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.
Effects of Sedation on Rectal Temperature During Equine Dental Procedures Performed in Cold to Warm Ambient Temperatures. Sedation is important for safe equine dental procedures, but it is unknown if there is a higher risk of sedation causing hypothermia in procedures performed during cold months. The authors hypothesize that sedation for a dental procedure will significantly decrease rectal body temperature in cold as compared to warm ambient temperatures. Adult equids ( = 246), from a private equine dentistry practice, that underwent dental equilibration, were selected for the study. Each horse's weight was estimated and sedation was administered intravenously (0.01 mg/kg detomidine and 0.01 mg/kg butor...
Laparoscopic cryptorchidectomy in 10 equids using a single incision laparoscopic surgery (SILS) port device. Minimally invasive laparoscopic surgical techniques are desirable in horses and other equids. A new approach called "modified single incision laparoscopic surgery (SILS) for equine cryptorchidectomy" is described, along with the postoperative outcomes of 10 equids. A SILS Port device (Covidien) was placed a 30- to 40-millimeter incision in combination with 1 or 2 15-millimeter para-inguinal incisions to exteriorize the intra-abdominal testicles. Ten animals, 2 bilateral abdominal cryptorchid horses and 8 unilateral abdominal cryptorchid equids, underwent cryptorchidectomy using the SILS tech...
Global survey on the utilisation and experiences with different retrobulbar anaesthesia techniques in horses. Retrobulbar anaesthesia (RBA) is relevant for ocular surgery in standing sedated horses. Objective: Gathering insights on experiences with RBA techniques. Methods: Cross-sectional survey. Methods: An online survey collected information on the respondents' professional background, indications, injection methods, use of ultrasound assistance, medication, and complications associated with RBA in horses. Results: Two-hundred and thirty-eight veterinarians from 25 countries contributed. 86.1% were members of veterinary specialty colleges. RBA indications were enucleation (97.8%), corneal surgery (2...
Optimizing equine standing sedation: continuous infusion of detomidine and butorphanol enhances stability but prolongs ataxia. This study aimed to compare the sedation quality and cardiorespiratory and behavioral effects of detomidine administered intravenously, either in intermittent boluses or as a continuous rate infusion, with butorphanol in horses pre-medicated with acepromazine for odontoplasty procedures. Unassigned: A prospective clinical study was conducted with fifteen adult horses randomly assigned to two groups: Bolus group (BG, = 7) and Infusion group (IG, = 8). Both groups received acepromazine premedication, followed by detomidine administration (bolus or infusion). Butorphanol was administered either...
Analgesic and Gastrointestinal Effects of Methadone in Horses Undergoing Orchiectomy. A multimodal approach is recommended to optimize perioperative pain control in animals, although opioid use in horses remains limited due to the risks of central nervous system (CNS) stimulation and reduced intestinal motility. A group of 19 healthy, male, mixed-breed horses were divided into two groups and medicated with acepromazine (0.05 mg kg) and detomidine (10 µg kg), with methadone (0.05 mg kg) (ADM) or saline (ADS) administered intravenously (IV). Physiological variables, intestinal motility, gastric distention, and facial pain (EQUUS-FAP) were evaluated one day before (DB), before th...
The effect of cervical epidural injection of morphine and the combination of morphine and detomidine on recovery from anesthesia in adult horses. To evaluate the effect of cervical epidural injection of morphine alone and morphine in combination with detomidine on recovery from anesthesia in horses. Methods: Blinded, randomized, crossover, Latin square design. Methods: A group of six healthy adult horses aged 9 ± 3 years and weighing 471 ± 76 kg (mean ± standard deviation). Methods: Horses were administered each of three treatments during a 1 hour general anesthetic with a 4 day washout period. Treatments were: 1) cervical epidural injection of saline 0.011 mL kg (S); 2) morphine 0.1 mg kg (M); and 3) morphine 0.1 mg kg with detomidi...
Surgical Assessment and Post-Operative Complications Following Video-Assisted Thoracoscopic Surgery (VATS) of Horses with Severe Equine Pasture Asthma During Asthma Exacerbation and Remission. The aim of this retrospective clinical study was to assess surgical duration and surgical and post-operative complications associated with Video-Assisted Thoracoscopic Surgery (VATS) and lung biopsy in horses with severe Equine Pasture Asthma (EPA) and paired control horses. Twelve horses (6 EPA-affected, 6 control) were sex, age and breed matched. Twenty-four thoracic surgeries were performed. Surgery of each matched pair (EPA-affected and healthy) was performed during asthma exacerbation (summer) and remission (winter). Surgical times were shorter with uncomplicated thoracoscopy (85 min) and...
An Ultrasound-Guided Thoracolumbar Erector Spinae Plane Block: An Experimental Preliminary Study in Horses. The objective of this study was to evaluate the feasibility and efficacy of the ultrasound-guided thoracolumbar erector spinae plane (TL-ESP) block in standing horses. A total of 24 injections ( = 12) were performed at the L1 level using either 0.1 mL/kg of saline solution (SS group) or 2% lidocaine (LID group). The block feasibility was assessed based on needle visualization and injection time, while efficacy was evaluated through craniocaudal and dorsoventral (DV) spread using the pinprick technique over 270 min. Desensitization was observed at least once in 100% of horses in the LID group a...
Description and Complications of a New Modified Semi-Closed Castration Technique in Horses. Castration remains a common surgical procedure in equids, yet postoperative complications such as hemorrhage, infection, and eventration persist, influencing surgical outcomes. This retrospective study introduced a novel modified semi-closed castration technique aimed at minimizing these complications. Eighty-five sexually intact mature male equids (including horses, ponies, and donkeys) underwent the described inguinal castration procedure under general anesthesia. The technique involved a carefully managed opening and subsequent secure closure of the parietal vaginal tunic, enabling direct i...
Sedative effects of detomidine and midazolam combination in horses. The combination of detomidine and midazolam may provide safer sedation with muscle-relaxant effects, which are particularly necessary during standing procedures. Unassigned: Thus, the objective of this study was to evaluate the sedative and muscle-relaxant effects of the detomidine/midazolam combination in horses through a pharmacodynamic study. Unassigned: Five horses were used and subjected to four experimental protocols: 15 µg/kg of detomidine (D15); a combination of detomidine (15 µg/kg) with 25 µg/kg (DM25), 50 µg/kg (DM50), or 75 µg/kg (DM75) of midazolam administered intravenously....
Pregabalin contributes to increased recovery time from isoflurane anaesthesia for magnetic resonance imaging in horses. Pregabalin reduces excitatory neurotransmitter release and is used for anxiolysis in humans, cats, and horses. The effects of pregabalin on equine recovery following isoflurane anaesthesia are unknown. Objective: To determine if pre-anaesthetic oral pregabalin influences recovery time and/or quality from isoflurane anaesthesia in horses undergoing elective magnetic resonance imaging (MRI) of the appendicular skeleton. Methods: Retrospective cohort study. Methods: Anaesthetic and recovery data from 52 healthy horses in which pregabalin (PG) was administered and 76 control horses (CG) undergoing...
Equine skin grafting using the punch graft technique. This tutorial aims to illustrate and instruct on the technique of punch skin grafting in the horse. Unassigned: A 10-year-old paint gelding with a 9 X 6-cm chronic granulating wound to the left forelimb was utilized for this tutorial. Unassigned: The chronic wound was debrided with sharp dissection, and the limb was pressure bandaged overnight. Twenty-four hours later, the horse was sedated for punch skin grafting. The ventral pectoral region was aseptically prepared for skin harvest and locally anesthetized. An 8-mm biopsy punch was used to harvest the grafts. The subcutaneous tissue was then...
A comparison of a transdermal eutectic lidocaine/prilocaine cream and subcutaneous lidocaine injection prior to jugular vein catheterization in horses: a randomized crossover study. To compare horses' aversive behavioural responses to the application of 5% prilocaine/lidocaine eutectic mixture of local anaesthetics (EMLA) cream versus subcutaneous infiltration of 2% lidocaine, followed by jugular vein catheterization. Methods: Blinded, randomized study. Methods: A group of 26 university-owned research horses. Methods: Each horse received both treatments at opposite jugular sites with ≥ 12 hours between procedures. One randomly assigned jugular site received 1 g cm of 5% EMLA cream 60 minutes before catheterization, while the contralateral site received 1.5 mL of 2% lido...
Haemoglobin concentration measurement agreement obtained from three different devices in anaesthetised horses. Accurate measurement of haemoglobin concentration is crucial for monitoring the oxygen-carrying capacity in anaesthetised horses. This prospective study aimed to determine the agreement in haemoglobin concentration in anaesthetised horses using the SpHb pulse co-oximeter, an Epoc® blood gas analyser, and values derived from packed cell volume (PCV), which served as the reference method in this study. The study included 34 horses undergoing elective surgeries. Blood samples were collected from each horse and divided for analysis using the microhaematocrit method to estimate haemoglobin concent...
Donkey and Hybrid Anaesthetic Mortality in an Observational, Prospective, Multicentre Cohort Study. Equid anaesthetic mortality is of interest to practitioners. Data for donkey and hybrid mortality have not been specifically described. The main aim of this worldwide observational, prospective, multicentre cohort study was to report on mortality in the 7 days following a general anaesthetic or standing sedation in donkeys and hybrids. This study hypothesised that donkeys and hybrids would have higher mortalities compared to horses. Data were collected as part of the fourth Confidential Enquiry into Perioperative Equine Fatalities (CEPEF4). A total of 825 cases were included, with 757 donkeys ...
Comparison of early and late time-controlled adaptive ventilation on pulmonary gas exchange in anesthetized horses. To compare early versus late time-controlled adaptive ventilation (TCAV) for setting airway pressure release ventilation (APRV) on arterial oxygenation in dorsally recumbent anesthetized horses. Methods: A crossover, nonrandomized, experimental study. Methods: Six healthy adult horses. Methods: Each horse underwent two anesthetics: 1) volume-controlled ventilation (VCV) began for 30 minutes before switching to APRV using the TCAV method (late TCAV, TCAV); and 2) ventilation began immediately with TCAV (early TCAV, TCAV). The study lasted 180 minutes, with arterial blood gases and respiratory m...
Prevalence of musculoskeletal injuries associated with lameness in Australian campdraft horses. Campdrafting is a unique Australian cow horse sport, which evolved from mustering cattle and is one of Australia's fastest growing equine sports. This discipline is associated with its own unique set of musculoskeletal injuries yet to be reported. Objective: To describe the prevalence, anatomical location, and diagnostic modality used to localise lameness in campdrafting horses to better assist efficient orthopaedic management of the campdraft horse. Methods: Retrospective case series. Methods: Medical records were examined from one private practice equine group and one university veterinary h...
The Confidential Enquiry into Perioperative Equine Fatalities: phase 4 (CEPEF4) – a worldwide observational, prospective, multicentre cohort study in 2025. To report on the Confidential Enquiry into Perioperative Equine Fatalities 4 (CEPEF4). Methods: Confidential, observational, prospective, multicentre, cohort study. Methods: 47,396 horses/ponies undergoing general anaesthesia (GA). Methods: Characteristics of each GA (249 variables) were collected. Outcomes after seven days were ALIVE (or discharged), EUTHANASIA or DEAD. Logistic regression analysed patient demographics and the anaesthetic drugs (p < 0.05). Results: Data were collected from 47,396 GAs in 93 centres in 28 countries. Death rates were 1.2% overall, 0.6% for cases classified as NO...
[Sonographic diagnosis of lingual abscess formation in 2 horses with feeding difficulties]. Feeding disorders in horses may have various underlying causes. A thorough clinical examination of the oral cavity is essential for clarification and is often supplemented by imaging techniques such as oral endoscopy, radiography, and computed tomography (CT) of the head. Sonographic examinations of the head and oral cavity are less commonly described diagnostic methods for the investigation of feeding disorders. This case report describes 2 horses presented to the clinic due to impaired feed intake. In both cases the radiographic examination of the head did not reveal any abnormalities relate...
The Suitability of Dried Blood Spot Sampling for Pharmacokinetic Studies in Veterinary Medicine. Dried blood spot (DBS) sampling has emerged as a promising microsampling technique in biomedical and clinical research, offering advantages such as reduced invasiveness, minimal blood volume requirements, and enhanced analyte stability. Although well established in human medicine for neonatal screening and diagnostic applications, its potential in veterinary pharmacology remains underexplored. This study investigated the feasibility of using DBS samples to quantify anesthetic agents-ketamine and medetomidine in cats and lidocaine in horses-during routine surgical procedures at a veterinary tea...
How to perform abdominocentesis and interpret abdominal fluid in equine patients. To describe and demonstrate the collection of abdominal fluid from a standing, sedated equine patient. Unassigned: 1 healthy university-owned animal was used for abdominocentesis demonstration. Images from various clinical cases from the University of Illinois Veterinary Teaching Hospital are shown. Unassigned: Under standing sedation, a 10 X 10-cm area is clipped and aseptically prepared on the most dependent portion of the abdomen to the right of midline. One to 2 mL of 2% lidocaine is instilled subcutaneously and into the abdominal musculature at the abdominocentesis site. A stab incision i...
Surgical technique, outcome, complications, and recurrence rate for removal of extensive perianal melanomas: 50 treated horses. To describe surgical treatment and outcome for horses with extensive perianal melanomas. Unassigned: Gray horses treated surgically for extensive perianal melanoma between July 1, 2020, and July 31, 2023, were eligible. Horses without the entire perianal skin covered with coalescing or ulcerating melanomas were excluded. Unassigned: 59 horses (30 mares, 27 geldings, and 2 stallions) met the inclusion criteria. Median age was 16 years (range, 7 to 28 years). Clinical signs included tenesmus (n = 53), weight loss (3), and hind limb lameness (1). Six horses presented with no complaints; in these ...
Sixty years of equine anaesthesia – are we getting better at it? To present the essence of the presentation 'CEPEF - what we knew then and what we know now' given at the autumn meeting of the Association of Veterinary Anaesthetists in 2024, celebrating its 60th anniversary. Methods: (this is not a formal systematic review). PubMed, Scopus, Google Scholar and the 4th Confidential Enquiry into Equine Perioperative Fatalities (CEPEF4). Search terms used: horse; pony; equine; anaesthesia; anesthesia; recovery; morbidity and mortality. Conclusions: It is well recognized that general anaesthesia carries a greater risk of mortality in horses than in other domestic...
Allele Frequencies and Genotypes for the Ryanodine Receptor 1 Variant Causing Malignant Hyperthermia and Fatal Rhabdomyolysis With Hyperthermia in Horses. Fatal anesthesia-induced malignant hyperthermia (MH) and rhabdomyolysis with hyperthermia documented in Quarter Horses (QH) breeds are caused by a missense variant in the ryanodine receptor 1 gene (RYR1: XP_023505430.1.:p.(R2454G), designated as MH). The reported cases to date have all been heterozygous, and the allele frequency is suspected to be low. Objective: To determine an accurate estimate of MH allele frequency in multiple horse breeds and investigate whether homozygous animals exist in the population. Methods: In total, 159 227 horses from 16 breeds who were either submitted for cli...
Acute changes in serum iron concentrations in anesthetized healthy horses. To determine if serum iron concentrations decrease acutely during and after general anesthesia in healthy horses. Methods: Prospective experimental study. Methods: A convenience sample of 24 healthy adult horses (eight females, 16 geldings), weighing 545 ± 33 kg (mean ± standard deviation). Methods: Horses were anesthetized for 120 minutes with isoflurane, after premedication with intravenous (IV) xylazine (0.8 mg kg-1) and induction with IV midazolam (0.1 mg kg-1) and ketamine (2.2 mg kg-1). Blood samples for serum iron analysis were obtained just before premedication (baseline), after 60 m...
Survey on outcomes of emergency standing caesarean section in equids. Standing caesarian section (C-section) in mares is poorly documented in the literature. It is reportedly straightforward to perform for veterinarians experienced in bovine practice and is more accessible and less expensive than recumbent techniques. The study aimed to create a survey to report the outcomes of in field C-section through a flank laparotomy with the mare standing under sedation. Unassigned: A survey was developed for field veterinarians practicing standing C-sections. Data were collected regarding the veterinarian's experience and practice type, details about the mare and the rea...
The effect of 0.5 mL mepivacaine administered as an abaxial sesamoid nerve block on lameness of horses with digital pain did not differ significantly from that of 2.5 mL of mepivacaine. To compare the effect of 2.5 mL 2% mepivacaine to the effect of 0.5 mL 2% mepivacaine administered over each palmar digital nerve, as an abaxial sesamoid nerve block (ASNB), to 6 horses lame because of naturally occurring digital pain. Unassigned: In a crossover study design with 3 horses in each group, the trotting gait of the horses was analyzed with an inertial sensor-based, motion-analysis system (Q with Lameness Locator; Equinosis LLC) immediately before and after treatment with either 0.5 or 2.5 mL mepivacaine administered over each nerve near the base of the proximal sesamoid bone of th...
Sublingual microcirculation in isoflurane-anesthetized horses receiving dexmedetomidine and lidocaine constant rate infusion. To assess the sublingual microcirculation in horses anesthetized with isoflurane and undergoing constant rate infusion of dexmedetomidine (DEX) and lidocaine (LID). Unassigned: 16 horses undergoing arthroscopy were included in a blind, randomized study comparing 2 groups: a DEX group (DEX-LID; 1.75 μg·kg-1·h-1 with a LID bolus of 1.3 mg·kg-1 followed by a continuous infusion of 0.05 mg·kg-1·min-1) and a LID-only group (LID; at the same dose). Hemodynamic variables, including mean, systolic, and diastolic blood pressure; heart rate; capnography; blood gas analysis; blood lactate; and orth...
Use of the rectus sheath block for perioperative analgesia in three foals undergoing omphalectomy and cystoplasty. Locoregional techniques promote multimodal analgesia and may reduce general anaesthetic requirements. However, there is limited evidence in foals. The rectus sheath block (RSB) is an interfascial plane block previously described in other species such as dogs, cats, pigs, and calves, and recently in foals, which targets desensitization of ventral abdominal midline. This block may provide an efficacious analgesic alternative for ventral celiotomies and umbilical surgeries. This case series reports the use of a bilateral RSB with 0.25-0.3 mL kg-1 bupivacaine (maximum dose of 2 mg kg-1) per hemiab...
Incidence of complications from perioperative urinary catheterisation in horses. Catheterisation of the urinary bladder is a common procedure during perioperative care of horses. Benefits of urinary catheters include a reduction in the risk of recovery-associated slip hazards as a consequence of voided urine and the measurement of urine output during anaesthesia. However, there is little information regarding the risks associated with this procedure. A retrospective cohort study was undertaken in horses admitted to a university teaching hospital for surgery during which a urinary catheter was placed perioperatively. Data were retrieved from clinical records including signa...