sevoflurane MAC was then determined before and after intraperitoneal administration of the opioids or saline. The duration of the sevoflurane MAC reduction and basic cardiovascular and respiratory measurements were also recorded. The baseline MAC was 2.5 (0.3) vol%. Methadone, tramadol and morphine reduced the sevoflurane MAC (low dose: 31 ± 10, 38 ± 15 and 30 ± 13% respectively; high dose: 100 ± 0, 83 ± 17 and 77 ± 25%, respectively) in a dose-dependent manner. The low and high doses of butorphanol reduced the sevoflurane MAC to a similar extent (33 ± 7 and 31 ± 4%, low and high doses, respectively). Two rats developed apnoea following administration of high-dose butorphanol and methadone. These anaesthetic-sparing effects are clinically relevant and may reduce the adverse effects associated with higher doses of inhalational anaesthetics.
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Affiliation(s)
- Mariana Abreu
- Department of Animal Medicine and Surgery, Veterinary Faculty, Complutense University of Madrid (UCM), Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
- Department of Experimental Surgery, La Paz University Hospital, 28046 Madrid, Spain
| | - Delia Aguado
- Department of Animal Medicine and Surgery, Veterinary Faculty, Complutense University of Madrid (UCM), Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
- Department of Experimental Surgery, La Paz University Hospital, 28046 Madrid, Spain
| | - Javier Benito
- Comparative Pain Research Laboratory, Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University (NCSU), Raleigh NC 27606, USA
| | - Ignacio A Gómez de Segura
- Department of Animal Medicine and Surgery, Veterinary Faculty, Complutense University of Madrid (UCM), Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
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Shilo Y, Pypendop BH, Barter LS, Epstein SE. Thymoma removal in a cat with acquired myasthenia gravis: a case report and literature review of anesthetic techniques. Vet Anaesth Analg 2012; 38:603-13. [PMID: 21988817 DOI: 10.1111/j.1467-2995.2011.00648.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
UNLABELLED HISTORY AND PRESENTATION: A 12 year old, 4.2 kg, domestic long hair, castrated male cat was presented with regurgitation, inability to retract the claws, general weakness, cervical ventroflexion and weight loss. A thymic mass was evident on radiographs. Acetylcholine receptor antibody titer was positive for acquired myasthenia gravis (MG). Thymectomy via midline sternotomy was scheduled. ANESTHETIC MANAGEMENT: Oxymorphone and atropine were administered subcutaneously as premedication, and anesthesia was induced with etomidate and diazepam given intravenously to effect. The cat's trachea was intubated and anesthesia was maintained with isoflurane in oxygen, and continuous infusions of remifentanil and ketamine. Epidural analgesia with preservative-free morphine was administered prior to surgery. Postoperative analgesia was provided by oxymorphone subcutaneously, interpleural bupivacaine, and fentanyl infusion. Postoperative complications included airway obstruction, hypoxemia and hypercapnia. FOLLOW-UP The cat was discharged 3 days after surgery. Discharge medications included pyridostigmine and prednisone. Nine days after surgery, the cat had a significant increase in its activity level, and medications were discontinued. Histopathologically, the mass was consistent with a thymoma. Approximately 6 weeks later the cat became weak again and pyridostigmine and prednisone administration was resumed. CONCLUSION The perioperative management of patients with MG for transsternal thymectomy is a complex task. The increased potential for respiratory compromise requires the anesthesiologist to be familiar with the underlying disease state, and the interaction of anesthetic and non-anesthetic drugs with MG. Careful monitoring of ventilation and oxygenation is indicated postoperatively.
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Affiliation(s)
- Yael Shilo
- Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA.
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Aguado D, Abreu M, Benito J, Garcia-Fernandez J, Gómez de Segura IA. The effects of gabapentin on acute opioid tolerance to remifentanil under sevoflurane anesthesia in rats. Anesth Analg 2012; 115:40-5. [PMID: 22523419 DOI: 10.1213/ane.0b013e3182542727] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Tolerance to remifentanil during sevoflurane anesthesia may blunt the ability of this drug to reduce anesthetic requirements. Gabapentin has been shown to be effective in reducing postoperative narcotic usage, a reduction that may be associated with a reduction in opioid-induced tolerance and hyperalgesia. We sought to determine whether gabapentin might prevent the observed acute opioid tolerance (AOT) produced by remifentanil in sevoflurane minimum alveolar concentration (MAC). METHODS Wistar rats were anesthetized with sevoflurane and the effects of gabapentin alone on sevoflurane MAC were determined at doses of 150 and 300 mg · kg(-1). In a second experiment, gabapentin 300 mg · kg(-1) was administered before remifentanil (120 and 240 μg · kg(-1) · h(-1)). The MAC was determined before gabapentin administration and 3 more times at 1.5-hour intervals after drug administration to assess AOT. MAC was determined from intratracheal gas samples using a sidestream gas analyzer; tail clamping was used as a supramaximal stimulus. Statistical analysis was performed with the 1-way analysis of variance test. RESULTS Remifentanil reduced MAC (2.5 ± 0.2%) by 16% ± 5% and 36% ± 6% (120 and 240 μg · kg(-1) · h(-1), respectively, P < 0.01) with a further reduction produced by coadministration with gabapentin 300 mg · kg(-1) to 39% ± 12% and 62% ± 14%, respectively (P < 0.01 versus remifentanil alone). Gabapentin given alone at 150 and 300 mg · kg(-1) reduced MAC by 26% (both doses, P < 0.01). AOT was observed with remifentanil and characterized by a lower degree of MAC reduction, approximately 1.5 hours later (P < 0.05). However, when remifentanil was administered with gabapentin, the AOT to remifentanil was not observed (P > 0.05). CONCLUSIONS Gabapentin reduced the sevoflurane MAC and enhanced the MAC reduction produced by remifentanil. This enhancement may limit AOT in rats.
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Affiliation(s)
- Delia Aguado
- Department of Animal Medicine and Surgery, Veterinary Faculty, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
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Ge RL, Pejo E, Haburcak M, Husain SS, Forman SA, Raines DE. Pharmacological studies of methoxycarbonyl etomidate's carboxylic acid metabolite. Anesth Analg 2011; 115:305-8. [PMID: 22052979 DOI: 10.1213/ane.0b013e318239c6ca] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Methoxycarbonyl etomidate (MOC-etomidate) is a rapidly metabolized and ultrashort-acting etomidate analog that does not produce prolonged adrenocortical suppression after bolus administration. Its metabolite (MOC-ECA) is a carboxylic acid whose pharmacology is undefined. We hypothesized that MOC-ECA possesses significantly lower pharmacological activity than MOC-etomidate, accounting for the latter's very brief duration of hypnotic action and inability to produce prolonged adrenocortical suppression after bolus administration. To test this hypothesis, we compared the potencies of MOC-ECA and MOC-etomidate in 3 biological assays. METHODS The hypnotic potency of MOC-ECA was assessed in tadpoles using a loss-of-righting reflexes assay. The γ-aminobutyric acid type A (GABA(A)) receptor modulatory potencies of MOC-ECA and MOC-etomidate were compared by defining the concentrations of each required to directly activate α(1)(L264T)β(2)γ(2L) GABA(A) receptors. The adrenocortical inhibitory potencies of MOC-ECA and MOC-etomidate were compared by defining the concentrations of each required to inhibit in vitro cortisol production by adrenocortical cells. RESULTS MOC-ECA's 50% effective concentration for loss-of-righting reflexes in tadpoles was 2.8 ± 0.64 mM as compared with a previously reported value of 8 ± 2 μM for MOC-etomidate. The 50% effective concentrations for direct activation of GABA(A) receptors were 3.5 ± 0.63 mM for MOC-ECA versus 10 ± 2.5 μM for MOC-etomidate. The half-maximal inhibitory concentration for inhibiting in vitro cortisol production by adrenocortical cells was 30 ± 7 μM for MOC-ECA versus 0.10 ± 0.02 μM for MOC-etomidate. CONCLUSIONS In all 3 biological assays, MOC-ECA's potency was approximately 300-fold lower than that of MOC-etomidate.
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Affiliation(s)
- Ri Le Ge
- Department of Anesthesia, Critical Care, and Pain Medicine, 55 Fruit St., Boston, MA 02114-2621, USA
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Pypendop BH, Brosnan RJ, Ilkiw JE. Use of naltrexone to antagonize high doses of remifentanil in cats: a dose-finding study. Vet Anaesth Analg 2011; 38:594-7. [DOI: 10.1111/j.1467-2995.2011.00649.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Padilha ST, Steagall PVM, Monteiro BP, Kahvegian MAP, Ubukata R, Rodrigues EO, Rosa AL, Aguiar AJA. A clinical comparison of remifentanil or alfentanil in propofol-anesthetized cats undergoing ovariohysterectomy. J Feline Med Surg 2011; 13:738-43. [PMID: 21873092 PMCID: PMC10832767 DOI: 10.1016/j.jfms.2011.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/09/2011] [Indexed: 11/23/2022]
Abstract
Sixteen cats were used to compare the cardiovascular and anesthetic effects of remifentanil (REMI) or alfentanil (ALF) in propofol-anesthetized cats undergoing ovariohysterectomy. After premedication with acepromazine, anesthesia was induced and maintained with a constant rate infusion of propofol (0.3 mg/kg/min). REMI or ALF infusions were administered simultaneously with propofol. Heart rate (HR), systolic arterial pressure (SAP), pulse oximetry (SpO(2)), rectal temperature (RT), and response to surgical stimulation were recorded at predefined time points during anesthesia. Data [mean±standard deviation (SD)] were analyzed by analysis of variance (ANOVA) for repeated measures followed by a Dunnett's test and Student t-test (P<0.05). SAP was significantly lower in ALF group than in REMI group. Extubation time was significantly shorter in REMI than in ALF group. Overall infusion rate of REMI and ALF was 0.24±0.05 μg/kg/min and 0.97±0.22 μg/kg/min, respectively. The combination of propofol and REMI or ALF provided satisfactory anesthesia in cats undergoing ovariohysterectomy.
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Affiliation(s)
- Samanta T Padilha
- Department of Veterinary Surgery and Anesthesiology, School of Veterinary Medicine and Animal Science, Sao Paulo State University, UNESP, Botucatu, Brazil
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Aguado D, Abreu M, Benito J, García-Fernández J, Gómez de Segura IA. Ketamine and remifentanil interactions on the sevoflurane minimum alveolar concentration and acute opioid tolerance in the rat. Anesth Analg 2011; 113:505-12. [PMID: 21778336 DOI: 10.1213/ane.0b013e318227517a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Ketamine is used at low doses for its analgesic and antihyperalgesic properties when combined with opioids but also when opioid-induced hyperalgesia and tolerance appear. In this study we determined the interaction of ketamine and remifentanil on the minimum alveolar concentration (MAC) of sevoflurane in rats and to determine whether ketamine may block acute opioid tolerance (AOT). METHODS Male Wistar rats were anesthetized with sevoflurane, and the MAC was determined before and after ketamine administration (10, 20, 40, and 80 mg kg(-1) or saline) alone or combined with remifentanil (120 and 240 μg kg(-1) h(-1), low and high doses, respectively). One additional group received the lowest ketamine dose after starting a remifentanil infusion. Finally, naloxone was administered to determine the potential action of ketamine on opioid receptors. MAC was determined from intratracheal gas samples, and tail clamping was used as a supramaximal stimulus. End-tidal anesthetic concentrations were assayed using a side stream gas analyzer. Statistical analysis was performed with an analysis of variance. RESULTS Ketamine and remifentanil dose-dependently reduced the MAC. Adding the low dose of remifentanil to ketamine did not improve the MAC reduction, whereas the high dose of remifentanil enhanced ketamine reduction in a subadditive fashion. Nevertheless, ketamine was unable to block the development of AOT to remifentanil at either dose. Finally, naloxone blocked the MAC reduction produced by ketamine. CONCLUSIONS A subadditive effect between ketamine and remifentanil was found on the sevoflurane MAC reduction rats. In addition, ketamine was unable to block AOT. The clinical relevance of these findings should be elucidated in future studies to reduce anesthetic requirements.
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Affiliation(s)
- Delia Aguado
- Department of Animal Medicine and Surgery, Veterinary Faculty, Complutense University of Madrid, Avda, Puerta de Hierro s/n, 28040 Madrid, Spain
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Abstract
The ability of reptiles to "feel" pain and the significance of pain or nociception on physiologic homeostasis is an exceedingly complex question requiring integration of both physiologic and behavioral evidence. Until further information is available, it would seem most ethical for veterinarians to assume that reptiles are capable of feeling pain, and to treat or manage pain when there is reasonable evidence that pain is present. With increased information available regarding analgesic use in reptiles and with the heightened awareness of the importance of analgesia for zoologic companion animals, it is likely that more veterinarians will provide pain relief to their reptile patients.
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Reid P, Pypendop BH, Ilkiw JE. The Effects of Intravenous Gabapentin Administration on the Minimum Alveolar Concentration of Isoflurane in Cats. Anesth Analg 2010; 111:633-7. [DOI: 10.1213/ane.0b013e3181e51245] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Pypendop BH, Siao KT, Ilkiw JE. Effects of tramadol hydrochloride on the thermal threshold in cats. Am J Vet Res 2009; 70:1465-70. [DOI: 10.2460/ajvr.70.12.1465] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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