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Topic:Anesthesia
Anesthesia in horses involves the administration of drugs to induce a temporary loss of sensation or consciousness, facilitating surgical procedures and other medical interventions. This complex process requires a deep understanding of equine physiology and pharmacology to ensure the safety and well-being of the animal. Anesthesia in horses can be challenging due to their size, temperament, and unique anatomical and physiological characteristics. Common anesthetic agents used in equine practice include inhalants like isoflurane and sevoflurane, as well as injectable drugs such as ketamine and xylazine. The management of anesthesia in horses also involves careful monitoring of vital signs and the use of supportive measures to prevent complications such as hypotension, hypoventilation, and post-anesthetic myopathy. This page compiles peer-reviewed research studies and scholarly articles that explore the techniques, advancements, and clinical outcomes associated with anesthesia in equine medicine.
Evaluation of a vessel-sealing device for laparoscopic granulosa cell tumor removal in standing mares. To describe a laparoscopic technique for granulosa cell tumor removal using a vessel sealing device (LigaSuretrade mark) in standing mares. Methods: Retrospective study. Methods: Eight mares (8-24 years old; weighing, 406-525 kg). Methods: Before surgery, ovarian size and adjacent body wall thickness was determined by ultrasonography. Mares were sedated and after local anesthesia (inverted L and local infiltration), laparoscopic cannulation was performed without insufflation. The mesovarium was anesthetized and the LigaSure instrument applied to the mesovarium for hemostasis and resection to r...
Laparoscopic-assisted cystotomy for urolith removal in geldings. To describe a technique for laparoscopic-assisted removal of cystic calculi in geldings and report outcome. Methods: Clinical report. Methods: Four geldings with cystic calculi. Methods: Laparoscopic-assisted cystotomy and urolith retrieval was performed in 4 anesthetized geldings positioned in dorsal recumbency. With a laparoscope portal located at the umbilicus, the abdomen was insufflated and then the surgical table was tilted (30 degrees head-down position) before an instrumental portal was created parallel and 2-3 cm medial to the left external inguinal ring. Laparoscopic grasping forceps...
Analgesic effects of subarachnoidally administered hyperbaric opioids in horses. To evaluate the effects of subarachnoidally administered hyperbaric morphine, buprenorphine, and methadone on avoidance threshold to noxious electrical stimulation of the perineal, sacral, lumbar, and thoracic regions in horses. Methods: 6 healthy adult horses. Methods: Horses were assigned to receive subarachnoid administration of hyperbaric morphine (0.01 mg/kg), buprenorphine (0.001 mg/kg), methadone (0.01 mg/kg), or 10% dextrose solution in equal volumes (5 mL). Electrical stimulation was applied every 10 minutes for 60 minutes and every 30 minutes for 120 minutes after subarachnoid inject...
Dissociative anaesthesia during field and hospital conditions for castration of colts. The principal aim of this study was to evaluate dissociative anaesthesia for castration of colts during field conditions. Three dissociative anaesthetic protocols were evaluated during castration of colts in an animal hospital. The protocol considered to be the most suitable was thereafter evaluated during castration of colts under field conditions. Respiratory and haemodynamic parameters and the response to surgery were determined during anaesthesia. All horses breathed air spontaneously during anaesthesia. Under hospital conditions 26 colts were randomised to receive one of three anaesthetic...
Effect of defocused CO2 laser on equine tissue perfusion. Treatment with defocused CO2 laser can have a therapeutic effect on equine injuries, but the mechanisms involved are unclear. A recent study has shown that laser causes an increase in equine superficial tissue temperature, which may result in an increase in blood perfusion and a stimulating effect on tissue regeneration. However, no studies have described the effects on equine tissue perfusion. The aim of the present study was to investigate the effect of defocused CO2 laser on blood perfusion and to correlate it with temperature in skin and underlying muscle in anaesthetized horses. Differenc...
The effects of i.v. fentanyl administration on the minimum alveolar concentration of isoflurane in horses. Fentanyl decreases the minimum alveolar concentration (MAC) of inhaled anaesthetics and has been used clinically to reduce the requirements of other anaesthetic drugs in humans and small animals. We hypothesized that i.v. fentanyl would decrease the MAC of isoflurane in horses in a dose-dependent manner. Methods: Following determination of baseline MAC of isoflurane, fentanyl was administered i.v. to target plasma concentrations of 1, 8 and 16 ng ml(-1). Each horse was randomly assigned two of three target concentrations administered in ascending order. Loading and infusion doses for each hors...
Evaluation of surgical treatment for signs of acute abdominal pain in draft horses: 72 cases (1983-2002). To determine whether heavy (> or = 680 kg [> or = 1,500 lb]) draft horses undergoing surgical treatment for acute signs of abdominal pain were at a greater risk for anesthetic and postoperative complications and lower postoperative survival rates than light ( 1 year) follow-up information was available was 50%. Conclusions: Draft horses weighing > 680 kg that underwent surgery because of acute signs of abdominal pain had longer durations of anesthesia, more postoperative complications, and higher mortality rates than draft horses weighing < 680 kg.
Gait abnormalities caused by selective anesthesia of the suprascapular nerve in horses. To assess gait abnormalities associated with selective anesthesia of the suprascapular nerve (SSN) achieved by use of perineural catheterization and thereby determine the function of that nerve as it relates to gait in horses. Methods: 3 adult horses with no preexisting clinically apparent lameness at a walk. Methods: Each horse was anesthetized; the right SSN was exposed surgically for placement of a perineural catheter to permit delivery of 1 mL of 2% mepivacaine hydrochloride. Six hours after recovery from anesthesia, each horse was videotaped while walking (50-step data acquisition period)...
Evaluation of administration of isoflurane at approximately the minimum alveolar concentration on depression of a nociceptive withdrawal reflex evoked by transcutaneous electrical stimulation in ponies. To investigate effects of isoflurane at approximately the minimum alveolar concentration (MAC) on the nociceptive withdrawal reflex (NWR) of the forelimb of ponies as a method for quantifying anesthetic potency. Methods: 7 healthy adult Shetland ponies. Methods: Individual MAC (iMAC) for isoflurane was determined for each pony. Then, effects of isoflurane administered at 0.85, 0.95, and 1.05 iMAC on the NWR were assessed. At each concentration, the NWR threshold was defined electromyographically for the common digital extensor and deltoid muscles by stimulating the digital nerve; additional el...
Morphine administration in horses anaesthetized for upper respiratory tract surgery. To determine the effect of morphine administration on commonly monitored cardio-respiratory variables and recovery quality in horses undergoing anaesthesia and surgery. Methods: Prospective, randomized clinical study. Methods: Thirty-eight thoroughbred horses, 32 geldings and six mares, 3-13 years old, weighing 411-600 kg. Methods: A standard anaesthetic technique was used. Twenty minutes after induction of anaesthesia horses received 0.1 mg kg(-1) (0.1 m) or 0.2 mg kg(-1) (0.2 m) morphine by intravenous injection. A control group did not receive morphine. Heart rate, respiratory rate (fr), me...
The effect of hyoscine on dobutamine requirement in spontaneously breathing horses anaesthetized with halothane. To determine whether hyoscine has a sparing effect on the volume of dobutamine required to maintain mean arterial pressure (MAP) at 70 mmHg in horses anaesthetized with halothane. Methods: Prospective, randomized, controlled clinical trial. Methods: Twenty adult horses weighing 507 +/- 97 kg (mean +/- SD), aged 10 +/- 5 years. Methods: Pre-anaesthetic medication in all horses was intramuscular (IM) acepromazine (40 mug kg(-1)) and intravenous (IV) detomidine (0.02 mg kg(-1)). Anaesthesia was induced with ketamine (2.2 mg kg(-1) IV) and diazepam (0.02 mg kg(-1) IV), and maintained with halothan...
Pleuropneumonia as a sequela of myelography and general anaesthesia in a Thoroughbred colt. A 3-year-old Thoroughbred colt was presented to the University Veterinary Centre Camden for evaluation of ataxia. The horse was anaesthetised to facilitate cervical radiography and myelographic examination of the spinal cord. Recovery from anaesthesia was uneventful. Five days after general anaesthesia the horse re-presented with pleuropneumonia. It was euthanased 24 hours after presentation on humane grounds. Necropsy revealed severe tracheal erosion over the middle third of the ventral surface of the trachea, pleuropneumonia and narrowing of the cervical cord between C4 and C6. It is postula...
Evaluation of total intravenous anesthesia with propofol or ketamine-medetomidine-propofol combination in horses. Objective-To compare the anesthetic and cardiorespiratory effects of total IV anesthesia with propofol (P-TIVA) or a ketamine-medetomidine-propofol combination (KMP-TIVA) in horses. Design-Randomized experimental trial. Animals-12 horses. Procedure-Horses received medetomidine (0.005 mg/kg [0.002 mg/lb], IV). Anesthesia was induced with midazolam (0.04 mg/kg [0.018 mg/lb], IV) and ketamine (2.5 mg/kg [1.14 mg/lb], IV). All horses received a loading dose of propofol (0.5 mg/kg [0.23 mg/lb], IV), and 6 horses underwent P-TIVA (propofol infusion). Six horses underwent KMP-TIVA (ketamine [1 mg/kg/...
Electroencephalographic and electromyographic changes during the use of detomidine and detomidine-butorphanol combination in standing horses. Clinically, the use of detomidine and butorphanol is suitable for sedation and deepening of analgosedation. The aim of our study was to establish the influence of detomidine used alone and a butorphanol-detomidine combination on brain activity and to evaluate and compare brain responses (using electroencephalography, EEG) by recording SEF90 (spectral edge frequency 90%), individual brain wave fractions (beta, alpha, theta and delta) and electromyographic (EMG) changes in the left temporal muscle in standing horses. Ten clinically healthy cold-blooded horses were divided into two groups of five...
Arthroscopically assisted arthrodesis of the distal interphalangeal joint with transarticular screws inserted through a dorsal hoof wall approach in a horse. A 16-year-old Thoroughbred gelding was examined because of chronic right forelimb lameness. Results: On radiographs of the right front foot, the distal interphalangeal (DIP) joint space was narrow, and osteophytes and periarticular bony proliferation indicative of severe osteoarthritis were seen. Arthrodesis of the right DIP joint was recommended to improve the horse's comfort on the limb. Results: The horse was anesthetized, and palmar and dorsal arthroscopic approaches were used to remove as much of the articular cartilage as was accessible. Holes were then drilled through the dorsal aspect ...
Effect of intratesticular injection of lidocaine on cardiovascular responses to castration in isoflurane-anesthetized stallions. 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...
The influence of butorphanol dose on characteristics of xylazine-butorphanol-propofol anesthesia in horses at altitude. To characterize behavioral and physiological responses to short-term, unsupplemented intravenous (IV) anesthesia in healthy horses at high altitude (2240 m), and to test the hypothesis that the dose of butorphanol modifies the response of the horse to propofol anesthesia following xylazine pre-medication. Methods: Randomized prospective butorphanol dose cross-over experimental design. Animals Eight healthy horses, 13 +/- 6 (mean +/- SD) years of age, and weighing 523 +/- 26 kg. Methods: Each horse was anesthetized three times with at least 3 weeks between each anesthesia. After collecting pre-...
Clinical observations surrounding an increased incidence of postanesthetic myopathy in halothane-anesthetized horses. During an 8-year period of clinic improvements, an increased incidence of postanesthetic myopathy (PAM) was observed in horses undergoing anesthesia. A request was made for an independent anesthesiologist to examine possible reasons for this increase. Routine methods used for anesthesia were then compared with new methods introduced by the anesthesiologist. Methods: Investigative observations were conducted from October 1999 to April 2000. Following premedication with xylazine or detomidine, anesthesia was induced with diazepam or guiaifenesin followed by ketamine. Maintenance of anesthesia wa...
Influence of gastrointestinal tract disease on pharmacokinetics of lidocaine after intravenous infusion in anesthetized horses. 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...
Effects of an alveolar recruitment maneuver on cardiovascular and respiratory parameters during total intravenous anesthesia in ponies. To evaluate pulmonary and cardiovascular effects of a recruitment maneuver (RM) combined with positive end-expiratory pressure (PEEP) during total intravenous anesthesia in ponies. Methods: 6 healthy adult Shetland ponies. Methods: After premedication with detomidine (10 microg/kg, IV), anesthesia was induced with climazolam (0.06 mg/kg, IV) and ketamine (2.2 mg/kg, IV) and maintained with a constant rate infusion of detomidine (0.024 mg/kg/h), climazolam (0.036 mg/kg/h), and ketamine (2.4 mg/kg/h). The RM was preceded by an incremental PEEP titration and followed by a decremental PEEP titrati...
Comparison of hemodynamic, clinicopathologic, and gastrointestinal motility effects and recovery characteristics of anesthesia with isoflurane and halothane in horses undergoing arthroscopic surgery. To compare hemodynamic, clinicopathologic, and gastrointestinal motility effects and recovery characteristics of halothane and isoflurane in horses undergoing arthroscopic surgery. Methods: 8 healthy adult horses. Methods: Anesthesia was maintained with isoflurane or halothane (crossover study). At 6 intervals during anesthesia and surgery, cardiopulmonary variables and related derived values were recorded. Recovery from anesthesia was assessed; gastrointestinal tract motility was subjectively monitored for 72 hours after anesthesia. Horses were administered chromium, and fecal chromium concen...
Evaluation of safety and pharmacokinetics of vancomycin after intravenous regional limb perfusion in horses. To evaluate clinical variables, regional concentrations, and pharmacokinetics of vancomycin in the synovial fluid of distal forelimb joints of horses after IV regional limb perfusion. Methods: 6 horses. Methods: Vancomycin was administered via IV regional limb perfusion to the distal portion of the forelimbs of anesthetized horses. Drug (300 mg of vancomycin hydrochloride in 60 mL of saline [0.9% NaCl] solution) was infused into 1 forelimb, whereas the contralateral limb served as a control and was perfused with 60 mL of saline solution. Solutions were injected into the lateral digital vein af...
Bilateral ureterocystostomy to correct left ureteral atresia and right ureteral ectopia in an 8-month-old standardbred filly. To report the diagnosis and outcome after surgical correction of bilateral distal ureteral anomalies in a Standardbred filly. Methods: Clinical case report. Methods: An 8-month-old, 310 kg Standardbred filly with left ureteral atresia and right ureteral ectopia. Methods: The filly was admitted for evaluation of incontinence since birth and severe urine scalding of the hindquarters. Diagnosis was made by both direct (cystoscopy and vaginoscopy) and indirect (intravenous pyelography, ultrasonography, and scintigraphy) evaluation of the ureters and bladder. The filly had left ureteral atresia, hy...
Subtotal ostectomy of dorsal spinous processes performed in nine standing horses. To describe and evaluate subtotal ostectomy of dorsal spinous processes (DSP) performed in standing horses. Methods: Retrospective study. Methods: Nine adult horses. Methods: The diseased portions of the DSP were removed with the horses standing and sedated after infiltrating a local anesthetic agent around the affected DSP. Medical records of affected horses were reviewed to determine history, findings of physical and radiographic examination, surgical technique, postoperative complications, and outcome. Results: Five horses had subtotal ostectomy of DSP because of osteomyelitis, and 4 becaus...
Use of the Anderson Sling suspension system for recovery of horses from general anesthesia. To describe a sling recovery system (Anderson Sling) for horses and to evaluate outcome of high-risk horses recovered from general anesthesia by a sling. Methods: Retrospective study. Methods: Horses (n=24) recovered from general anesthesia. Methods: Complete medical and anesthetic records (1996-2003) for horses recovered from general anesthesia using the Anderson Sling system were evaluated retrospectively. Information retrieved included anesthetic protocol, surgical procedure, recovery protocol, recovery time, and quality of the recovery. Horses were recovered from anesthesia supported by th...
Synovial fluid and plasma concentrations of ceftiofur after regional intravenous perfusion in the horse. To determine radiocarpal (RC) joint synovial fluid and plasma ceftiofur concentrations after regional intravenous perfusion (RIP) and systemic intravenous (IV) administration. Methods: Experimental cross-over study. Methods: Five normal adult horses. Methods: One RC joint was randomly selected for RIP and the contralateral RC joint was sampled to determine intrasynovial ceftiofur concentrations after IV administration. Wash-out between IV and RIP was > or = 14 days. After surgical introduction of an intraarticular catheter, ceftiofur (2 g) was administered under general anesthesia either IV or...
Laparoscopic ovariectomy using the endo-GIA stapling device and endo-catch pouches and evaluation of analgesic efficacy of epidural morphine sulfate in 10 mares. To evaluate use of ENDO-GIA staples and ENDO-Catch pouches for ovariectomy in mares and to evaluate the efficacy of epidural morphine analgesia. Methods: Randomized clinical trial. Methods: Mares (n = 10) with normal ovaries. Methods: An Endo-GIA II stapler (United States Surgical Corp., Norwalk, CT) was used to amputate the ovaries bilaterally, in standing mares, and Endo-Catch II pouches (United States Surgical Corp.) were used for retrieval. Epidural morphine was used in 5 mares, and procedure duration, volume of lidocaine required to desensitize the ovarian pedicle, and sedation were compa...
Effect of romifidine on the nociceptive withdrawal reflex and temporal summation in conscious horses. To investigate the action of a single IV administration of romifidine on the thresholds of the nociceptive withdrawal reflex (NWR) and temporal summation in conscious horses. Methods: 10 adult horses. Methods: Single electrical stimulations were applied on the digital nerves to evoke NWR from the left forelimb and hind limb. Repeated electrical stimulations (10 stimuli, 5 Hz) were given to obtain temporal summation. Surface electromyographic reflex activity was recorded from the common digital extensor and cranial tibial muscles. After baseline assessment of NWR and temporal summation threshol...
Effect of a constant rate infusion of lidocaine on the quality of recovery from sevoflurane or isoflurane general anaesthesia in horses. Lidocaine constant rate infusions (CRIs) are common as an intraoperative adjunct to general anaesthesia, but their influence on quality of recovery has not been thoroughly determined. Objective: To determine the effects of an intraoperative i.v. CRI of lidocaine on the quality of recovery from isoflurane or sevoflurane anaesthesia in horses undergoing various surgical procedures, using a modified recovery score system. Objective: The administration of intraoperative lidocaine CRI decreases the quality of recovery in horses. Methods: Lidocaine (2 mg/kg bwt bolus followed by 50 microg/kg bwt/min...
