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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.
Adverse reactions in horses that underwent general anesthesia and cervical myelography. The study was prompted by a perceived high prevalence of myelographic complications varying in severity and type, and attributed to the contrast material or the procedure. Objective: 1. Any adverse reaction (AAR) is associated with a change in CSF volume induced either by removal of CSF or addition of contrast material. 2. AAR occurs more frequently in horses with higher premyelography neurologic grade. 3. Nonspecific hyperthermia is attenuated by anti-inflammatory and osmotic agents. Methods: Horses (n = 278) that underwent myelography between 2000 and 2012 at 5 institutions: A (87), B (68), ...
Comparison of cardiorespiratory variables in dorsally recumbent horses anesthetized with guaifenesin-ketamine-xylazine spontaneously breathing 50% or maximal oxygen concentrations. This study compared cardiorespiratory variables in dorsally recumbent horses anesthetized with guaifenesin-ketamine-xylazine and spontaneously breathing 50% or maximal (> 90%) oxygen (O2) concentrations. Twelve healthy mares were randomly assigned to breathe 50% or maximal O2 concentrations. Horses were sedated with xylazine, induced to recumbency with ketamine-diazepam, and anesthesia was maintained with guaifenesin-ketamine-xylazine to effect. Heart rate, arterial blood pressures, respiratory rate, lithium dilution cardiac output (CO), inspired and expired O2 and carbon dioxide partial pr...
Refinement and partial validation of the UNESP-Botucatu multidimensional composite pain scale for assessing postoperative pain in horses. Quantification of pain plays a vital role in the diagnosis and management of pain in animals. In order to refine and validate an acute pain scale for horses a prospective, randomized, blinded study was conducted. Twenty-four client owned adult horses were recruited and allocated to one of four following groups: anaesthesia only (GA); pre-emptive analgesia and anaesthesia (GAA,); anaesthesia, castration and postoperative analgesia (GC); or pre-emptive analgesia, anaesthesia and castration (GCA). One investigator, unaware of the treatment group, assessed all horses at time-points before and afte...
Effect of dantrolene premedication on various cardiovascular and biochemical variables and the recovery in healthy isoflurane-anesthetized horses. To determine the effect of dantrolene premedication on various cardiovascular and biochemical variables and recovery in isoflurane-anesthetized horses. Methods: 6 healthy horses. Methods: Each horse was anesthetized twice with a 21- to 28-day washout period between anesthetic sessions. Food was not withheld from horses before either session. During each session, dantrolene (6 mg/kg in 2 L of water) or water (2 L) was administered via a nasogastric tube 1 hour before anesthesia was induced. Anesthesia was maintained with isoflurane for 90 minutes, during which blood gas analyses and lithium-dil...
Intraarterial Injection of Iodinated Contrast Medium for Contrast-Enhanced Computed Tomography of the Equine Head. Minimizing the volume of contrast administered for contrast-enhanced computed tomography (CT) of the equine head is desirable for reducing costs and risks of adverse reactions, however evidence-based studies on the effects of varying volumes on image quality are currently lacking. The objective of the current study was to determine whether low-volume intraarterial administration of contrast medium would result in an equivalent image quality and tissue attenuation vs. high-volume intravenous bolus administration. A prospective cross-over experimental design was used in a sample of six horses. A...
Effects of isoflurane and sevoflurane on the neutrophil myeloperoxidase system of horses. Volatile anaesthestics have shown to modulate the oxidative response of polymorphonuclear neutrophils (PMNs). We investigated the effects of isoflurane and sevoflurane on the degranulation of total and active myeloperoxidase (MPO) from horse PMNs and their direct interaction with MPO activity. Whole blood from horse was incubated in 1 and 2 minimal alveolar concentrations (MAC) of isoflurane or sevoflurane for 1h and PMNs were stimulated with cytochalasin B (CB) plus N-formyl-méthionyl-leucyl-phenylalanine (fMLP). After stimulation, the plasma was collected to measure total and active MPO by ...
Desflurane and sevoflurane elimination kinetics and recovery quality in horses. To evaluate pharmacokinetics, recovery times, and recovery quality in horses anesthetized with 1.2 times the minimum alveolar concentration of sevoflurane or desflurane. Methods: 6 healthy adult horses. Methods: Anesthesia was maintained with sevoflurane or desflurane for 2 hours at 1.2 times the minimum alveolar concentration. Horses recovered without assistance. During recovery, end-tidal gas samples were collected until horses spontaneously moved. Anesthetic concentrations were measured by use of gas chromatography. After a 1-week washout period, horses were anesthetized with the other inha...
Efficacy of a portable oxygen concentrator with pulsed delivery for treatment of hypoxemia during equine field anesthesia. Hypoxemia is common during equine field anesthesia. Our hypothesis was that oxygen therapy from a portable oxygen concentrator would increase PaO2 during field anesthesia compared with the breathing of ambient air. Methods: Prospective clinical study. Methods: Fifteen yearling (250 - 400Â kg) horses during field castration. Methods: Horses were maintained in dorsal recumbency during anesthesia with an intravenous infusion of 2000Â mg ketamine and 500Â mg xylazine in 1Â L of 5% guaifenesin. Arterial samples for blood gas analysis were collected immediately post-induction (PI), and at 15 and 30Â...
Perianesthetic development of diaphragmatic hernia in a horse with equine pituitary pars intermedia dysfunction (PPID). A 21-year-old Thoroughbred gelding with a history of equine pituitary pars intermedia dysfunction (PPID) presented with priapism of 2 days' duration. The horse received a caudal morphine epidural and then underwent corpus cavernosum lavage and phallectomy under general anesthesia. The patient's recovery featured multiple unsuccessful attempts to stand and his respiratory distress persisted for several hours until he acutely developed severe colic and was euthanized. Necropsy findings revealed a pituitary adenoma of the pars intermedia, bilateral adrenal cortical hyperplasia, and diaphragmatic ...
Unilateral choristoma of the nictitating membrane in a horse. A 2-year-old Morgan mare was evaluated because of a corneal ulceration. Results: An irregular, deep stromal corneal ulcer in an area of malacia was noted in the left eye. Hypopyon was present in the ventral portion of the anterior chamber with moderate aqueous flare. The nictitating membrane of the left eye had hairs originating from its leading edge that contacted the corneal surface. Results: General anesthesia was induced, and a bulbar pedicle conjunctival graft was performed. The conjunctiva at the leading edge of the nictitating membrane, including the aberrant hair follicles, was excised...
Caesarean in mare by Marcenac incision under local anaesthesia. A nulliparous non-descript mare was presented with a complaint of dystocia. The mare was recumbent and physical examination revealed that the animal was in shock. There was no straining and foetal forelimbs were visible outside the vulva. The foetus was dead as there was no pedal reflex. Vaginal examination revealed anterior presentation with dorso-sacral position and rigid lateral head deviation. Pre-operatively, the mare was given 5 ml Tetanus toxoid and 3 g Ceftriaxone as intramuscular injection, and 5 ml Dexamethasone in 15 L of 5% Dextrose Normal Saline (DNS) as intravenous (i/v) infusion...
Detomidine and the combination of detomidine and MK-467, a peripheral alpha-2 adrenoceptor antagonist, as premedication in horses anaesthetized with isoflurane. To investigate MK-467 as part of premedication in horses anaesthetized with isoflurane. Methods: Experimental, crossover study with a 14 day wash-out period. Methods: Seven healthy horses. Methods: The horses received either detomidine (20 μg kg(-1) IV) and butorphanol (20 μg kg(-1) IV) alone (DET) or with MK-467 (200 μg kg(-1) IV; DET + MK) as premedication. Anaesthesia was induced with ketamine (2.2 mg kg(-1) ) and midazolam (0.06 mg kg(-1) ) IV and maintained with isoflurane. Heart rate (HR), mean arterial pressure (MAP), end-tidal isoflurane concentration, end-tidal carbon ...
Effects of a continuous rate infusion of butorphanol in isoflurane-anesthetized horses on cardiorespiratory parameters, recovery quality, gastrointestinal motility and serum cortisol concentrations. To assess the cardiorespiratory parametes, recovery, gastrointestinal motility and serum cortisol concentrations in horses anesthetized with isoflurane with or without a continuous rate infusion (CRI) of butorphanol for orchiectomy. Methods: Twelve adult, intact, male horses weighing 332 ± 55 kg were included in the study. Xilazine was administered as premedication. Anesthesia was induced with ketamine and midazolam and maintained with isoflurane. Butorphanol (0.025 mg kg-1 bolus) or an equivalent volume of saline (0.9%) was given intravenously followed by a CRI of butorphanol (BG) (13 µg kg...
Cardiovascular effects of total intravenous anesthesia using ketamine-medetomidine-propofol (KMP-TIVA) in horses undergoing surgery. Cardiovascular effects of total intravenous anesthesia using ketamine-medetomidine-propofol drug combination (KMP-TIVA) were determined in 5 Thoroughbred horses undergoing surgery. The horses were anesthetized with intravenous administration (IV) of ketamine (2.5 mg/kg) and midazolam (0.04 mg/kg) following premedication with medetomidne (5 µg/kg, IV) and artificially ventilated. Surgical anesthesia was maintained by controlling propofol infusion rate (initially 0.20 mg/kg/min following an IV loading dose of 0.5 mg/kg) and constant rate infusions of ketamine (1 mg/kg/hr) and medetomidine (1.25...
Effects of approach and injection volume on diffusion of mepivacaine hydrochloride during local analgesia of the deep branch of the lateral plantar nerve in horses. To compare the effects of 2 approaches and 2 injection volumes on diffusion of mepivacaine hydrochloride for local analgesia of the deep branch of the lateral plantar nerve (DBLPN) in horses. Methods: Experimental study. Methods: 16 adult horses. Methods: Either 2 mL (low volume) or 8 mL (high volume) of mepivacaine hydrochloride-iohexol (50:50 mixture) was injected by means of 1 of 2 techniques to produce analgesia of the DBLPN. For technique 1, the needle was inserted 15 mm distal to the head of the fourth metatarsal bone and directed perpendicular to the limb. For technique 2, the needle wa...
Effects of pulse-delivered inhaled nitric oxide administration on pulmonary perfusion and arterial oxygenation in dorsally recumbent isoflurane-anesthetized horses. To image the spatial distribution of pulmonary blood flow by means of scintigraphy, evaluate ventilation-perfusion (VA/Q) matching and pulmonary blood shunting (Qs/Qt) by means of the multiple inert gas elimination technique (MIGET), and measure arterial oxygenation and plasma endothelin-1 concentrations before, during, and after pulse-delivered inhaled nitric oxide (PiNO) administration to isoflurane-anesthetized horses in dorsal recumbency. Methods: 3 healthy adult Standardbreds. Methods: Nitric oxide was pulsed into the inspired gases in dorsally recumbent isoflurane-anesthetized horses. As...
Use of micro-lightguide spectrophotometry for evaluation of microcirculation in the small and large intestines of horses without gastrointestinal disease. To evaluate the use of a micro-lightguide tissue spectrophotometer for measurement of tissue oxygenation and blood flow in the small and large intestines of horses under anesthesia. Methods: 13 adult horses without gastrointestinal disease. Methods: Horses were anesthetized and placed in dorsal recumbency. Ventral midline laparotomy was performed. Intestinal segments were exteriorized to obtain measurements. Spectrophotometric measurements of tissue oxygenation and regional blood flow of the jejunum and pelvic flexure were obtained under various conditions that were considered to have a potent...
Percutaneous ultrasound-guided arterial angiography for transarterial coil placement in anesthetized and standing horses. To (1) describe ultrasound-guided percutaneous introduction of a transarterial angiographic catheter into the common carotid artery (CCA); (2) investigate the feasibility of using angiography of the carotid arteries in the guttural pouch region and assess transarterial coil (TAC) placement into the internal carotid artery (ICA). Methods: Experimental study. Methods: Healthy Standardbred horses (n = 6), aged 5-8 years. Methods: Six horses had ultrasound-guided percutaneous CCA catheterization and angiography under general anesthesia. Catheterization sites were ultrasonographically evaluated pos...
Modified lamellar keratoplasties for the treatment of deep stromal abscesses in horses. To describe a surgical modification of deep lamellar endothelial keratoplasty (DLEK) and posterior lamellar keratoplasty (PLK) procedures, to facilitate surgery on standing horses under-sedation. Methods: Four client-owned horses, for which the owners declined surgery under general anesthesia, underwent standing corneal lamellar keratoplasty procedures for the treatment of deep corneal stromal abscesses. Methods: All four horses were placed in stocks and sedated with detomidine. Local eyelid and retrobulbar blocks were performed to provide local analgesia and akinesia, and each horse's head wa...
Comparison of midazolam and diazepam as co-induction agents with ketamine for anaesthesia in sedated ponies undergoing field castration. To compare intravenous (IV) midazolam and diazepam administered with ketamine for induction of anaesthesia in ponies, already sedated with detomidine, undergoing field castration. Methods: Prospective, randomised, 'blinded', clinical study. Methods: Twenty Welsh pony yearlings. Methods: After IV injection of detomidine (20 μg kg(-1) ) and phenylbutazone (4.4 mg kg(-1) ) ponies were allocated to receive either IV midazolam (group M) or diazepam (group D) (both 0.06 mg kg(-1) ) with ketamine (2.2 mg kg(-1) ) for induction of anaesthesia. Using simple descriptive scales, quality of sedat...
Scintigraphic tracking of mesenchymal stem cells after intravenous regional limb perfusion and subcutaneous administration in the standing horse. To assess distribution, uptake, and persistence of radiolabeled mesenchymal stem cells (MSC) using scintigraphy after intravenous regional limb perfusion (RLP) and subcutaneous injections in standing, sedated horses. Methods: Experimental study. Methods: Horses (n = 12). Methods: Six horses had RLP performed through the cephalic vein on 1 limb and subcutaneous injection in the metacarpal area in the opposite limb. The other 6 horses had RLP performed through the lateral palmar digital vein and subcutaneous injection in the coronary band. A pneumatic tourniquet was used for the RLP. MSC were la...
Surgical correction of nephrosplenic entrapment of the large colon in 3 horses via standing left flank laparotomy. To describe a technique for surgical correction of nephrosplenic entrapment via standing left flank laparotomy. Methods: Case series. Methods: Horses (n = 3). Methods: Nephrosplenic entrapment was diagnosed by abdominal palpation per rectum in all 3 horses and confirmed by transabdominal ultrasonography in 2 horses. Duration of colic was variable and failed to resolve after medical management, phenylephrine administration, and jogging. With sedation and local analgesia, standing left flank laparotomy using a modified grid approach was performed to correct the entrapment. Follow-up information ...
Clinical pharmacokinetics of tramadol and main metabolites in horses undergoing orchiectomy. Tramadol is a synthetic codeine analogue used as an analgesic in human and veterinary medicine. It is not approved for use in horses, but could represent a valid tool for pain treatment in this species. Objective: The serum pharmacokinetic profile and urinary excretion of tramadol and its metabolites (O-desmethyltramadol [M1], N-desmethyltramadol [M2] and N,O-desmethyltramadol [M5]) was investigated in a multidrug anaesthetic and analgesic approach for orchiectomy in horses. The evaluation of the degree of cardiovascular stability, the intraoperative effect and postoperative analgesia obtained...
Endoscopic, transoral, reduction of epiglottic entrapment via wire snare technique. To describe the use of a wire snare technique for epiglottic entrapment. Methods: Case series. Methods: Eight adult horses. Methods: Under general anesthesia, a modified mouth gag was placed in the oropharynx. An endoscope was passed through the gag until there was adequate visualization of the entrapped epiglottis. The entrapping mucosa was grasped with bronchoesophageal forceps and pulled rostrally, releasing the epiglottis. A custom snare was passed down the bronchoesophageal forceps to encircle the redundant subepiglottic mucosa. Tension was applied to the entrapping mucosa via the forceps...
Short-term complications after colic surgery in geriatric versus mature non-geriatric horses. To compare in geriatric and mature horses the occurrence of short-term complications and short-term outcome associated with complications after colic surgery. Methods: Retrospective case-control study. Methods: Horses aged ≥20 years (geriatric, n = 78) and 4-15 years (mature non-geriatric, n = 156) that had exploratory celiotomy for colic and survived recovery from general anesthesia. Methods: Medical records (2000-2010) of horses that recovered from general anesthesia after colic surgery were reviewed. Postoperative complications evaluated included postoperative reflux (POR), diarrh...
Buprenorphine provides better anaesthetic conditions than butorphanol for field castration in ponies: results of a randomised clinical trial. A prospective, randomised, blinded, clinical trial in 47 ponies compared butorphanol and buprenorphine administered intravenously with detomidine prior to castration under anaesthesia. Detomidine 12 μg/kg intravenously was followed by butorphanol 25 μg/kg (BUT) or buprenorphine 5 μg/kg (BUP) before induction of anaesthesia with intravenous ketamine and diazepam. Quality of sedation, induction and recovery from anaesthesia, response to tactile stimulation, and surgical conditions were scored. If anaesthesia was inadequate 'rescue' was given with intravenous ketamine (maximum three dose...
Second carpal bone slab fracture and subluxation of the middle carpal joint in a horse subsequent to arthrodesis of the carpometacarpal joint. To report complications of arthrodesis of the carpometacarpal (CMC) joint using a drilling technique in an adult horse. Methods: Case report. Methods: Horse (n = 1). Methods: A 12-year-old Quarter Horse mare with CMC osteoarthritis (CMC-OA) had arthrodesis under general anesthesia in right lateral recumbency. Under fluoroscopic guidance, a 4.5 mm drill bit was inserted at 3 drilling sites 5-6 cm into the CMC joint and was fanned 30-45° in the plane of the joint and 5-10° in the long axis of the limb to destroy articular cartilage and expose the subchondral bone. Results: The horse pr...
