Anaesthesia In Horses Research Articles

The use of an air-inflated pillow for assisted recovery after general anaesthesia in horses

The use of an air-inflated pillow for assisted recovery after general anaesthesia in horses

The use of pedometers for objective scoring of recovery from general anaesthesia in horses

The use of pedometers for objective scoring of recovery from general anaesthesia in horses

An Explorative Anatomical Study on Inter-Individual Variation of the Tibial Nerve and Landmarks for Perineural Anesthesia in Horses.

Perineural anesthesia of the tibial nerve can be performed ultrasound-guided or blindly, with the latter still being commonly used in equine practice due to practical constraints, despite its lower accuracy and hence, common failure to achieve desensitization. This may be associated with anatomical variations or inadequate landmarks for injection. To examine the course of the tibial nerve, document potential anatomical variations, and determine optimal landmarks for perineural injection, dissection was conducted along the medial aspect of the tibia in 10 paired cadaver hindlimbs. No anatomical variations of the tibial nerve were observed. Mean tibial nerve thickness was 6 ± 1 mm. The junction with the plantar nerves was located at a maximum of 85 mm and the junction with the medial cutaneous branch was at a maximum of 150 mm proximal to the proximal aspect of the calcaneal tubercle. The mean distance of the tibial nerve to the cranial border of the superficial digital flexor was 11 ± 6 mm. In conclusion, problems with perineural anesthesia of the tibial nerve cannot simply be attributed to anatomical variations. The thickness of the nerve and the amount of perineural tissue may present specific challenges for achieving adequate desensitization. Our results support the generally recommended site for tibial nerve perineural injection at 100 mm proximal to the calcaneal tubercle and 11 mm cranial to the superficial digital flexor.

Clinical and Hematological Effect of Constant Rate Infusion of Ketamine Alone and Ketamine-dexmedetomidine Combination on Isoflurane Anesthesia in Horses

Background: Anaesthetic management of horses for a successful surgery is of utmost importance but a risky procedure than other companion animals. Peri-aneasthetic morbidity and mortality in horses could be alarming if proper combinations of drugs were not used. Balanced anaesthetic combinations are being explored by various authors to find safer combinations.Therefore current study was planned to evaluate the effect of CRI of ketamine alone and ketamine-dexmedetomidine combination for isoflurane anesthesia in horses. Methods: Twenty four clinical cases of horses were randomly divided into three groups S, D and DK, having eight animals in each. Xylazine (1 mg/kg) and butorphanol (0.05 mg/kg) were given intravenously for premedication and ketamine (2 mg/kg) and midazolam (0.2 mg/kg) were used for induction of anesthesia. Normal saline (1000 ml/hour), ketamine alone (2 mg/kg/hr), ketamine (2 mg/kg/hr) and dexmedetomidine (2 µg/kg/hr) combination were given as CRI in groups S, K and KD, respectively. Thiopentone sodium (200 mg bolus, 5%) was given as fast intravenous to facilitate endotracheal intubation in some of the cases. Anesthesia was maintained with isoflurane in oxygen and anesthetic efficacy was evaluated based on clinical and haematological parameters. Result: Overall quality of sedation, muscle relaxation, response to surgical stimuli, quality of intubation, anesthetic depth and quality of recovery was significantly (p less than 0.05) better in group KD. Down-time (min) and duration of anesthesia were non significantly less in group KD. CRI of ketamine and dexmedetomidine combination was having significant (p less than 0.05) thiopentone sodium and isoflurane sparing effect. Heart rateand RR, did not show any significant variation among groups but rectal temperature was significantly low in KD group than groups S and K. CRI of ketamine-Dexmedetomidine combination produced a better quality of anesthesia and significant thiopentone sodium and isoflurane sparing effect thus was found suitable for anesthesia of horses.

A newly developed recovery-enhancing device improves recovery scores during emergence from general anesthesia in horses: a randomized trial.

To compare the quality of recovery in horses emerging from general anesthesia with or without the assistance of a novel device (recovery-enhancing device [RED]) designed to minimize high-energy falls. 20 mixed-breed horses, between July 1, 2023, and January 24, 2024. A computer-controlled belay system designed to slow the acceleration of a horse during a fall was evaluated in this study. Horses were randomly assigned to 1 of 2 treatment groups: RED (belay, assisted) or FREE (unassisted). An inertia-measuring unit was fitted to all horses and data were live streamed and recorded onto a computer for further analysis. Recoveries were scored using the composite grading scale (CGS; 0 to 100) by 3 independent observers. Two additional unitless recovery scores (RS and RS'), based on accelerometry values (high accelerations, less desirable), were calculated for each recovery. All the recovery scores were compared between the 2 treatment groups. Composite grading scale scores were 26 ± 10 and 46 ± 13 in the RED and FREE groups, respectively (P = .001). The RS was 120 ± 79 and 198 ± 34 for the RED and FREE treatment groups, respectively (P = .015). The RS' was 32 (7 to 50) and 46 (28 to 44) for the RED and FREE treatment groups, respectively (P = .038). The RED improves the recovery scores compared with unassisted recoveries. This device may lead to a potential reduction in the number and severity of injuries in horses and personnel involved during the recovery period.

Effect of hospitalization on equine local intestinal immunoglobulin A (IgA) concentration measured in feces

During hospitalization horses may develop gastrointestinal conditions triggered by a stress-associated weak local immune system. The prospective, clinical trial was conducted to find out whether fecal immunoglobulin A (IgA) concentrations could be determined in hospitalized horses and how they changed during hospitalization and in response to various stressors. Samples were obtained from 110 horses and a control group (n = 14). At arrival in the hospital, horses were categorized into pain grades (1-5), and elective versus strenuous surgery (> 2 hours, traumatic and emergency procedures). Feces were collected on day 1, day 2, day 3, and day 7 in all horses. Blood samples were obtained at the same intervals, but additionally after general anaesthesia in horses undergoing surgery (day 2). IgA concentration in feces was determined by ELISA and measured in optical density at 450nm. The control group showed constant IgA concentrations on all days (mean value 0.30 OD450 ±SD 0.11, 1.26 mg/g; n = 11). After general anaesthesia fecal IgA concentrations decreased considerably independent of duration and type of surgery (P < 0.001 for elective and P = 0.043 for traumatic surgeries). High plasma cortisol concentrations were weakly correlated with low fecal IgA on the day after surgery (P = 0.012, day 3, correlation coefficient r = 0.113). Equine fecal IgA concentrations showed a decline associated with transport, surgery, and hospitalization in general, indicating that stress has an impact on the local intestinal immune function and may predispose horses for developing gastrointestinal diseases such as enterocolitis.

Comparison of two different doses of xylazine and ketamine versus medetomidine for partial intravenous anaesthesia in horses

Thirty horses were randomly divided into three groups and sedated with xylazine (1.1 mg/kg). General anaesthesia was induced with diazepam (0.03 mg/kg) and ketamine (2.5 mg/kg). Partial intravenous anaesthesia was maintained with isoflurane and constant rate infusion (CRI) consisting of xylazine 0.33 mg/kg/h and ketamine 1.5 mg/kg/h (X+K); or, higher dose of xylazine 1.2 mg/kg/h and ketamine 3.6 mg/kg/h (XX+KK); or, medetomidine 3.5 μg/kg/h (MED). Horses in each group breathed spontaneously. Heart rate, respiratory rate, peripheral oxygen saturation, palpebral and corneal reflexes, rescue doses with ketamine, invasive arterial blood pressure, inspired and expired gas compositions were measured. Anaesthesia, surgery, and recoveries were timed, and recovery was scored. The xylazine with ketamine groups showed a higher respiratory rate, a significant decrease in consumption of isoflurane, and a shorter time to standing in comparison with the medetomidine group. Recovery of the lowest quality was observed in group MED and a significantly improved recovery was observed in group X+K. The CRI consisting of xylazine with ketamine was shown to be a suitable alternative to CRI with medetomidine in horses undergoing arthroscopy.

Pharmacokinetics of dexmedetomidine in anaesthetized horses following repeated subcutaneous administration and intravenous constant rate infusion

BackgroundThe inclusion of dexmedetomidine (DEX) within a balanced general anaesthesia protocol is effective in improving the clinical outcome and recovery quality of anaesthesia in horses. This study aimed to determine the pharmacokinetic profile of DEX following repeated subcutaneous (SC) administration at 2 µg/kg every 60 min till the end of the procedure in comparison to intravenous constant rate infusion (CRI) at 1 µg/kg/h in anaesthetized horses undergoing diagnostic procedures up to the end of the diagnostic procedure.ResultsIn the CRI and SC groups DEX maximum concentrations (Cmax) were 0.83 ± 0.27 ng/mL and 1.14 ± 0.71 ng/mL, respectively, reached at a time (Tmax) of 57.0 ± 13.4 min and 105.5 ± 29.9 min. Mean residence time to the last measurable concentration (MRTlast) was 11.7 ± 6.2 and 55.8 ± 19.7 min for the CRI group and SC groups, respectively. The apparent elimination half-life was 18.0 ± 10.0 min in the CRI group and 94.8 ± 69.8 min for the SC group, whereas the area under the curve (AUC0-last) resulted 67.7 ± 29.3 and 83.2 ± 60.5 min*ng/mL for CRI and SC group, respectively. Clearance was 16.26 ± 8.07 mL/min/kg for the CRI group. No signs of adverse effects were recorded in both groups.ConclusionsThe pharmacokinetic profile of DEX following repeated SC administration in anaesthetized horses was comparable to intravenous CRI administration during the intranaesthetic period and beneficial during the recovery phase from general anaesthesia. The SC route could be considered as an alternative to CRI for improving the recovery quality of equine patients undergoing general anaesthesia.

Influence of hypoxaemia, hypotension and hypercapnia (among other factors) on quality of recovery from general anaesthesia in horses

Influence of hypoxaemia, hypotension and hypercapnia (among other factors) on quality of recovery from general anaesthesia in horses

Remifentanil constant rate infusion combined with sevoflurane- medetomidine anesthesia in horses

Remifentanil constant rate infusion combined with sevoflurane- medetomidine anesthesia in horses

The influence of hypoxaemia, hypotension and hypercapnia (among other factors) on quality of recovery from general anaesthesia in horses

ObjectiveTo investigate the effect of hypoxaemia, hypotension and hypercapnia, among others, on quality of recovery from general anaesthesia in horses. Study designRetrospective, single-centre study. AnimalsA sample of 1226 horses that underwent general anaesthesia between June 2017 and June 2021. MethodsHorses and ponies weighing > 200 kg, aged > 6 months, anaesthetized using a xylazine- or medetomidine-isoflurane balanced anaesthesia protocol and presenting a complete anaesthetic record were included. Data were extracted from the clinic record system and from the original anaesthesia records. Recoveries were divided into ‘good’ and ‘bad’ based on the available recovery scores. Influence of hypoxaemia [PaO2 < 60 mmHg (7.99 kPa)], hypotension (mean arterial pressure < 70 mmHg for at least 15 minutes) and hypercapnia [PaCO2 > 60 mmHg (7.99 kPa)], anaesthesia protocol, body weight, age, breed, sex, American Society of Anesthesiologists status, type of procedure, emergency or nonemergency, duration of anaesthesia, positioning, times spent in lateral and sternal recumbency during recovery, time until standing and nonassisted or assisted recovery on the assigned recovery score (good/bad) were investigated using generalized linear regression analysis (p < 0.05). ResultsHypoxaemia and prolonged duration of anaesthesia were significantly associated with a bad recovery score. No other factors had a significant influence on recovery quality. Conclusion and clinical relevanceHypoxaemia and prolonged anaesthesia duration have a negative effect on quality of anaesthetic recovery in horses. Clinically, this highlights the importance of keeping anaesthetic time as short as possible and to monitor oxygenation and treat hypoxaemia as soon as possible.

Metaraminol en la reversión de la hipotensión en anestesia equina con isoflurano y dexmedetomidina: Reporte de caso

Systemic hypotension is the most frequent complication of inhalational anesthesia in horses and is directly related to increased post-anesthetic morbidity and mortality. The treatment of hypotension depends on the physiological cause and can be performed with positive chronotropic, inotropic and vasopressor drugs, individually or combined. However, there are few drugs used in horses and the effects of these drugs on cardiovascular support in these animals during anesthesia are poorly described. For this reason, this study aimed to report the action of metaraminol (Aramin®), a vasopressor with direct and indirect action on adrenergic receptors, in the correction of hypotension in a horse submitted to elective orchiectomy, anesthetized with isoflurane and continuous infusion of dexmedetomidine. Cardiovascular changes with different infusion rates of 1, 2 and 4 µg/kg/min are described. Metaraminol reversed hypotension at a rate of 4 µg/kg/min, increasing systolic blood pressure by 93 mmHg, mean blood pressure by 74 mmHg, diastolic blood pressure by 66 mmHg, and reduced cardiac output by 7.1 L/min and heart rate to 32 bpm, in relation to mean arterial pressure of 58 mmHg, cardiac output of 13.4 L/min and heart rate of 36 bpm at the expired rate of 1.3% isoflurane. Furthermore, it improved cardiac contractility at the rate of 2 and 4 µg/kg/min and did not cause arrhythmia at any infusion rates.

The effect of halogen-containing anesthetics on the indicators of the gas composition of the blood of horses

The aim of the work was to determine the parameters of the gas composition and acidbase state (CBS) of blood to assess the adequacy of general anesthesia of horses with halogen-containing anesthetics in clinical and instrumental studies. The object of the study was 18 horses aged four to six years, which were castrated. The paper compared the dynamics of blood gas composition indicators at various stages of inhalation anesthesia with fluorotane, isoflurane and sevoflurane in order to prevent and timely detect hypoxemia and hypercapnia in horses. Based on a comprehensive assessment of the clinical examination data, laboratory studies of the gas composition of arterial blood, objectively determine the severity of hypoxemia and hypercapnia, which made it possible to provide the necessary assistance to the animal in a timely manner. The study of blood gas composition indicators has established that the amount of carbon dioxide tension in arterial blood (РaСO2) with both types of anesthesia is subject to the greatest changes during induction and during awakening. During the induction period, it increased both with the inhalation of fluorotane and with the use of isoflurane and sevoflurane, respectively, by 41%, 3.1% and 3.4% compared to the initial values. During the period of awakening, the value of РaСO2 returned to the initial level with anesthesia with isoflurane, with anesthesia with sevoflurane and fluorotane remained above the initial values by 21.8% and 42.8%, respectively. Early detection of signs of hypoxemia and hypercapnia made it possible to avoid the development of further complications during general anesthesia in horses

Influence of acupuncture on recovery quality in isoflurane-anesthetized horses

Introduction: The objective was to evaluate the effect of acupuncture at GV26 and Wei Jian (WJ) on the recovery from inhalant anesthesia in horses.

Standing oral surgery for the management of mandible and maxilla fractures in horses: a case series of 15 horses

Fractures of the mandible and maxilla are common in horses. The present study was conducted on fifteen horses referred for the management of mandible or maxilla fractures. Fixation methods were used to repair the fractures in these horses, including tension band and cerclage wires, dynamic compression plates, and lag screw fixation. All procedures were performed under chemical restraint and regional nerve block anesthesia in the standing position. According to the results, the long term follow-up of the horses was satisfactory, and no severe complications were observed. Jaw fractures are most successfully treated by early diagnosis and fracture fixation. The surgical management of most oral region injuries may be readily performed in the standing position, to avoid the risks associated with general anesthesia in horses.

Effects of detomidine or romifidine during maintenance and recovery from isoflurane anaesthesia in horses

ObjectiveTo evaluate the effects of detomidine or romifidine on cardiovascular function, isoflurane requirements and recovery quality in horses undergoing isoflurane anaesthesia. Study designProspective, randomized, blinded, clinical study. AnimalsA total of 63 healthy horses undergoing elective surgery during general anaesthesia. MethodsHorses were randomly allocated to three groups of 21 animals each. In group R, horses were given romifidine intravenously (IV) for premedication (80 μg kg–1), maintenance (40 μg kg–1 hour–1) and before recovery (20 μg kg–1). In group D2.5, horses were given detomidine IV for premedication (15 μg kg–1), maintenance (5 μg kg–1 hour–1) and before recovery (2.5 μg kg–1). In group D5, horses were given the same doses of detomidine IV for premedication and maintenance but 5 μg kg–1 prior to recovery. Premedication was combined with morphine IV (0.1 mg kg–1) in all groups. Cardiovascular and blood gas variables, expired fraction of isoflurane (Fe′Iso), dobutamine or ketamine requirements, recovery times, recovery events scores (from sternal to standing position) and visual analogue scale (VAS) were compared between groups using either anova followed by Tukey, Kruskal-Wallis followed by Bonferroni or chi-square tests, as appropriate (p < 0.05). ResultsNo significant differences were observed between groups for Fe′Iso, dobutamine or ketamine requirements and recovery times. Cardiovascular and blood gas measurements remained within physiological ranges for all groups. Group D5 horses had significantly worse scores for balance and coordination (p = 0.002), overall impression (p = 0.021) and final score (p = 0.008) than group R horses and significantly worse mean scores for VAS than the other groups (p = 0.002). Conclusions and clinical relevanceDetomidine or romifidine constant rate infusion provided similar conditions for maintenance of anaesthesia. Higher doses of detomidine at the end of anaesthesia might decrease the recovery quality.

Use of dexmedetomidine repeated subcutaneous administration for balanced anaesthesia in horses

BackgroundA balanced anaesthetic protocol is a common concept in modern veterinary anaesthesia and aims to maintain good intraoperative cardiopulmonary function. In horses, alpha-2-agonists produce sedation and analgesia and have been shown to reduce inhalational anaesthetic requirements when administered intravenously. Furthermore, these drugs can improve recovery quality. Preliminary investigations of subcutaneous dexmedetomidine administration in humans demonstrated a reduced haemodynamic impact if compared with the intravenous route suggesting that dexmedetomidine is adequately absorbed with both administration routes. The aim of the study was to compare two different dexmedetomidine (DEX) administration routes: intravenous constant rate infusion (CRI) versus repeated subcutaneous (SC) injections on cardiopulmonary function and recovery in anaesthetized horses.ResultsNo significant differences between groups in heart rate and systolic arterial pressure were detected. A significantly higher mean and diastolic arterial pressure were detected in the SC group at T25 (p = 0.04; p = 0.02), T75 (p = 0.02; p = 0.009), and T85 (p = 0.001; p = 0.005). In SC group there was a significantly lower dobutamine infusion rate (p = 0.03) and a significantly higher urinary output (p = 0.02). Moreover, recovery quality was higher (p = 0.01).ConclusionsCardiopulmonary effects in both groups were comparable and within clinical ranges with less dobutamine requirement in the subcutaneous group. Recovery was of better quality with fewer attempts in horses receiving subcutaneous dexmedetomidine. The present study suggests that intravenous constant rate infusion and subcutaneous repeated administration of dexmedetomidine at indicated dosage can be useful in balanced anaesthesia without any systemic or local adverse effects; moreover, in healthy horses undergoing general anaesthesia, repeated subcutaneous dexmedetomidine administration may be a suitable alternative if constant rate infusion is not feasible.

Effect of Constant Rate Infusion of Different Anaesthetic Adjuvants Undergoing Thiopentone Sodium Total Intravenous Anaesthesia in Horses

Background: Co-administration of anesthetic adjuvants as continuous rate infusion (CRI) can be controlled and hence is considered safer, as it can reduce the cardiopulmonary alterations in horses and is also adaptable in field conditions. Hence this study was planned to evaluate the effect of CRI of dexmedetomidine, ketamine, butorphanol and midazolam during thiopentone TIVA in horses. Methods: Thirty horses were randomly divided into five groups S, D, K, B and M having six animals in each. Premedication was done with Xylazine (1 mg/kg) and butorphanol (0.05 mg/kg) intravenously. Ketamine (2 mg/kg) and midazolam (0.2 mg/kg) were used IV for induction. CRI of normal saline alone, dexmedetomidine @ 2 µg/kg/hr., butorphanol @ 0.2 mg/kg/hr., midazolam @ 0.2 mg/kg/hr. and ketamine @ 2 mg/kg/hr. were administered in groups S, D, B, M and K, respectively. Thiopentone sodium (5%) was given as a fast intravenous bolus whenever required to provide adequate anesthesia. Depth of anesthesia was evaluated on the based on clinical, haemato-biochemical, hemodynamic and endocrine variables. Result: First head lift, sternal recumbency time, standing time and quality of recovery showed no significant difference between the groups. Heart rate, RR, RT, SBP, DBP, CVP and MAP, BUN, creatinine, ALT, AST, cortisol, ACTH and ghrelin did not show significant variation among groups. Hb, PCV, TLC, TEC and neutrophil found significantly decreased and blood glucose remained significantly higher than the baseline value in all groups post induction. CRI of ketamine produced a better quality of recovery and thiopentone sparing effect and was found suitable for moderating stress response to anesthesia, inflammation and metabolic changes in horses administered with TIVA.

The Effect of Inhaled Albuterol on PaO2 in Anesthetized Horses Receiving a FiO2 of 0.5 or >0.95

Impairment of oxygen uptake can occur during general anesthesia in horses resulting in hypoxemia. Multiple treatments have been investigated for correction of hypoxemia with varying levels of success. In clinical trials, albuterol, a short-acting β2 adrenergic agonist, improved arterial oxygen partial pressure (PaO2) in anesthetized horses unresponsive to adjustments in mechanical ventilation and administration of positive inotropic drugs. However, controlled studies comparing the magnitude of change and duration of effect of albuterol on PaO2 in healthy, nonhypoxemic anesthetized horses are lacking. In a prospective study, 14 horses were anesthetized and received a FiO2 of 0.5 (n = 7) or > 0.95 (n = 7). Horses were maintained on isoflurane and mechanically ventilated. After 15 minutes, baseline PaO2 was determined. Within each FiO2 group, five horses were administered inhaled albuterol (2 µg/kg) and two horses received no treatment. At 10, 20, 30, and 40 minutes after baseline, PaO2 was measured. Data for horses that received albuterol were analyzed with repeated measures analysis of variance with significance at P < .05. Horses that received albuterol had an increase in PaO2 for at least 40 minutes after baseline. Albuterol administered via inhalation, was associated with an increased PaO2 of at least 40 minutes compared to baseline in healthy, nonhypoxemic horses undergoing anesthesia at similar depth, using a FiO2 of 0.5 and > 0.95. Side effects were mild and consisted of increased heart rate and sweating. Albuterol administered at 2 μg/kg via inhalation may be useful for increasing PaO2 in anesthetized horses.

An Analysis of Risk Factors for a Fracture or Luxation in Recovery From General Anesthesia in Horses: A Single Centre Study☆

Catastrophic fractures or luxations (FoL) sustained during recovery from general anesthesia are a significant cause of mortality during equine anesthesia. There is a lack of evidence regarding potential risk factors for a FoL occurring in the immediate anesthetic recovery period. A single center, retrospective, case-matched study was performed to identify risk factors for sustaining a catastrophic FoL during recovery from general anesthesia. Clinical data were obtained for horses which sustained a catastrophic FoL when recovering from general anesthesia from January 2011 to June 2020 in a single center referral population. Multivariable logistical regression analysis was performed to identify risk factors which were significant in horses where a FoL occurred. Statistically significant risk factors in our population of horses of sustaining a FoL in recovery included intraoperative administration of intratracheal salbutamol, intraoperative administration of ketamine and increasing age. Further research in this area, particularly with regards to salbutamol administration, is required.