Twenty years later: a single-centre, repeat retrospective analysis of equine perioperative mortality and investigation of recovery quality

A Retrospective Study on Pre- and Intraoperative Predictors on the Recovery Quality of Horses After General Anesthesia

Equine anesthesia is related to high morbidity and mortality rates and recent studies suggested that the period of recovery remains the phase associated with the greatest risk of mortality in horses. Intraoperative hypotension, hypoxemia, and hypercapnia are recognized as potential determinants of recovery quality. This study, conducted at the Equine University Hospital of Liege, aimed to explore how these factors influence recovery outcomes and compare complications between non-emergency and emergency procedures. We analyzed data from 1057 horses, with a mean weight of 498 kg (ranging from 150 to 850 kg) and a mean age of 10.7 (ranging from 0.5 to 37 years), undergoing standardized general anesthesia for non-emergency and emergency procedures to assess which factors influence recovery quality. Recoveries were graded as 'good' or 'bad' and age, sex, breed, American Society of Anesthesiologists (ASA) physical status classification, weight, anesthesia duration, presence of hypotension, hypoxemia, and hypercapnia were compared with a logistic regression analysis. Our findings highlight the multifactorial nature of anesthetic recovery in horses, with breed, age, anesthesia and recovery duration, and emergency status emerging as significant influencing factors. Additionally, monitoring and managing hypoxemia and hypotension remain critical due to their recognized impact on recovery quality. However, despite their clinical relevance, the specific effects of these variables on anesthetic recovery in horses remain insufficiently studied, emphasizing the need for further research to refine perioperative management strategies and improve outcomes.

Effect of an adjustable ceiling to prevent premature rising attempts after general anesthesia in healthy ponies and horses: A pilot study

OBJECTIVE

This study aimed to assess and compare the recovery of ponies and horses following general anesthesia in two different settings: a recovery box with an inflexible, adjustable ceiling, and free recovery without restraints. Our primary objective was to evaluate the effect of adjustable ceilings on the prevention of premature attempts to rise during recovery. The secondary aim was to compare the physiological stress indicators during recovery.

STUDY DESIGN

Prospective, randomized, experimental study.

ANIMALS

Six healthy ponies and 10 healthy horses.

METHODS

This study used a crossover design with two settings: an inflexible, adjustable ceiling and free recovery. Recovery was scored using a quality scoring system. Heart rate, and lactate, glucose, and cortisol levels were analyzed and compared between the animals and recoveries.

RESULTS

All animals had a higher recovery quality (p = .026) with an adjustable ceiling than with free recovery. No differences were observed in glucose level or heart rate between the two settings. However, horses had higher blood lactate, 2.9 ± 1.2 mmol/L versus 1.6 ± 0.7 mmol/L (p = .025), and serum cortisol, 184 ± 81 nmol/L versus 93 ± 20 nmol/L (p = .031) in restricted recovery than free recovery, respectively.

CONCLUSION

An inflexible, adjustable ceiling improved the quality of recovery and prevented premature rising attempts; however, it was associated with increased lactate and cortisol levels, indicating an increased level of stress.

CLINICAL SIGNIFICANCE

Limiting premature rising attempts with an adjustable ceiling during recovery phase has the potential to improve the quality of recovery in horses. Further research is needed to draw conclusions for clinical use.

Effect of Bio-Electro-Magnetic-Energy-Regulation (BEMER) Horse Therapy on Cardiopulmonary Function and Recovery Quality After Isoflurane Anesthesia in 100 Horses Subjected to Pars-Plana Vitrectomy: An Investigator-Blinded Clinical Study

The use of Bio-Electro-Magnetic-Energy-Regulation (BEMER) therapy during general anesthesia has not previously been reported in horses. This randomized, investigator-blinded, placebo-controlled trial evaluates equine cardiopulmonary function and recovery quality after BEMER therapy application for 15 min in 100 horses during general anesthesia using isoflurane for pars-plana vitrectomy surgery as treatment for recurrent uveitis. Visually identical blankets were used in the two groups (1:1 ratio), one with a functional BEMER module and the other with a placebo module. Arterial blood pressure, blood gas, lactate, and creatine kinase (CK) values were measured at different timepoints, and each timepoint was compared between the groups using paired t-tests. The quality of recovery from anesthesia was assessed by one blinded veterinary surgeon using a 10-category scoring system with scores ranging from 10 (best) to 72 (worst) and compared by an ordinary least squares regression analysis. The placebo group had a significantly better recovery (mean 16.1, standard deviation 7.15) than the BEMER-therapy group (mean 22.4, SD 13.0). Arterial blood pressure and blood lactate were lower in the BEMER-therapy group without reaching statistical significance, while CK and blood gas values were comparable. BEMER-horse therapy showed an effect on the recovery quality of horses undergoing general anesthesia.

Evaluation of Recovery Time and Quality After Two Different Post-Operative Doses of Medetomidine in Spanish Purebred Horses Anaesthetized with Medetomidine-Isoflurane Partial Intravenous Anaesthesia

Recovery from general anaesthesia is risky in horses. Alpha2-agonist administration after anaesthesia enhances the quality of recovery but may prolong this phase. Recovery time and quality were investigated after medetomidine administration at the end of general anaesthesia in a prospective, randomised, masked and clinical study. Horses underwent medetomidine-isoflurane partial intravenous anaesthesia. Medetomidine (0.5 or 1 µg/kg) IV was administered just after isoflurane was discontinued. The duration of different recovery phases and the number of attempts were recorded. A composite scale (from 1-excellent to 6-accident) was used for quality assessment. Mann-Whitney U-test was performed (p < 0.05). Twenty-seven horses per group were included. Results for 0.5 and 1 µg/kg groups were as follows: lateral recumbency time: 35 (24-45) and 43 (35-55) minutes; sternal recumbency time: 6 (3-15) and 5 (2-15) minutes; total recovery time: 47 (40-59) and 49 (42-62) minutes; number of attempts to sternal: 1 (1-1) and 1 (1-2) and to standing: 1 (1-3) and 1 (1-2); and, quality: 2 (1-2) and 2 (1-2), respectively. No significant differences between the groups were found. Medetomidine 0.5 µg/kg dose did not decrease the recovery time but maintained the recovery quality.

A review of equine anesthetic induction: Are all equine anesthetic inductions "crash" inductions?

Horses are the most challenging of the common companion animals to anesthetize. Induction of anesthesia in the horse is complicated by the fact that it is accompanied by a transition from a conscious standing position to uncconconscious recumbency. The purpose of this article is to review the literature on induction of anesthesia with a focus on the behavioral and physiologic/pharmacodynamic responses and the actions and interactions of the drugs administered to induce anesthesia in the healthy adult horse with the goal of increasing consistency and predictability.

Risk assessment in equine anesthesia: a first evaluation of the usability, utility and predictivity of the two-part CHARIOT

Introduction

An accurate risk score that can predict peri-anesthetic morbidity and mortality in equine patients could improve peri-operative management, outcome and client communication.

Materials and methods

Three hunded horses underwent pre-anesthetic risk assessment using the American Society of Anesthesiologists-Physical Status augmented with equine-specific diseases (ASA-PS-Equine), a multifactorial 10-part rubric risk scale (10-RS), and a combination of both, the Combined horse anesthetic risk identification and optimization tool (CHARIOT). Intra-and post-anesthetic complications, the recovery phase and mortality were recorded over a period of 7 days following general anesthesia. To compare the utility and predictive power of the 3 scores, data were analyzed using binominal logistic regression (p ≤ 0.05) and receiver operating characteristic curve analysis. In addition, inter-observer reliability, speed, safety, ease of use and face validity of the ASA-PS-Equine and the 10-RS were analyzed based on five hypothetical patients.

Results

All scores showed statistically significant associations with various intra-anesthetic complications and parameters of the recovery phase. The discriminant ability of the scores related to the occurrence of intra-anesthetic (AUC = 0.6093-0.6701) and post-anesthetic (AUC = 0.5373-0.6194) complications was only low. The highest diagnostic accuracy for all scores was observed for overall mortality (AUC = 0.7526-0.7970), with the ASA-PS-Equine differentiating most precisely (AUC = 0.7970; 95% CI 0.7199-0.8741). Inter-observer reliability was fair for the 10-RS (κ = 0.39) and moderate for the ASA-PS-Equine (κ = 0.52). Patient assignment to the CHARIOT was predominantly rated as rather easy and quick or very quick.

Limitations and conclusion

The main limitations of the study are the monocentric study design and failure to obtain the full range of points. In conclusion, all 3 scores provide useful information for predicting the mortality risk of equine patients undergoing general anesthesia, whereas intra-and postoperative complications cannot be predicted with these scores.

Incidence of and risk factors for poor recovery quality in dogs recovering from general anaesthesia-a prospective case control study

OBJECTIVE

To investigate the incidence of and identify risk factors associated with poor quality of recovery in dogs recovering from general anaesthesia.

STUDY DESIGN

Case controlled study.

METHODS

All dogs undergoing general anaesthesia at the University of Liverpool Small Animal Teaching Hospital between January 2020 and January 2021 were eligible for recruitment. Signalment, anaesthetic case management and a recovery score were recorded. Univariable and multivariable logistic and ordinal logistic regression analysis were used to identify factors which impact incidence of poor quality of recovery.

RESULTS

A total of 247 dogs undergoing general anaesthesia were included. Overall, 72 [29.1%; 95% confidence interval (CI) 23.8%-35.1%] dogs experienced a poor quality recovery. Of these, 40 (55.5%) required sedation to manage behaviours associated with poor recovery. Multivariable logistic regression revealed American Society of Anesthesiologists (ASA) physical status classification of III or higher was associated with a decreased incidence of poor quality recovery [odds ratio (OR) = 0.34, 95% CI 0.12-0.93, p = 0.037] and the use of multiple inhalational anaesthetics during one procedure was associated with an increased incidence of poor quality of recovery (OR = 42.5, 95% CI 3.0-598.3, p = 0.005).

CONCLUSIONS AND CLINICAL RELEVANCE

Poor quality recovery is common in dogs recovering from general anaesthesia and sedation is often required for resolution. It is more likely to occur in healthy veterinary patients (ASA I and II). The use of multiple inhalational anaesthetic agents during one procedure should be discouraged as this may increase the likelihood of poor quality of recovery.

Anaesthesia-related morbidity associated with recumbent, low-field magnetic resonance imaging of horses

CASE HISTORY

Medical records from 2009 to 2021 from a private equine referral hospital in Rochester, NH, USA were analysed for cases that underwent general anaesthesia for low-field MRI of the distal limb. These were used to determine peri-anaesthetic morbidity and mortality.

CLINICAL FINDINGS AND OUTCOME

Two hundred and forty-three anaesthetic episodes were recorded in horses undergoing low-field MRI. The peri-anaesthetic complication rate prior to discharge was 6.2% (15/243). No patients experienced a fatal complication. Ninety two of the 243 patients had multiple sites imaged, 90/243 received pre-anaesthetic dantrolene, 134/243 received intra-anaesthetic dobutamine, and 15/243 were positioned in dorsal recumbency. Complications included: abdominal discomfort ("colic"; 9/243), myopathy (4/243), hyphaema (1/243) and carpal fracture (1/243). At the time of discharge, 14/15 complications had resolved. Of 135 horses for which data were available 55 became hypotensive during the procedure (lowest mean arterial pressure < 65 mmHg). Median body weight was 553 (min 363, max 771) kg. Horses were anaesthetised for a median of 150 (min 45, max 210) minutes. There was no evidence of an association between higher body weight (p = 0.051) or longer duration of anaesthesia (p = 0.421) and development of an anaesthetic complication. For categorical variables (dantrolene administration pre-anaesthesia, dobutamine administration during anaesthesia, hypotension (mean < 65 mmHg) during anaesthesia, dorsal vs. lateral recumbency, and imaging of single vs. multiple sites), the 95% CI for the OR included 1, indicating a lack of effect of the variable on the odds of complication.

CLINICAL RELEVANCE

The cases included in this series suggest that low-field MRI under general anaesthesia is a viable option for diagnostic imaging in otherwise healthy horses. Complications occur, but most resolve before discharge.

The Effects of Antimicrobial Protocols and Other Perioperative Factors on Postoperative Complications in Horses Undergoing Celiotomy: A Retrospective Analysis, 2008-2021

Recognition of antimicrobial resistance in equine practice has increased over the past decade. The objective of this study was to provide an updated retrospective review of antimicrobial regimens in one tertiary referral hospital and to evaluate the association with postoperative complications. A secondary objective was to evaluate other perioperative factors including surgical procedure, anesthetic and recovery parameters, and the effect of perioperative medications on complications and outcomes. A computerized search of medical records was performed to identify horses undergoing exploratory celiotomy from 1 January 2008 to 31 December 2021. A total of 742 celiotomies were performed (608 completed, 134 terminated intraoperatively). Factors recorded were evaluated using logistic regression for the presence of either incisional infection, postoperative ileus, or other complications postoperatively. Antimicrobial type or timing (pre-, intra-, or postoperative) were not associated with decreased risk of incisional infection or postoperative ileus; however, the duration of NSAID use was positively associated with incisional infection (OR 1.14 per day). Lidocaine and alpha-2-agonist administration postoperatively were also associated with increased incidence of postoperative ileus (OR 21.5 and 1.56, respectively). Poor recovery quality (OR 4.69), the addition of other antimicrobials besides penicillin/gentamicin postoperatively (OR 3.63), and an increased number of different NSAID classes used (OR 1.46 per additional) were associated with other complications. Implementation of enterotomy was associated with decreased risk of other complications (OR 0.64). These findings provide an updated summary of factors associated with postoperative complications in horses undergoing celiotomy.

Risk of anesthesia-related complications in draft horses: a retrospective, single-center analysis

OBJECTIVE

To report anesthetic-related complications and determine risks associated with anesthesia in draft horses.

STUDY DESIGN

Retrospective study.

ANIMALS

A total of 401 anesthetic records for draft horse breeds that underwent general anesthesia from January 2010 through December 2020 were reviewed; horses euthanized during general anesthesia were excluded.

METHODS

Demographics, perioperative drugs used, procedure type and duration, time to extubation, number of attempts to stand, use of sling in recovery and perioperative morbidity and mortality were investigated. Morbidity and mortality statistical evaluation included univariable logistic regression analysis and ordinal regression analysis.

RESULTS

American Society of Anesthesiologists (ASA) status I-II, ASA III-V and total mortality rate for all cases was 0.69% (2/288), 6.19% (7/113) and 2.24% (9/401), respectively, with Belgian horses being overrepresented (6/9). Cardiac arrest occurred in six out of nine horses that died without euthanasia, and five out of six of these horses underwent colic surgery. Factors associated with increased mortality risk included ASA status of III-V, increased body weight, emergency status and horses presenting for colic. Hypotension, hypercarbia and hypoxemia occurred in 56% (224/401), 46% (186/401) and 14% (58/401) of horses, respectively. During recovery from anesthesia, lighter horses and horses undergoing shorter anesthetic procedures were more likely to be successful on the first or second attempt to stand and were less likely to require a sling in recovery.

CONCLUSIONS AND CLINICAL RELEVANCE

Draft horses undergoing general anesthesia had a higher mortality rate than previously reported for all types and breeds of horses.

A single-cohort retrospective analysis of factors associated with morbidity and mortality in 193 anesthetized domestic goats

OBJECTIVE

To define the morbidity and mortality rates in goats undergoing general anesthesia at a large animal teaching hospital.

STUDY DESIGN

Retrospective, single-cohort, observational study.

ANIMALS

Records of 193 client-owned goats.

METHODS

Data were collected from 218 medical records on 193 goats undergoing general anesthesia between January 2017 and December 2021. Demographic data, anesthetic management, recovery period and perianesthetic complications were recorded. Perianesthetic death was defined as anesthesia-related or anesthesia-contributory death occurring within 72 hours after recovery. Records of goats that were euthanized were reviewed to ascertain the cause of euthanasia. Each explanatory variable was individually investigated by univariable penalized maximum likelihood logistic regression, followed by multivariable analysis. Statistical significance was set at p < 0.05.

RESULTS

Perianesthetic mortality was 7.3%, but was 3.4% when considering only goats undergoing elective procedures. Multivariable analysis showed that gastrointestinal surgeries [odds ratio (OR) 19.17, standard error (SE) 12.99, 95% confidence interval (CI) 5.08-72.33; p < 0.01] and requirement for perianesthetic norepinephrine infusion (OR 10.85, SE 8.82, 95% CI 2.21-53.33; p < 0.01) were associated with increased mortality. Maintaining other variables equal, the use of perianesthetic ketamine infusion was associated with decreased mortality (OR 0.09, SE 0.09, 95% CI 0.01-0.73; p = 0.02). Anesthesia-related or anesthesia-contributory complications included hypothermia (52.4%), bradycardia (38.1%), hypotension (35.3%), hypoxemia (14.8%), regurgitation/aspiration (7.3%), azotemia/acute renal failure (4.6%), myopathies/neuropathies (4.1%) and fever of unknown origin (2.7%).

CONCLUSIONS AND CLINICAL RELEVANCE

In this population, gastrointestinal surgeries and the requirement for perianesthetic norepinephrine infusion were associated with increased mortality in goats undergoing general anesthesia, while ketamine infusion may have a protective effect.

Retrospective Study on Risk Factors and Short-Term Outcome of Horses Referred for Colic from 2016 to 2022

Simple Summary

Colic syndrome is the most common out-of-hours call for equine practitioners. In most cases, medical treatment at home is effective for the resolution of the disorders. In 20% of cases, hospital intensive care is required. Several factors have been addressed as predisposing to the disorder. Cardiovascular and hemodynamic variables are the most reliable indicators of the severity of the condition and, thus, are important prognostic factors. The aim of the study was to highlight the predisposing factors and best prognostic clinical signs for discharge in a cohort of horses referred for colic syndrome. Medical records from 2016 to 2022 were examined. One hundred and fifty-seven horses were included in the study. Month and time of admission were the main predisposing factors. Cardiovascular variables (heart rate on admission and after 3–6 h, packed cell volume, capillary refill time, and mucosal membranes) and the presence of gastric reflux were negatively associated with discharge as well as time to standing after surgery. The results from this retrospective study may help the clinician in evaluating prognosis, deciding on the best treatment, and adequately informing the owner of the rates of success.

Abstract

(1) Background: colic syndrome is a multifactorial life-threatening condition in equids. Awareness of predisposing and prognostic indicators is useful to adequately inform the owner of the outcome and plan the best treatment. The aim of the study was to identify the variables associated with short-term survival in a cohort of horses referred for colic to a veterinary teaching hospital; (2) Methods: medical records of horses referred for colic from 2016 to 2022 were retrospectively reviewed. Univariate and multivariate regression models were built to assess the odds ratios of discharge from the hospital, both on the whole sample and in those patients undergoing surgery; (3) Conclusions: Month, time of admission, cardiovascular variables (heart rate on admission and after 3–6 h, packed cell volume, capillary refill time, and mucosal membranes), and presence of gastric reflux were significantly associated with discharge in the univariate regression in all horses and in those surgically treated. In the multivariate regression model, heart rate, packed cell volume, and capillary refill time showed significant association with the outcome in the whole sample. Although comparison between this study and previous studies is difficult due to the number and type of variables included, cardiovascular variables and markers of hypovolemia were also shown to be associated with outcome.

Nasal and tracheobronchial nitric oxide production and its influence on oxygenation in horses undergoing total intravenous anaesthesia

BACKGROUND

The present study aimed to investigate the effect of endotracheal intubation on nasal and tracheal endogenous NO concentrations, gas exchange and oxygenation in horses undergoing general anaesthesia. In many species a major part of physiological nitric oxide (NO) production takes place in the nasopharynx. Inhaled NO acts as a pulmonary vasodilator and regulates lung perfusion and endotracheal intubation bypasses the nasopharynx. Six horses were randomly assigned to either the "intubated" (INT) or the "non-intubated" (nINT) treatment group. Horses were premedicated with dexmedetomidine (5 μg/kg IV). Anaesthesia was induced with 2.5 mg/kg ketamine and 0.05 mg/kg diazepam IV, and it was maintained by administration of a triple-drip (100 mg/kg/h guaifenesin, 4 mg/kg/h ketamine, 7 μg/kg/h dexmedetomidine). The horses were spontaneously breathing room air. Heart rate, cardiac output, arterial blood pressure, pulmonary arterial blood pressures and respiratory rate were recorded during a 100-min anaesthesia period. Arterial, venous and mixed venous blood samples were taken every 10 minutes and analysed for partial pressure of oxygen (PO₂) and carbon dioxide (PCO₂), oxygen saturation and haemoglobin content. Standard oxygenation indices were calculated. Nasal and tracheal endogenous NO concentration was determined by chemiluminescence.

RESULTS

Cardiovascular variables, respiratory rate, PO₂, PCO₂, oxygen saturation, haemoglobin content, CaO₂, O₂ER, P_(a-ET)CO₂ and Q_s/Q_t did not differ significantly between the two treatment groups. The P_(A-a)O₂ was significantly higher in INT (6.1 ± 0.3 kPa) compared to nINT (4.9 ± 0.1 kPa) (p = 0.045), respectively. The nasal (8.0 ± 6.2 ppb) and tracheal (13.0 ± 6.3 ppb) endogenous NO concentration differed significantly in INT (p = 0.036), but not in nINT (nasal: 16.9 ± 9.0 ppb; tracheal: 18.5 ± 9.5 ppb) (p = 0.215).

CONCLUSION

Endotracheal intubation reduces the nasal and tracheal endogenous NO concentration. The influence on pulmonary gas exchange and oxygenation is negligible in horses breathing room air.

An analysis of risk factors for a fracture or luxation in recovery from general anaesthesia in horses: a single centre study

Catastrophic fractures or luxations (FoL) sustained during recovery from general anaesthesia are a significant cause of mortality during equine anaesthesia. There is a lack of evidence regarding potential risk factors for a FoL occurring in the immediate anaesthetic recovery period. A single centre, retrospective, case-matched study was performed to identify risk factors for sustaining a catastrophic FoL during recovery from general anaesthesia. Clinical data were obtained for horses which sustained a catastrophic FoL when recovering from general anaesthesia from January 2011- June 2020 in a single centre 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 intra-operative administration of intra-tracheal salbutamol, intra-operative administration of ketamine and increasing age. Further research in this area, particularly with regards to salbutamol administration, is required.

Effects of pulsed inhaled nitric oxide delivery on the distribution of pulmonary perfusion in spontaneously breathing and mechanically ventilated anesthetized ponies

OBJECTIVE

To measure changes in pulmonary perfusion during pulsed inhaled nitric oxide (PiNO) delivery in anesthetized, spontaneously breathing and mechanically ventilated ponies positioned in dorsal recumbency.

ANIMALS

6 adult ponies.

PROCEDURES

Ponies were anesthetized, positioned in dorsal recumbency in a CT gantry, and allowed to breathe spontaneously. Pulmonary artery, right atrial, and facial artery catheters were placed. Analysis time points were baseline, after 30 minutes of PiNO, and 30 minutes after discontinuation of PiNO. At each time point, iodinated contrast medium was injected, and CT angiography was used to measure pulmonary perfusion. Thermodilution was used to measure cardiac output, and arterial and mixed venous blood samples were collected simultaneously and analyzed. Analyses were repeated while ponies were mechanically ventilated.

RESULTS

During PiNO delivery, perfusion to aerated lung regions increased, perfusion to atelectatic lung regions decreased, arterial partial pressure of oxygen increased, and venous admixture and the alveolar-arterial difference in partial pressure of oxygen decreased. Changes in regional perfusion during PiNO delivery were more pronounced when ponies were spontaneously breathing than when they were mechanically ventilated.

CLINICAL RELEVANCE

In anesthetized, dorsally recumbent ponies, PiNO delivery resulted in redistribution of pulmonary perfusion from dependent, atelectatic lung regions to nondependent aerated lung regions, leading to improvements in oxygenation. PiNO may offer a treatment option for impaired oxygenation induced by recumbency.

Retrospective study of the prevalence of factors contributing to successful standing at first attempt in horses recovering from general anesthesia

OBJECTIVE

Several factors affect the quality of recovery from general anesthesia in horses. These can increase the likelihood of injury. Body and limb position during recovery may correlate with successful standing. The objective of this study was to identify the prevalence of and the factors associated with successful standing at the first attempt in horses undergoing general anesthesia.

STUDY DESIGN

Retrospective study.

METHODS

Video of recovery and anesthetic records from 221 equine patients were reviewed by six veterinary students. Cases with poor video quality or incomplete anesthetic records were excluded. Demographic variables, type of procedure, perioperative drugs administered, assistance during recovery and body and limb positions during the first attempt to stand were recorded. Association between putative variables (including specific descriptors for body and limb position) and success for standing were analyzed using backward logistic regression; significance was set at 0.05. A decision tree for a successful attempt was created to predict the outcome of a recovery attempt based on these variables.

RESULTS

Extension of the carpal joints, head and neck alignment with the thoracic limbs, greater time in lateral recumbency, coordination during sternal recumbency, longer time to first attempt to stand and pelvic limb position were associated with successful standing at the first attempt. The association between extension of the carpal joints with wide base positioning of the pelvic limbs provided the best success rate for standing, whereas the association of flexed carpal joints and head and neck orientation different from the thoracic limbs resulted in a worse success rate.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that certain limb and body positions displayed by horses during recovery may be associated with the likelihood of successful standing at the first attempt. These variables may be useful for assessing recovery quality in future research.

Recovery of horses from general anaesthesia: A systematic review (2000-2020) of the influence of anaesthetic protocol on recovery quality

BACKGROUND

The recovery phase after equine general anaesthesia (GA) is a time of considerable risk and therefore has been the subject of extensive research over the last 20 years. Various pharmacological interventions have been developed and studied with the objective of improving recovery quality and reducing anaesthetic-related mortality and morbidity. Nevertheless, some controversy remains regarding the influence of anaesthetic protocol choice on recovery quality from GA and its implications for recovery-related mortality and morbidity. A systematic review of the literature investigating the influence of anaesthetic protocol choice on recovery quality is currently lacking.

OBJECTIVES

To perform a detailed evaluation of the equine veterinary literature investigating the effect of anaesthetic protocol choice on equine recovery quality utilising the GRADE framework.

STUDY DESIGN

A systematic evaluation of the equine veterinary literature was performed using the GRADE framework.

METHODS

A literature search was performed and studies were assessed for eligibility by both authors utilising PRISMA guidelines. Studies meeting inclusion criteria were evaluated by both authors, categorically summarised and the quality of evidence for each sub-topic was assessed using the GRADE framework.

RESULTS

A total of 124 studies were identified which directly assessed the impact of anaesthetic protocol choice on recovery quality after GA in horses. Evaluation of the available evidence indicated that certain partial intravenous anaesthesia (PIVA) agents, cessation of intravenous lidocaine 30 minutes prior to recovery and provision of adequate analgesia improves recovery quality.

MAIN LIMITATIONS

The validity of the results of some studies may have been compromised by missing data and small sample sizes.

CONCLUSIONS

There is evidence to indicate that certain PIVA agents, cessation of intravenous lidocaine 30 minutes prior to recovery and provision of adequate analgesia improves recovery quality.

Demographic, preoperative and anaesthesia-related risk factors for unsatisfactory recovery quality in horses undergoing emergency abdominal surgery

OBJECTIVE

To determine demographic, preoperative and anaesthesia-related variables that may be associated with unsatisfactory recovery quality in horses undergoing emergency abdominal surgery (colic) in an equine teaching hospital.

STUDY DESIGN

Retrospective case series.

ANIMALS

A total of 313 horses.

METHODS

The anaesthetic records of horses admitted for surgical treatment of colic between 2005 and 2018 were examined. Overall quality of recovery was assessed as dangerous, poor, fair, good or excellent. The following categories were constructed as a dichotomic variable: unsatisfactory recovery (poor and dangerous recoveries) and satisfactory recovery (excellent, good and fair recoveries). Univariable and multivariable analyses were performed to evaluate the association between all studied variables and recovery.

RESULTS

All recoveries were unassisted. Unsatisfactory recovery quality totalled 17.2% (3.5% and 13.7% were dangerous and poor recoveries, respectively), whereas satisfactory recoveries totalled 82.8% (26.2%, 40.9% and 15.7% were fair, good and excellent recoveries, respectively). Univariable analysis showed that unsatisfactory recoveries were associated with high preoperative packed cell volume, pain behaviour, poor premedication and induction quality, high intraoperative mean heart rate, low mean arterial blood pressure, dobutamine dose ≥1.5 μg kg^-1 minute^-1, non-administration of romifidine, long anaesthesia time and prolonged time to stand. The multivariable model showed that factors strongly associated with unsatisfactory recovery quality were dobutamine dose ≥1.5 μg kg^-1 minute^-1 [adjusted odds ratio (AOR) = 6.60; 95% confidence interval (CI), 2.91-14.96], poor premedication quality (AOR=4.60; 95% CI, 1.73-12.23) and a time to stand > 70 minutes (AOR=2.59; 95% CI, 1.13-5.91).

CONCLUSIONS AND CLINICAL RELEVANCE

Our study shows that high dobutamine requirements, poor premedication quality and a prolonged time to stand are risk factors for unsatisfactory recovery quality in horses undergoing anaesthesia for colic surgery. Addressing these factors may enable clinicians to improve the quality of recovery phase.

Avian anaesthesia related mortality and the associated risk factors in a UK zoological collection

OBJECTIVE

To analyse avian anaesthesia-related mortality in a UK zoological collection over a 5-year period and identify risk factors for mortality.

STUDY DESIGN

Retrospective cohort study.

ANIMALS

A total of 135 individual birds across 37 species, anaesthetized during 206 events in a UK zoological collection between 1 January 2014 and 30 June 2019 (inclusive).

METHODS

Anaesthesia records were reviewed and variables such as age, body condition, weight, sex, duration of anaesthesia and health status were collated. Anaesthesia-related mortality was defined as those deaths occurring during anaesthesia and up to 7 days postanaesthesia. Outcome was analysed using multivariable conditional logistic regression. Overall mortality was defined and included birds euthanised during anaesthesia for non-anaesthesia related reasons. Data were summarised as median (range). A value of p < 0.05 was considered significant. Relative risks and 95% confidence intervals (95% CI) were calculated for the association between risk factors and anaesthetic death where a statistically significant difference was found.

RESULTS

The overall mortality rate was 10.19% (95% CI = 6.06-14.3%), while anaesthesia-related mortality was 3.88% (95% CI = 1.69-7.51%). Birds with an abnormal health status had a 15.53-fold (95% CI = 1.95-123.63) increased risk of death compared with those with a normal health status. The duration of anaesthesia was also a statistically significant risk factor (p = 0.021) in the univariable analysis, but not when combined with health status. No other variables were associated with anaesthesia-related mortality.

CONCLUSIONS AND CLINICAL RELEVANCE

Abnormal health status and longer anaesthetic procedures were associated with a significantly increased risk of anaesthesia-related death in this population of birds. It is recommended that anaesthetic duration is minimized, and pre-existing diseases are diagnosed where possible prior to general anaesthesia of birds. Anaesthetizing healthy birds was associated with a low risk of mortality.

Head and tail rope-assisted recovery improves quality of recovery from general anaesthesia in horses undergoing emergency exploratory laparotomy

BACKGROUND

In equine anaesthesia, the recovery period is critical, accounting for most anaesthesia-related fatalities reported. Horses may recover unassisted or may be assisted, for example, using a head and tail rope recovery method.

OBJECTIVES

To compare the impact of head and tail rope and unassisted recovery method on quality of recovery in horses undergoing colic surgery under general anaesthesia (GA).

STUDY DESIGN

Single centre retrospective cross-sectional study, with prospective model performance analysis.

METHODS

Clinical data were obtained from horses undergoing emergency exploratory laparotomy over a 6-year period. Multivariable logistic regression analysis was used to identify the perioperative factors that affect quality of recovery. The final prediction model was assessed prospectively.

RESULTS

Records from 502 general anaesthetics (490 horses) were included. Multivariable logistic regression analysis showed that head and tail rope recovery (OR 2.2, 95% CI 1.4-3.3, P < .001) and sevoflurane administration (OR 1.6, 95% CI 1.2-2.3, P = .02) were associated with better quality of recovery when compared with unassisted recovery and isoflurane administration respectively. Increasing GA duration (OR 1.0, 95% CI 0.99-1.0, P = .03), increasing intraoperative dosages (in mg/kg) of thiopental (OR 0.85, 95% CI 0.75-0.98, P = .02) or ketamine (OR 0.67, 95% CI 0.46-0.99, P = .04) were linked to poor quality of recovery. No statistically significant difference was found between recovery groups in terms of mortality.

MAIN LIMITATIONS

The clinical prediction model obtained is only applicable to the specific facilities, recovery methodology, referral population and anaesthetic protocols practiced at our institution.

CONCLUSIONS

Head and tail rope recovery is significantly associated with better quality of recovery, compared with unassisted recovery, in horses undergoing emergency exploratory laparotomy. Sevoflurane administration, in detriment of isoflurane, was associated with better quality of recovery. Other risk factors, such as increasing GA duration, the use of higher intra-operative dosages of ketamine and/or thiopental, were associated with poor quality of recovery.

Recovery of horses from general anaesthesia: A systematic review (2000-2020) of risk factors and influence of interventions during the recovery period

BACKGROUND

In equine anaesthesia, the recovery period is a time of considerable risk and has been the focus of prolific research. Risk factors, including age, type and duration of procedure or temperament may influence recovery quality. Unfortunately, the anaesthetist is unable to control for these factors, therefore various pharmacological interventions and recovery methods have been developed with the objective of improving recovery quality. However, no consensus among anaesthetists has been reached for many of these interventions and their implications for recovery-related mortality and morbidity.

OBJECTIVES

To conduct a systematic review of the published evidence relating to risk factors and interventions in the recovery period which may influence recovery quality from equine general anaesthesia (GA).

STUDY DESIGN

A systematic evaluation of the equine veterinary literature using the GRADE framework.

METHODS

A literature search was performed and studies were assessed for eligibility by both authors utilising PRISMA guidelines. Studies meeting inclusion criteria were evaluated by both authors, categorically summarised and the quality of evidence for each sub-topic was assessed using the GRADE framework.

RESULTS

Thirty-nine studies were identified which directly assessed the impact of risk factors and recovery interventions on recovery quality after equine GA. There was evidence to support that peri-anaesthetic risk factors such as anaesthesia duration, American Society of Anesthesiologists (ASA) physical status and surgical procedure influenced recovery quality. We also identified sufficient evidence that administration of α-2 adrenoreceptor agonists immediately prior to recovery, improves recovery quality.

MAIN LIMITATIONS

The validity of the results of some studies may have been compromised by missing data and small sample sizes.

CONCLUSIONS

Recovery quality is influenced by factors including: anaesthesia duration, ASA physical status and surgical procedure. Recovery quality can be improved by the administration of an α-2 adrenoreceptor agonist immediately prior to recovery.

Standing flank laparotomy for colic: 37 cases

BACKGROUND

Standing flank laparotomy can be an alternative to ventral midline laparotomy in horses with colic. Standing flank laparotomy avoids general anaesthesia, provides excellent access to some regions of the abdominopelvic cavity and costs less than ventral midline laparotomy.

OBJECTIVE

To report a series of cases of peritoneal and intestinal diseases other than SC diseases managed with standing flank laparotomy.

STUDY DESIGN

Retrospective case series.

METHODS

Records from equids with colic subjected to standing flank laparotomy at five hospitals (2003-2020) were reviewed. Descriptive data analysis was performed.

RESULTS

Thirty horses (sixteen survived to discharge), six ponies (four survived) and one donkey (euthanised) were subjected to standing flank laparotomy via the left flank (n = 31), right flank (n = 2) or both flanks (n = 4). The primary disease affected the peritoneum (0/5 survived), SI (5/9 survived) and caecum and/or LC (15/23 survived). Enterotomy was performed in four animals (all survived). Partial typhlectomy was performed in one horse (euthanised). Resection-anastomosis of the SI or LC was performed in three animals (one survived). Three animals had intraoperative complications that negatively affected the outcome: Two ponies had intolerance to abdominopelvic exploration; one mare had spontaneous exteriorisation of a long segment of the SI leading to a large tear in the mesentery. In seven cases, severe/extensive lesions found during standing flank laparotomy warranted immediate euthanasia. The survival rate was 54%. All owners were satisfied with the decision to perform standing flank laparotomy.

MAIN LIMITATIONS

The retrospective design, lack of a control group, small number of cases and lack of standardised protocols between hospitals.

CONCLUSIONS

Although ventral midline laparotomy is the standard of care for horses with colic, standing flank laparotomy is a viable approach for some types of colic. Systemic administration of analgesics may not produce sufficient peritoneal analgesia, which can lead to intolerance to abdominopelvic exploration during standing flank laparotomy in horses with colic and may negatively affect the outcome.

Data Collection for the Fourth Multicentre Confidential Enquiry into Perioperative Equine Fatalities (CEPEF4) Study: New Technology and Preliminary Results

Simple Summary

New technologies allow researchers to improve the methods for immediate, accurate data collection, cleaning and analysis, with minimal geographical limitations. Although much has improved in the field of equine anaesthesia in recent years, we are still far from reducing anaesthetic-related mortality in this species in comparison with small animal anaesthesia. The aim of this multicentre study was to probe the usefulness of an internet-based method that utilised an electronic questionnaire and statistical software to show the data and report outcomes from horses undergoing general anaesthesia and certain procedures using standing sedation. Within six months, 8656 cases from 69 centres were collected: 6701 procedures under general anaesthesia and 1955 under standing sedation. The results demonstrated (i) the utility of the method and (ii) that some horses died unexpectedly when undergoing not only general anaesthesia, but also standing sedation. Finally, (iii) we present some descriptive data that outline the current anaesthesia practice compared with the previous CEPEF2. We concluded that our internet-based method is suitable for this type of study. New techniques may reduce the mortality rate. However, the results presented here should be interpreted cautiously as these are only preliminary data with lower numbers than CEPEF2.

Abstract

It is almost 20 years since the largest observational, multicentre study evaluating the risks of mortality associated with general anaesthesia in horses. We proposed an internet-based method to collect data (cleaned and analysed with R) in a multicentre, cohort, observational, analytical, longitudinal and prospective study to evaluate peri-operative equine mortality. The objective was to report the usefulness of the method, illustrated with the preliminary data, including outcomes for horses seven days after undergoing general anaesthesia and certain procedures using standing sedation. Within six months, data from 6701 procedures under general anaesthesia and 1955 standing sedations from 69 centres were collected. The results showed (i) the utility of the method; also, that (ii) the overall mortality rate for general anaesthesia within the seven-day outcome period was 1.0%. In horses undergoing procedures other than exploratory laparotomy for colic (“noncolics”), the rate was lower, 0.6%, and in “colics” it was higher, at 3.4%. For standing sedations, the overall mortality rate was 0.2%. Finally, (iii) we present some descriptive data that demonstrate new developments since the previous CEPEF2. In conclusion, horses clearly still die unexpectedly when undergoing procedures under general anaesthesia or standing sedation. Our method is suitable for case collection for future studies.

Recovery after General Anaesthesia in Adult Horses: A Structured Summary of the Literature

Simple Summary

Recovery is the most dangerous phase of general anaesthesia in horses. Numerous publications have reported about this phase, but structured reviews that try to reduce the risk of bias of narrative reviews/expert opinions, focussing on the topic are missing. Therefore, the aim of the present article was to publish the first structured review as a summary of the literature focussing on the recovery phase after general anaesthesia in horses. The objective was to summarise the available literature, taking into account the scientific evidence of the individual studies. A structured approach was followed with two experts in the field independently deciding on article inclusion and its level of scientific evidence. A total number of 444 articles, sorted by topics and classified based on their levels of evidence, were finally included into the present summary. The most important findings were summarised and discussed. The present structured review can be used as a compilation of the publications that, to date, focus on the recovery phase after general anaesthesia in adult horses. This type of review tries to minimise the risk of bias inherent to narrative reviews/expert opinions.

Abstract

Recovery remains the most dangerous phase of general anaesthesia in horses. The objective of this publication was to perform a structured literature review including levels of evidence (LoE) of each study with the keywords “recovery anaesthesia horse”, entered at once, in the search browsers PubMed and Web of Science. The two authors independently evaluated each candidate article. A final list with 444 articles was obtained on 5 April 2021, classified as: 41 “narrative reviews/expert opinions”, 16 “retrospective outcome studies”, 5 “surveys”, 59 “premedication/sedation and induction drugs”, 27 “maintenance with inhalant agents”, 55 “maintenance with total intravenous anaesthesia (TIVA)”, 3 “TIVA versus inhalants”, 56 “maintenance with partial intravenous anaesthesia (PIVA)”, 27 “other drugs used during maintenance”, 18 “drugs before/during recovery”, 18 “recovery systems”, 21 “respiratory system in recovery”, 41 “other factors”, 51 “case series/reports” and 6 “systems to score recoveries”. Of them, 167 were LoE 1, 36 LoE 2, 33 LoE 3, 110 LoE 4, 90 LoE 5 and 8 could not be classified based on the available abstract. This review can be used as an up-to-date compilation of the literature about recovery after general anaesthesia in adult horses that tried to minimise the bias inherent to narrative reviews.

Sevoflurane or isoflurane anaesthesia? A prospective, randomised blinded clinical trial in horses undergoing elective surgery

BACKGROUND

Isoflurane is the only volatile anaesthetic agent licensed for equine use in the United Kingdom, but sevoflurane is also commonly used. The two agents have rarely been compared for use in clinical elective surgery.

METHODS

This single centre, prospective, randomised, blinded clinical investigation recruited 101 healthy client owned horses undergoing elective surgery. Anaesthesia was standardised and horses randomly assigned to receive isoflurane (I) or sevoflurane (S) for maintenance of anaesthesia in 100% oxygen. Horses were ventilated to normocapnia and received intravenous fluid therapy and haemodynamic support with dobutamine to maintain mean arterial blood pressure above 60 mm Hg. Recovery was timed and video-recorded to allow offline evaluation by two experienced clinicians unaware of the volatile agent used. No post-anaesthetic sedation was administered.

RESULTS

There was no significant difference between groups in terms of haemodynamic support required during anaesthesia nor in quality or duration of recovery. Inotropic support to maintain MAP above 60 mm Hg was required by 67 of 101 (67%) of horses. Five horses in the I group required additional ketamine or thiopentone to improve the plane of anaesthesia.

CONCLUSIONS

Haemodynamic support needed during anaesthesia as well as the duration and quality of recovery were similar with isoflurane and sevoflurane.

Effect of Aerosolised Salbutamol Administration on Arterial Potassium Concentration in Anaesthetised Horses

Aerosolized salbutamol has been associated with hypokalemia in horses undergoing colic surgery. The objective of this study was to evaluate the effect of aerosolized salbutamol on arterial potassium concentration ([K +]) in healthy anaesthetized horses undergoing elective surgery. Anesthetic records were reviewed from healthy adult horses undergoing elective surgery over a 3-year period with two complete sets of arterial electrolyte (sodium [Na +], potassium [K +], chloride [Cl -], calcium [Ca 2+]) concentration measurements. Records were excluded if intra-operative electrolyte supplementation, antimicrobial administration or noncrystalloid fluid administration were documented or if salbutamol was administered prior to electrolyte measurement. Sixty records which fulfilled inclusion criteria were divided into two groups depending on whether or not aerosolized salbutamol (2μg kg -1) (to treat hypoxemia) was administered after baseline electrolyte measurement and before the second electrolyte measurement. Aerosolized salbutamol was administered (Group S) in 22 horses and not administered (group NS) in 38 horses. There was a significant reduction in [K +] and [Ca 2+] between baseline and the second electrolyte measurement in both groups (P< .001). The reduction in [K +] between baseline and the second electrolyte measurement was significantly greater in group S (12.3%) compared to group NS (6.9%) (P= .017) and was significantly associated with salbutamol administration (P= .04). The results of this study indicate that monitoring [K +] is important in anaesthetized horses, particularly after aerosolized salbutamol administration.

Subconjunctival enucleation with orbital implant placement in standing horses: 20 cases (2014-2017)

OBJECTIVE

To develop a protocol for subconjunctival enucleation and orbital implant placement in standing horses and to document short- and long-term complications, cosmesis, and client satisfaction.

ANIMALS

20 horses with nonneoplastic ocular disease requiring enucleation.

PROCEDURES

A standardized protocol of surgical suite cleaning, patient preparation, sedation, local nerve blocks, surgical procedure, and postoperative care was performed. Owners were required to provide follow-up information at 1 year after surgery during a phone questionnaire. Additionally, some owners provided follow-up information at 1.8 to 4 years postoperatively.

RESULTS

11 mares, 6 geldings, and 3 stallions with a mean age of 9 years (range, 0.5 to 25 years) were included in this study. Reasons for enucleation included corneal lacerations (n = 3), perforated ulcers (4), end-stage uveitis (7), fungal keratitis (3), endophthalmitis (1), glaucoma (1), and stromal abscess (1). The mean surgery time was 64 minutes (range, 50 to 83 minutes). The most common implant size used was 45-mm diameter (range, 43- to 47-mm diameter). Complications included mild postoperative colic (n = 4), incisional swelling (1), and drainage from the surgical site (1) that resolved without implant removal. One-year follow-up information was available for 19 of 20 horses. Fourteen owners were very satisfied and 5 owners were satisfied with the cosmetic appearance. One horse was lost to follow-up.

CONCLUSIONS AND CLINICAL RELEVANCE

Subconjunctival enucleation and orbital implant placement in standing horses was a safe and efficient alternative to general anesthesia when a standardized perioperative protocol was used. No horse developed clinically relevant complications, and owner satisfaction and cosmesis were good.

Ex vivo comparison of standing and recumbent repair of incomplete parasagittal fractures of the first phalanx in horses

OBJECTIVE

To assess suspensory ligament extensor branch location and fracture gap reduction with simulation of standing and recumbent cortical bone screw repair of experimental incomplete parasagittal proximal phalanx (P1) fractures.

STUDY DESIGN

Controlled laboratory study.

SAMPLE POPULATION

Twenty equine cadaver forelimbs.

METHODS

Simulated fractures were repaired twice in random order. A proximal cortical bone screw was placed in lag fashion with the limb unloaded (simulated recumbent repair) and loaded to 38% of body weight (range, 375-568 kg; simulated standing repair). Changes in fracture gap width were assessed on computed tomography (CT) images and with intraplanar force-sensitive resistors measuring voltage ratios (V_△ ) between loaded recumbent (R-1) and standing repair simulations (R-2). Extensor branch borders were determined relative to implant position and sagittal P1 width on transverse CT images. P ≤ .05 was considered significant.

RESULTS

Standing repair simulation-associated fracture gaps were not wider than in R-1 while controlling for confounding factors (loading weight, implant position, or animal age; P > .7, repeated-measures analysis of variance). Voltage ratio data associated with R-2 were not smaller than with R-1 (mean difference, 0.002 ± 0.052; one-sided Wilcoxon signed-rank test, P = .27). More of P1 width was approachable palmar to extensor branches when limbs were loaded (0.804 ± 0.314 cm) vs unloaded (0.651 ± 0.31 cm; paired Student's t test, P < .001).

CONCLUSION

Simulated standing repair was not associated with inferior fracture reduction compared with loaded simulations of recumbent repairs. Limb loading affected extensor branch location relevant to implant positioning.

CLINICAL SIGNIFICANCE

Unloading during standing repair of incomplete parasagittal proximal P1 fractures may not be required to optimize fracture reduction.

Investigation of innate immune function in adult and geriatric horses

In order to better understand the influence of age on innate immune function in horses, blood was collected from twelve adult horses (aged 10-16 years; mean: 13 years) and ten geriatric horses (aged 18-26 years; mean: 21.7 years) for analysis of plasma myeloperoxidase, complete blood counts, and cytokine and receptor expression in response to in vitro stimulation with heat-inactivated Rhodococcus equi, heat-inactivated Escherichia coli, and PMA/ionomycin. Gene expression was measured using RT-PCR for IFNγ, IL-1β, IL-6, IL-8, IL-10, IL-12α, IL-13, IL-17α, TLR2, TLR4, and TNFα. Endocrine function and body weight were measured to assess any potential impacts of ACTH, insulin, or body weight on immune function; none of the horses had pituitary pars intermedia dysfunction. The geriatric horse group had lower concentrations of plasma myeloperoxidase (P = 0.0459) and lower absolute monocyte counts (P = 0.0477); however, the difference in monocyte counts was no longer significant after outliers were removed. Additionally, only two significant differences in cytokine/receptor expression in whole blood were observed. Compared with adult horses, the geriatric horses had increased TNFα expression after in vitro stimulation with heat-inactivated R. equi (P = 0.0224) and had decreased IL-17α expression after PMA/ionomycin stimulation when one outlier was excluded (P = 0.0334). These changes may represent a compensatory mechanism by which geriatric horses could ensure adequate immune responses despite potentially dysfunctional neutrophil activity and/or decreased monocyte counts. Aging may influence equine innate immune function, and additional research is warranted to confirm and further explore these findings.

Questionnaire on the process of recovering horses from general anesthesia and associated personnel injury in equine practice

OBJECTIVE

To collect data about the current practice of recovering horses from general anesthesia and recovery personnel safety.

STUDY DESIGN

Online survey.

METHODS

An online questionnaire, including questions on general demographic data, recovery drugs, modality and characteristics of equine recovery and morbidity and mortality, was designed and distributed via e-mail to equine practitioners worldwide.

RESULTS

Practitioners from 22 countries completed 373 questionnaires; 53% of the participants were board-certified equine surgeons, and the remainder were board-certified anesthesiologists (18%), large animal residents (8%), general practitioners (7%), large animal interns (6%), anesthesia residents (4.5%) and veterinary technicians (1.6%). Respondents were employed by academia (58%) or private practice (42%). Of the respondents employed at a university, 93% had a board-certified anesthesiologist on staff compared with 7% of respondents employed at a private practice. Most of the respondents assist horses during recovery, with 23% assisting every recovery and 44% assisting recovery in the majority of cases. Reasons for choosing to assist horses during recovery were: orthopedic procedures (57%), neurological deficits (49%), bad health (47%), history of poor recovery (44%), foals (42%), draft breeds (30%), magnetic resonance imaging (17%) and computed tomography (16%). Unacceptable recoveries were reported by 77% of participants. Commonly reported complications during recovery with any method were: orthopedic injury (66%), myopathy (54%), skin abrasion (53%) and airway obstruction (37%). The incidences of unacceptable quality of recovery (p = 0.09) or personnel injury (p = 0.56) were not different between assisted and nonassisted recoveries; however, more equine fatalities were reported for assisted recoveries (p < 0.006). Practitioners in academia reported more unacceptable recoveries (p < 0.0007) and personnel injuries (p < 0.002) compared with those in private practice.

CONCLUSIONS

The method of recovery differs among hospitals. Recovery personnel injuries associated with assisting horses during recovery are an important and previously unreported finding.

Epidural administration of opioid analgesics improves quality of recovery in horses anaesthetised for treatment of hindlimb synovial sepsis

BACKGROUND

Opioid epidural analgesia has been shown to provide effective analgesia in horses. There is a lack of evidence regarding the effect of opioid epidural analgesia on quality of recovery in horses.

OBJECTIVES

Identify whether opioid epidural analgesia influences quality of recovery in horses undergoing general anaesthesia required for management of hindlimb synovial sepsis.

STUDY DESIGN

Single-centre retrospective cross-sectional study.

METHODS

Data were obtained from the clinical records of horses which had undergone arthroscopic or tenoscopic surgery for management of hindlimb synovial sepsis over a 9-year period in a referral hospital population. Multivariable logistic regression analysis was used to identify the perioperative factors that impact on quality of recovery.

RESULTS

Records from 149 horses, undergoing 170 general anaesthetics were included. Multivariable logistic regression analysis showed that opioid epidural analgesia (OR 3.0, 95% CI 1.2 to 7.2, P = .02) was associated with good quality of recovery, whereas Cob breeds (OR 0.16, 95% CI 0.06 to 0.46, P = .001), age (in years) (OR 0.90, 95% CI 0.83 to 0.97, P = .004) increasing intraoperative dosages (in mg/kg) of thiopental (OR 0.64, 95% CI 0.46 to 0.90, P = .01) or ketamine (OR 0.42, 95% CI 0.18 to 0.98, P = .04) were associated with poor quality of recovery.

MAIN LIMITATIONS

Certain variables that may influence quality of recovery, such as patient temperament and hindlimb orthopaedic co-morbidities were not recorded. The clinical prediction model obtained is only applicable to the specific facilities, population and perianaesthetic management practiced at our institution.

CONCLUSIONS

Opioid epidural analgesia is significantly associated with good quality of recovery in horses undergoing general anaesthesia required for management of hindlimb synovial sepsis. Other risk factors, such as increasing age, cob breed, use of higher intraoperative dosages (in mg/kg) of ketamine and/or thiopental, were associated with poor quality of recovery.

Clinical Assessment of an Ipsilateral Cervical Spinal Nerve Block for Prosthetic Laryngoplasty in Anesthetized Horses

The nociceptive blockade of locoregional anesthesia prior to surgical stimulation can decrease anesthetic agent requirement and thereby potential dose-dependent side effects. The use of an ipsilateral second and third cervical spinal nerve locoregional anesthetic block for prosthetic laryngoplasty in the anesthetized horses has yet to be described. Anesthetic records of 20 horses receiving locoregional anesthesia prior to laryngoplasty were reviewed and compared to 20 horses of a similar patient cohort not receiving locoregional anesthesia. Non-blocked horses were 11 times more likely to require adjunct anesthetic treatment during surgical stimulation (P = 0.03) and were 7.4 times more likely to receive partial intravenous anesthesia in addition to inhalant anesthesia (P = 0.01). No horse in the blocked group received additional sedation/analgesia compared to the majority of non-blocked horses (75%) based on the anesthetist's perception of anesthetic quality and early recovery movement. No difference in recovery quality was observed between groups (P > 0.99). Cervical spinal nerve locoregional anesthesia appears well-tolerated and useful in reducing cumulative anesthetic agent requirement and may decrease the need for additional sedation/analgesia in horses undergoing anesthetized prosthetic laryngoplasty.

A pilot study of optical neuronavigation-guided brain biopsy in the horse using anatomic landmarks and fiducial arrays for patient registration

Background

Optical neuronavigation‐guided intracranial surgery has become increasingly common in veterinary medicine, but its use has not yet been described in horses.

Objectives

To determine the feasibility of optical neuronavigation‐guided intracranial biopsy procedures in the horse, compare the use of the standard fiducial array and anatomic landmarks for patient registration, and evaluate surgeon experience.

Animals

Six equine cadaver heads.

Methods

Computed tomography images of each specimen were acquired, with the fiducial array rigidly secured to the frontal bone. Six targets were selected in each specimen. Patient registration was performed separately for 3 targets using the fiducial array, and for 3 targets using anatomic landmarks. In lieu of biopsy, 1 mm diameter wire seeds were placed at each target. Postoperative images were coregistered with the planning scan to calculate Euclidian distance from the tip of the seed to the target.

Results

No statistical difference between registration techniques was identified. The impact of surgeon experience was examined for each technique using a Mann‐Whitney U test. The experienced surgeon was significantly closer to the intended target (median = 2.52 mm) than were the novice surgeons (median = 6.55 mm) using the fiducial array (P = .001). Although not statistically significant (P = .31), for the experienced surgeon the median distance to target was similar when registering with the fiducial array (2.47 mm) and anatomic landmarks (2.58 mm).

Conclusions and Clinical Importance

Registration using both fiducial arrays and anatomic landmarks for brain biopsy using optical neuronavigation in horses is feasible.