2020 AAHA Anesthesia and Monitoring Guidelines for Dogs and Cats

Retrospective evaluation of preanesthetic oral gabapentin in cats receiving total injectable anesthesia in a high-quality, high-volume spay-neuter setting

This retrospective study investigated an anesthetic protocol for 573 cats (221 males, 352 females) in a high-quality, high-volume spay-neuter (HQHVSN) program, with a focus on the role of oral gabapentin in this protocol. Gabapentin (100 mg/cat) was administered to 233 cats (86 males, 147 females) approximately two hours preoperatively. All cats received intramuscular medetomidine (20 μg/kg) and ketamine (5 mg/kg) for induction, with anesthesia maintained via intermittent intravenous boluses of ketamine (2.5 mg/kg) and diazepam (0.125 mg/kg). Local lidocaine (4 mg/kg) administered intraperitoneally or intratesticularly. Meloxicam (0.3 mg/kg) was given preoperatively, and tramadol (1 mg/kg) was used as rescue analgesia. Anesthetic requirements and physiological variables, including preoperative respiratory rate (RR) and intraoperative averages for RR, pulse rate (PR), systolic arterial pressure (SAP), and hemoglobin oxygen saturation (SpO2), were compared between gabapentin and non-gabapentin cohorts. Gabapentin reduced preoperative RR and ketamine-diazepam requirements. Higher PR and SAP were observed in non-gabapentin cohorts. Transient apnea, the most common complication, resolved spontaneously. SpO2 was lower in non-gabapentin cohorts, with more cats showing SpO2 < 90 in females. No differences were noted in the need for atipamezole or tramadol rescue analgesia. Gabapentin effectively reduced anesthetic drug requirements without adversely affecting vital signs. Further prospective studies are required to validate these findings.

Efficacy of locally infiltrated tramadol compared to bupivacaine during elective ovariohysterectomy procedures in canine patients: A double-blinded randomized parallel study

Effective acute pain management is an integral component of modern veterinary surgery, in particular for pain arising from surgical wounds. Peri-incisional local anaesthetics are indicated to manage both intra- and postoperative pain. The aim of the study was to evaluate the use of tramadol as a local anaesthetic agent and its effects on postoperative pain. Sixteen dogs undergoing elective ovariohysterectomies were randomly assigned to receive either tramadol or bupivacaine as local anaesthetics. Acute postoperative pain levels were assed at 2-, 4-, and 6-h postinfiltration using a Glasgow Composite Measure Pain Scale - Short Form. Local wound effects, including swelling and bruising were also evaluated at 6- and 20-h intervals. No significant differences were found in pain scores between the tramadol and bupivacaine groups at any time interval (2-h: 2.5/24 compared to 3.5/24, p = 0.31; 4-h: 1.5/24 compared to 3/24. p = 0.31; 6-h: 0.5/24 compared to 1.5/24, p = 0.83, respectively). However tramadol demonstrated significantly less swelling compared to bupivacaine at the 20-h interval (1/3 compared to 2/3, p = 0.04). No difference in swelling scores at the 6-h interval, or bruising scores at the 20-h interval were found. Locally infiltrated tramadol offered comparable analgesic and local wound effects to that of bupivacaine, although further studies with larger sample sizes are required. This study shows the importance of discussions surrounding alternative local analgesic agents within the veterinary industry, which may ultimately lead to better patient care and outcomes.

Evaluation of the performance of three pulse oximeters at different probe positions in awake rabbits

In rabbits, pulse oximetry plays a crucial role in monitoring oxygen saturation (SpO2) and pulse rate (PR), but it can be challenging due to their small size, variable anatomy, limited measurement sites, and potential motion artifacts during measurements. This prospective randomized study aimed to assess the reliability of three pulse oximeters on the forelimb and tail of fifty awake, healthy European rabbits. Two pulse oximeters, the Masimo Rad-5 (device 1) and the Edan VE-H100B, were tested, with the latter using both a Y-clip (device 2) and the Nellcor OxiMax adhesive finger sensor (device 3). Reliable values of SpO2 and PR were considered ≥ 95% and ≥ 151 bpm, respectively, which are normal values in a healthy rabbit. Success rates of the devices were calculated as the ratio of reliable to unreliable/missing values and compared using χ2 tests. Correlation and agreement between PR and clinically measured heart rate (cHR) were assessed using the Pearson correlation coefficient (r) and Bland-Altman analysis, respectively. Success rates differed significantly among devices (p < 0.001). The SpO2 success rates were 46%, 95.6%, and 94.4% for devices 1, 2, and 3, respectively. The PR success rates were 54.6%, 63%, and 72.8% for devices 1, 2, and 3, respectively. Success rates were higher on the forelimb (>66%) than on the tail (>26%) across devices. Correlation between PR and cHR was stronger on forelimb (r > 0.80) than on tail (r < 0.70). Agreement between PR and cHR was similar among devices, with a mean bias ranging from -6.6 to 6.7 bpm, and limits of agreement from -33.8 to 41.5 bpm. The Edan devices showed superior ability to detect reliable values of SpO2 and PR compared to the Masimo in rabbits. The forelimb appears to be a more reliable site for pulse oximetry in rabbits than the tail.

Comparison of lidocaine incisional block techniques on early postoperative pain scores in dogs undergoing ovariohysterectomy

OBJECTIVE

To compare postoperative pain scores following lidocaine incisional block techniques (infiltration versus splash methods) with an intraperitoneal splash block in dogs undergoing ovariohysterectomy.

STUDY DESIGN

Prospective, randomized, double-blinded, clinical study.

ANIMALS

A total of 30 client-owned female dogs.

METHODS

All dogs were premedicated with intramuscular acepromazine (0.02 mg kg-1). General anesthesia was induced with intravenous propofol and maintained with isoflurane in oxygen. Fentanyl (2 μg kg-1) was administered intravenously before skin incision, and lidocaine (4 mg kg-1) splashed intraperitoneally during surgery. Dogs were randomly divided into two groups (n = 15 per group) based on incisional block technique, with blocks performed at the end of surgery. Group INC was administered incisional infiltration of lidocaine (2 mg kg-1 plus equal volume of saline, final dilution of 1%), with injection into subcutaneous tissues along in the incision. Group SP was administered an incisional splash of lidocaine on the subcutaneous tissues before skin closure. Both techniques were performed in each group, lidocaine for the designated treatment and saline for the other. Postoperative physiological variables were measured and pain was evaluated using the Glasgow Composite Measure Pain Scale-Short Form (CMPS-SF) at 30, 60, 90 and 120 minutes after extubation. Data were statistically analyzed using a linear mixed model with Bonferroni correction.

RESULTS

At 120 minutes after extubation, CMPS-SF pain scores were significantly lower in group SP than in group INC (1.9 ± 0.9 versus 2.9 ± 0.9, p = 0.002; mean ± standard deviation). However, pain scores in both groups were below the intervention threshold for rescue. No dogs required rescue analgesia.

CONCLUSIONS AND CLINICAL RELEVANCE

Both lidocaine incisional infiltration and splash, combined with intraperitoneal splash, provided effective analgesia for up to 2 hours postoperatively in dogs undergoing ovariohysterectomy. Lidocaine incisional splash is recommended as a simpler technique associated with lower pain scores.

Evaluation of Two Veterinary Oscillometric Noninvasive Blood Pressure (NIBP) Measurement Devices (petMAP Graphic II and High-Definition Oscillometry) in Dogs

Noninvasive blood pressure (NIBP) device performance in dogs may be influenced by extreme pressures and altered systemic vascular resistance (SVR). This study evaluated the agreement of two NIBP devices (HDO and petMAP) with invasive blood pressure (IBP) measurements, compliance with hypertension consensus statement criteria, and their trending ability (TA) across varying blood pressure and SVR ranges in awake and anesthetized dogs. Seven healthy Beagles were studied, with IBP recorded from the dorsal metatarsal artery and NIBP cuffs placed randomly on the front limb, hind limb, or base of the tail. Cardiac output was determined by thermodilution, and the systemic vascular resistance index (SVRI) was calculated by a standard formula. Bland-Altman, concordance rate, and polar plot analyses were used for statistical analysis. A total of 752 and 640 paired measurements were obtained for HDO and petMAP, respectively. Both devices showed good agreement with IBP for mean arterial pressure (MAP) at low blood pressure and the SVRI. At high blood pressure and the SVRI, agreement weakened, with substantial underestimation of systolic arterial pressure (SAP). Both devices demonstrated moderate to good TA for MAP and SAP. Overall, the best agreement was observed for MAP at a low SVRI, while agreement was moderate at hypertension (petMAP) and a high SVRI (petMAP, HDO).

Effect of perfusion index on oxygen reserve index accuracy in estimating arterial oxygen tension in anesthetized dogs: Data reanalysis

Multi-wave CO-oximetry, utilizing the oxygen reserve index (ORi), estimates arterial partial pressure of oxygen (PaO2) in mild hyperoxemia, between 100 and 200 mmHg, and concurrently quantifies local perfusion at the measurement site using the perfusion index (PI). This study explores how variations in PI influence the accuracy of ORi in estimating PaO2 in anesthetized dogs. Data from 37 mechanically ventilated dogs were retrospectively reanalyzed using a different approach. ORi and PI values were collected using a CO-oximeter. The data were categorized into four groups based on PI quartiles. In each group, the relationship between ORi and PaO2 was assessed using linear regression analysis, and the area under the receiver operating characteristic curve (AUROC) investigated the diagnostic performance of ORi in detecting PaO2 >  150 mmHg. Strong relationships between ORi and PaO2 were observed in groups with PI values <  2 (r2 ≥  0.63). The AUROC of ORi for identifying PaO2 > 150 mmHg decreased with PI >  2 compared to lower values (0.76 vs >  0.88). In this study, PI values >  2 negatively impacted ORi's ability to estimate PaO2, likely due to fluctuations in blood flow perfusing the measurement site. The results of this study suggests that consideration of the PI value is essential when titrating oxygen therapy using ORi in anesthetized dogs.

Assessment of ultrasound-guided external oblique intercostal block injections in dogs

OBJECTIVE

To describe a technique for an ultrasound-guided external oblique intercostal (EOI) block and compare the anatomic spread of two different volumes of new methylene blue injectate in dogs.

STUDY DESIGN

Blinded, prospective, experimental cadaveric study.

ANIMALS

A total of six Beagle dogs weighing 9.5 (8-12) kg [median (range)].

METHODS

To determine technique feasibility, computed tomography-based visualization of iodinated contrast spread following EOI injections in a single dog was performed. Subsequently, ultrasound-guided injections were performed bilaterally in six anesthetized dogs (12 hemithoraces), in the fascial plane between the external abdominal oblique and intercostal muscles, at the T9-T10 thoracic space. We assessed two randomly assigned injectate volumes: low volume (LV; 0.25 mL kg-1) and high volume (HV; 0.5 mL kg-1). Animals were then euthanized and immediately dissected to assess the spread of methylene blue and nerves stained.

RESULTS

Total distance of injectate spread was 100.3 ± 8.8 mm (mean ± standard deviation) and 81.2 ± 12.0 mm in HV and LV groups, respectively. Cranial distribution of stain terminated at intercostal spaces T7-8, T8-9 and T9-10 in 5/12 (HV, n = 3; LV, n = 2), 6/12 (HV, n = 3; LV, n = 3) and 1/12 (LV, n = 1) injections, respectively. Caudal distribution of stain terminated at intercostal spaces T10-11, T11-12, and T12-13 in 1/12 (HV, n = 1), 9/12 (HV, n = 3; LV, n = 6) and 2/12 (HV, n = 2) injections, respectively. HV and LV injections stained 1.8 ± 0.8 and 1.0 ± 0.6 intercostal nerves, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

The pattern of spread observed following ultrasound-guided EOI injections may be consistent with providing desensitization to nerves innervating the cranial and lateral abdomen. Further studies are needed to assess the clinical impact of these findings.

Incidence of postoperative acute kidney injury in dogs without pre-existing renal disease

Acute kidney injury (AKI) is defined as a sudden reduction in renal function, characterized by a rapid increase in serum creatinine (sCr) ≥ 0.3 mg/dL within 48 h with or without azotemia (sCr ≥ 1.7 mg/dL) and/or oliguria (urinary output <1 mL/kg/h for more than 6 h). Acute kidney injury is associated with increased mortality, prolonged hospitalization, and higher costs in both human and veterinary medicine. This study aimed to determine the incidence of postoperative AKI in dogs without pre-existing renal disease. A total of 170 dogs, admitted for elective surgery (ASA I-II) at a single university center, were included. The sCr levels were measured at the following times: procedure day (before anesthesia), 24 h, 48 h, and 7 days post-surgery (0 h, 24 h, 48 h, and 7d). Potential risk factors for AKI including patient characteristics (age, sex, pathologies, treatments), anesthetic protocol (drugs, type and rate of fluid therapy, procedure duration) and intraoperative complications were analyzed. Postoperative AKI was identified in 5 dogs (2.9, 95% CI: 1.3-6.7%) based on a sCr increase ≥0.3 mg/dL within 48 h post-surgery. A decrease in sCr (Mean: 0.87 SD = 0.2) was observed at 48 h (Mean: 0.84 SD = 0.24) (p < 0.001), returning to baseline by day 7 (Mean:0.89 SD = 0.22) (p = 0.127). Only a relationship between surgery duration and the probability of developing postoperative AKI was found (p = 0.037). Further studies are warranted to identify risk factors for AKI in dogs undergoing GA and improve its prevention optimizing postoperative management and prognosis.

A Preliminary Study: Evaluation of Oral Trazodone as a Strategy to Reduce Anesthetic Requirements in Bitches Undergoing Ovariectomy

The objective of this study was to evaluate the effects of trazodone as part of premedication in routine surgical procedures. A prospective, randomized, double-blinded clinical study was conducted on 16 adult female dogs undergoing elective ovariectomy. Behavioral responses were assessed after oral administration of trazodone (5 mg/kg) in eight dogs and compared with a control group (n = 8). Sedation levels at the time of induction and the required dose of propofol were recorded. Additionally, intraoperative fentanyl IV boluses (2.5 µg/kg) administered in response to surgical pain, along with heart rate (HR) and non-invasive arterial pressure (NIAP), were compared between groups. Dogs receiving trazodone exhibited significantly lower stress scores on the Clinic Dog Stress Scale (CDSS) and fewer episodes of vomiting after premedication, and they required lower doses of both propofol and intraoperative analgesia. These findings suggest that oral trazodone administration two hours before hospital arrival may help reduce preoperative stress in dogs undergoing elective ovariectomy. However, further studies with larger sample sizes are needed to confirm these results and fully evaluate the role of trazodone in preoperative protocols.

INTRAMUSCULAR MIDAZOLAM AND BUTORPHANOL ADMINISTERED PRIOR TO INTRAVENOUS ALFAXALONE PROVIDES SAFE AND EFFECTIVE ANESTHESIA IN GENTOO PENGUINS (PYGOSCELIS PAPUA)

General anesthesia is a crucial tool in health care and clinical practice involving wildlife, including penguins. A balanced general anesthetic technique that combines multiple drugs is beneficial for achieving sufficient anesthesia while minimizing the side effects of individual agents. However, only a few studies have explored the use of multimodal anesthesia in penguins. This study examined the effects of midazolam (benzodiazepine) and butorphanol (mixed j-opioid agonist and weak l-opioid antagonist) as preanesthetic agents in gentoo penguins (Pygoscelis papua). Midazolam and butorphanol were administered intramuscularly at 0.25 mg/kg each, followed by anesthesia induction and maintenance with alfaxalone administered intravenously. Sedation level, required alfaxalone dose, recovery time, heart rate, and noninvasive blood pressure were evaluated during anesthesia. Sedation intensity increased over time after premedication. When midazolam and butorphanol were used as preanesthetics, the required alfaxalone dose for induction was 4.8 ± 0.8 mg/kg, and the mean infusion rate of alfaxalone required to maintain anesthesia was 0.12 ± 0.05 mg/kg per minute. Recovery from anesthesia took 3 (1-7) (median [interquartile range]) min for extubation and 20 ± 12 (mean ± SD) min for complete recovery. Heart rates were maintained within the normal physiological range, and noninvasive blood pressure remained stable. Compared with previous investigations on anesthesia induction and maintenance using alfaxalone alone, the intramuscular administration of 0.25 mg/kg midazolam and 0.25 mg/kg butorphanol reduced the alfaxalone dose requirement for anesthesia induction and maintenance, thereby shortening recovery times.

Comparison of Perioperative Analgesic Efficacy of Lidocaine Intratesticular Block and Spermatic Cord Instillation in Feline Castration

Intratesticular block is an effective local anesthetic technique for castration; however, its use may be limited in cases of testicular masses or infections. Instillation is a simple technique used in several procedures, though studies investigating its application in feline castration remain scarce. Therefore, this study aimed to compare the perioperative analgesic efficacy of lidocaine intratesticular block and spermatic cord instillation in feline castration. Forty-five male cats were randomly divided into three groups: the intratesticular block group (IT), the spermatic cord instillation group (S), and the control group (C). All cats were anesthetized using the same protocol and both techniques were performed based on group assignments. Lidocaine (2 mg/kg) was administrated according to the designated route, while 0.9% normal saline was used for the alternative route and in the C group. Intraoperative parameters were recorded, showing that noninvasive blood pressure in the IT and S groups was significantly lower than in the C group. Although both lidocaine intratesticular block and spermatic cord instillation effectively reduce surgical noxious stimulation, intratesticular block is recommended as it provides more stable intraoperative vital signs and less postoperative pain. Therefore, spermatic cord instillation can be considered as an optional technique for managing pain in feline castration.

Agreement and Diagnostic Accuracy of New Linear Deflection Oscillometry and Doppler Devices for Hypotension Detection Compared to Invasive Blood Pressure in Anesthetized Dogs

Blood pressure (BP) monitoring is essential during anesthesia to maintain cardiovascular stability and detect hypotension. This study evaluated the agreement and diagnostic accuracy of linear deflection oscillometry (LDO) and Doppler compared to invasive blood pressure (IBP) in anesthetized dogs. Eleven healthy dogs were anesthetized, and BP measurements were taken using LDO, Doppler, and IBP methods under normotensive and hypotensive conditions. The LDO device demonstrated superior agreement, assessed using Bland-Altman analysis, with IBP, especially in hypotensive conditions, compared to the Doppler method. LDO showed bias and standard deviation in the hypotensive state, with a mean and systolic arterial pressure (MAP and SAP) of -5.1 ± 7.9 and -5.6 ± 12.5 mmHg, respectively. Conversely, Doppler measurements tended to overestimate SAP during hypotension, presenting a bias of -13 ± 15.45 mmHg. The LDO achieved an area under the curve (AUC) of 0.809 for hypotension detection, with an MAP cutoff of ≤72 mmHg (sensitivity: 90%, specificity: 63%). Meanwhile, the best threshold for Doppler measurements was an AUC of 0.798, SAP ≤ 100 mmHg (sensitivity: 77.8%, specificity: 81.8%). These results indicate that LDO is a reliable method for hypotension detection in anesthetized dogs, with potential applications for real-time monitoring. In contrast, the Doppler method may help confirm hypotension diagnoses.

Comparison of the Anesthetic Effects of Alfaxalone Combined with Xylazine or Dexmedetomidine in Captive Formosa Serows (Capricornis swinhoei)

Formosan serows are an endemic species in Taiwan. Alfaxalone, a γ-aminobutyric acidA agonist, induces or maintains anesthesia in various veterinary species with reported potential adverse effects of respiratory depression and tachycardia. α2-Adrenoceptor agonists exert sedative and muscle relaxation effects, along with substantial cardiovascular adverse effects. Here, we aimed to evaluate the anesthetic effects of alfaxalone combined with xylazine or dexmedetomidine (AX vs. AD, respectively) in Formosan serows. In this randomized, masked study, AX was administered to four serows, and AD was administered to five serows intramuscularly via blow dart. The time and score of induction and recovery were recorded. Post-intubation, isoflurane was administered for maintenance anesthesia. Heart rate (HR), respiratory rate (RR), peripheral saturation of oxygenation (SpO2), rectal temperature (RT), and end-tidal CO2 (EtCO2) were recorded every five to eight minutes. Atipamezole and tolazoline were administered to antagonize dexmedetomidine and xylazine post-procedure, respectively. Both combinations allowed smooth induction and recovery. The AD group exhibited significantly lower HR and SpO2 and significantly higher RT and EtCO2 than the AX group (both p < 0.01). The AD-treated serows exhibited notable muscle rigidity after induction and significant hypoventilation and hypoxemia during the procedure. Although alfaxalone combined with dexmedetomidine or xylazine can produce satisfactory induction and recovery in Formosa serows, notable hypoxemia and hypoventilation are induced by the alfaxalone-dexmedetomidine combination compared to the alfaxalone-xylazine combination.

Trazodone-gabapentin association increases sedation scores with mild hemodynamic and echocardiographic impact in healthy cats

Despite the increasing use of drugs to facilitate feline management in veterinary care, there is still a lack of information on the anxiolytic and sedative effects and their specific physiological impacts. We aimed to compare the sedative, hematological, biochemical and cardiovascular effects of oral single-dose trazodone and gabapentin, alone or in combination, in 8 healthy adult mixed-breed domestic cats on a prospective, randomized, cross-over, and placebo-controlled study. Cats were assigned to receive an oral single dose of trazodone (50 mg) (TG), gabapentin (100 mg) (GG), trazodone (50 mg) and gabapentin (100 mg) (GTG), or placebo (PG). Sedation score, physiological, hematological, biochemical, and cardiovascular variables were assessed at baseline and 120 minutes after drug administration. The mean dose of trazodone was 12.1± 1.1 mg/kg and gabapentin 24.2± 2.3 mg/kg. All data were normally distributed. Blood tests remained within the reference range, but plasma protein increased by 3.78 % in TG. Trazodone alone and associated with gabapentin significantly reduced respiratory rate and systolic blood pressure compared to baseline and placebo. GTG showed a reduction in heart rate and the highest sedation scores. Short-duration excitatory reactions were observed in 37.5 % of the cats in GTG and 12.5 % in TG. Isovolumetric relaxation time (IVRT) increased in GTG and differed statistically from GG. On ECG, no clinically relevant changes were observed. The association of trazodone (50 mg/cat) and gabapentin (100 mg/cat) increases sedation scores compared to gabapentin alone, with a mild impact on HR, RR, BP, and IVRT in cats.

Evidence of renal tubular injury in canine patients after elective desexing

OBJECTIVE

To investigate the frequency of perioperative acute kidney injury (AKI) in American Society of Anesthesiologists (SA) Grade I canine patients undergoing elective desexing using urine microscopy techniques and assess if pre- and intraoperative factors affect risk of developing AKI.

DESIGN

Prospective observational clinical study conducted between September 2020 and October 2020.

SETTING

University teaching hospital.

ANIMALS

Thirty-two female and four male dogs between 5 months and 5 years of age classified as ASA I undergoing elective desexing surgery.

METHODS

Urinalysis was performed preoperatively and 20-24 h postoperatively to identify markers of renal tubular injury (RTI), particularly the presence of granular and renal tubular epithelial cell (RTEC) casts on sediment analysis. Dogs underwent a full physical examination and a preoperative assessment including measurement of urine specific gravity (USG), packed cell volume (PCV), total plasma protein and serum creatinine (sCr) was conducted as a part of the desexing programme. Anaesthetic records were examined for any evidence of intraoperative hypotension, defined as a mean arterial pressure (MAP) of <60 mmHg for any duration of time. MAP was measured using an indirect oscillometric technique. For analysis, animals were subdivided into affected and nonaffected groups, with affected animals those that had postoperative increases in granular and RTEC casts. Categorical and comparative analyses were then performed between groups to identify associations of increased casts with pre-, intra- and postoperative variables.

RESULTS

A frequency of RTI of 5.6% was identified. This was accompanied by a significant association between increases in casts with total duration (p = 0.027) and number (p = 0.016) of hypotensive episodes.

CONCLUSIONS

RTI is an anaesthetic consideration in ASA I veterinary patients undergoing elective desexing surgery. The identification of an association between the total duration and number of hypotensive episodes and the frequency of RTI highlights the importance of early detection of hypotension along with prompt and effective intervention in veterinary patients.

The Effectiveness of Liposome-Encapsulated Bupivacaine Compared to Standard Bupivacaine for Anesthesia of the Maxilla in Dogs

Medical and surgical procedures involving the canine maxilla can be painful both during and for several hours post-procedure. The length of this pain may exceed the predicted duration of standard bupivacaine or lidocaine. The goal of this study was to determine the duration and efficacy of sensory blockade of the maxilla produced by liposome-encapsulated bupivacaine (LB), compared to standard bupivacaine (B) or saline (0.9% NaCl) (S), when administered as a modified maxillary nerve block in dogs. Eight maxillae were studied bilaterally from 4 healthy dogs of the same breed and similar age. This prospective, randomized, crossover, blinded study evaluated a modified maxillary nerve block using 1.3% LB at 0.1 mL/kg, 0.5% B, or S at an equivalent volume. An electronic von Frey aesthesiometer (VFA) was used to evaluate mechanical nociceptive thresholds at 4 locations on each hemimaxilla at baseline and at specific intervals up to 72-h post-treatment. Both B and LB treatments resulted in significantly higher VFA thresholds when compared to S. Dogs that received B had VFA thresholds significantly higher than S for 5 to 6 h. Dogs that received LB had thresholds significantly higher than S for 6 to 12 h depending on the site of measurement. No complications were observed. Maxillary nerve block with B provided up to 6 h, and LB 12 h, of sensory blockade depending on the site tested.

Advances in Canine Anesthesia: Physiologically Based Pharmacokinetic Modeling for Predicting Propofol Plasma Profiles in Canines with Hepatic Impairment

Background: A PBPK model allows the prediction of the concentration of drug amounts in different tissues and organs over time and can be used to simulate and optimize different therapeutic protocols in healthy and sick individuals. The objective of this work was to create a PBPK model to predict propofol doses for healthy canines and canines with hepatic impairment. Methods: The study methodology was divided into two major phases, in which the first phase consisted of creating the PBPK model for healthy canines, and in the second phase, this model was adjusted for canines with hepatic impairment. The model for healthy canines presented good predictive performance, evidenced by the value of the performance measure of the geometric mean fold error that ranged from 0.8 to 1.25, meeting the double error criterion. The simulated regimen for healthy canines, i.e., of 5 mg/kg (administered as a bolus) followed by a continuous infusion at a rate of 0.13 mg/kg/min, was sufficient and ensured that all simulated subjects achieved the target plasma concentration. Canines with 60% and 40% liver function had infusion rate adjustments to ensure that individuals did not exceed the therapeutic window for maintenance of anesthesia. Results: The results presented in this manuscript are suggestive of the effectiveness and practicality of a PBPK model for propofol in canines, with a particular focus on hepatic impairment.

The effects of general anaesthesia on body temperature of dogs subjected to ovariohysterectomy or orchiectomy performed by veterinary students in a teaching hospital

Hypothermia during anaesthesia is a significant concern in veterinary practice, as it can lead to various complications, making it essential to understand the factors that contribute to temperature regulation in animals undergoing surgical procedures. This retrospective study aimed to evaluate the change in body temperature over the course of anaesthesia in dogs undergoing elective ovariohysterectomy and orchiectomy, and determine the effect of gender, dose of premedication, weight, age and duration of anaesthesia of the change of body temperature over time. One-hundred and ten dogs (n=110) that underwent elective ovariohysterectomy (n=75) and orchiectomy (n=35) surgery performed by veterinary students at the University of Adelaide were enrolled in this study. Dogs' anaesthesia records were evaluated for change in body temperature over the course of anaesthesia, and correlated with gender, two premedication doses of acepromazine (mg/kg), body weight (kg), age (months) and anaesthesia times (minutes). The analyses were performed at TPm (temperature at premedication), T0 (induction), T15, T30, T60, T90, T120 and TRec (recovery) minutes. Statistical analysis was performed using the GenStat software and included repeated measures analysis and ANOVA. Significance was considered when p < 0.05. The data showed a significant time-by-gender interaction with female dogs experienced a greater degree of heat loss than male dogs at T60 (p<0.01), T90 (p<0.01) and T120 (p<0.01). At recovery, female average temperature was higher than in males (p<0.01). There was no significant difference in body temperature when other covariates were used in the analysis. The core body temperature of female dogs decreased significantly over time compared to males, with the most pronounced differenced during the intraoperative period. However, the study's retrospective nature and limited sample size may influence the generalizability of these findings.

Comparative study between lateral versus latero-ventral quadratus lumborum block for perioperative analgesia in canine laparoscopic ovariectomy

OBJECTIVE

To compare the perioperative analgesic effect of lateral versus latero-ventral quadratus lumborum block (QLB) in dogs undergoing laparoscopic ovariectomy.

STUDY DESIGN

Randomized, blinded clinical study.

ANIMALS

A total of 15 client-owned female dogs undergoing laparoscopic ovariectomy.

METHODS

Animals were randomly assigned to receive a bilateral QLB, performed with 0.3 mL kg-1 ropivacaine 0.5%, either with lateral (group LQLB, n = 7) or latero-ventral approach (group LVQLB, n = 7). Dogs were premedicated intramuscularly with methadone 0.2 mg kg-1 and dexmedetomidine 3 μg kg-1. General anaesthesia was induced intravenously (IV) with propofol and maintained with isoflurane. Cardiovascular and respiratory variables were continuously monitored and recorded every 5 minutes during surgery. Fentanyl 3 μg kg-1 was administered IV if there was a 20% increase in heart rate and/or mean arterial pressure from previous values recorded 5 minutes before. Meloxicam 0.2 mg kg-1 was administered IV to all dogs during recovery. The short-form of the Glasgow Composite Pain Scale was used hourly for 8 hours post-QLB. Methadone 0.2 mg kg-1 was administered IV when pain score was ≥ 6/24. A chi-square test compared the number of dogs requiring intraoperative rescue fentanyl. A Friedman test with a Dunn's post hoc was used to evaluate the trend in postoperative pain scores within each group, and a Mann-Whitney U test compared scores between the groups at each time point; p < 0.05.

RESULTS

Significantly fewer dogs required intraoperative rescue fentanyl in group LQLB than in group LVQLB. No dog required postoperative rescue methadone, and there were no significant differences in pain scores.

CONCLUSIONS AND CLINICAL RELEVANCE

Bilateral QLB performed with lateral approach reduced the number of dogs requiring intraoperative rescue analgesia in comparison with the latero-ventral approach. No differences were detected postoperatively, possibly owing to the confounding effects of methadone, dexmedetomidine and meloxicam.

Retrospective evaluation of the induction of anaesthesia with alfaxalone or propofol in cats undergoing caesarean section

OBJECTIVES

Several anaesthetic protocols for caesarean section (c-section) have been described in dogs; however, anaesthesiological studies in cats undergoing c-section are lacking. The aim of this study was to assess the viability and outcome of kittens born from queens undergoing emergency c-section and receiving propofol or alfaxalone for anaesthetic induction and isoflurane for maintenance of general anaesthesia.

METHODS

All cats admitted to the Veterinary Teaching Hospital of the University of Bologna between January 2014 and December 2022 for dystocia that had undergone an emergency c-section were analysed in this retrospective study. The queens received propofol 2-6 mg/kg IV (group P) or alfaxalone 1-3 mg/kg IV (group A) administered slowly; general anaesthesia was maintained with isoflurane. Survival of all the kittens was evaluated at birth and after 24 h; in addition, heart rate, respiratory rate and mucous membrane colour were evaluated in the kittens at birth.

RESULTS

Of the 14 cats included in the study, eight received alfaxalone (group A) and six received propofol (group P) for induction of the general anaesthesia. A total of 50 kittens were born by c-section: 30 kittens in group A and 20 in group P. The overall survival of the kittens was 90% at birth: 96.7% (29/30) for group A and 80% (16/20) for group P. The 24 h survival rate was 93.1% for group A and 87.5% for group P.

CONCLUSIONS AND RELEVANCE

The results of the present study demonstrated that in cats undergoing c-section, both alfaxalone and propofol are feasible for the induction of general anaesthesia.

Comparative evaluation of chlorhexidine gluconate with alcohol and polyhexamethylene biguanide with Tris-EDTA as antiseptic solutions for pre-operative skin preparation in dogs

Background and Aim

Skin antisepsis plays a crucial role in pre-operative skin preparation, with chlorhexidine gluconate and alcohol being historically the preferred choice. However, concerns have risen regarding the development of bacterial resistance to chlorhexidine. Polyhexamethylene biguanide (PHMB) combined with Tris-ethylenediaminetetraacetic acid (Tris-EDTA) has recently emerged as a skin and wound antiseptic. This study aimed to compare the antibacterial efficacy and local safety of 2% chlorhexidine gluconate with 70% alcohol (CG+Alc) and 0.3% PHMB with 6% Tris and 1.86% EDTA (PHMB+Tris-EDTA) for pre-operative skin preparation in dogs.

Materials and Methods

Twenty-four adult dogs underwent aseptic preparation on both sides of their ventral abdomens, with one side receiving CG+Alc and the other side receiving PHMB+Tris-EDTA, assigned randomly. Skin swab samples were collected pre-antisepsis and at 3-, 10-, and 60-min post-antisepsis to quantify bacterial colony-forming units (CFUs). Local skin reactions (erythema and edema) were evaluated after hair clipping, pre-antisepsis, and at 3-, 10-, 30-, and 60-min post-antisepsis.

Results

There was no significant difference in bacterial CFU counts between the two antiseptic groups pre-antiseptic. Both solutions significantly reduced CFU counts (p < 0.05) at all post-antisepsis sampling times compared with pre-antisepsis. However, dogs treated with PHMB+Tris-EDTA showed a significantly higher incidence of edema at 10 min (p = 0.02) and 30 min (p = 0.003) and a higher incidence of erythema at 10 min (p = 0.043) post-antisepsis compared with CG+Alc. No skin reactions were observed in either group at 60 min post-antisepsis.

Conclusion

CG+Alc and PHMB+Tris-EDTA reduced bacterial counts in pre-operative skin preparation in dogs. However, acute transient skin reactions were observed more frequently following the application of PHMB+Tris-EDTA.

Effects of a synergic interaction between magnesium sulphate and ketamine on the perioperative nociception in dogs undergoing tibial plateau leveling osteotomy: a pilot study

Introduction

Magnesium Sulphate (MgSO4) is commonly used in human medicine for the management of perioperative pain in different types of procedures. However, in veterinary medicine, the use of MgSO4 has not been evaluated for its analgesic efficacy in dogs, which has generated conflicts of opinion in this area of veterinary anesthesiology. The aim of this study was to evaluate the perioperative analgesic efficacy of MgSO4 in combination with Ketamine in dogs undergoing Tibial Plateau Leveling Osteotomy (TPLO). Our hypothesis is that MgSO4 plus ketamine have a synergistic action in the management of intra-and postoperative pain.

Methods

Twenty adult mixed breed dogs with average age 5.9 ± 2.6 years and weight 27.8 ± 9.2 kg were included in this prospective, clinical, randomized study. Dogs were randomly assigned to two groups. The MK group received ketamine (0.5 mg/kg as starting bolus followed by continuous infusion rate at 1 mg/kg/h). At the end of the ketamine bolus, MgSO4 (50 mg/kg over 15 min) was administered by the same route, followed by a constant rate infusion (CRI) at 15 mg/kg/h, IV. K group received a bolus of ketamine followed by a CRI at the same dosage described in MK group. Main cardiorespiratory parameters were recorded 10 min before the start of surgery (BASE), after the ketamine bolus (T1) and the MgSO4 bolus (T2), during the skin incision (SKIN), the osteotomy (OSTEOTOMY) and skin suturing (SUTURE). In the postoperative period, the short form of Glasgow Composite Pain scale (SF-CMPS) was used to assess pain at 30, 60, 120, and 180 min after extubation (Post30, Post60, Post120, and Post180, respectively). The main blood electrolytes (Mg2+, Ca2+, Na+, K+) were analyzed at BASE, T2, OSTEOTOMY, SUTURE and T3 (one hour after stopping MgSO4 infusion). Number of rescue analgesia and administration times were recorded both in the intra-and postoperative period.

Results

In K group 7 out of 10 dogs required intraoperatory rescue analgesia compared to MK group (3/10). Furthermore, mean arterial pressure (MAP) and heart rate (HR) were significantly higher at OSTEOTOMY compared to BASE time in both groups. In the postoperative period, at T120, ICMPS-SF score was higher in K group than MK group.

Conclusion

The administration of MgSO4 could guarantee better analgesia in the perioperative period in dogs undergoing TPLO, performing a synergistic action with ketamine.

Electroencephalographic and Cardiovascular Assessments of Isoflurane-Anesthetized Dogs

This study investigated the use of frontal electroencephalography (EEG) to monitor varying levels of isoflurane anesthesia in dogs. The patient state index (PSI), burst suppression ratio (SR), and waveforms, were continuously recorded while mean arterial blood pressure (MBP), heart rate, responses to electric stimuli, and subjective anesthetic "depth" were assessed every 3 min. At deep anesthesia (2.5× MAC - 3.2%), the PSI (6.5 ± 10.8) and MBP (45.6 ± 16.4 mmHg) were the lowest, and SR was the highest (78.3 ± 24.0%). At 1× MAC (1.3%), the PSI and MBP increased significantly to 47.8 ± 12.6 and 99.8 ± 13.2, respectively, and SR decreased to 0.5 ± 2.5%. The EEG was predominantly isoelectric at 2×-2.5× MAC, indicating unconsciousness and unresponsiveness. As anesthesia lightened, waveforms transitioned to flatter and faster activity patterns with a response to noxious stimuli, suggesting regained consciousness. The PSI and MBP exhibited a stronger correlation (ρ = 0.8098, p = 0.001) than the relationship of PSI with heart rate (ρ = -0.2089, p = 0.249). Five of the six dogs experienced rough recovery, possibly due to high SR and low MBP. These findings suggest that EEG monitoring in dogs can be a valuable tool for the real-time tracking of brain states and can be used to guide the management of isoflurane anesthesia.

Perioperative anaesthetic complications in healthy cats undergoing anaesthesia for neutering in first opinion practice

OBJECTIVES

The aim of the present study was to identify the incidence of common perioperative anaesthetic complications in cats undergoing anaesthesia for neutering in three UK first opinion practices.

METHODS

A retrospective anaesthetic record analysis was performed on cats anaesthetised for neutering at practices 1 and 2 between 9 December 2017 and 2 February 2021 and practice 3 between 9 March 2020 and 7 January 2021. A search of the practice management system identified all cats that had undergone neutering in the selected timeframe. Data from 1019 cats were included in the study. Information relating to patient characteristics and data from the anaesthesia session were extracted from electronic patient records and anaesthesia record charts and entered into an Excel spreadsheet. A definition of the complications was created after reviewing the literature and their incidence determined from the data set. Comparisons between different groups of cats in the study were made using a χ2 test for homogeneity or Fisher's exact tests to identify factors associated with increased incidence of complications.

RESULTS

The anaesthetic-related mortality was 1/1019 (0.10%). The most common complications were hypotension (22.6%), bradycardia (16.7%) and hypothermia (13.8%). Less common complications were hypocapnia (12.7%), hypercapnia (8.7%), tachycardia (6.6%), apnoea (3.1%), hyperthermia (1.7%), hypertension (1.4%), endotracheal tube obstruction (1.1%), hypoxia (0.3%), undesirable recovery (0.6%) and cardiac arrhythmia (0.2%). Factors associated with increased risk of hypotension were acepromazine pre-anaesthetic medication, higher maximum isoflurane dose, longer anaesthetic duration and lower body weight. Factors associated with increased risk of bradycardia were medetomidine pre-anaesthetic medication, longer anaesthetic duration and higher body weight. Factors associated with increased risk of hypothermia were higher maximum isoflurane dose, increased anaesthetic duration and lower body weight.

CONCLUSIONS AND RELEVANCE

This study showed that anaesthetic complications were frequently observed, with complications documented in 53.4% of the cats in the study. The information in this study may help to guide prioritisation of monitoring in feline anaesthesia.

Evaluation of three doses of oral trazodone and their impact on handling, activity, and physiological parameters in rabbits: a prospective, blinded, randomized cross-over study

No study has determined the minimal effective dose of trazodone required to induce behavioral changes and its safety profile in rabbits. Therefore, this study aimed to determine the minimal effective dose of trazodone to improve compliance to handling, and to evaluate associated changes in motor activity, physiological and arterial blood gas parameters. Eight intact female New Zealand White rabbits (2-month-old; 1.66 ± 0.12 kg) were included in this prospective, blinded, randomized cross-over study. After a 10-day acclimation, rabbits randomly received placebo or trazodone 10, 20 or 30 mg/kg orally (PLAC, TRAZ10, TRAZ20, TRAZ30) with a 1-week wash-out period. Compliance scoring (dynamic interactive visual analog scale; DIVAS), activity levels measured with accelerometry (T0-T600), physiological parameters (temperature, heart, and respiratory rates), and arterial blood gas parameters (up to T240) were evaluated. Compliance scores, accelerometry, physiological and arterial blood gas parameters and hypoxemia prevalence (PaO2 <60 mmHg) were analyzed using linear mixed models and Chi-squared tests, respectively (P<0.05). When compared with PLAC, DIVAS scores were significantly higher at T80-120, T40-120 and T120-200 in TRAZ10, TRAZ20 and TRAZ30 post-administration, respectively. When compared with baseline, DIVAS scores were significantly higher from T80-160, T40-240 and T80-200 in TRAZ10, TRAZ20 and TRAZ30, respectively. All other parameters were not significantly different. In TRAZ30, hypoxemia was observed in 2/8 rabbits (P=0.104). In conclusion, oral trazodone improved rabbit compliance at all studied dosages, especially 20 mg/kg improved rabbit compliance without decreasing motor activity or causing hypoxemia.

Anaesthetic practices and attitudes to patient safety in a sample of Australian veterinary practices

OBJECTIVE

To survey anaesthetic practices and attitudes towards veterinary patient safety in Australia.

STUDY DESIGN

This was a cross-sectional sample population from Australian veterinary practices, including first opinion small animal, mixed animal and referral small animal practices. The survey included practices' anaesthetic management, monitoring equipment and topics regarding patient safety.

RESULTS

Responses were obtained from 310/1700 (18%) veterinary practices, with 208 respondents from small animal practices (67%), 71 mixed animal practices (23%) and 31 referral small animal centres (10%). Overall, 61% of respondents reported always having a dedicated staff member monitoring the anaesthetic, who was most commonly a certified veterinary nurse (89%). In 22% of the practices, some of the staff monitoring an anaesthetic did not have any qualification. Completion of anaesthetic plans for each animal prior to an anaesthetic was reported by 24.5% of respondents and labelling of syringes was completed in 80% of practices. Pulse oximetry (98%) and temperature (88%) were the most common clinical variables monitored. The use of capnography (46%) or an electrocardiogram (48%) was also reported by the respondents. Emergency drugs, airway and ventilation equipment are available in 96%, 88% and 59% of practices, respectively. A defibrillator was available in 11% of practices with only 54% respondents being confident in using it. Of the respondents 60% were aware of anaesthesia safety interventions and clinical guidelines regarding patient safety during anaesthesia.

CONCLUSIONS AND CLINICAL RELEVANCE

Despite practices showing a relative improvement over the years in the standard of anaesthesia care, most of them are still not meeting international guidelines. Areas where changes could lead to improved safety practices could include: a trained person dedicated to monitor anaesthesia, pain scoring evaluation in patients recovering from anaesthesia, an increased use of standardised handover checklists, record keeping and an increase in open discussion of adverse events by the veterinary team.

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.

Case report: Side effects of etomidate in propylene glycol in five Göttingen Minipigs

Etomidate, an agonist of the GABA A receptors, is available for clinical use either in combination with 35% propylene glycol or in a lipid emulsion. Its recognized ability to minimally impact the cardiovascular system made etomidate a suitable option for cardiac-compromised patients. Myoclonus and pain at the injection site are recognized side effects of etomidate in propylene glycol, affecting both human and veterinary species. There is no information available concerning potential side effect in minipigs. In the present case series, we report the side effects related to the use of etomidate in 35% propylene glycol in five Ellegaard Göttingen Minipigs that underwent general anesthesia for cardiac magnetic resonance imaging days or weeks after experimentally induced myocardial infarction. Following intravenous injection of etomidate, laryngeal edema and hyperemia were observed in one case. In another case, tachycardia, apnea, and decreased oxygen saturation, accompanied by laryngeal edema and hyperemia, were observed, which resolved spontaneously in a few minutes. In the arterial or venous samples collected shortly after the induction of general anesthesia, hemolysis was macroscopically visible and subsequently confirmed with a hematological exam in all five cases, as well as hemoglobinuria. Necropsies carried out immediately after euthanasia confirmed macroscopic laryngeal edema, marked diffuse lung alveolar and interstitial edema and hyperemia at histology in one animal, and marked acute lung congestion in another animal. These side effects were not observed when etomidate in a lipid emulsion was injected into another 24 animals. The role played by the different formulations (propylene glycol versus lipidic formulation) has not yet been fully elucidated. Based on our observations, we recommend caution in using the formulation of etomidate in 35% propylene glycol in Göttingen Minipigs.

Anaesthetic mortality in cats: A worldwide analysis and risk assessment

BACKGROUND

Patient safety is essential in small animal anaesthesia. This study aimed to assess anaesthesia-related deaths in cats worldwide, identify risk and protective factors and provide insights for clinical practice.

METHODS

A prospective multicentre cohort study of 14,962 cats from 198 veterinary centres across different countries was conducted. Data on anaesthesia-related deaths, from premedication up to 48 hours postextubation, were collected. Logistic regression was used to analyse patient demographics, American Society of Anesthesiologists (ASA) classification, procedure type and anaesthetic drugs.

RESULTS

The anaesthesia-related mortality was 0.63%, with 74.5% of deaths occurring postoperatively. Cats with cachexia, a higher ASA status or who underwent abdominal, orthopaedic/neurosurgical or thoracic procedures exhibited elevated mortality. Mechanical ventilation use was associated with increased mortality. Mortality odds were reduced by the use of alpha2-agonist sedatives, pure opioids in premedication and locoregional techniques.

LIMITATIONS

Limitations include non-randomised sampling, potential biases, unquantified response rates, subjective death cause classification and limited variable analysis.

CONCLUSIONS

Anaesthetic mortality in cats is significant, predominantly postoperative. Risk factors include cachexia, higher ASA status, specific procedures and mechanical ventilation. Protective factors include alpha2-agonist sedatives, pure opioids and locoregional techniques. These findings can help improve anaesthesia safety and outcomes. However, further research is required to improve protocols, enhance data quality and minimise risks.

Anaesthetic mortality in dogs: A worldwide analysis and risk assessment

BACKGROUND

Ensuring patient safety during small animal anaesthesia is crucial. This study aimed to assess anaesthetic-related deaths in dogs globally, identify risks and protective factors and inform clinical practice.

METHODS

This prospective cohort multicentric study involved 55,022 dogs from 405 veterinary centres across various countries. Data on anaesthesia-related deaths from premedication to 48 hours post-extubation were collected. Logistic regression was used to analyse patient demographics, American Society of Anesthesiologists (ASA) classification, procedure type and anaesthetic drugs used.

RESULTS

Anaesthetic-related mortality was 0.69%. Most deaths occurred postoperatively (81%). Age, obesity and a higher ASA classification score were associated with increased mortality. Urgent procedures, non-urgent but unscheduled anaesthesias and short procedures also had higher mortality. Some sedatives, systemic analgesics, hypnotics and the use of locoregional anaesthesia were linked to a decrease in mortality.

LIMITATIONS

The limitations of the study include the non-randomised sample, potential selection bias, lack of response rate quantification, variable data quality control, subjectivity in classifying causes of death and limited analysis of variables.

CONCLUSION

Careful patient evaluation, drug selection and monitoring can be associated with reduced mortality. These findings can be used to develop guidelines and strategies to improve patient safety and outcomes. Further research is needed to refine protocols, enhance data quality systems and explore additional risk mitigation measures.

Effects of intramuscular alfaxalone and dexmedetomidine alone and combined on ocular, electroretinographic, and cardiorespiratory parameters in normal cats

Background

This study aimed to determine the effects of intramuscular (IM) administration of alfaxalone with or without dexmedetomidine on short electroretinography (ERG), ocular parameters and cardiorespiratory in healthy cats.

Methods

Eight healthy female spayed cats were treated with three sedation protocols: IM administration of 5 μg/kg dexmedetomidine (DEX), 5 mg/kg alfaxalone (ALF), and 5 μg/kg dexmedetomidine plus 5 mg/kg alfaxalone (DEX + ALF). The washout period after each treatment was 2 weeks. Physiological parameters, time metrics, intraocular pressure (IOP), Schirmer tear test 1 (STT-1) and a short ERG protocol were recorded. For age data, weight data, time metrics and ERG data, one-way ANOVA with Bonferroni posterior comparisons were performed. For physiological parameters, IOP and STT-1 data, two-way repeated measures ANOVA with Bonferroni posterior comparisons were performed. Statistical significance was set at a p-value <0.05.

Results

IOPs were increased in all three groups compared to baseline and showed no significant differences among three groups at any time point. STT-1 values were decreased significantly during the process. Significant differences were noticed between a-wave amplitude in the dark-adapted response between DEX and ALF, and a-wave amplitude in light-adapted response between ALF and DEX + ALF.

Conclusion

This study demonstrates the feasibility of three sedation protocols for short ERG recording in cats. All these treatments resulted in increased IOP values and reduced STT-1 values. But baseline data of ERG was not obtained as a blank control in cats.

Changes in echocardiographic indices and left ventricular strain values by two-dimensional speckle-tracking echocardiography following pre-anesthetic oral pimobendan administration compared with intravenous pimobendan in dogs

Introduction

The effects of pre-anesthetic single-dose oral pimobendan during inhalational anesthesia, including the comparison with the effects of single intravenous pimobendan under anesthesia, remain unexplored. Therefore, this study aimed to determine changes in hemodynamic and echocardiographic parameters induced by pre-anesthetic administration of oral pimobendan under isoflurane general anesthesia and to compare them with those induced by intravenous pimobendan.

Methods

Thirteen clinically normal dogs (4 laboratory and 9 client-owned dogs) with no clinical signs and not on any medical treatment were included. Anesthesia was performed three times: no pimobendan (Control), oral pimobendan (PIMO PO, 0.3 mg/kg), and intravenous pimobendan (PIMO IV, 0.15 mg/kg). Echocardiographic and hemodynamic parameters were monitored at 30-min intervals in all groups.

Results

Compared to the Control group, end-systolic volume index (ESVI) and normalized left ventricular internal diameter at end-systole (LVIDSN) were significantly lower, and fractional shortening (FS) and ejection fraction (EF) were significantly higher in the PIMO PO and IV groups (p < 0.001). Global radial strain (GRS) was significantly higher in the PIMO PO and IV groups (p = 0.015).

Conclusion

Under general anesthesia, oral pimobendan preserved LV systolic and myocardial function in a manner comparable to intravenous pimobendan. Pre-anesthetic administration of oral pimobendan can be used to compensate for cardiac systolic function in dogs who require therapeutic and diagnostic procedures under general anesthesia with potential risk of circulatory failure.

Exploring oxygen reserve index for timely detection of deoxygenation in canine patients recovering from anesthesia

Pulse oximetry (SpO2) identifies a decrease in the partial pressure of oxygen (PaO2) when it falls below 80 mmHg, while oxygen reserve index (ORi), a dimensionless index ranging from 0 to 1, detects PaO2 changes between 100 and 200 mmHg. This study investigates the usefulness of ORi in detecting impending deoxygenation before traditional SpO2. Fifty-one dogs undergoing anesthesia were mechanically ventilated maintaining a fraction of inspired oxygen of 0.50 and an ORi of 1. Animals were classified according to their body condition score (BCS) as normal-fit (BCS 4-5/9), overweight (BCS 6-7/9), or obese (BCS 8-9/9). At the end of the procedure, dogs were placed in sternal recumbency, and after 10 min disconnected from the ventilator and maintained in apnea. ORi added warning time was determined at various ORi values as the time difference in reaching SpO2 of 95% from ORi of 0.9 and 0.5, compared to the SpO2 warning time from SpO2 of 98%. During apnea, ORi decreased before noticeable SpO2 changes. An ORi of 0.9 anticipated an SpO2 of 95% in normal-fit dogs by 87 (33-212) [median (range)] seconds or in those with a BCS ≥ 6/9 by 49 (7-161) seconds. Regardless of the BCS class, the median time from ORi of 0.5 to SpO2 of 95% was 30-35 s. ORi declined from 0.9 to 0.0 in 68 compared to 33 s between normal-fit and obese dogs (p < 0.05). In dogs, ORi added warning time could facilitate timely intervention, particularly in obese patients.

Computer-controlled closed-loop norepinephrine infusion system for automated control of mean arterial pressure in dogs under isoflurane-induced hypotension: a feasibility study

Introduction

Intra-operative hypotension is a common complication of surgery under general anesthesia in dogs and humans. Computer-controlled closed-loop infusion systems of norepinephrine (NE) have been developed and clinically applied for automated optimization of arterial pressure (AP) and prevention of intra-operative hypotension in humans. This study aimed to develop a simple computer-controlled closed-loop infusion system of NE for the automated control of the mean arterial pressure (MAP) in dogs with isoflurane-induced hypotension and to validate the control of MAP by the developed system.

Methods

NE was administered via the cephalic vein, whereas MAP was measured invasively by placing a catheter in the dorsal pedal artery. The proportional-integral-derivative (PID) controller in the negative feedback loop of the developed system titrated the infusion rate of NE to maintain the MAP at the target value of 60 mmHg. The titration was updated every 2 s. The performance of the developed system was evaluated in six laboratory Beagle dogs under general anesthesia with isoflurane.

Results

In the six dogs, when the concentration [median (interquartile range)] of inhaled isoflurane was increased from 1.5 (1.5-1.5)% to 4 (4-4)% without activating the system, the MAP was lowered from 95 (91-99) to 41 (37-42) mmHg. In contrast, when the concentration was increased from 1.5 (1.0-1.5)% to 4 (4-4.8)% for a 30-min period and the system was simultaneously activated, the MAP was temporarily lowered from 92 (89-95) to 47 (43-49) mmHg but recovered to 58 (57-58) mmHg owing to the system-controlled infusion of NE. If the acceptable target range for MAP was defined as target MAP ±5 mmHg (55 ≤ MAP ≤65 mmHg), the percentage of time wherein the MAP was maintained within the acceptable range was 96 (89-100)% in the six dogs during the second half of the 30-min period (from 15 to 30 min after system activation). The median performance error, median absolute performance error, wobble, and divergence were - 2.9 (-4.7 to 1.9)%, 2.9 (2.0-4.7)%, 1.3 (0.8-1.8)%, and - 0.24 (-0.34 to -0.11)%·min-1, respectively. No adverse events were observed during the study period, and all dogs were extubated uneventfully.

Conclusion

This system was able to titrate the NE infusion rates in an accurate and stable manner to maintain the MAP within the predetermined target range in dogs with isoflurane-induced hypotension. This system can be a potential tool in daily clinical practice for the care of companion dogs.

What is the best treatment for hypotension in healthy dogs during anaesthesia maintained with isoflurane?

Hypotension is a common and potentially life-threatening complication of general anaesthesia in dogs. Due to the combination of cardiovascular side effects of many anaesthetic, sedative and analgesic drugs used peri-operatively hypotension is frequently reported even in healthy dogs undergoing elective procedures. Several treatment options for hypotension have been advocated. Potential treatments include rapid administration of either crystalloid or colloid fluids; pharmacological treatments to increase cardiac output and/or systemic vascular resistance; or reduction in the delivery of the volatile anaesthetic agents. This critical appraisal considers the current evidence for which treatment is the best option for treating hypotension in healthy euvolemic dogs undergoing general anaesthesia maintained with isoflurane. Fourteen relevant studies were appraised, including 12 laboratory studies and two small clinical trials. One study demonstrated that reduction in the delivery of isoflurane may correct hypotension, but this treatment may not always be feasible. In general, rapid administration of fluids did not increase blood pressure and failed to correct hypotension. Synthetic colloids demonstrated some efficacy, but results were inconsistent between studies and large volumes may be required. Infusion of dopamine appears to be the most reliable pharmacological option consistently increasing blood pressure, cardiac output and correcting hypotension.

Medication errors in veterinary anesthesia: a literature review

OBJECTIVE

To provide an overview of medication errors (MEs) in veterinary medicine, with a focus on the perianesthetic period; to compare MEs in veterinary medicine with human anesthesia practice, and to describe factors contributing to the risk of MEs and strategies for error reduction.

DATABASES USED

PubMed and CAB abstracts; search terms: [("patient safety" or "medication error∗") AND veterin∗].

CONCLUSIONS

Human anesthesia is recognized as having a relatively high risk of MEs. In veterinary medicine, MEs were among the most commonly reported medical error. Predisposing factors for MEs in human and veterinary anesthesia include general (e.g. distraction, fatigue, workload, supervision) and specific factors (e.g. requirement for dose calculations when dosing for body mass, using several medications within a short time period and preparing syringes ahead of time). Data on MEs are most commonly collected in self-reporting systems, which very likely underestimate the true incidence, a problem acknowledged in human medicine. Case reports have described a variety of MEs in the perianesthetic period, including prescription, preparation and administration errors. Dogs and cats were the most frequently reported species, with MEs in cats more commonly associated with harmful outcomes compared with dogs. In addition to education and raising awareness, other strategies described for reducing the risk of MEs include behavioral, communication, identification, organizational, engineering and cognitive aids.

Correlation of opioid antinociception and hypothermia in dogs-An animal welfare refinement

The purpose of this study was to assess antinociception and correlation of antinociception and hypothermic effects after intravenous opioids in dogs. Nine healthy male Beagles were enrolled in the study. They were acclimated to a thermal nociceptive device, then received three IV treatments (saline, butorphanol 0.4 mg/kg and methadone 0.5 mg/kg) in a randomized complete block design. Rectal temperature and thermal withdrawals were assessed prior to and 0.5-6 h after drug administration. One dog was excluded due to lack of withdrawal to thermal stimuli. Rectal temperatures were not significantly different between treatments at time 0, but significantly decreased from 0.5 to 5 h for both opioids compared to saline. Withdrawals were significantly decreased, compared to saline, from 0.5 to 4 h for butorphanol and 0.5-5 h for methadone. A significant (p = .0005) and moderate (R2  = .43) correlation between antinociception and hypothermia occurred. Based on these data, intravenous butorphanol (0.4 mg/kg) and methadone (0.5 mg/kg) provided 4 and 5 h of antinociception, respectively. Opioid hypothermia can serve as an easy, noninvasive and humane manner for preclinical assessment of opioid antinociception in dogs prior to evaluation in clinical trials. This is a major refinement in animal welfare for assessing novel opioids, opioid doses and dose intervals in dogs.

Comparison of analgesic efficacy of tramadol, morphine and methadone in cats undergoing ovariohysterectomy

OBJECTIVES

The aim of this study was to compare the analgesic efficacy and the effect on physiological variables and behavior of the use of tramadol, methadone and morphine as preoperative analgesia in healthy cats undergoing elective ovariohysterectomy.

METHODS

Cats undergoing ovariohysterectomy were randomly assigned to receive one of the following premedication treatments intramuscularly: methadone (0.2 mg/kg; n = 10); morphine (0.2 mg/kg; n = 10); or tramadol (3 mg/kg; n = 10). Induction of anesthesia was done with propofol, and maintenance of anesthesia was done with isoflurane. Intraoperative heart rate, arterial blood pressure, respiratory rate, end-tidal isoflurane concentration and frequency of rescue analgesia (fentanyl 2.5 µg/kg) were compared between groups. Postoperative analgesia was assessed using the UNESP-Botucatu Multidimensional Composite Pain Scale, and perioperative serum glucose, cortisol concentrations and postoperative rescue analgesia were evaluated.

RESULTS

Intraoperative rescue analgesia was required in 76.5% of cats at some time during surgery, and 27% of cats required postoperative rescue analgesia up to 6 h after extubation. There were no significant differences between groups with respect to intraoperative and postoperative rescue analgesia, pain scale scores and end-tidal isoflurane concentrations. In the immediate postoperative period, after extubation, most of the patients presented with hypothermia; however, 1-6 h postoperatively, hyperthermia was observed in most of the patients, and was most common in the tramadol group.

CONCLUSIONS AND CLINICAL RELEVANCE

Under the conditions of this study, methadone, morphine and tramadol produced satisfactory postoperative analgesia in most of the cats undergoing ovariohysterectomy, and the effects lasted up to 6 h postoperatively. Intraoperative analgesia was not sufficient in most cases. Significant cardiovascular or respiratory effects contraindicating the use of these drugs were not found. Postanesthetic hyperthermia occurred with all opioids studied and was more frequent in the tramadol group.

Efficacy of Preemptive Analgesia with Amantadine for Controlling Postoperative Pain in Cats Undergoing Ovariohysterectomy

This study aimed to evaluate the effect of the preemptive administration of amantadine on postoperative analgesia in cats undergoing ovariohysterectomy and its influence on the physiological parameters. Twenty healthy domestic cats scheduled to undergo ovariohysterectomy at the Santa Cruz State University, Ilhéus, were divided into two groups: the control group (Group C; n = 10) and the amantadine group (Group A; n = 10). The cats in Group C received placebo capsules 30 min prior to the standard anesthetic protocol, whereas those in Group A received 5 mg/kg of amantadine orally 30 min prior to the standard anesthetic protocol. Postoperative pain was assessed using the visual analog scale and the UNESP-Botucatu multidimensional scale for the evaluation of postoperative pain in cats. The administration of amantadine had no effect on the physiological parameters evaluated. The pain scores in Group A were lower than those in Group C, indicating that the frequency of rescue analgesic administration cats in Group A was lower. That way, preemptive oral administration of amantadine at a dose of 5 mg/kg was effective at controlling postoperative pain in cats undergoing ovariohysterectomy. Moreover, no adverse effects or alterations in the physiological patterns were observed in the treated animals.

The effects of anesthetic drug choice on heart rate variability and echocardiography parameters in cats

Heart rate variability (HRV) is one of the assessments of cardiovascular risk during general anesthesia. This study aimed to assess the effects of an anesthetic drug on HRV in cats and to provide information for clinical applications. Twenty-four healthy client-owned cats of various breeds, 12 females and 12 males scheduled for elective surgery, were enrolled in this study. The cats were premedicated and induced with 4 protocols: protocol 1, diazepam (0.3 mg/kg) and propofol (2-4 mg/kg) IV; protocol 2, diazepam (0.3 mg/kg) and alfaxalone (1-3 mg/kg) IV; protocol 3, diazepam (0.3 mg/kg) and ketamine (3-5 mg/kg) IV; and protocol 4, xylazine (1 mg/kg) and tiletamine/zolazepam (Zoletil) (5 mg/kg) IM. The heart rate and HRV of the 24 cats were collected before and at least 1 h after administering the anesthetic drugs. Echocardiography was performed to evaluate heart function. Oscillometric blood pressure monitoring was used to obtain the mean blood pressure. After anesthetic drug administration, higher heart rates were found in cats premedicated and induced with alfaxalone (p = 0.045) than in the other protocols. The lowest heart rate (HR) values were found in cats in protocol 4 using xylazine and Zoletil. The HRV low frequency (LF) and high frequency (HF) power ratios increased in all protocols except for cats premedicated and intubated with propofol. The standard deviation of the regular sinus beats (SDNN) was higher in cats premedicated and induced with ketamine than in other anesthetic protocols (p = 0.015). An increase in sympathetic activity and reduced HRV is associated with high blood pressure and left atrial dimension. The percentage of fractional shortening (FS) decreased in cats premedicated with ketamine. The results showed that the anesthesia method using diazepam and propofol caused the least disturbance of HRV compared with other anesthesia methods that were used in this study.

Evaluation of lidocaine administration into the ovarian pedicle for the control of intraoperative and early postoperative pain during ovariohysterectomy in dogs

OBJECTIVE

To evaluate effects of lidocaine 2% administration into the ovarian pedicle on intraoperative nociception and early postoperative pain in dogs undergoing ovariohysterectomy.

STUDY DESIGN

Prospective, randomized, blinded clinical study.

ANIMALS

A total of 20 healthy adult female dogs of different breeds.

METHODS

Dogs were premedicated with acepromazine (0.02 mg kg-1) and morphine (0.5 mg kg-1) intramuscularly, anesthesia induced with propofol and maintained with isoflurane. Dogs were randomly assigned to be administered 2 mL of saline (group S) or lidocaine 2% (group L) into the mesovarium (1 mL each side). Heart rate (HR) and noninvasive systemic arterial pressure were recorded before surgery (T0), before (T1) and during ligation of the right ovarian pedicle (T2), before (T3) and during ligation of the left ovarian pedicle (T4). Rescue treatment (propofol) was administered if HR or systolic arterial pressure (SAP) increased by 20% compared with the previous time point. Pain, assessed with the Glasgow Composite Measure Pain Scale-Short Form (CMPS-SF) was recorded before premedication (baseline) and after extubation. Administration of postoperative rescue analgesia was recorded.

RESULTS

In group S, HR was higher at T2 than T1 (112 ± 18 versus 89 ± 21 beats minute-1, p = 0.001) There were no significant differences between treatments at any time. SAP was higher at T2 than T1 in group S (110 ± 12 versus 100 ± 10 mmHg, p = 0.031). SAP was higher in group S than group L at T3 (113 ± 12 and 91 ± 10 mmHg, respectively, p = 0.001). No dogs required propofol intraoperatively. All dogs required postoperative rescue analgesia. Compared with baseline, CMPS-SF increased 60 minutes after extubation (group S; p = 0.019, group L; p = 0.043).

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of lidocaine 2% into the mesovarium did not reduce intraoperative nociception and did not improve postoperative analgesia.

A novel minimally invasive fixation method for flail chest management in a Canine model: an animal research

BACKGROUND

Multiple rib fractures can lead to flail chest with up to 35% mortality rate due to severe pulmonary complications. Current treatments of flail chest remain controversial. Studies have shown that surgical treatments can improve outcomes and reduce mortality, comparing to non-operative treatments. Current surgical fixation methods focus on stabilization of ribs on the outward facing side, and they require division of intercostal muscles. Damages to surrounding nerves and vessels may lead to chronic pain. This study tests a novel interior fixation method that minimizes neurovascular injuries.

METHODS

Twelve healthy canines were divided in two surgical operation groups for exterior and interior fixation using titanium metal plates. Osteotomy with oblique fractures was prepared under general anesthesia. Exterior fixation was performed in open surgery. Interior fixation was minimally invasive using custom made tools including a flexible shaft extension screwdriver, solid plate stand, guiding wire loop and metal plates with threaded holes.

RESULTS

Respiratory and cardiovascular functions (RR, PO2, PCO2, SpO2, and HR) together with body temperature were measured before anesthesia and within 48 h after surgery. The difference in measurements was not statistically significant between the two groups before surgery with P values greater than 0.05. However, the interior group canines had better RR and PO2 values starting from the 24th hour, and better PCO2, SpO2, and HR values starting from the 48th hour. It took longer operation time to complete the minimally invasive interior fixation surgery (P value less than 0.001), but the total blood loss was less than the exterior fixation group (P value less than 0.001). Results also showed that interior group canines suffered less pain, and they had quicker recovery in gastrointestinal and physical mobility.

CONCLUSIONS

The investigative interior fixation method was safe and effective in rib stabilization on a canine rib fracture model, comparing to the exterior fixation method. The interior fixation was minimally invasive, with less damages to tissues and nerves surrounding the ribs, leading to better postoperative outcomes.

Non-invasive assessment of oxygenation status using the oxygen reserve index in dogs

BACKGROUND

The oxygen reserve index (ORi) is a real-time, continuous index measured with multi-wavelength pulse CO-oximetry technology. It estimates mild hyperoxemia in humans, which is defined as a partial pressure of oxygen (PaO2) level between 100 and 200 mmHg. The objectives of this study were to assess the correlation between ORi and PaO2, as well as to determine its ability in detecting mild hyperoxemia in dogs.

METHODS

This prospective observational study enrolled 37 anaesthetised and mechanically ventilated dogs undergoing elective procedures. Simultaneous measurements of ORi and PaO2 were collected, using a multi-wavelength pulse CO-oximeter with a probe placed on the dog's tongue, and a blood gas analyser, respectively. A mixed-effects model was used to calculate the correlation (r2) between simultaneous measurements of ORi and PaO2. The trending ability of ORi to identify dependable and proportional changes of PaO2 was determined. The diagnostic performances of ORi to detect PaO2 ≥ 150 mmHg and ≥ 190 mmHg were estimated using the area under the receiver operating characteristic curve (AUROC). The effects of perfusion index (PI), haemoglobin (Hb), arterial blood pH and partial pressure of carbon dioxide (PaCO2) on AUROC for PaO2 ≥ 150 mmHg were evaluated.

RESULTS

A total of 101 paired measurements of ORi and PaO2 were collected. PaO2 values ranged from 74 to 258 mmHg. A strong positive correlation (r2 = 0.52, p < 0.001) was found between ORi and PaO2. The trending ability ORi was 90.7%, with 92% sensitivity and 89% specificity in detecting decreasing PaO2. An ORi value ≥ 0.53 and ≥ 0.76 indicated a PaO2 ≥ 150 and ≥ 190 mmHg, respectively, with ≥ 82% sensitivity, ≥ 77% specificity and AUROC ≥ 0.75. The AUROC of ORi was not affected by PI, Hb, pH and PaCO2.

CONCLUSIONS

In anaesthetised dogs, ORi may detect mild hyperoxaemia, although it does not replace blood gas analysis for measuring the arterial partial pressure of oxygen. ORi monitoring could be used to non-invasively assess oxygenation in dogs receiving supplemental oxygen, limiting excessive hyperoxia.

Occurrence and clinical relevance of postoperative hypernatremia in dogs undergoing cholecystectomy

BACKGROUND

Patients undergoing cholecystectomy have not been reported previously to develop clinically relevant postoperative hypernatremia.

OBJECTIVES

Describe the frequency of postoperative hypernatremia in dogs undergoing cholecystectomy and its clinical relevance (duration of hospitalization and survival).

ANIMALS

Thirty-seven dogs undergoing cholecystectomy at 2 private referral hospitals.

METHODS

Retrospective study of dogs undergoing cholecystectomy with available preoperative and postoperative serum sodium concentrations.

RESULTS

Postoperative hypernatremia (>150 mEq/L) was common (56%; 95% confidence interval [CI], 40%-70%) and was associated with significantly higher mortality compared to nonhypernatremic patients (52%; 95% CI, 30%-70% vs 12.5%; 95% CI, 2%-40%; P = .02). Nonsurvivors had higher mean postoperative peak serum sodium concentrations (155 mEq/L; range, 146-172) than survivors (150 mEq/L; range, 142-156; P = .01). Dogs developing hypernatremia within 6 hours after surgery had 7.7 higher odds of nonsurvival (odds ratio [OR], 7.7; 95% CI, 5.9-9.4). A delta value (serum sodium concentration on admission [T0] - serum sodium concentration 6 hours postoperatively [T2]) of ≥10 mEq/L carried 3.3 higher odds of mortality (OR, 3.3; 95% CI, 1.6-5.1). All dogs with a postoperative peak sodium concentration >160 mEq/L did not survive. Admission acute patient physiologic laboratory evaluation fast (APPLEfast ) scores were not different between survivors and nonsurvivors or between postoperative hypernatremic and normonatremic patients. Hospitalization time was no different between hypernatremic and normonatremic patients (6 days vs 4.5 days; P = .15). Dogs with gallbladder mucocele were more likely to develop postoperative hypernatremia and have poorer outcomes.

CONCLUSIONS

Hypernatremia was a common and clinically relevant postoperative complication in dogs after cholecystectomy. Detection of hypernatremia within 6 hours after surgery may be associated with poorer outcomes.

Cervical ultrasound for endotracheal intubation confirmation in dogs by veterinary students: a cadaveric study

Although endotracheal intubation is usually a simple and fast procedure in dogs, some situations can be challenging and lead to the risk of tube misplacement in the esophagus-a life-threatening complication. Hence, confirming intubation is a cornerstone whenever this procedure is performed. Methods such as direct visualization or capnography present limitations insofar as they may be unreliable or unavailable under some circumstances. Ultrasound has emerged as a promising tool to confirm intubation in medicine. However, so far little research has been done on the subject in veterinary medicine. This study's main goal was to investigate ultrasound performed by veterinary students as a confirmation method for intubation in canine cadavers after a brief training session (25 minutes). A total of 160 exams were performed with a microconvex probe by 20 students in 11 different cadavers on left and right recumbencies. Overall accuracy was 70.6% with a median success rate of 75% and a median time to diagnosis of 25 seconds. The number of correct diagnoses was statistically higher than the wrong ones (p<0.05) without difference between recumbencies. Sensitivity, specificity, and positive and negative predictive values were 72.5%, 68.8%, 69.9%, and 71.4%, respectively. The fastest diagnosis was performed in just 4 seconds, and among the top-performers, one student had 100% accuracy with a mean time to diagnosis of 16.8 seconds, and four students had approximately 88% accuracy. This study showed for the first time that even inexperienced veterinary students can have acceptable accuracy in confirming endotracheal intubation in dogs after a brief training session.

Use of wound infusion catheters for postoperative local anaesthetic administration in cats

OBJECTIVES

The present study aimed to document the use of the wound infusion catheter (WIC) following a variety of surgical procedures in cats, investigating complications and risk factors associated with catheter placement or local anaesthetic (LA) administration.

METHODS

A retrospective, multicentric study was performed. Medical databases of eight veterinary referral hospitals from 2010 to 2021 were searched to identify records of cats where WICs were used. Information regarding signalment, type of surgery, size and type of WIC placed, and LA protocol used, as well as postoperative complications, were retrieved.

RESULTS

One hundred and sixty-six cases fulfilled the inclusion criteria. Feline injection site sarcoma resection was the most common surgery. Overall complications were identified in 22/166 cats (13.2%). Thirteen cats (7.8%) experienced wound-related complications, whereas nine cats (5.4%) experienced drug-delivery complications. The only factor associated with an increased risk of complications was the amount of a single dose of LA delivered through the catheter (P <0.001). An amount higher than 2.5 ml of LA delivered at each administration was associated with an increased risk of complications. All complications were minor and self-limiting.

CONCLUSIONS AND RELEVANCE

WICs were used for a large variety of surgical procedures with different protocols of LA administration as part of a multimodal analgesic plan in cats. The risk of complications was relatively low and self-limiting, suggesting its safe use in cats. Further prospective studies are required to evaluate efficacy of postoperative analgesia and to determine the suitable protocol for WIC handling and maintenance.

A Comparison of Dobutamine, Norepinephrine, Vasopressin, and Hetastarch for the Treatment of Isoflurane-Induced Hypotension in Healthy, Normovolemic Dogs

Isoflurane is a commonly used inhalation anesthetic in species undergoing veterinary care that induces hypotension, impacting organ perfusion, making it imperative to minimize its occurrence or identify effective strategies for treating it. This study evaluated and compared the hemodynamic effects of DOB, NEP, VAS, and HES in twelve isoflurane-anesthetized Beagle dogs. The order of the first three treatments was randomized. HES was administered last. Data were collected before treatments (baseline) and after 10 min of a sustained MAP of <45 mmHg induced by a high end-tidal isoflurane concentration (T0). Once treatment was initiated and the target MAP was achieved (65 to 80 mmHg) or the maximum dose reached, data were collected after 15 min of stabilization (T1) and 15 min after (T2). A 15 min washout period with a MAP of ≥65 mmHg was allowed between treatments. The intravenous dosage regimens started and were increased by 50% every five minutes until the target MAP or maximum dose was reached. The dosages were as follows: DOB, 5-15 μg/kg/min; NEP, 0.1-2 μg/kg/min; VAS, 0.5-5 mU/kg/min; and HET, 6% 1-20 mL/kg/min. DOB improved CO, DO2, and VO2, but reduced SVR. VAS elevated SVR, but decreased CO, DO2, and VO2. HES minimally changed BP and mildly augmented CO, DO2, and VO2. These treatments failed to reach the target MAP. NEP increased the arterial BP, CO, MPAP, and PAWP, but reduced HR. Norepinephrine infusion at 0.44 ± 0.19 μg/kg/min was the most efficient therapy for correcting isoflurane-induced hypotension.

Comparison between the effects of epidural lidocaine, tramadol, and lidocaine-tramadol on postoperative pain in cats undergoing elective orchiectomy

BACKGROUND

In veterinary clinical practice, orchiectomy is one of the most common surgical procedures for cats and is performed mainly in young animals. The purpose of this study was to compare three different epidural (EP) analgesic protocols used in cats undergoing orchiectomy in order to determine which protocol resulted in superior outcomes in terms of perioperative analgesia. Twenty-one client-owned male cats were premedicated with a combination of dexmedetomidine (10 µg/kg) and midazolam (0.2 mg/kg) injected intramuscularly. Anesthesia was induced intravenously with propofol. Cats were randomly divided in three treatment groups of seven animals each: Group L received EP lidocaine (2 mg/kg), Group T received EP tramadol (1 mg/kg), and Group LT received EP lidocaine (2 mg/kg) plus tramadol (1 mg/kg). The post-operative pain level was assessed using two different scales: the Glasgow Composite Measure Pain Scale-Feline (CMPS-F) and the Feline Grimace Scale (FGS). Rescue analgesia was administered when the CMPS-F total score was ≥5 or the FGS total score was ≥4.

RESULTS

No adverse effects related to tramadol or lidocaine were observed. Based on post-operative pain assessments, significant differences between groups were observed according to both pain scoring systems. In particular, in Group LT, the CMPS-F and FGS scores decreased significantly in the first six hours following castration.

CONCLUSIONS

Based on our results, EP lidocaine plus tramadol provided the best post-operative analgesic effects in cats submitted to orchiectomy lasting 6 h and could also be a choice to consider for longer surgical procedures.