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Topic:Lidocaine

Lidocaine is a local anesthetic commonly used in equine medicine to manage pain and perform minor surgical procedures. It functions by blocking sodium channels, which inhibits nerve impulse conduction and results in temporary loss of sensation in targeted areas. In horses, lidocaine is utilized for various applications, including nerve blocks, epidural anesthesia, and as an adjunct in pain management protocols. Its pharmacokinetics, efficacy, and safety profile in equine patients are subjects of ongoing research. This page compiles peer-reviewed research studies and scholarly articles that explore the pharmacological properties, clinical applications, and potential side effects of lidocaine in horses.
Cardiorespiratory effects of enoximone in anaesthetised colic horses.
Equine veterinary journal    January 26, 2010   Volume 41, Issue 8 778-785 doi: 10.2746/042516409x424117
Schauvliege S, Gozalo Marcilla M, Duchateau L, Martens A, Vlaminck L, Pille F, Declercq J, Levet T, Gasthuys F.No studies have been reported on the effects of enoximone in anaesthetised colic horses. Objective: To examine whether enoximone improves cardiovascular function and reduces dobutamine requirement in anaesthetised colic horses. Methods: Forty-eight mature colic horses were enrolled in this prospective, randomised clinical trial. After sedation (xylazine 0.7 mg/kg bwt) and induction (midazolam 0.06 mg/kg bwt, ketamine 2.2 mg/kg bwt), anaesthesia was maintained with isoflurane in oxygen and a lidocaine constant rate infusion (15 mg/kg bwt, 2 mg/kg/h). Horses were ventilated (PaCO2 < 8.00 kPa)...
The use of an acoustic device to identify the extradural space in standing horses.
Veterinary anaesthesia and analgesia    December 19, 2009   Volume 37, Issue 1 57-62 doi: 10.1111/j.1467-2995.2009.00491.x
Iff I, Mosing M, Lechner T, Moens Y.To determine the usefulness of an acoustic device to confirm correct placement of extradural needles in horses. Methods: Prospective experimental study. Methods: Twelve adult healthy horses weighing between 434 and 640 kg. Methods: Horses were sedated, placed in stocks and subjected to caudal extradural anaesthesia using lidocaine 2%. For extradural puncture an 18 gauge Tuohy needle connected to an acoustic device via an electronic pressure transducer was used. This device allowed recording of the extradural pressure profile and the transformation of pressure changes into an audible signal. Ex...
ECG of the month. Cardiac arrhythmias in a horse after lidocaine administration.
Journal of the American Veterinary Medical Association    November 17, 2009   Volume 235, Issue 10 1156-1158 doi: 10.2460/javma.235.10.1156
Mullen KR, Gelzer AR, Kraus MS, Mitchell K, Divers TJ.No abstract available
Analgesic effects of butorphanol tartrate and phenylbutazone administered alone and in combination in young horses undergoing routine castration.
Journal of the American Veterinary Medical Association    November 17, 2009   Volume 235, Issue 10 1194-1203 doi: 10.2460/javma.235.10.1194
Sanz MG, Sellon DC, Cary JA, Hines MT, Farnsworth KD.To compare the analgesic efficacy of administration of butorphanol tartrate, phenylbutazone, or both drugs in combination in colts undergoing routine castration. Methods: Randomized controlled clinical trial. Methods: 36 client-owned colts. Methods: Horses received treatment with butorphanol alone (0.05 mg/kg [0.023 mg/lb], IM, prior to surgery and then q 4 h for 24 hours), phenylbutazone alone (4.4 mg/kg [2.0 mg/lb], IV, prior to surgery and then 2.2 mg/kg [1.0 mg/lb], PO, q 12 h for 3 days), or butorphanol and phenylbutazone at the aforementioned dosages (12 horses/group). For single-drug-tr...
Anti-inflammatory effects of intravenously administered lidocaine hydrochloride on ischemia-injured jejunum in horses.
American journal of veterinary research    October 3, 2009   Volume 70, Issue 10 1259-1268 doi: 10.2460/ajvr.70.10.1259
Cook VL, Jones Shults J, McDowell MR, Campbell NB, Davis JL, Marshall JF, Blikslager AT.To investigate effects of lidocaine hydrochloride administered IV on mucosal inflammation in ischemia-injured jejunum of horses treated with flunixin meglumine. Methods: 24 horses. Methods: Horses received saline (0.9% NaCl) solution (SS; 1 mL/50 kg, IV [1 dose]), flunixin meglumine (1 mg/kg, IV, q 12 h), lidocaine (bolus [1.3 mg/kg] and constant rate infusion [0.05 mg/kg/min], IV, during and after recovery from surgery), or both flunixin and lidocaine (n = 6/group). During surgery, blood flow was occluded for 2 hours in 2 sections of jejunum in each horse. Uninjured and ischemia-injured jejun...
Postoperative ileus: pathogenesis and treatment.
The Veterinary clinics of North America. Equine practice    July 8, 2009   Volume 25, Issue 2 351-362 doi: 10.1016/j.cveq.2009.04.011
Doherty TJ.Surgical manipulation of the intestines activates intestinal macrophages that release cytokines and nitric oxide, which results in inhibition of intestinal motility. Subsequent infiltration of circulating leukocytes into the intestinal wall contributes to cytokine and nitric oxide release and exacerbates ileus. Other factors contributing to ileus are endotoxemia; edema of the intestine wall subsequent to excessive fluid therapy; hypocalcemia; and long abdominal incisions. Because treatment of ileus with prokinetic drugs has not proven to be very effective, efforts should be directed at reducin...
Clinical evaluation of ketamine and lidocaine intravenous infusions to reduce isoflurane requirements in horses under general anaesthesia.
Veterinary anaesthesia and analgesia    June 16, 2009   Volume 35, Issue 4 297-305 doi: 10.1111/j.1467-2995.2007.00391.x
Enderle AK, Levionnois OL, Kuhn M, Schatzmann U.To compare isoflurane alone or in combination with systemic ketamine and lidocaine for general anaesthesia in horses. Methods: Prospective, randomized, blinded clinical trial. Methods: Forty horses (ASA I-III) undergoing elective surgery. Methods: Horses were assigned to receive isoflurane anaesthesia alone (ISO) or with ketamine and lidocaine (LKI). After receiving romifidine, diazepam, and ketamine, the isoflurane end-tidal concentration was set at 1.3% and subsequently adjusted by the anaesthetist (unaware of treatments) to maintain a light plane of surgical anaesthesia. Animals in the LKI ...
Short-term anaesthesia with xylazine, diazepam/ketamine for castration in horses under field conditions: use of intravenous lidocaine.
Equine veterinary journal    May 8, 2009   Volume 41, Issue 2 149-152 doi: 10.2746/042516408x371928
Sinclair M, Valverde A.Lidocaine single boluses and/or constant rate infusions are commonly administered intraoperatively during inhalant anaesthesia to lower inhalant concentrations, promote or maintain gastrointestinal motility, and potentially supplement analgesia. The benefits of using lidocaine with injectable anaesthesia for field surgeries has not been fully explored to determine advantages and disadvantages of lidocaine as an anaesthetic and analgesic adjunct in these conditions and impact on recovery quality. Objective: To evaluate the use of systemic lidocaine with a standard field injectable anaesthetic p...
Risk factors for equine postoperative ileus and effectiveness of prophylactic lidocaine.
Journal of veterinary internal medicine    April 21, 2009   Volume 23, Issue 3 606-611 doi: 10.1111/j.1939-1676.2009.0311.x
Torfs S, Delesalle C, Dewulf J, Devisscher L, Deprez P.Postoperative ileus (POI) is a frequent and often fatal complication of colic surgery. Reliably effective treatments are not available. Objective: To determine risk factors and protective factors associated with POI, and to assess the effect of lidocaine IV on short-term survival. Methods: One hundred and twenty-six horses that underwent small intestinal colic surgery and that survived for at least 24 hours postoperatively. Methods: Retrospective cross-sectional study. The association of 31 pre-, intra-, and postoperative variables with POI and the association of lidocaine treatment with short...
Castration of horses under total intravenous anaesthesia: analgesic effects of lidocaine.
Veterinary anaesthesia and analgesia    February 26, 2009   Volume 36, Issue 2 173-179 doi: 10.1111/j.1467-2995.2008.00445.x
Portier KG, Jaillardon L, Leece EA, Walsh CM.To evaluate the effects of local anaesthesia with lidocaine for castration of horses under intravenous anaesthesia. Methods: Prospective, randomized, blinded clinical trial. Methods: Fifteen equidae, scheduled to undergo castration under total intravenous anaesthesia, were randomly distributed in two groups. One group received lidocaine injections (group L: two ponies, four horses, two donkeys) and the other received saline (group S: two ponies, three horses, two donkeys). Methods: Behaviour, heart rate (HR) and respiratory rate (f(R)) were evaluated prior to anaesthesia. Body mass was measure...
Evaluation of continuous infusion of lidocaine on gastrointestinal tract function in normal horses.
Veterinary surgery : VS    January 13, 2009   Volume 37, Issue 6 564-570 doi: 10.1111/j.1532-950X.2008.00421.x
Rusiecki KE, Nieto JE, Puchalski SM, Snyder JR.To determine the effect of continuous infusion of lidocaine on fecal transit time in normal horses. Methods: Experimental randomized cross-over study. Methods: Healthy horses (n=6). Methods: Barium-filled microspheres were administered to horses by nasogastric intubation and feces were collected every 2 hours for 4 days. A bolus of 2% lidocaine (1.3 mg/kg) was administered randomly, followed by a continuous infusion of lidocaine (0.05 mg/kg/min) for 3 days or an equivalent volume of saline. The washout period was 10 days. Variables assessed included defecation frequency, weight of feces produc...
The effect of lidocaine on in vitro adhesion and migration of equine neutrophils.
Veterinary immunology and immunopathology    December 11, 2008   Volume 129, Issue 1-2 137-142 doi: 10.1016/j.vetimm.2008.12.017
Cook VL, Neuder LE, Blikslager AT, Jones SL.The effect of lidocaine on in vitro migration and adhesion of equine neutrophils was evaluated. Neutrophils were isolated from equine whole blood using a Percoll-gradient centrifugation protocol. Purified neutrophils were incubated with lidocaine at concentrations from 0.1 to 1000 microg/ml for 30 min at 37 degrees C, after calcein loading. Neutrophil integrin-mediated adhesion in response to stimulation with 100 nM LTB(4), 100 nM PAF, or 100 ng/ml IL-8, or integrin-mediated migration in response to stimulation with 100 nM LTB(4), 150 nM PAF, or 100 ng/ml IL-8 was assessed. Statistical signifi...
Effects of mosapride citrate, metoclopramide hydrochloride, lidocaine hydrochloride, and cisapride citrate on equine gastric emptying, small intestinal and caecal motility.
Research in veterinary science    August 23, 2008   Volume 86, Issue 2 302-308 doi: 10.1016/j.rvsc.2008.07.008
Okamura K, Sasaki N, Yamada M, Yamada H, Inokuma H.Although extensive work has been done to elucidate the beneficial and unfavorable effects of gastrointestinal prokinetic agents in humans, little is known on the effects of these agents in horses. In this study, we compared the effects of mosapride, metoclopramide, cisapride, and lidocaine on equine gastric emptying, jejunal and caecal motility and evaluated these agents' adverse drug reactions (ADRs). Methods: Seven healthy adult Thoroughbreds. Methods: Mosapride 1.0mg/kg and 2.0mg/kg, metoclopramide 0.2mg/kg, and cisapride 1.0mg/kg were dissolved in 100mL distilled water for oral administrat...
Use of systemically administered lidocaine in horses with gastrointestinal tract disease.
Journal of the American Veterinary Medical Association    April 17, 2008   Volume 232, Issue 8 1144-1148 doi: 10.2460/javma.232.8.1144
Cook VL, Blikslager AT.No abstract available
Pressure profile in the caudal extradural space of standing horses before and after extradural drug administration.
Veterinary journal (London, England : 1997)    April 11, 2008   Volume 180, Issue 1 112-115 doi: 10.1016/j.tvjl.2007.10.024
Iff I, Mosing M, Moens Y.The objectives of this study were to measure the pressure in the caudal extradural space of standing horses and to evaluate the usefulness of pressure waves to identify correct needle placement. Caudal extradural pressure was measured in 12 healthy horses. The pressure and any extradural pressure waves were recorded for 3min after puncture, for 1min after testing for lack of resistance (LOR), and for 10min after lidocaine injection. Successful extradural drug administration was confirmed in all horses. The median extradural pressure findings after puncture, after LOR, immediately after injecti...
Attenuation of ischaemic injury in the equine jejunum by administration of systemic lidocaine.
Equine veterinary journal    March 7, 2008   Volume 40, Issue 4 353-357 doi: 10.2746/042516408X293574
Cook VL, Jones Shults J, McDowell M, Campbell NB, Davis JL, Blikslager AT.Absorption of endotoxin across ischaemic-injured mucosa is a major cause of mortality after colic surgery. Recent studies have shown that flunixin meglumine retards mucosal repair. Systemic lidocaine has been used to treat post operative ileus, but it also has novel anti-inflammatory effects that could improve mucosal recovery after ischaemic injury. Objective: Systemic lidocaine ameliorates the deleterious negative effects of flunixin meglumine on recovery of mucosal barrier function. Methods: Horses were treated i.v. immediately before anaesthesia with either 0.9% saline 1 ml/50 kg bwt, flun...
Serum concentrations of lidocaine and its metabolites after prolonged infusion in healthy horses.
Equine veterinary journal    February 13, 2008   Volume 40, Issue 4 348-352 doi: 10.2746/042516408X284664
Dickey EJ, McKenzie HC, Brown KA, de Solis CN.Continuous-rate infusions (CRI) of lidocaine are often used for prolonged duration but, to date, only limited time/concentration relationships administered as a short term (24 h) CRI have been reported. Objective: To determine the time/concentration profile of lidocaine and its active metabolites glycinexylidide (GX) and monoethylglycinexylidide (MEGX) during a 96 h lidocaine infusion. Methods: Lidocaine was administered to 8 mature healthy horses as a continuous rate infusion (0.05 mg/kg bwt/min) for 96 h. Blood concentrations of lidocaine, GX and MEGX were determined using high performance l...
Meperidine prolongs lidocaine caudal epidural anaesthesia in the horse.
Veterinary journal (London, England : 1997)    September 24, 2007   Volume 178, Issue 2 294-297 doi: 10.1016/j.tvjl.2007.08.003
Derossi R, Medeiros U, de Almeida RG, Righetto FR, Frazílio FO.The aim of the study was to evaluate and compare the effects of caudal epidural administration of meperidine (MP), lidocaine (LD), and a combination of the two (MPLD) in six mature saddle horses. Horses were randomly assigned to receive three treatments (MP 0.3 mg/kg; LD 0.2 mg/kg; and MPLD: MP 0.3 mg/kg and LD 0.2 mg/kg), with at least 1 week between treatments. Drugs were injected into the epidural space between the first and second coccygeal areas in conscious standing horses. Analgesia, ataxia, sedation, cardiovascular and respiratory effects, and rectal temperature were recorded at differ...
Lack of systemic absorption of lidocaine from 5% patches placed on horses.
Veterinary anaesthesia and analgesia    August 13, 2007   Volume 34, Issue 6 443-446 doi: 10.1111/j.1467-2995.2007.00348.x
Bidwell LA, Wilson DV, Caron JP.To measure concentrations of lidocaine serum after application of two 5% patches on horses. Methods: Prospective experimental trial Methods: Six client-owned, systemically healthy horses. Methods: The hair was clipped on the medial aspect above the carpus of both fore limbs and 2 patches of 5% lidocaine were applied within 30 minutes of jugular catheter placement and the area was then bandaged. Venous blood was drawn from a jugular vein catheter that was inserted using lidocaine as a local block. Samples were drawn immediately before and at 2, 4, 6, 8, and 12 hours after patch application. The...
Left- and right-sided laparoscopic-assisted nephrectomy in standing horses with unilateral renal disease.
Veterinary surgery : VS    August 10, 2007   Volume 36, Issue 6 568-572 doi: 10.1111/j.1532-950X.2007.00306.x
Röcken M, Mosel G, Stehle C, Rass J, Litzke LF.To describe a technique for, and outcome after, left- or right-sided laparoscopic-assisted nephrectomy in standing horses with unilateral renal disease. Methods: Clinical report. Methods: Horses (n=3) with unilateral renal disease. Methods: Horses were sedated with detomidine (0.01 mg/kg intravenously [IV]) and levomethadone (0.05 mg/kg IV). Paravertebral anesthesia and infiltration-anesthesia with 2% lidocaine were used to create a surgical field incorporating the 17th intercostal space and paralumbar fossa. Two separate, ipsilateral portals and a mini-laparotomy were used. The perirenal peri...
A clinical comparison of two anaesthetic protocols using lidocaine or medetomidine in horses.
Veterinary anaesthesia and analgesia    June 15, 2007   Volume 34, Issue 4 257-268 doi: 10.1111/j.1467-2995.2006.00321.x
Ringer SK, Kalchofner K, Boller J, Fürst A, Bettschart-Wolfensberger R.To compare the effects of two balanced anaesthetic protocols on end-tidal isoflurane (Fe'ISO), cardiopulmonary performance and quality of recovery in horses. Methods: Prospective blinded randomized clinical study. Methods: Sixty-nine client-owned horses, American Society of Anesthesiologists category I and II, undergoing elective surgery. Methods: The horses were premedicated with acepromazine (0.03 mg kg(-1)) IM 30-60 minutes before induction of anaesthesia and were randomly assigned to one of two treatments: in group L (37 horses) xylazine (1 mg kg(-1)) and in group M (31 horses) medetomidin...
The effect of lidocaine on postoperative jejunal motility in normal horses.
Veterinary surgery : VS    April 28, 2007   Volume 36, Issue 3 214-220 doi: 10.1111/j.1532-950X.2007.00255.x
Milligan M, Beard W, Kukanich B, Sobering T, Waxman S.To measure the effect of lidocaine on the duration of the migrating myoelectric complex (MMC) and Phases I, II, and III of the MMC, spiking activity of the jejunum, and number of Phase III events when administered postoperatively to normal horses. Methods: Nonrandomized cross-over design. Methods: Horses were anesthetized and via flank laparotomy 4 silver-silver chloride bipolar electrodes were sutured to the proximal jejunum. Electrical activity was recorded for 6 hours during 3 recording sessions beginning 24, 48, and 72 hours postoperatively. Saline (0.9% NaCl) solution was administered for...
Determination of lidocaine and its two N-desethylated metabolites in dog and horse plasma by high-performance liquid chromatography combined with electrospray ionization tandem mass spectrometry.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences    January 18, 2007   Volume 852, Issue 1-2 180-187 doi: 10.1016/j.jchromb.2007.01.010
Maes A, Weiland L, Sandersen C, Gasthuys F, De Backer P, Croubels S.A sensitive method for the quantification of lidocaine and its metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX), in animal plasma using high-performance liquid chromatography combined with electrospray ionization mass spectrometry is described. The sample preparation includes a liquid-liquid extraction with methyl tert-butylmethyl ether after addition of 2M sodium hydroxide. Ethylmethylglycinexylidide (EMGX) is used as an internal standard. For chromatographic separation, an ODS Hypersil column was used. Isocratic elution was achieved with 0.01 M ammonium acetate and aceto...
Comparison of intraoperative pain responses following intratesticular or mesorchial injection of lidocaine in standing horses undergoing laparoscopic cryptorchidectomy.
Journal of the American Veterinary Medical Association    December 6, 2006   Volume 229, Issue 11 1779-1783 doi: 10.2460/javma.229.11.1779
Joyce J, Hendrickson DA.To compare pain responses in stallions undergoing standing laparoscopic cryptorchidectomy following intratesticular or mesorchial infiltration of lidocaine. Methods: Clinical trial. Methods: 20 stallions with 1 or 2 undescended testes. Methods: Standing horses were administered a nonsteroidal anti-inflammatory drug and a caudal epidural injection of detomidine hydrochloride and underwent laparoscopic cryptorchidectomy. The undescended testis (1/horse) was grasped to determine the preoperative pain response (present vs absent) and assess severity of pain (by use of a visual analog scale [VAS])....
The disposition of lidocaine during a 12-hour intravenous infusion to postoperative horses.
Journal of veterinary pharmacology and therapeutics    November 7, 2006   Volume 29, Issue 6 495-499 doi: 10.1111/j.1365-2885.2006.00797.x
Milligan M, Kukanich B, Beard W, Waxman S.Lidocaine is administered as an intravenous infusion to horses for a variety of reasons, but no study has assessed plasma lidocaine concentrations during a 12-h infusion to horses. The purpose of this study was to evaluate the plasma concentrations and pharmacokinetics of lidocaine during a 12-h infusion to postoperative horses. A second purpose of the study was to evaluate the in vitro plasma protein binding of lidocaine in equine plasma. Lidocaine hydrochloride was administered as a loading dose, 1.3 mg/kg over 15 min, then by a constant rate IV infusion, 50 microg/kg/min to six postoperativ...
Effects of the bronchoalveolar lavage procedure on lung function in horses with clinical exacerbation of recurrent airway obstruction.
American journal of veterinary research    November 3, 2006   Volume 67, Issue 11 1929-1933 doi: 10.2460/ajvr.67.11.1929
Léguillette R, Lavoie JP.To evaluate whether bronchoalveolar lavage (BAL) alters respiratory mechanics of horses with recurrent airway obstruction (ie, heaves) over a 48-hour period. Methods: 6 horses affected with heaves. Methods: Horses were subjected to a complete BAL procedure, which included sedation with xylazine and butorphanol, intratracheal administration of lidocaine, and instillation and aspiration of two 250-mL boluses of saline (0.9% NaCl) solution through an endoscope (study 1). To evaluate the effects of saline solution, horses were subjected to the same procedure without saline solution instillation an...
A comparison of N-butylscopolammonium and lidocaine for control of rectal pressure in horses.
Veterinary therapeutics : research in applied veterinary medicine    October 14, 2006   Volume 7, Issue 3 243-248 
Luo T, Bertone JJ, Greene HM, Wickler SJ.In its FDA approved formulation, N-butylscopolammonium bromide (Buscopan Injectable Solution, Boehringer Ingelheim Vetmedica) is an anticholinergic spasmolytic agent indicated for management of abdominal pain associated with spasmodic colic, flatulent colic, and simple impactions in horses. Use of this drug ablates gastrointestinal peristalsis and rectal pressure. It ahs been suggested that N-butylscopolammonium bromide could be used to facilitate rectal examinations in horses. This study compared the effects of N-butylscopolammonium bromide versus lidocaine and a saline control on rectal pres...
Effect of head position on intraocular pressure in horses.
American journal of veterinary research    July 5, 2006   Volume 67, Issue 7 1232-1235 doi: 10.2460/ajvr.67.7.1232
Komáromy AM, Garg CD, Ying GS, Liu C.To evaluate the effect of head position on intraocular pressure (IOP) in horses. Methods: 30 horses. Methods: Horses were sedated with detomidine HCl (0.01 mg/kg, IV). Auriculopalpebral nerve blocks were applied bilaterally with 2% lidocaine HCl. The corneas of both eyes were anesthetized with ophthalmic 0.5% proparacaine solution. Intraocular pressures were measured with an applanation tonometer with the head positioned below and above heart level. The mean of 3 readings was taken for each eye at each position for data analysis. The effect of head position on IOP was assessed and generalized ...
Effect of intratesticular injection of lidocaine on cardiovascular responses to castration in isoflurane-anesthetized stallions.
American journal of veterinary research    March 2, 2006   Volume 67, Issue 3 403-408 doi: 10.2460/ajvr.67.3.403
Haga HA, Lykkjen S, Revold T, Ranheim B.To evaluate the effect of intratesticular administration of lidocaine on cardiovascular responses and cremaster muscle tension during castration of isoflurane-anesthetized stallions. Methods: 28 healthy stallions (mean +/- SD age, 4.2 +/- 2.8 years) with no testicular abnormalities that were scheduled for castration. Methods: Each horse was given acepromazine (20 microg/kg, IM), romifidine (50 microg/kg, IV), and butorphanol (20 microg/kg, IV). Anesthesia was induced with ketamine (2.5 mg/kg, IV) and midazolam (50 microg/kg, IV) and maintained with isoflurane (1.7% end-tidal concentration). Af...
Influence of gastrointestinal tract disease on pharmacokinetics of lidocaine after intravenous infusion in anesthetized horses.
American journal of veterinary research    February 4, 2006   Volume 67, Issue 2 317-322 doi: 10.2460/ajvr.67.2.317
Feary DJ, Mama KR, Thomasy SM, Wagner AE, Enns RM.To determine the disposition of lidocaine after IV infusion in anesthetized horses undergoing exploratory laparotomy because of gastrointestinal tract disease. Methods: 11 horses (mean +/- SD, 10.3 +/- 7.4 years; 526 +/- 40 kg). Methods: Lidocaine hydrochloride (loading infusion, 1.3 mg/kg during a 15-minute period [87.5 microg/kg/min]; maintenance infusion, 50 microg/kg/min for 60 to 90 minutes) was administered IV to dorsally recumbent anesthetized horses. Blood samples were collected before and at fixed time points during and after lidocaine infusion for analysis of serum drug concentration...