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.
Foramen epiploicum mesh closure (FEMC) through a ventral midline laparotomy. Preventive laparoscopic closure of the epiploic foramen (EF) has previously been described, but methods for EF closure during laparotomy for treatment of colic are lacking. Objective: To describe the foramen epiploicum mesh closure (FEMC) technique through a ventral midline laparotomy in horses under general anaesthesia and its outcome. Methods: Terminal surgical experiment and in vivo study. Methods: In a pilot study, a standard ventral midline laparotomy was performed under general anaesthesia in 10 experimental horses and a three-dimensional expandable diabolo-shaped mesh construct was manu...
The effects of multiple anaesthetic episodes on equine recovery quality. Although rare, 70% of equine fatalities during recovery from general anaesthesia (GA) are due to catastrophic fractures from poor recovery quality. Objective: To determine the effect of repeated GA recovery on GA recovery quality. Methods: Experimental blinded trial. Methods: Eight adult horses underwent six GA events on sevoflurane for distal limb MRI examination over a 14-week period. Prior to GA recovery, xylazine was administered. Randomly ordered video-recorded GA recoveries were scored by three blinded board certified veterinary anaesthesiologists, unaware of patient identity or GA event...
Effects of dobutamine, dopamine, phenylephrine and noradrenaline on systemic haemodynamics and intestinal perfusion in isoflurane anaesthetised horses. In the horse, effects of cardiovascular-active drugs on local perfusion of the gastrointestinal tract are poorly understood. Objective: To determine the effect of drugs commonly used to support blood pressure, on local intestinal blood flow and tissue oxygenation under isoflurane anaesthesia. Methods: In vivo randomised crossover experiment. Methods: Ten horses were anaesthetised with isoflurane. After 90 min of equilibration three doses (μg/kg bwt/min) of dobutamine (DOB 0.5/1/3), dopamine (DA 1/2/5), noradrenaline (NA 0.1/0.2/0.5) and phenylephrine (PHE 0.5/1/3) were infused for 15 min, in ...
Sedative and cardiopulmonary effects of dexmedetomidine infusions randomly receiving, or not, butorphanol in standing horses. Dexmedetomidine (DEX) alone, or combined with butorphanol (BUT), may be administered by constant rate infusions (CRIs) in standing horses. This blinded, randomised, crossover study in six healthy adult horses aimed to determine the sedative and cardiopulmonary effects of DEX (dexmedetomidine (3.5 µg/kg+5 µg/kg/hour CRI) and DEX/BUT (dexmedetomidine (3.5 µg/kg+3.5 µg/kg/hour CRI) and butorphanol (20 µg/kg+24 µg/kg/hour CRI)). Head height above ground (HHAG), ataxia, responses to tactile/auditory stimuli and cardiopulmonary variables were recorded before, at 5/15/30/60/90 min...
The relationship between intestinal and oral mucosa microcirculation in anaesthetized horses. To compare alteration in intestinal blood flow in anaesthetized horses with changes in oral mucosa blood flow. Methods: Prospective, randomized clinical study. Methods: Eight warmblood horses. Methods: After induction with guaifenesin and ketamine, anaesthesia was maintained with isoflurane at 1.5 vol% in oxygen. The tissue blood flow was measured using laser Doppler flowmetry at the jejunum, colon, rectal mucosa, oesophageal mucosa and the oral mucosa. After three baseline measurements, blood flow was first increased by dobutamine infusion and thereafter decreased by increasing isoflurane con...
18 F-sodium fluoride positron emission tomography of the equine distal limb: Exploratory study in three horses. Positron emission tomography (PET) is a cross-sectional, functional imaging modality that has recently become available to the horse. The use of 18 F-sodium fluoride (18 F-NaF), a PET bone tracer, has not previously been reported in this species. Objective: To assess the feasibility of 18 F-NaF PET in the equine distal limb and explore possible applications in the horse in comparison with other imaging modalities. Methods: Exploratory descriptive study involving three research horses. Methods: Horses were placed under general anaesthesia prior to intravenous (i.v.) administration of 1.5 MBq/kg...
Effect of lidocaine on inflammation in equine jejunum subjected to manipulation only and remote to intestinal segments subjected to ischemia. OBJECTIVE To examine effects of continuous rate infusion of lidocaine on transmural neutrophil infiltration in equine intestine subjected to manipulation only and remote to ischemic intestine. ANIMALS 14 healthy horses. PROCEDURES Ventral midline celiotomy was performed (time 0). Mild ischemia was induced in segments of jejunum and large colon. A 1-m segment of jejunum was manipulated by massaging the jejunal wall 10 times. Horses received lidocaine (n = 7) or saline (0.9% NaCl) solution (7) throughout anesthesia. Biopsy specimens were collected and used to assess tissue injury, neutrophil inf...
Pharmacokinetic profile and partitioning in red blood cells of romifidine after single intravenous administration in the horse. The aims of this study were to assess the plasma concentrations of romifidine in horses after intravenous injection, to evaluate the red blood cell (RBC) partitioning of the anaesthetic drug, and to improve knowledge regarding its sedative effect in horses describing the pharmacokinetic model. Eight adult Standardbred horses received a single bolus of romifidine at a dosage of 100 g/kg. Blood samples (5 mL) were collected immediately before romifidine administration (), and at 2, 5, 10, 15, 20, 25, 30, 40, 50, 60, 75, 90, 105, 120, 150 and 180 min after injection. A sedation score was recor...
Duration of action of mepivacaine and lidocaine in equine palmar digital perineural blocks in an experimental lameness model. To establish and compare the onset and duration of action of 2 local anesthetics based on objective lameness and skin sensitivity assessment. Methods: Interventional crossover experimental trial with balanced randomization. Methods: Eight horses. Methods: Reversible forelimb lameness was induced in 8 horses. A palmar digital nerve block (PDNB) was applied with mepivacaine or lidocaine (both 2%). Quantitative lameness and skin sensitivity data were collected with an inertial sensor system and a force gauge, respectively. The times to lameness resolution/skin desensitization (T1), consistent lam...
Regional ventilation distribution and dead space in anaesthetized horses treated with and without continuous positive airway pressure: novel insights by electrical impedance tomography and volumetric capnography. The aim of this study was to evaluate the effect of continuous positive airway pressure (CPAP) on regional distribution of ventilation and dead space in anaesthetized horses. Methods: Randomized, experimental, crossover study. Methods: A total of eight healthy adult horses. Methods: Horses were anaesthetized twice with isoflurane in 50% oxygen and medetomidine as continuous infusion in dorsal recumbency, and administered in random order either CPAP (8 cmHO) or NO CPAP for 3 hours. Electrical impedance tomography (and volumetric capnography (VCap) measurements were performed every 30 minutes. L...
Successful use of lipid emulsion to resuscitate a foal after intravenous lidocaine induced cardiovascular collapse. Lipid emulsion has been reported to be effective for the treatment of local anaesthetic overdoses in rats, dogs and man. Objective: To describe the successful treatment of cardiovascular lidocaine toxicity in a foal with intravenous lipid administration. Methods: Observational study: case report. Methods: An 8-month-old Arabian cross foal was anaesthetised for removal of the right alar fold and nasal plate. Anaesthesia was maintained with isoflurane in oxygen and lidocaine administered with a loading dose followed by a continuous rate infusion (CRI). The anaesthetic period was uneventful and 3...
Regional Nerve Blocks for Equine Dentistry. Regional nerve blocks are necessary to facilitate equine oral surgery in the standing sedated patient. Step-by-step instruction on how to perform common regional nerve blocks are discussed, including infraorbital, maxillary, middle mental, and inferior alveolar nerve blocks. Regional nerve blocks are critical when performing dental procedures in the standing horse. The infraorbital and maxillary nerve blocks provide anesthesia of the infraorbital nerve, which is a branch of the maxillary nerve. Both nerve blocks provide adequate anesthesia for all maxillary dental procedures. When the infraorb...
Internal fixation of fractured ribs in neonatal foals with nylon cable tie using a modified technique. Nylon cable tie has been shown to be an effective and economical method for fixing fractured ribs in the neonatal foal. This article describes a modification of the previously described technique. Under general anesthesia, the fractured ribs were exposed and a hole was drilled in the dorsal and ventral fragments. The fracture was not reduced, leaving the fragments overriding each other. The nylon cable tie was passed through the hole in the dorsal fragment from the external surface of the rib. The free end of the cable tie was then passed through the hole in the ventral fragment from the exter...
End-to-side anastomosis of the left ventral colon to the small colon in a neonatal foal with segmental agenesis of the large colon. A newborn foal was referred for evaluation because it had not passed meconium, despite the administration of four enemas. Abdominal radiographs and ultrasound scans showed generalised gaseous distension of the intestine and there was no observable meconium in the colon. Positive contrast colography showed contrast medium extending to the transverse colon. An exploratory laparotomy confirmed the absence of the left and right dorsal colon and the pelvic and diaphragmatic flexures. An end-to-side anastomosis of the left ventral colon to the midpoint of the small colon was performed. The foal reco...
Assessment of agreement among diplomates of the American College of Veterinary Anesthesia and Analgesia for scoring the recovery of horses from anesthesia by use of subjective grading scales and development of a system for evaluation of the recovery of horses from anesthesia by use of accelerometry. OBJECTIVE To evaluate agreement among diplomates of the American College of Veterinary Anesthesia and Analgesia for scores determined by use of a simple descriptive scale (SDS) or a composite grading scale (CGS) for quality of recovery of horses from anesthesia and to investigate use of 3-axis accelerometry (3AA) for objective evaluation of recovery. ANIMALS 12 healthy adult horses. PROCEDURES Horses were fitted with a 3AA device and then were anesthetized. Eight diplomates evaluated recovery by use of an SDS, and 7 other diplomates evaluated recovery by use of a CGS. Agreement was tested with...
An Ambulatory Electroencephalography System for Freely Moving Horses: An Innovating Approach. Electroencephalography (EEG) that has been extensively studied in humans presents also a large interest for studies on animal brain processes. However, since the quality of the recordings is altered by muscular activity, most EEG recordings on animals are obtained using invasive methods with deeply implanted electrodes. This requires anesthesia and can thus only be used in laboratory or clinical settings. As EEG is a very useful tool both for detecting brain alterations due to diseases or accidents and to evaluate the arousal and attentional state of the animal, it seemed crucial to develop a ...
Laparoscopic evaluation of the small intestine in the standing horse: Technique and effects. To evaluate the feasibility and clinical outcomes after laparoscopic evaluation of the small intestines via laparoscopy. Methods: Prospective pilot study. Methods: Healthy adult horses (n = 5). Methods: Horses were restrained in standing stocks and received an infusion of detomidine. One port was placed in the left last intercostal space and 3 ports were placed in the right paralumbar fossa. The small intestine was run with atraumatic laparoscopic grasping forceps, from the duodenocolic plica to the ileocecal plica. Postoperative pain was scored every 4 hours for the first 48 hours. Horses...
Clinical comparison of dexmedetomidine and medetomidine for isoflurane balanced anaesthesia in horses. To compare the effects of two balanced anaesthetic protocols (isoflurane-dexmedetomidine versus medetomidine) on sedation, cardiopulmonary function and recovery in horses. Methods: Prospective, blinded, randomized clinical study. Methods: Sixty healthy adult warm blood horses undergoing elective surgery. Methods: Thirty horses each were sedated with dexmedetomidine 3.5 μg kg (group DEX) or medetomidine 7 μg kg (group MED) intravenously. After assessing and supplementing sedation if necessary, anaesthesia was induced with ketamine/diazepam and maintained with isoflurane in oxygen/air and ...
Determination of physiological dead space in anaesthetized horses: a method-comparison study. To compare two methods of Bohr-Enghoff physiological dead space to tidal volume ratio (Vd/Vt) determination using a mixing chamber and an E-CAiOVX metabolic monitor. Methods: Prospective, clinical, method-comparison study. Methods: Twenty horses anaesthetized for elective orthopaedic procedures. Methods: Horses were anaesthetized with isoflurane in oxygen and the lungs were mechanically ventilated (Vt 15±2 mL kg). Arterial blood was sampled to provide arterial partial pressure of carbon dioxide (PaCO) for dead space calculation using a metabolic monitor. Mixed expired partial pressure of ca...
Sedative and antinociceptive effects of different combinations of detomidine and methadone in standing horses. To evaluate intravenous (IV) detomidine with methadone in horses to identify a combination which provides sedation and antinociception without adverse effects. Methods: Randomized, placebo-controlled, blinded, crossover. Methods: A group of eight adult healthy horses aged (mean ± standard deviation) 7 ± 2 years and 372 ± 27 kg. Methods: A total of six treatments were administered IV: saline (SAL); detomidine (5 μg kg; DET); methadone (0.2 mg kg; MET) alone or combined with detomidine [2.5 (MLD), 5 (MMD) or 10 (MHD) μg kg]. Thermal, mechanical and electrical nociceptive thresholds were mea...
Pulsed inhaled nitric oxide improves arterial oxygenation in colic horses undergoing abdominal surgery. To evaluate the effect of pulsed inhaled nitric oxide (INO) on arterial oxygenation in horses during abdominal surgery. Methods: Prospective, randomized, clinical trial. Methods: Thirty horses that underwent abdominal surgery at the University Animal Hospital in Uppsala, Sweden. Methods: Anaesthesia was induced according to a standard protocol - romifidine, butorphanol, diazepam and ketamine and maintained with isoflurane in oxygen. Fifteen horses were administered pulsed INO and 15 served as controls. After baseline data collection, pulsed INO delivery commenced. Arterial and venous blood wer...
Alfaxalone for maintenance of anaesthesia in ponies undergoing field castration: continuous infusion compared with intravenous boluses. To compare alfaxalone as continuous intravenous (IV) infusion with intermittent IV injections for maintenance of anaesthesia in ponies undergoing castration. Methods: Prospective, randomized, 'blinded' clinical study. Methods: A group of 33 entire male Welsh ponies undergoing field castration. Methods: After preanaesthetic medication with IV detomidine (10 μg kg) and butorphanol (0.05 mg kg), anaesthesia was induced with IV diazepam (0.05 mg kg) followed by alfaxalone (1 mg kg). After random allocation, anaesthesia was maintained with either IV alfaxalone 2 mg kg hour (group A; n ...
Maxillary nerve blocks in horses: an experimental comparison of surface landmark and ultrasound-guided techniques. The aim of this preliminary proof-of-concept study was to evaluate and compare the success and complication rate of infiltration of the maxillary nerve of cadaver heads using previously described surface landmarks, standard ultrasound and a novel needle guidance positioning ultrasound system (SonixGPS). Methods: Prospective, anatomical, method-comparison study. Methods: Thirty-eight equine cadaver heads. Methods: Twenty-six veterinary students performed the three methods consecutively on cadaver heads using an 18 gauge, 8.9 cm spinal needle and 0.5 mL iodinated contrast medium. Computed tomog...
Effect of detomidine or romifidine constant rate infusion on plasma lactate concentration and inhalant requirements during isoflurane anaesthesia in horses. Influence of detomidine or romifidine constant rate infusion (CRI) on plasma lactate concentration and isoflurane requirements in horses undergoing elective surgery. Methods: Prospective, randomised, blinded, clinical trial. Methods: A total of 24 adult healthy horses. Methods: All horses were administered intramuscular acepromazine (0.02 mg kg) and either intravenous detomidine (0.02 mg kg) (group D), romifidine (0.08 mg kg) (group R) or xylazine (1.0 mg kg) (group C) prior to anaesthesia. Group D was administered detomidine CRI (10 μg kg hour) in lactated Ringer's solution (LRS), group...
Effect of the α2 -receptor agonists medetomidine, detomidine, xylazine, and romifidine on the ketamine metabolism in equines assessed with enantioselective capillary electrophoresis. The combination of ketamine and an α -receptor agonist is often used in veterinary medicine. Four different α -receptor agonists, medetomidine, detomidine, xylazine, and romifidine, which differ in their chemical structure and thus in selectivity for the α -receptor and in the sedative and analgesic potency, are typically employed during surgery of equines. Recovery following anesthesia with ketamine and an α -receptor agonist is dependent on the α -receptor agonist. This prompted us to investigate (i) the inhibition characteristics for the N-demethylation of ketamine to norketamine and (...
Laparoscopic cryptorchidectomy with a vessel-sealing device in dorsal recumbent horses: 43 cases. To document laparoscopic cryptorchidectomy with a vessel-sealing device in dorsal recumbent horses. Methods: Retrospective study. Methods: Forty-three male horses. Methods: Food was withheld for 36 hours before horses were placed under general anesthesia and positioned in dorsal recumbency. One laparoscopic portal and 2 instrument portals were placed for the laparoscopic procedure. A third instrument portal was created in bilateral cryptorchid horses. A vessel-sealing device was used for hemostasis and transection of retained testes. Descended testes were removed via closed castration with pri...