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.
Traub-Dargatz JL, Schlipf JW, Boon J, Ogilvie GK, Bennett DG, Wingfield WE, Hutchison JM.Ventricular tachycardia develops less frequently than supraventricular dysrhythmias and generally is more indicative of cardiac disease. The horse in this report had clinical signs of lethargy and hypophagia and was determined to have sustained ventricular tachycardia. Echocardiography was a valuable diagnostic tool and revealed an echodense area in the left ventricle that had subnormal ventricular performance. A primary heart problem of an inflammatory nature was suspected. The horse responded favorably to treatment with lidocaine, antimicrobials, and aspirin, as well as stall rest. The horse...
Kamerling SG.The recognition and alleviation of animal pain is a growing veterinary and public concern. Pain can be of an acute or chronic nature with different behavioral manifestations. Physiologically, pain is a dynamic and complex phenomenon that produces changes in the central and autonomic nervous systems as well as in the endocrine system. Horses and other animals appear to possess an endogenous pain-suppressing system involving the brainstem and spinal cord. This system can modulate pain perception and the responses to it. The recently discovered endogenous opioid peptides (endorphins and enkephali...
Moon PF, Suter CM.The caudal border of the last rib was used as a reliable point of orientation while performing paravertebral thoracolumbar anaesthesia (PTLA) on 10 horses undergoing standing flank laparotomy. The local anaesthetic in all horses was 2% lidocaine. The PTLA procedure was completed in 9.8 +/- 1.8 mins (mean +/- sd). Sedation was provided by a combination of intravenous morphine with xylazine or detomidine. Overall analgesia, provided by the combination of PTLA and sedation, was rated as excellent in 2 horses and good in 6 horses. In the remaining 2 horses, overall analgesia was rated as fair beca...
Grubb TL, Riebold TW, Huber MJ.Caudal epidural analgesia was achieved in 6 adult horses on 3 successive occasions at weekly intervals by injection of lidocaine, xylazine, and a combination of lidocaine/xylazine through indwelling epidural catheters. Analgesia was defined as a lack of response to pinprick and hemostat pressure in the skin of the perineal area. A significant (P < 0.05) difference was not found for time of onset of analgesia between lidocaine (4.3 +/- 0.8 minutes, mean +/- SEM) and the lidocaine/xylazine combination (5.3 +/- 1.3 minutes). Time to onset of analgesia after administration of xylazine was signi...
Day TK, Skarda RT.Understanding of the pharmacology of local anesthesia is important for selection of a local anesthetic for use in equine standing surgery. In general, the action potential is inhibited by local anesthetics by preventing the influx of sodium ions across the axonal membrane. The physicochemical properties of each local anesthetic determine the onset of action, potency, and duration of action. Procaine, chlorprocaine, lidocaine, and mepivacaine are the local anesthetics still used clinically in horses; lidocaine is the most widely used. The future of equine local anesthesia may see the introducti...
Fikes LW, Lin HC, Thurmon JC.Xylazine (0.35 mg/kg) or lidocaine (0.35 mg/kg) was injected into the epidural space of six ponies to compare their effectiveness as epidural analgesics. Each pony received both treatments at 1 week intervals with the order of treatments randomized. Xylazine produced analgesia of significantly longer duration (247 +/- 58 minutes) than that produced by an equal dose of lidocaine (135 +/- 22 minutes). Mild transient ataxia of no clinical significance developed in all ponies with both treatments. Spinal cords were removed from two ponies and examined histologically. No discernible pathologic chan...
White KK, Hodgson DR, Hancock D, Parry BW, Cordell C.The effects of repeated arthrocentesis and injection of local anesthetic agents, lidocaine HCl or mepivacaine HCl on the equine middle carpal joint were investigated. Synovial fluid samples were evaluated before, and 12, 24 and 48 hours following, treatment. The greatest changes from pretreatment values occurred in synovial fluid cellularity. Repeated arthrocentesis caused a moderate increase in cell counts, while injection of local anesthetics caused a greater increase. Alterations in mucin clot quality, hyaluronic acid content, fluid viscosity, total protein and immunoglobulin G were general...
LeBlanc PH, Caron JP, Patterson JS, Brown M, Matta MA.Local anesthetics given in the epidural space of a horse may cause hind limb weakness in addition to analgesia. Because alpha 2 agonists given by epidural injection cause sensory blockade without motor effects in human beings and other species, their use in veterinary anesthesia is appealing. This study was designed to examine the effectiveness of xylazine HCl, an alpha 2 agonist commonly used in horses. Xylazine, 0.9% NaCl, and lidocaine were given by epidural injection to horses subjected to perineal electrical stimulation. Administration of xylazine (0.17 mg/kg of body weight, diluted to a ...
Craig AM, Blythe LL, Appell LH, Slizeski ML.Dimethyl sulfoxide (DMSO) had been postulated to be a 'masking agent' when used concurrently with therapeutic or prohibited drugs in racing animals. Eight drugs (flunixin, furosemide, caffeine, apomorphine, phenylbutazone, lidocaine, cocaine, and acepromazine maleate) were administered to six horses singly and with concurrent intravenous DMSO. Urine samples were analyzed for the presence of the drugs and/or their metabolites by thin layer chromatography. Direct comparison of thin layer chromatograms of extracts of positive urine samples with and without DMSO verified that DMSO did not interfer...
Skarda RT, Muir WW, Couri D.Arterial and/or central venous plasma concentrations of lidocaine were determined in 12 nonmedicated adult horses (422 +/- 59 kg of body weight, mean +/- SD) after injecting a 1% lidocaine HCl solution into the cervicothoracic ganglion (CTG). A mean dosage of 2.9 +/- 0.5 mg of lidocaine/kg of body weight was used to induce unilateral CTG blockade in 8 horses and 4.8 +/- 0.8 mg was used to induce bilateral CTG blockade in 4 horses. Blood samples were collected before and at 5, 15, 30, 45, 60, 75, 90, 105, and 120 minutes after injection. The plasma lidocaine concentrations were determined by us...
Muir WW, McGuirk S.Knowledge of the dosage, rate and route of administration, and potential side effects of drugs used to treat cardiac disease in horses has been refined. The judicious use of these drugs can increase exercise capacity, improve health, and potentially prolong life. Currently, antiarrhythmics (quinidine, lidocaine), positive inotropies (digoxin), and diuretics (furosemide) are the primary agents used to treat cardiovascular disease in horses. The development of newer drugs (verapamil, milrinone, bumetanide) and their usefulness in therapy for horses with cardiovascular disease require further inv...
Engelking LR, Blyden GT, Lofstedt J, Greenblatt DJ.Previous studies demonstrated that plasma clearance of organic anions such as bilirubin, bile acid, sulfobromophthalein (BSP) and indocyanine green (ICG), was reduced from 36% (bile acid) to 55% (ICG) in fasted (3 days) horses. It is believed that a general decline in carrier-mediated hepatic uptake may have accounted for those changes. However, fasting may also affect hepatic blood flow, thereby contributing to reduced clearance of these compounds. In order to test this hypothesis, plasma clearance of antipyrine, acetaminophen and lidocaine, drugs known to be cleared by the liver yet not susp...
Engelking LR, Lofstedt J, Blyden GT, Greenblatt DJ.The following studies were designed to evaluate plasma elimination kinetics of intravenously administered antipyrine, acetaminophen and lidocaine among 9 healthy adult horses and 9 healthy drug-free humans (3 each per drug group), in order to compare potential species differences in drug-metabolizing ability. Acetaminophen is largely biotransformed in humans by hepatic glucuronide and sulfate conjugation, whereas both antipyrine and lidocaine are oxidized by hepatic microsomal mixed-function oxidases. Thus, plasma clearances of these drugs are thought to reflect differences in hepatic oxidativ...
Skarda RT, Muir WW, Swanson CR, Hubbell JA.Seven adult horses were used to compare the cardiovascular and respiratory effects of unilateral (right side) and bilateral cervicothoracic ganglion (CTG) blockade. An 18-gauge, 25-cm needle was placed midventrally between articulations of the 1st and 2nd ribs from a cranial and paratracheal site. One gram of lidocaine HCl in aqueous solution (100 ml) was used to infiltrate the CTG. Cervicothoracic sympathetic blockade was characterized by Horner's syndrome, increased skin temperature and profuse sweating over the face, neck, and thoracic limb. Comparison of base-line data with data obtained d...
Muir WW, McGuirk SM.The rational therapy of cardiovascular disease in horses requires a thorough knowledge of the pharmacology and pharmacokinetics of several specific drugs (digitalis, digoxin). Calcium solutions, dopamine, and dobutamine are frequently used to treat congestive heart failure in horses. Quinidine, procainamide, lidocaine, and propranolol are used to treat a variety of supraventricular and ventricular arrhythmias. Furosemide, a highly potent loop diuretic, is used to eliminate edema and promote diuresis. A thorough understanding of the applied pharmacology, dosage recommendations, toxicity, and pr...
Schelling CG, Klein LV.A double-blind comparison of carbonated lidocaine and lidocaine hydrochloride in caudal epidural anesthesia was performed in 8 horses. Among 5 horses with successfully paired bilateral caudal epidural blockades, no significant differences in onset time, duration, or sensory blockade were demonstrated. In the present study, carbonated lidocaine did not offer an advantage over the hydrochloride salt for caudal epidural anesthesia in the horse.
Krpan MK.Transtracheal aspiration is used to obtain samples for culture and cytologic examination of respiratory tract secretions and exudates. A 15-cm-long area of the ventral midcervical region is surgically prepared, a small site infiltrated SC with 2-3 ml lidocaine, and a stab incision made in the skin. A trocar with cannula is inserted through the incision and annular ligament into the trachea and the trocar removed. An 8-Fr polypropylene catheter is inserted about 35-40 cm down the trachea and attached to a 30-ml syringe, containing 20 ml sterile saline, with a 3-way stopcock . The saline is rapi...
Green EM, Cooper RC.A technique for continuous caudal epidural anesthesia in the horse was developed in trials involving 8 healthy adult horses. The injection site was the first intercaudal (intercoccygeal) space. A Huber point directional needle (Tuohy or Hustead) with a stylet was preplaced into the epidural space, used as a guide for an epidural catheter, and then removed, leaving the catheter in situ in the epidural space. A 2% solution of lidocaine hydrochloride was used as the anesthetic agent at an initial dose of 8 ml for an adult animal (474 kg to 560 kg). Repeated 4-ml doses were administered immediatel...
Rédua MA, Valadão CA, Duque JC, Balestrero LT.To evaluate the pre-emptive analgesic effect of pre-incisional epidural ketamine. Methods: A blinded, randomized experimental study. Methods: Sixteen mixed breed mares, 7.6 ± 2.8 years old, weighing 352 ± 32 kg. Methods: In a pilot study, an incision was made on one lateral thigh using a lidocaine block and no further analgesics, and it was verified that the nociceptive threshold was lower on the incised side than nonincised side (p ≤ 0.05), and that von Frey filaments evoked a pain response. The 16 animals were divided into group A (ketamine, n = 9) and B (saline, n = 7). An epidural cath...
Guedes A, Aleman M, Davis E, Tearney C.To determine physiologic responses to apnea-induced severe hypoxemia in anesthetized horses. Methods: Prospective experimental study. Methods: Six university-owned horses with a median (range) body weight of 500 (220-510) kg and aged 13.5 (0.8-24.0) years scheduled for euthanasia. Methods: Xylazine-midazolam-ketamine-anesthetized horses breathing room air spontaneously were instrumented with a facial artery catheter for pressure measurement and blood sampling, and were made apneic with atlanto-occipital intrathecal lidocaine (4 mg kg ). Cardiopulmonary, biochemical and hematologic variable...
Gonzalez GA, Betbeze C, Wills R, Eddy A, Mochal-King C, Fontenot RL.To evaluate corneal sensitivity and adverse events following subconjunctival administration of three local anesthetics in horses. Methods: Randomized, masked, crossover study. Methods: Twelve healthy adult mares. Methods: The subconjunctival space of the treated eye was injected with 0.2 mL of liposomal bupivacaine (1.3%), ropivacaine (0.5%), or mepivacaine (2%). All horses received each medication once and the contralateral eye received saline (control). Corneal touch threshold (CTT) was measured using a Cochet-Bonnet esthesiometer before sedation, after sedation, and at specified intervals...
Nannarone S, Cenani A, Gialletti R, Pepe M.To compare, in horses undergoing laparotomy for colic, the effects of administering or not administering a loading intravenous (IV) bolus of lidocaine prior to its constant rate infusion (CRI). Effects investigated during isoflurane anaesthesia were end-tidal isoflurane concentration (Fe'ISO), cardiovascular function, anaesthetic stability and the quality of recovery. Methods: Prospective, randomized clinical study. Methods: Thirty-six client-owned horses. Methods: Horses were assigned randomly to receive lidocaine as a CRI (50 μg kg(-1) minute(-1) ) either preceded (LB) or not preceded (L...
Southwood LL.Horses with large colon volvulus (LCV) often require intensive postoperative medical management. Although early referral and surgical intervention are critical for minimal postoperative complications and a successful outcome, this is often not possible for many reasons. Endotoxemia, extensive mucosal damage with subsequent severe hypoproteinemia, and focal ischemic necrosis are the major causes of postoperative morbidity and mortality. Although fluid therapy, flunixin meglumine, and antimicrobials are still the mainstay of perioperative management, synthetic colloids are being used to maintain...
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...
Robertson SA.Several ocular procedures, including examination, removal of corneal foreign bodies, nictitans surgery, eyelid repair, and tumor excision,can be successfully performed in the appropriately restrained and sedated standing horse. Sedation is best achieved with xylazine,with or without the addition of acepromazine. Additional analgesia can be provided with appropriate local anesthetic blocks. Surgical conditions are greatly improved by using an auriculopalpebral and supraorbital block and topical anesthetics. More elaborate standing sedation involving continuous rate infusions of lidocaine or det...
Kristinsson J, Thordarson TH, Johannesson T.The pharmacokinetics of lignocaine was studied in four Icelandic horses after infiltration anaesthesia. A total of 240 mg of the drug was injected on either side of the left foreleg, over the medial and lateral branches of the palmar nerve. Blood samples were collected up to seven hours after injection and the concentrations of the drug in plasma were determined by gas chromatography/mass spectrometry. The results showed that lignocaine was rapidly absorbed. A mean maximum concentration of 232 ng/ml was observed after 20 minutes. In three of the horses the decline in the plasma concentration o...
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)...
Boye JK, Katzman SA, Kass PH, Dujovne GA.In equids, it is common to inject lidocaine into the testicles at the time of routine castration to provide analgesia. The effects of lidocaine on equine sperm have not been evaluated in vitro or on epididymal sperm collected following castration. The aims of this study were to determine effects of clinically relevant doses of lidocaine on equine spermatozoa in vitro using freshly collected semen and to compare the characteristics of epididymal spermatozoa after routine castration with or without intra-testicular lidocaine administration. We hypothesized that increasing concentrations of lid...
Delli-Rocili MM, Cribb NC, Trout DR, Thomason JJ, Valverde A.To compare the effectiveness of a paravertebral nerve block vs local portal blocks for laparoscopic closure of the nephrosplenic space in standing sedated research horses. Methods: Randomized clinical trial. Methods: Twelve horses were randomly allocated to two groups (n = 6 per group), paravertebral block of nerves T , L , and L or local blocks of the three laparoscopic portals. Methods: Horses were sedated with dexmedetomidine (4 μg/kg IV and constant rate infusion [CRI] of 2.5 μg/kg/h) and morphine (50 μg/kg IV and CRI of 30 μg/kg/h). According to group allocation, 20 mL of either lid...
Cerasoli I, Cornillie P, Gasthuys F, Gielen I, Schauvliege S.To investigate the anatomy of the ear innervation in horses and develop a new approach for the block of the internal and external pinna and acoustic meatus. Methods: Prospective, descriptive, cadaveric study. Methods: A total of 25 heads and necks from horse cadavers. Methods: Phase I: anatomical dissection and dye deposition on 19 heads. With the head positioned in lateral recumbency, 10 mL methylene blue (1:1 sterile water) for the internal auricular and 2 mL for the great auricular nerve block were injected in 21 ears (seven left, 10 right and two bilaterally). The anatomy of all the ears (...
Ruíz-López P, Cuypers C, Schauvliege S.This retrospective study investigated the effect of a xylazine infusion on heart rate; mean arterial pressure; blood gases; anesthetic and dobutamine requirements; recovery quality and duration; percentage of death/survival; and days to die/discharge in horses after colic surgery under partial intravenous anesthesia with isoflurane and lidocaine infusion. Anesthetic records of equine colic surgery were reviewed from similar periods in 2020-2021 and 2021-2022. In both groups, after sedation with xylazine 0.7 mg/kg intravenously (IV) and induction with ketamine 2.2 mg/kg and midazolam 0.06 mg/kg...
Knych HK, Katzman S, McKemie DS, Arthur RM, Blea J.Lidocaine is a local anesthetic that is sometimes administered in combination with epinephrine. The addition of epinephrine increases the time lidocaine remains at the site of administration, thus prolonging the duration of effect. Due to their potential to prevent the visual detection of lameness, the administration of local anesthetics is strictly regulated in performance and racehorses. Recent reports of positive regulatory findings for lidocaine in racehorses suggests a better understanding of the behavior of this drug is warranted. The objective of the current study was to describe serum ...
Webster A, Pezzanite L, Hendrickson D, Griffenhagen G.Equine practitioners frequently inject local anaesthetics (LA) intra-articularly in both diagnosis of lameness and for pain management intra- or post-operatively with synovial endoscopy. Recent reviews of the human and veterinary literature support the concept that chondrotoxicity of LA on joint tissues depends on the type of drug, dose administered, and duration of exposure. The purpose of this review is to summarise the current literature describing intra-articular local anaesthetic use, including both in vitro and in vivo studies, and to draw some comparisons to literature from other specie...
Rockow M, Griffenhagen G, Landolt G, Hendrickson D, Pezzanite L.Recognition of antimicrobial resistance in equine practice has increased over the past decade. The objective of this study was to provide an updated retrospective review of antimicrobial regimens in one tertiary referral hospital and to evaluate the association with postoperative complications. A secondary objective was to evaluate other perioperative factors including surgical procedure, anesthetic and recovery parameters, and the effect of perioperative medications on complications and outcomes. A computerized search of medical records was performed to identify horses undergoing exploratory ...
Pereira GF, Fenelon ACG, Horr M, Nogueira GM, Delfiol DJZ.The analysis of cerebrospinal fluid has diagnostic, prognostic, and therapeutic value in neurological illnesses in horses. There are different methods for obtaining cerebrospinal fluid, with the collection between the C1 and C2 vertebrae being a more recent methodology, which allows the procedure to be performed in standing patients, without the limitations of general anesthesia and with a low contamination of the sample with blood, presenting itself as a practical alternative. This study evaluated the efficacy and safety of a local dural blockade in healthy horses submitted to cerebrospinal f...
Dzikiti TB, Maney JK, Thorogood J, Segabinazzi L, Peterson E, Dzikiti LN, Escobar A.Intravenous infusions of alpha-2 adrenoceptor sedatives and opioids can potentially facilitate surgery in donkeys while standing. Literature on this subject matter is scant. Objective: Evaluation of efficacy of sedation from α -adrenoceptors (dexmedetomidine or xylazine) and butorphanol during ovariectomy in standing donkeys. Methods: Randomised, masked in vivo experiment. Methods: Thirteen female donkeys were sedated with butorphanol (0.05 mg/kg bwt followed by 0.5 mg/kg bwt/h) IV. Concomitantly, 6 of the 13 jennies were sedated with dexmedetomidine 2.5 mcg/kg bwt followed by 2.5 mcg...
Lambertini C, Spaccini F, Mazzanti A, Spadari A, Lanci A, Romagnoli N.In horses, lidocaine infusion is administered intraoperatively for analgesia and for a reduction of inhalant anaesthetic requirement. The objective of the study was to describe the anaesthetic effects of lidocaine infusion in isoflurane anaesthetised foals. Unassigned: Twelve foals (<3 weeks old) undergoing surgery were included in the study (LIDO group). Foals were premedicated with midazolam and butorphanol IV, anaesthesia was induced with ketamine and propofol IV and maintained with isoflurane. Lidocaine was administered intraoperatively at 0.05 mg/kg/min. Also, the anaesthetic records o...
Fernandez-Barrientos MA, Flynn H, Ratliff B, Kilcoyne I.To highlight the use of procainamide as a potential alternative treatment modality in cases of ventricular tachycardia that are refractory to lidocaine and magnesium sulfate. Methods: 1 adult horse weighing 380 kg. Unassigned: A 25-year-old Arabian gelding presented with severe colic signs. Due to persistent pain, it was elected to carry out an exploratory laparotomy. During the procedure a diagnosis of severe, unstable ventricular tachycardia was made based on the ECG findings, with an initial heart rate of 195 beats per minute and severe hypotension. Results: Initial treatment consisted of d...
