Effects of midazolam on cardiovascular responses and isoflurane requirement during elective ovariohysterectomy in dogs

Background

A prospective, randomized, placebo-controlled, blinded clinical study was conducted to determine whether a single dose of midazolam affects the cardiovascular response to surgical manipulation of the ovaries during elective ovariohysterectomy. Thirty-nine client-owned dogs undergoing elective ovariohysterectomy were recruited. After scoring cage demeanour, dogs were premedicated with acepromazine (0.03 mg kg^-1) and pethidine (3 mg kg^-1) intramuscularly into the quadriceps muscle and 20 min later sedation was scored. Anaesthesia was induced with propofol intravenously (IV) to effect. The study treatment (group M: midazolam (0.25 mg kg^-1); or group P: placebo (Hartmann’s solution) (0.125 ml kg^-1)) was administered IV before the intra-operative manipulation of the first ovary. Anaesthesia was maintained with isoflurane in oxygen. Morphine (0.3 mg kg^-1 IV) was administered prior to the start of surgery. The vaporizer setting was adjusted according to the depth of anaesthesia. If an end-tidal isoflurane concentration (FE’Iso) above 1.6% was required additional analgesia was provided with fentanyl (2 μg kg^-1). Dogs received meloxicam (0.2 mg kg^-1 IV) at the end of procedure. Heart rate, mean arterial blood pressure, respiratory rate and end-tidal partial pressure of carbon dioxide as well as FE’Iso were recorded and analysed.

Results

A statistical significant difference between groups was detected in FE’Iso, with group M requiring a significantly lower FE’Iso than group P (14.3%) after administration of midazolam. No differences between groups was shown for percentage change in heart rate and mean arterial blood pressure, or end-tidal carbon dioxide and requirement for mechanical ventilation, or rescue analgesia. There was no statistically significant difference in the incidence of complications in group M and P. Group M received significantly more succinylated gelatin solution pre-administration of midazolam than group P, but no differences in fluid administration post-administration of the study treatment (midazolam/placebo) were detected. No statistical significant difference was demonstrated for the use of anticholinergic agents, dobutamine or noradrenaline.

Conclusion

No significant effect on cardiovascular parameters could be observed with administration of midazolam, but a modest (14.3%) isoflurane-sparing effect was detected.

Outcomes of elective gonadectomy procedures performed on dogs and cats by veterinary students and shelter veterinarians in a shelter environment

OBJECTIVE To determine complication rates for elective gonadectomy procedures performed by veterinary students on dogs and cats in an animal shelter, characterize these complications, and compare rates with those for shelter-employed veterinarians (SEVs). DESIGN Retrospective cohort study. ANIMALS 10,073 dogs and cats for which gonadectomy was performed by a veterinary student (n = 3,048 surgeries) or SEV (7,025 surgeries) at an urban animal shelter over a 16-month period. PROCEDURES Electronic medical records for included dogs and cats were reviewed and data collected regarding patient signalment, duration of gonadectomy, surgeon type (student or SEV), and types of surgical complications recorded (including death or euthanasia) during the period from anesthetic induction to 72 hours after surgery. Complication and mortality rates were compared between veterinary students and SEVs. RESULTS No significant differences were identified between students and SEVs regarding rates of overall complications for both species, minor complications for both species, major complications for both species, and overall complications for dogs or cats specifically. The most common complications were self-limiting, with no long-term consequences, for both students and SEVs. Differences in mortality rates between students and SEVs could not be definitively determined owing to low numbers of nonsurviving patients. CONCLUSIONS AND CLINICAL RELEVANCE With judicious case selection and as a part of a surgical training program, complication rates for veterinary student-performed gonadectomy procedures for dogs and cats were no different from those for SEV-performed gonadectomy procedures. We believe such information regarding patient outcomes will allow shelter staff to make informed decisions and help them in discussions with stakeholders who may have concerns about student participation.

Reduced risk of pneumonia after changes in anesthetic procedures for dogs receiving repeated anesthesia for radiation treatment

Radiation therapy requires repeated anesthetic administration to patients who often have multiple comorbidities contributing to an increased rate of anesthetic complications such as pneumonia. This is a retrospective observational study in which data were collected from 146 medical records of dogs receiving repeat anesthesia for radiation treatment from prior to management changes and compared to data from 149 cases treated after completion of management changes. The objective was to determine if changes in case management protocol that were put in place decreased the risk of pneumonia development among these patients. Management changes that were made included the following: decrease in anticholinergic and pure-mu opioid use, change in positioning during intubation and recovery, prophylactic treatment of nausea, timing of cuff inflation and deflation, and aseptic handling of intubation equipment. There was a significant association between diagnosis of pneumonia and the following: pre- vs. post-changes to protocol, presence of a neurologic tumor, presence of respiratory disease, presence of megaesophagus, and number of radiation fractions completed. Diagnosis of pneumonia did not vary significantly by age group, body weight category, or sex. In a multivariable logistic regression model that controlled for the effects of the three concurrent diseases and fractions completed, the odds of being diagnosed with pneumonia were approximately 10 times greater among dogs anesthetized prior to management changes (odds ratio = 9.9, 95% CI = 2.0-48.7, P = 0.005).

The ASA Physical Status Classification: What Is the Evidence for Recommending Its Use in Veterinary Anesthesia?-A Systematic Review

Background: The effectiveness of the American Society of Anesthesiologists (ASA) Physical Status (PS) classification to identify the animals at a greater risk of anesthesia-related death and complications is controversial. In this systematic review, we aimed to analyze studies associating the ASA PS scores with the outcome of anesthesia and to verify whether there was any evidence for recommending the use of the ASA PS in veterinary patients.

Methods: Research articles found through a systematic literature search were assessed for eligibility, and data were extracted and analyzed using random-effects analysis.

Results: A total of 15 observational prospective and retrospective studies including 258,298 dogs, cats, rabbits, and pigs were included. The analysis found consistency between the studies showing that dogs, cats and rabbits with an ASA-PS ≥III had 3.26 times (95% CI = 3.04–3.49), 4.83 times (95% CI = 3.10–7.53), and 11.31 times (95% CI = 2.70–47.39), respectively, the risk of anesthesia-related death within 24 h (dogs) and 72 h (cats and rabbits) after anesthesia compared with those with an ASA PS <III. In addition, the analysis showed that dogs and cats with ASA PS ≥III had 2.34 times the risk of developing severe hypothermia during anesthesia (95% CI = 1.82–3.01).

Conclusions: The simple and practical ASA PS was shown to be a valuable prognostic tool and can be recommended to identify an increased risk of anesthetic mortality until 24–72 h after anesthesia, and a greater risk of development severe intraoperative hypothermia.

Safety and feasibility of stereotactic radiotherapy using computed portal radiography for canine intracranial tumors

Stereotactic radiotherapy is a highly conformal treatment option for intracranial and extracranial malignancies. Stereotactic radiotherapy utilizes specialized equipment specifically designed to avoid normal tissue while delivering ablative treatments with submillimeter precision and accuracy. Linear accelerator based stereotactic radiotherapy incorporates on-board image guidance utilizing cone beam computed tomography (CT). Many institutions lack the ability to provide image guidance with cone beam CT but delivery of highly conformal treatments with submillimeter precision and accuracy is still feasible. The purpose of this retrospective, pilot study was to describe clinical outcomes for a group of dogs with neurological disease that were treated with an stereotactic radiotherapy technique utilizing intensity modulated radiation therapy, megavoltage computed portal radiography, a bite plate, thermoplastic mold, and mask based positioning system. Twelve dogs with neurological clinical signs were included. The diagnosis of intracranial tumor was made based on advanced imaging (12/12) and confirmed via histopathology (3/12). Twelve courses of stereotactic radiotherapy, utilizing three fractions of 8.0 Gy, were delivered on alternating days. Self-resolving neurological deterioration was observed in two patients during stereotactic radiotherapy. Neurological progression free interval and median survival time were 273 days (range: 16-692 days) and 361 days (range: 25-862 days). Stereotactic radiotherapy using computed portal radiography may be a safe treatment option for dogs with intracranial tumors.

The Association of Shelter Veterinarians' 2016 Veterinary Medical Care Guidelines for Spay-Neuter Programs

As community efforts to reduce the overpopulation and euthanasia of unwanted and unowned cats and dogs have increased, many veterinarians have increasingly focused their clinical efforts on the provision of spay-neuter services. Because of the wide range of geographic and demographic needs, a wide variety of spay-neuter programs have been developed to increase delivery of services to targeted populations of animals, including stationary and mobile clinics, MASH-style operations, shelter services, community cat programs, and services provided through private practitioners. In an effort to promote consistent, high-quality care across the broad range of these programs, the Association of Shelter Veterinarians convened a task force of veterinarians to develop veterinary medical care guidelines for spay-neuter programs. These guidelines consist of recommendations for general patient care and clinical procedures, preoperative care, anesthetic management, surgical procedures, postoperative care, and operations management. They were based on current principles of anesthesiology, critical care medicine, infection control, and surgical practice, as determined from published evidence and expert opinion. They represent acceptable practices that are attainable in spay-neuter programs regardless of location, facility, or type of program. The Association of Shelter Veterinarians envisions that these guidelines will be used by the profession to maintain consistent veterinary medical care in all settings where spay-neuter services are provided and to promote these services as a means of reducing sheltering and euthanasia of cats and dogs.

Puppy survival and vigor associated with the use of low dose medetomidine premedication, propofol induction and maintenance of anesthesia using sevoflurane gas-inhalation for cesarean section in the bitch

The safety of an anesthetic protocol consisting of medetomidine hydrochloride (7 μg/kg iv) as premedicant, propofol, (1-2 mg/kg iv) as induction agent and sevoflurane, at 2% in oxygen for maintenance of anesthesia was studied in 292 cesarean sections (CSs) and 2232 puppies delivered. Medetomidine effects were reversed using atipamezole hydrochloride at 50 μg/puppy sc immediately following delivery and in the bitch iv immediately following surgery. The protocol's safety for puppies was expressed using survival immediately, 2 h and 7 d after delivery, and Apgar scores (measurement starting 15 min after delivery of the last puppy). The maternal survival rate was established immediately, 2 h and 7 d after cesarean section (CS). The CSs included 148 on Boerboel, 84 on English bulldog and 60 on other purebred bitches, which resulted in 1378, 541 and 313 puppies, respectively. Boerboel, English bulldog and other purebred bitches yielded 97.39%, 96.67% and 91.69% live puppies at delivery, 95.43%, 88.35% and 89.78% alive by 2 h and 89.19%, 79.11% and 84.03% alive by 7 d. Sixteen (1.16%), 32 (5.59%) and 4 (1.28%) malformed Boerboel, English bulldog and other purebred puppies were euthanized. Thirty five, 18 and 26, Boerboel, English bulldog and other purebred puppies were stillborn respectively, of which 12, 9 and 15, respectively had been discovered dead upon ultrasound examination immediately before CS. After correction for fetuses found dead on ultrasound examination and malformed euthanized puppies, 98.21%, 95.60% and 94.30% of Boerboel, English bulldog and other purebred puppies survived until 2 h and 91.78%, 87.17% and 88.26% until 7 d. Two-hour survival rates are negatively correlated to the proportion of puppies in a litter with scores of 8 or below (r = 0.14, P = 0.01, n = 292 litters) and tends to be positively correlated to the lowest Apgar score in a litter (r = 0.11, P = 0.05, n = 292 litters). This study shows that medetomidine hydrochloride in the protocol used is a safe premedicant in bitches prior to cesarean section and is associated with good puppy vigor as well as 2 h and 7 d puppy survival rates. The use of medetomidine as premedicant permitted use of less than half the dose of propofol usually required as induction agent.

Perioperative support reduces mortality of obese BALB/c mice after ovariectomy

The incidence of obesity is on the rise in most western countries and represents major risks to health. Obesity causes complex metabolic dysfunctions and can be associated with a large number of secondary diseases. To investigate causal mechanisms of obesity and develop better options for treatment, researchers study the condition in animal models. In addition to genetically engineered animal models, diet-induced obesity is often used because it occurs similarly in animals as it does in humans. For several types of investigations that use obesity models, investigators must carry out surgical interventions and they frequently encounter severe perioperative complications induced by anesthesia. In an example of this problem, we observed 100% mortality in obese BALB/c mice after ovariectomy, despite no obvious surgical complications. We supposed that a failure to recover from surgery was the primary cause of this increased mortality. Therefore, to support their recovery from surgery we administered atropine to obese mice in order to facilitate blood circulation, and we also increased the oxygen content of the ambient air. With this specific support before and after surgery, we increased the survival rate of obese ovariectomized mice up to 83%. These results confirm the assumption that obesity is a risk factor for the recovery of obese animal models after ovariectomy, and they highlight the need to provide additional interventions for such experimental animals.

Perianesthetic morbidity and mortality in dogs undergoing cervical and thoracolumbar spinal surgery

OBJECTIVE

To evaluate and compare perioperative morbidity and mortality in dogs undergoing cervical and thoracolumbar spinal surgery.

STUDY DESIGN

Prospective case series.

ANIMALS

157 dogs undergoing cervical or thoracolumbar spinal surgery.

METHODS

Data were collected sequentially on canine cases presented from the Neurology Section of the North Carolina State University Veterinary Teaching Hospital for anesthesia and surgery for cervical spinal cord disease. Simultaneously, data were collected on all thoracolumbar spinal surgery cases during the same time period. Data included signalment, drugs administered, surgical approach, disease process, cardiac arrhythmias during anesthesia, and outcome.

RESULTS

Data were collected from 164 surgical events in 157 dogs. There were 52 cervical approaches; four dorsal and 48 ventral. All thoracolumbar surgeries were approached dorsolaterally. Four dogs 4/52 (7.6%) undergoing a cervical approach did not survive to discharge. Two dogs (2/8; 25%) underwent atlanto-axial (AA) stabilization and suffered cardiovascular arrest and two dogs (2/38; 5.2%) undergoing cervical ventral slot procedures were euthanized following anesthesia and surgery due to signs of aspiration pneumonia. All dogs undergoing thoracolumbar surgery survived until discharge (112/112). Mortality in dogs undergoing cervical spinal surgery was greater compared with dogs undergoing thoracolumbar spinal surgery (p = 0.009), however, in dogs undergoing decompressive disc surgery, intraoperative death rates were not different between dogs undergoing a cervical compared with thoracolumbar approaches (p = 0.32) nor was there a significant difference in overall mortality (p = 0.07).

CONCLUSION AND CLINICAL RELEVANCE

Overall, dogs undergoing cervical spinal surgery were less likely to survive until discharge compared with dogs undergoing thoracolumbar spinal surgery. Mortality in dogs undergoing cervical intervertebral disc decompression surgery was no different than for dogs undergoing thoracolumbar intervertebral disc decompression surgery. However, dogs undergoing cervical intervertebral disc decompression surgery should be considered at risk for aspiration pneumonia.

Perianesthetic complications in dogs undergoing magnetic resonance imaging of the brain for suspected intracranial disease

OBJECTIVE

To evaluate the occurrence of perianesthetic complications in dogs undergoing MRI for suspected intracranial disease and identify risk factors associated with observed complications.

DESIGN

Retrospective case-control study.

ANIMALS

238 client-owned dogs undergoing MRI of the brain.

PROCEDURES

Signalment, clinical signs, neurologic examination findings, presumptive diagnosis, anesthesia-related variables, whether CSF was collected and CSF analysis results, severe perianesthetic complications (need for a ventilator following anesthesia or perianesthetic death), and anesthetic recovery time were recorded. Selected factors were compared between dogs with and without intracranial lesions and dogs with and without perianesthetic complications (including severe complications and prolonged anesthetic recovery [> 20 minutes from the end of anesthesia to extubation]).

RESULTS

3 of 149 (2%) dogs with and 0 of 89 dogs without intracranial lesions required ventilation following anesthesia; the difference was nonsignificant. Recovery time was significantly longer in dogs with (median, 15 minutes) than in dogs without (10 minutes) intracranial lesions. Abnormal mentation prior to anesthesia was the only clinical sign that differed significantly between dogs with (15/26 [58%]) and without (70/212 [33%]) perianesthetic complications. A significantly larger proportion of dogs with perianesthetic complications had intracranial masses (13/26 [50%]), compared with dogs without these complications (56/212 [26%]).

CONCLUSIONS AND CLINICAL RELEVANCE

Dogs with complications were more likely to have had intracranial lesions than were dogs without complications, but few dogs had severe complications. Abnormal mentation was more common in dogs with than in dogs without complications. Prospective studies to further evaluate perianesthetic risk factors and procedures for improving outcomes in these patients are warranted.

Veterinary and human anaesthesia: an overview of some parallels and contrasts

The history of human and veterinary anaesthesia is both intertwined and parallel. Physicians and anaesthetists often first experimented on animals and developments from human anaesthesia have been incorporated into veterinary medicine. Within veterinary medicine, anaesthesia is a specialty discipline as it is in human medicine. Veterinary anaesthetists undertake additional training and rigorous examinations for a diploma or fellowship. In contrast to human anaesthesia in Australia and New Zealand, veterinary anaesthesia is often performed by non-specialists and by veterinary nurses. Veterinary anaesthesia uses many of the same drugs for premedication, induction and maintenance of anaesthesia as human anaesthesia. However, there are species specific effects of some of the drugs used that differ from the effects in humans. Furthermore, some agents, particularly alpha-2 adrenoreceptor agonists and ketamine, are used very widely in veterinary practice. Also in contrast to most human anaesthesia, in large animal and exotic animal practice the patients can present a physical danger to the anaesthetist. The most notable contrast between human and veterinary anaesthesia is in the reported perioperative complication and mortality rates, with a species dependent perianaesthetic mortality of up to 2% in dogs, cats and horses and greater than 2% in guinea pigs and birds, which is up to 100-fold higher than in human anaesthesia.

An evidence-based medicine approach to small animal anaesthetic mortality in a referral practice: the influence of initiating three recommendations on subsequent anaesthetic deaths

OBJECTIVE

To evaluate anaesthetic death after implementation of recommendations and its risk factors in a small animal practice.

STUDY DESIGN

Observational cohort study.

ANIMALS

All cats and dogs anaesthetized at the Centre Hospitalier Vétérinaire des Cordeliers during two periods, from April 15th, 2008 to April 15th, 2010 (period 1) and from June 15th, 2010 to August 24th, 2011 (period 2).

METHODS

Death occurring during or before full recovery from anaesthesia was recorded. At the end of period 1, a logistic regression model was generated to describe anaesthetic death and identify risk factors. Potential risk factors in our practice setting were identified, and three recommendations, relating to improving physical status and anaesthetic/analgesic regimen implemented for period 2. The relationship between anaesthetic death and recorded variables were analyzed, and where relevant, compared between periods.

RESULTS

Six thousand two hundred and thirty-one animals underwent general anaesthesia. The overall death rate during period 1 was 1.35% (48 in 3546, 95% CI [1.0-1.7%]) and during period 2 was 0.8% (21 in 2685, 95% CI [0.6-1.2%]). For sick animals (ASA status 3 and over), the overall death rate was 4.8% (45 of 944 95% [CI 3.5-6.4%]) during period 1 and 2.2% (18 of 834 95% CI [1.3-3.5%]) during period 2; this represented a significant decrease in death rate in period 2 (p = 0.002). In period 2, the main factors associated with an increased odds ratio of anaesthetic death were poor health status (ASA physical status classification) and old age. Species, gender, anaesthetic regimen, the nature and urgency of the procedure were not associated with risk.

CONCLUSION AND CLINICAL RELEVANCE

Following evidence based recommendations, the death rate related to anaesthesia was significantly decreased during period 2 compared to period 1. Application of evidence-based medicine may contribute to an effective approach to decrease death rates. Other factors, not monitored in this study, may also have had an impact.

Predictors of outcome in dogs undergoing thoracic surgery (2002-2011)

OBJECTIVE

To evaluate mortality in a canine population undergoing thoracic surgery and identify factors which may be associated with outcome.

STUDY DESIGN

Retrospective cohort study.

ANIMALS

286 dogs anaesthetized for thoracic surgery at the Royal Veterinary College between June 2002 - June 2011.

METHODS

Variables examined included: signalment; ASA status; nature of disease; presence of co-morbidities; pre-anaesthetic oxygen requirement; surgical approach; anaesthesia management [anaesthetic agents; requirement for thoracocentesis; central venous pressure measurement; duration of surgery and anaesthesia; use of colloids, blood products, inotropes or neuromuscular blocking agents (NMBA)]. Outcome was defined as either non-survival to 24 hours after surgery or (having survived to 24 hours) to discharge. Univariate and multivariable logistic regressions were performed to identify risk factors associated with non-survival.

RESULTS

Overall non-survival (excluding those euthanased) to discharge was 5.9%. Non-survival was 2.2% at 24 hours and 3.6% at time of discharge. Non-survival to 24 hours was associated with pre-anaesthetic oxygen requirement (odds ratio (OR) 12.2 [95% CI 1.8-84.5]) and NMBA use (OR 9.6 [95% CI 1.6-57.9]). Non-survival to discharge was associated with surgical duration, with surgeries >180 minutes having OR 16.9 [95% CI 2.0-144.0] compared to surgeries ≤90 minutes and blood product use (OR 4.6 [95% CI 1.3-14.6]). No association was found between ASA category and non-survival at 24 hours (OR 1.4 [95% CI 0.2-11.7]) or discharge (OR 4.4 [95% CI 0.6-34.3]). Significant associations were found between NMBA use and ASA category (p = 0.046), surgical duration (p = 0.002), use of colloids (p = 0.011), blood products (p = 0.001) and inotropes and/or vasopressors (p < 0.001).

CONCLUSIONS AND CLINICAL RELEVANCE

Variables significantly associated with non-survival from canine thoracic surgery at 24 hours include NMBA use and pre-anaesthetic oxygen requirement. Blood product use and increasing surgical duration were associated with non-survival to hospital discharge. The associations may relate to the need for such products in the most complicated cases.

Canine anaesthetic death in Spain: a multicentre prospective cohort study of 2012 cases

OBJECTIVE

To study current perianaesthetic mortality in dogs in Spain and to identify the main risk factors predisposing to perianaesthetic mortality in our country.

STUDY DESIGN

A multicentre prospective cohort study.

ANIMAL POPULATION

Dogs anaesthetised for different surgical and diagnostic procedures at 39 Spanish veterinary clinics between February 2007 and March 2008.

METHODS

Data of patients, procedures and anaesthetic management were recorded. Anaesthetic death was defined as perioperative death within 24 hours of the procedure end. A multivariate study evaluated perinanaesthetic death using logistic binary regression models with the Wald technique.

RESULTS

2012 animals were included in the analyses. Twenty-six dogs died. The global mortality rate was 1.29% (95% Confidence interval (95% CI): 0.88-1.89%). ASA I-II was 0.33% (95 CI: 0.14-0.78%); ASA III-V was 4.06% (95% CI: 2.67-6.13%). Most deaths occurred during the post-operative period (20 dogs, 77%). The multivariate analysis revealed that high ASA grade was associated with an increased risk of mortality. The use of opioids plus NSAIDs during anaesthesia was related with a decrease of the risk.

CONCLUSIONS

Perianaesthetic mortality in dogs in Spain was 1.29% (95% CI: 0.88-1.89%). ASA grade was the main prognostic factor of likelihood of death. The use of some analgesics (opioids and NSAIDs) in the perioperative period was associated with reduced odds of death and may be protective.

CLINICAL RELEVANCE

Evaluation and stabilisation of patients before interventions may help lower risk of death during the anaesthesia. In addition to their use for welfare purposes, analgesics may be beneficial in reducing anaesthetic-related deaths.

Alfaxalone for total intravenous anaesthesia in dogs undergoing ovariohysterectomy: a comparison of premedication with acepromazine or dexmedetomidine

OBJECTIVE

To describe alfaxalone total intravenous anaesthesia (TIVA) following premedication with buprenorphine and either acepromazine (ACP) or dexmedetomidine (DEX) in bitches undergoing ovariohysterectomy.

STUDY DESIGN

Prospective, randomised, clinical study.

ANIMALS

Thirty-eight healthy female dogs.

METHODS

Following intramuscular buprenorphine (20 μg kg(-1) ) and acepromazine (0.05 mg kg(-1) ) or dexmedetomidine (approximately 10 μg kg(-1) , adjusted for body surface area), anaesthesia was induced and maintained with intravenous alfaxalone. Oxygen was administered via a suitable anaesthetic circuit. Alfaxalone infusion rate (initially 0.07 mg kg(-1) minute(-1) ) was adjusted to maintain adequate anaesthetic depth based on clinical assessment. Alfaxalone boluses were given if required. Ventilation was assisted if necessary. Alfaxalone dose and physiologic parameters were recorded every 5 minutes. Depth of sedation after premedication, induction quality and recovery duration and quality were scored. A Student's t-test, Mann-Whitney U and Chi-squared tests determined the significance of differences between groups. Data are presented as mean ± SD or median (range). Significance was defined as p < 0.05.

RESULTS

There were no differences between groups in demographics; induction quality; induction (1.5 ± 0.57 mg kg(-1) ) and total bolus doses [1.2 (0 - 6.3) mg kg(-1) ] of alfaxalone; anaesthesia duration (131 ± 18 minutes); or time to extubation [16.6 (3-50) minutes]. DEX dogs were more sedated than ACP dogs. Alfaxalone infusion rate was significantly lower in DEX [0.08 (0.06-0.19) mg kg(-1) minute(-1) ] than ACP dogs [0.11 (0.07-0.33) mg kg(-1) minute(-1) ]. Cardiovascular variables increased significantly during ovarian and cervical ligation and wound closure compared to baseline values in both groups. Apnoea and hypoventilation were common and not significantly different between groups. Arterial haemoglobin oxygen saturation remained above 95% in all animals. Recovery quality scores were significantly poorer for DEX than for ACP dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Alfaxalone TIVA is an effective anaesthetic for surgical procedures but, in the protocol of this study, causes respiratory depression at infusion rates required for surgery.

AAHA anesthesia guidelines for dogs and cats

Safe and effective anesthesia of dogs and cats rely on preanesthetic patient assessment and preparation. Patients should be premedicated with drugs that provide sedation and analgesia prior to anesthetic induction with drugs that allow endotracheal intubation. Maintenance is typically with a volatile anesthetic such as isoflurane or sevoflurane delivered via an endotracheal tube. In addition, local anesthetic nerve blocks; epidural administration of opioids; and constant rate infusions of lidocaine, ketamine, and opioids are useful to enhance analgesia. Cardiovascular, respiratory, and central nervous system functions are continuously monitored so that anesthetic depth can be modified as needed. Emergency drugs and equipment, as well as an action plan for their use, should be available throughout the perianesthetic period. Additionally, intravenous access and crystalloid or colloids are administered to maintain circulating blood volume. Someone trained in the detection of recovery abnormalities should monitor patients throughout recovery. Postoperatively attention is given to body temperature, level of sedation, and appropriate analgesia.

Anesthetic agents and complications in Vietnamese potbellied pigs: 27 cases (1999-2006)

OBJECTIVE

To document complications associated with preanesthetic and anesthetic agents used in Vietnamese potbellied pigs and identify predictors of complications.

DESIGN

Retrospective case series.

ANIMALS

27 potbellied pigs (14 female and 13 male) ranging in age from 0.25 to 15 years old and ranging in body weight from 5.9 to 169 kg (13.0 to 371.8 lb) that were anesthetized on 32 occasions between 1999 and 2006.

PROCEDURES

Data, including perianesthetic management, anesthetic agents and dosages, complications, and outcome, were retrieved from medical records. Patient information, anesthetic agents, and duration of anesthesia were evaluated as predictors for development of complications.

RESULTS

Anesthesia was maintained with isoflurane or sevoflurane during 30 anesthetic episodes. Commonly used premedicants were butorphanol, atropine, and midazolam administered in combination with xylazine or medetomidine and a combination of tiletamine-zolazepam and butorphanol. Anesthesia was induced with an inhalation agent on 15 occasions, via injection of ketamine on 10 occasions, and via injection of propofol on 3 occasions. Complications included hypoventilation (16/24 [67%]), hypotension (16/25 [64%]), hypothermia (15/31 [48%]), bradycardia (9/32 [28%]), and prolonged recovery time (7/32 [22%]). None of the factors evaluated were associated with development of these complications. All pigs survived anesthesia.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that a variety of anesthetic agent combinations can be used to provide anesthesia in potbellied pigs with satisfactory outcomes. Although there were high incidences of hypoventilation, hypotension, and hypothermia, no specific anesthetic agent was associated with development of these complications.

A comparison of anesthetic complications between diabetic and nondiabetic dogs undergoing phacoemulsification cataract surgery: a retrospective study

OBJECTIVE

To compare the incidence of anesthetic complications in diabetic and nondiabetic dogs undergoing general anesthesia and phacoemulsification cataract surgery.

PROCEDURE

The medical and anesthetic records of all dogs undergoing phacoemulsification cataract surgery at Davies Veterinary Specialists between 2005 and 2008 were reviewed. Anesthetic records were evaluated by an ECVAA Diplomate. Dogs for which records were incomplete were excluded. The anesthetic technique, including all drugs administered in the perioperative period, was recorded. The anesthetic complications investigated included hypotension (MAP (mmHg): >or=55 none/mild; <or=54 moderate/severe), bradycardia (<60 bpm associated with hypotension) and hypothermia (esophageal temperature <36.7 degrees C). Where hypotension was present, the method of and response to treatment was recorded. The incidence of severe hyperglycemia (blood glucose >13.75 mmol/L (250 mg/dL)) in the diabetic group was also assessed.

RESULTS

66 diabetic and 64 nondiabetic dogs were included in the study. Diabetic dogs were more likely to develop moderate and severe intraoperative hypotension than nondiabetic dogs. Forty-four percent of diabetic dogs had at least one episode of severe hyperglycemia whilst anesthetized.

CONCLUSIONS

Diabetic dogs undergoing phacoemulsification are more likely to suffer the anesthetic complications of moderate and severe hypotension than nondiabetic dogs. The increased incidence and severity of hypotension in diabetic dogs may be explained by hypovolemia secondary to hyperglycemia and resultant osmotic diuresis.

Survey of veterinary practice policies and opinions on neutering dogs

A cross-sectional survey was conducted in 2008 to obtain information on the advice veterinary practices currently give to their clients and the opinions of veterinary surgeons regarding neutering of dogs. An additional survey of dog owners was conducted to obtain information on the neuter status of the general dog population in Great Britain. A significantly higher proportion of practices had a policy for the age of neutering bitches than for dogs. The average recommended age for neutering bitches was 6.5 months (95 per cent confidence interval [CI] 3.1 to 9.7 months) and for dogs it was 7.5 months (95 per cent CI 1.4 to 13.6 months). There was very little agreement between veterinary practices as to whether bitches should be allowed to have their first season before neutering, with 164 of 973 respondents (16.9 per cent) always recommending this, 198 (20.3 per cent) recommending it most of the time, 203 (20.9 per cent) sometimes, 203 (20.9 per cent) rarely and 201 (20.6 per cent) never recommending it. The owner study showed that 54 per cent of dogs (233 of 431) were neutered, with the North region having the lowest proportion of neutered dogs (11 of 25; 44.0 per cent).

Comparison of invasive and non-invasive blood pressure monitoring during clinical anaesthesia in dogs

Monitoring blood pressure during anaesthesia is widely recommended in man and animals. The accuracy of any device used to measure blood pressure is an important consideration when selecting monitoring equipment, the ANSI/AAMI SP10 standard is widely cited in this respect in recent veterinary publications. Blood pressure was monitored using invasive and non-invasive techniques during clinical anaesthesia in 19 dogs. The results were compared using Bland-Altman analysis. The bias (and limits of agreement) between invasive and non-invasive measurement was 7.1 mmHg (+/-34.7) for systolic blood pressure, -1.8 mmHg (+/-27.4) for mean blood pressure and 6.9 mmHg (+/-27.5) for diastolic blood pressure. In a clinical setting the bias between invasive and non-invasive measurement techniques was similar or smaller than laboratory reports, however the limits of agreement were considerably wider suggesting that care should be exercised when interpreting NIBP values.

Clinical comparison of a novel extracapsular stabilization procedure and tibial plateau leveling osteotomy for treatment of cranial cruciate ligament deficiency in dogs

OBJECTIVE

To develop and test a novel extracapsular technique, TightRope CCL technique (TR), and compare its 6-month clinical outcomes to tibial plateau leveling osteotomy (TPLO) in dogs with cranial cruciate ligament (CCL) deficiency.

STUDY DESIGN

Prospective clinical cohort study.

ANIMALS

Medium, large, and giant breed dogs (n=47) with CCL deficiency.

METHODS

Before clinical use, TR was evaluated by mechanical testing and the surgical technique was developed and evaluated in canine cadavers. For the clinical study, dogs were assigned to either TR (n=24) or TPLO (n=23) groups and the assigned technique performed after arthroscopic assessment and treatment of joint pathology. Postoperative management was standardized for both groups. Outcome measures were performed immediately postoperatively and up to 6 months after surgery and included complication types and rate, subjective measurement of cranial drawer and tibial thrust, subjective assessment of radiographic progression of osteoarthritis (OA), and function using a validated client questionnaire (6 months only).

RESULTS

TR with a fiber tape suture had superior mechanical properties for creep, stiffness, yield load, and load at failure. Duration of anesthesia, total surgical time, and stabilization procedure (TR versus TPLO) were all significantly (P<.001) shorter for TR compared with TPLO. Complications requiring further treatment occurred in 12.5% of TR cases and 17.4% of TPLO cases. No significant differences were noted between groups for cranial tibial thrust, but cranial drawer was significantly (P<.05) lower in TR stifles at all postoperative time points. No significant differences were noted between groups for radiographic OA scores. No statistically or clinically significant differences were noted between TR and TPLO for scores for each of the client questionnaire categories.

CONCLUSIONS

TR resulted in 6-month outcomes that were not different than TPLO in terms of radiographic progression of OA and client-evaluated level of function. TR was associated with shorter anesthesia and surgery times as well as a lower complication rate.

CLINICAL RELEVANCE

The TR technique is safe and effective and can be considered an appropriate surgical option as part of the overall treatment plan for CCL deficiency in dogs.