Effects of intramuscular sedation with alfaxalone and butorphanol on echocardiographic measurements in healthy cats

The effects of alfaxalone on cardiac and pulmonary vascular size in cats evaluated by thoracic radiography and echocardiography

Alfaxalone is a neuroactive steroid that modulates the GABAA receptor, which has shown recent widespread use as a sedative and anesthetic agent in cats, especially in patients being screened for cardiovascular disease. This prospective, partially blinded, randomized experimental study aimed to determine if sedation with alfaxalone would alter the appearance of the cardiac silhouette or pulmonary vasculature on thoracic radiographs or echocardiographic indices of cardiac or pulmonary vascular size. Eleven apparently healthy adult cats were recruited from a research colony. Four-view thoracic radiographs and an echocardiogram were performed at baseline and following a 5 mg/kg intramuscular dose of alfaxalone. Vertebral heart score (VHS) and cranial and caudal lobar pulmonary vascular measurements were obtained at both time points by two independent blinded observers, and these were analyzed using two-way ANOVA. The nonblinded echocardiographer obtained echocardiographic measurements at both time points, which were analyzed using a paired t-test or Wilcoxon signed rank test. No significant differences were identified in VHS measurements or echocardiographic parameters between baseline and sedated cats. In healthy cats, alfaxalone does not appear to significantly affect the cardiovascular structures evaluated via thoracic radiography or echocardiography.

Aortic annular plane systolic excursion in cats with hypertrophic cardiomyopathy

BACKGROUND

Impairment of left ventricular (LV) longitudinal function is an early marker of systolic dysfunction in hypertrophic cardiomyopathy (HCM). Aortic annular plane systolic excursion (AAPSE) is a measure of LV longitudinal function in people that has not been evaluated in cats.

HYPOTHESIS

Aortic annular plane systolic excursion is lower in cats with HCM compared to control cats, and cats in stage C have the lowest AAPSE.

ANIMALS

One hundred seventy-five cats: 60 normal, 61 HCM stage B and 54 HCM stage C cats.

MATERIALS

Multicenter retrospective case-control study. Electronic medical records from 4 referral hospitals were reviewed for cats diagnosed with HCM and normal cats. HCM was defined as LV wall thickness ≥6 mm and normal cats ≤5 mm. M-mode bisecting the aorta in right parasternal short-axis view was used to measure AAPSE.

RESULTS

Aortic annular plane systolic excursion was lower in HCM cats compared to normal cats (3.9 ± 0.9 mm versus 4.6 ± 0.9 mm, P < .001) and was lowest in HCM stage C (2.4 ± 0.6 mm, P < .001). An AAPSE <2.9 mm gave a sensitivity of 83% (95% CI 71%-91%) and specificity of 92% (95% CI 82%-97%) to differentiate HCM stage C from stage B. AAPSE correlated with mitral annular plane systolic excursion (r = .6 [.4-.7], P < .001), and atrial fractional shortening (r = .6 [.5-.7], P < .001), but showed no correlation with LV fractional shortening.

CONCLUSIONS AND CLINICAL IMPORTANCE

Aortic annular plane systolic excursion is an easily acquired echocardiographic variable and might be a new measurement of LV systolic performance in cats with HCM.

Sedation Quality and Cardiorespiratory, Echocardiographic, Radiographic and Electrocardiographic Effects of Intramuscular Alfaxalone and Butorphanol in Spanish Greyhound Dogs

The quality of sedation and changes in cardiorespiratory variables after the intramuscular administration of alfaxalone and butorphanol in Spanish greyhound dogs were evaluated. Twenty-one adult dogs were included. The dogs received alfaxalone (2 mg/kg) and butorphanol (0.2 mg/kg) intramuscularly. Sedation scoring, cardiorespiratory parameters (including blood gas analysis), echocardiography, thoracic radiography and electrocardiography were performed before sedation and 30 min after drug administration. Moderate sedation was observed, and side effects, such as tremors, nystagmus and auditory hyperesthesia, were noticed. Statistically significant changes in heart rate, invasive blood pressure, pH, arterial saturation of O2 and partial pressure of O2 and CO2 were found. Echocardiographic variables, including end-diastolic volume, left ventricular diameter in diastole, aortic and pulmonic flow, diastolic transmitral flow and left atrial/aortic ratio, and electrocardiography parameters, including PQ interval and QT interval, showed statistically significant changes. In conclusion, the intramuscular administration of alfaxalone and butorphanol to healthy dogs produced moderate sedation with mild cardiorespiratory, echocardiographic and electrocardiographic changes, without alterations in cardiac size on radiographic images.

Clinical, Radiological, and Echocardiographic Findings in Cats Infected by Aelurostrongylus abstrusus

Cats infected by Aelurostrongylus abstrusus may show a plethora of clinical signs, and pulmonary hypertension (PH) seems to be one of the possible alterations induced by the infection; however, data on this association are scant and contradictory. Therefore, the aims of this study were to investigate the association between aelurostrongylosis and PH and to evaluate the correlation between the number of A. abstrusus larvae expelled in the faeces and the clinical, echocardiographic, and radiological alterations. Fifteen cats (i.e., eight males and seven females) older than 3 months and naturally infected by A. abstrusus with different parasitic loads, expressed as larvae per grams of faeces (l.p.g.), were enrolled in the study. Each animal underwent clinical, echocardiographic, and radiographic examinations. Most cats (i.e., 10/15) showed pathological patterns on thoracic radiograms; particularly, the alveolar pattern (four cats), interstitial-nodular pattern (five cats), and bronchial pattern (one cat). No significant echocardiographic findings of PH were detected. No correlation between the number of l.p.g. and the severity of clinical signs was observed, but a significant correlation with activated partial thromboplastin time (aPTT), radiographic alterations (interstitial nodular pattern), and ultrasonographic findings (RIVIDs) were noticed. These findings suggest that other factors such as animal age and health status, as well as comorbidity, may influence the presentation of the disease or the clinical manifestation and severity of the disease.

Comparison of two multimodal intramuscular anaesthetic protocols in uncooperative feline patients: effects on sedation and echocardiographic measurements

OBJECTIVES

The aims of this study were to compare the sedative effect, feasibility of venous angiocatheter placement and influence on heart rate (HR), systemic blood pressure (SBP) and echocardiographic variables of two multimodal anaesthetic protocols in uncooperative cats; and to compare their influence on HR, SBP and echocardiographic variables 20 mins after sedation and after elective ovariectomy.

METHODS

Eighteen stray female cats randomly received intramuscular (IM) ketamine (2 mg/kg) and methadone (0.3 mg/kg) plus dexmedetomidine (7 µg/kg; group D, n = 9) or alfaxalone (2 mg/kg; group A, n = 9). A sedation score (0-15 [from none to good sedation]) was assigned at 5 mins, 10 mins, 15 mins and 20 mins after IM injection. Venous angiocatheter placement and echocardiographic examination feasibility scores (both from 0 to 3 [from very difficult to very easy]) were recorded at 20 mins. Echocardiography, HR and blood pressure measurements (Doppler and oscillometric methods) were performed at 20 mins and at the end of surgery.

RESULTS

Sedation and angiocatheter feasibility scores did not differ significantly between groups (P >0.05); the feasibility score of echocardiographic examination was higher in cats in group D (P = 0.01). HR was higher in group A at 20 mins and after surgery (P <0.05). The systolic arterial pressure obtained with the Doppler method was statistically significantly higher in cats in group D than in group A at 20 mins (P = 0.01), while postoperatively there were no differences between groups. Cats in group D showed significantly higher atrial diameters (P <0.05) and slower atrial flows (P = 0.04) compared with group A; ventricular thickness and atrial function did not differ between groups (P >0.05). Most echocardiographic variables were not different at 20 mins vs postoperatively.

CONCLUSIONS AND RELEVANCE

Both protocols allowed for effective sedation; however, cats in group D presented alterations in some echocardiographic measurements; the use of alfaxalone, combined with ketamine and methadone, is recommended to obtain a reliable echocardiographic evaluation in uncooperative cats.

Effects of Aficamten on cardiac contractility in a feline translational model of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited cardiac disease in humans and cats and lacks efficacious pharmacologic interventions in the preclinical phase of disease. LV outflow tract obstruction (LVOTO) is commonly observed in HCM-affected patients and is a primary driver of heart failure symptoms and reduced quality of life. Novel small-molecule cardiac myosin inhibitors target actin-myosin interactions to alleviate overactive protein interactions. A prospective, randomized, controlled cross-over study was performed to evaluate pharmacodynamic effects of two doses (0.3 and 1 mg/kg) of a next-in-class cardiac myosin inhibitor, aficamten (CK-3773274, CK-274), on cardiac function in cats with the A31P MYBPC3 mutation and oHCM. Dose-dependent reductions in LV systolic function, LVOT pressure gradient, and isovolumetric relaxation times compared to baseline were observed. Promising beneficial effects of reduced systolic function warrant further studies of this next-in-class therapeutic to evaluate the benefit of long-term administration in this patient population.

Pharmacokinetics of a single dose of Aficamten (CK-274) on cardiac contractility in a A31P MYBPC3 hypertrophic cardiomyopathy cat model

Hypertrophic cardiomyopathy (HCM) is the most prevalent cardiac disease in cats and lacks efficacious preclinical pharmacologic intervention, prompting investigation of novel therapies. Genetic mutations encoding sarcomeric proteins are implicated in the development of HCM and small molecule myosin inhibitors are an emerging class of therapeutics designed to target the interaction of actin and myosin to alleviate the detrimental effects of inappropriate contractile protein interactions. The purpose of this study was to characterize the pharmacodynamic effects of a single oral dose of the novel cardiac myosin inhibitor aficamten (CK-274) on cardiac function in purpose bred cats with naturally occurring A31P MYBPC3 mutation and a clinical diagnosis of HCM with left ventricular outflow tract obstruction (LVOTO). Five purpose bred cats were treated with aficamten (2 mg/kg) or vehicle and echocardiographic evaluations were performed at 0, 6, 24, and 48 h post-dosing. High dose aficamten (2 mg/kg) reduced left ventricular fractional shortening (LVFS%) by increasing the LV systolic internal dimension (LVIDs) and reduced isovolumic relaxation time (IVRT) compared with baseline without significant adverse effects. The marked reduction in systolic function and reduced IVRT coupled with an increased heart rate in treated cats, suggest a lower dose may be optimal. Further studies to determine optimal dosing of aficamten are indicated.

Sedation quality of alfaxalone associated with butorphanol, methadone or pethidine in cats injected into the supraspinatus or the quadriceps muscle

OBJECTIVES

The aim of this study was to compare the quality of sedation with three different anaesthetic protocols (alfaxalone combined with butorphanol, methadone or pethidine) administered intramuscularly in cats, and to evaluate the influence of the injection site (between supraspinatus and quadriceps muscles) on the onset and quality of sedation.

METHODS

A total of 151 cats were selected for this study. Cats were sedated with alfaxalone (3 mg/kg) combined with either butorphanol (0.3 mg/kg; n = 50), methadone (0.3 mg/kg; n = 53) or pethidine (5 mg/kg; n = 48). The combination was injected intramuscularly into the supraspinatus (n = 79) or quadriceps muscle (n = 72). The data included a scoring system for the quality of sedation and physiological parameters, such as heart rate (HR), respiratory rate, body temperature and occurrence of mydriasis, monitored during the first 30 mins of anaesthesia.

RESULTS

The opioid associated with alfaxalone influenced the overall sedation score, the degree of myorelaxation, the occurrence of mydriasis and HR. The overall sedation score was poorer with butorphanol than with methadone (P = 0.008), and butorphanol induced a lower degree of myorelaxation than methadone (P = 0.013). The injection into the supraspinatus showed better qualitative results for sedation and a faster onset time (in about 3 mins) than that into the quadriceps (P <0.001). HR decreased from baseline (P <0.001) and over time (P <0.001), mainly in cats of the butorphanol-supraspinatus and pethidine-quadriceps groups (P = 0.004). The occurrence of mydriasis was lower after butorphanol than after methadone and pethidine (P = 0.025), while the incidence of side effects did not differ among groups.

CONCLUSIONS AND RELEVANCE

All three protocols provided a good quality of sedation and allowed performing the scheduled procedure. Moreover, the injection into the supraspinatus muscle showed superior results in all the qualitative scores of sedation and quicker onset time than that into the quadriceps muscle.

Sedative effects of alfaxalone and hydromorphone with or without midazolam in cats: a pilot study

OBJECTIVES

The aim of this pilot study was to compare the quality of sedation and ease of intravenous (IV) catheter placement following sedation using two intramuscular (IM) sedation protocols in cats: hydromorphone, alfaxalone and midazolam vs hydromorphone and alfaxalone.

METHODS

This was a prospective, randomized and blinded study. Cats were randomly assigned to receive an IM injection of hydromorphone (0.1 mg/kg), alfaxalone (1.5 mg/kg) and midazolam (0.2 mg/kg; HAM group), or hydromorphone (0.1 mg/kg) and alfaxalone (1.5 mg/kg; HA group). Sedation scoring (0-9, where 9 indicated maximum sedation) was performed at 0, 5, 10, 15 and 20 mins from the time of injection. At 20 mins, an IV catheter placement score (0-10, where 10 indicated least resistance) was performed.

RESULTS

Twenty-one client-owned adult cats were included in this study. Sedation and IV catheter placement scores were compared between groups using Wilcoxon rank sum tests. Peak sedation was significantly higher (P = 0.002) in the HAM group (median 9; range 7-9) than in the HA group (median 7; range 3-9), and IV catheter placement scores were significantly higher (P = 0.001) in the HAM group (median 9.5; range 7-10) compared with the HA group (median 7; range 4-9). Spearman correlations were calculated between IV catheter placement score and sedation scores. There was a significant positive correlation of average sedation over time (correlation 0.83; P <0.001) and sedation at 20 mins (correlation 0.76; P <0.001) with a higher, more favorable IV catheter placement score.

CONCLUSIONS AND RELEVANCE

These preliminary results suggest that the addition of midazolam to IM alfaxalone and hydromorphone produced more profound sedation and greater ease of IV catheter placement than IM alfaxalone and hydromorphone alone.

Hemodynamic, Echocardiographic, and Sedative Effects of Oral Gabapentin in Healthy Cats

The study objective was to evaluate sedative, hemodynamic, and echocardiographic effects of cats receiving single-dose, oral gabapentin. A prospective, double-blinded, placebo-controlled, crossover study was conducted with 10 client-owned cats. Vital parameters, physical exam, blood pressure, echocardiography, and sedation scoring were performed at each visit within 2 hr of receiving either a placebo or gabapentin capsule. Vital parameters, blood pressure recordings, and echocardiographic measurements were compared between baseline, gabapentin, and placebo; interobserver agreement for sedation scoring and correlation between variables were also evaluated. Seven of 10 cats exhibited mild sedation within 120 min after receiving gabapentin, and no adverse events occurred. Significant differences were detected with two-dimensional fractional shortening (P = .022), left ventricular internal diameter in systole using M-mode (P = .014), and left atrial volume (P < .0001). Interobserver agreement for sedation scoring was near-perfect (κ = 0.84). No significant correlation was found for gabapentin dosage and sedation score. Single-dose oral gabapentin is well tolerated in healthy cats and produces a modest decrease in several echocardiographic parameters of systolic function; however, all affected variables remained within established reference ranges. These results suggest gabapentin may be an appropriate sedative to administer before echocardiography in cats necessitating mild sedation.

Utility of Computed Tomographic Angiography for Pulmonary Hypertension Assessment in a Cohort of West Highland White Terriers With or Without Canine Idiopathic Pulmonary Fibrosis

West Highland white terriers (WHWTs) affected with canine idiopathic pulmonary fibrosis (CIPF) are at risk of developing precapillary pulmonary hypertension (PH). In humans, thoracic computed tomography angiography (CTA) is commonly used to diagnose and monitor patients with lower airway diseases. In such patients, CTA helps to identify comorbidities, such as PH, that could negatively impact prognosis. Diameter of the pulmonary trunk (PT), pulmonary trunk-to-aorta ratio (PT/Ao), and right ventricle-to-left ventricle ratio (RV/LV) are CTA parameters commonly used to assess the presence of PH. Pulmonary vein-to-right pulmonary artery ratio (PV/PA) is a new echocardiographic parameter that can be used in dogs to diagnose PH. The primary aim of this study was to evaluate the use of various CTA parameters to diagnose PH. An additional aim was to evaluate the correlation of RV/LV measurements between different CTA planes. CTA and echocardiography were prospectively performed on a total of 47 WHWTs; 22 affected with CIPF and 25 presumed healthy control dogs. Dogs were considered to have PH if pulmonary vein-to-right pulmonary artery ratio (PV/PA) measured on 2D-mode echocardiography was less than to 0.7. WHWTs affected with CIPF had higher PT/Ao compared with control patients. In WHWTs affected with CIPF, PT size was larger in dogs with PH (15.4 mm) compared with dogs without PH (13 mm, p = 0.003). A cutoff value of 13.8 mm predicted PH in WHWTs affected with CIPF with a sensitivity of 90% and a specificity of 87% (AUC = 0.93). High correlations were observed between the different CTA planes of RV/LV. Results suggest that diameter of the PT measured by CTA can be used to diagnose PH in WHWTs with CIPF.

Effects of Butorphanol With Alfaxalone or Dexmedetomidine on Feline Splenic Size and Appearance on Ultrasound and Computed Tomography

The purpose of the study was to determine the effects of intramuscular butorphanol with dexmedetomidine or alfaxalone on feline splenic size, echogenicity, and attenuation using ultrasound and computed tomography (CT). Ten healthy research cats underwent ultrasound and CT without sedation (controls), 15 min after protocol AB (alfaxalone 2 mg/kg and butorphanol 0.2 mg/kg) and 10 min after protocol DB (dexmedetomidine 7 μg/kg and butorphanol 0.2 mg/kg), with a one-week wash-out period between each sedation, using a cross-over study design. Images were randomized and anonymized for evaluation by a board-certified radiologist. On ultrasound, the sedative protocols affected splenic thickness, at the body and the tail (p = 0.002 and 0.0003, respectively). Post-hoc tests revealed that mean ± SEM thickness was greater after AB (body: 10.24 ± 0.30 mm; tail: 7.96 ± 0.33 mm) than for the control group (body: 8.71 ± 0.30 mm; tail: 6.78 ± 0.33 mm), while no significant difference was observed following DB. Splenic echogenicity was unchanged between treatments (p = 0.55). On CT, mean ± SEM splenic volume was increased after AB (37.82 ± 1.91 mL) compared to the control group (20.06 ± 1.91 mL) (p < 0.0001), but not after DB (24.04 ± 1.91 mL). Mean splenic attenuation increased after AB (p = 0.0009), but not DB. Protocol DB may be preferable for profound sedation in cats while avoiding changes in feline splenic imaging. When protocol AB is selected, splenomegaly should be expected, though mild on ultrasound. The increased splenic attenuation after AB is unlikely to be clinically relevant.

The effects of two intramuscular sedation protocols on echocardiographic variables in cats following sedation and blood donation

OBJECTIVE

To compare effects of 2 IM sedation protocols, alfaxalone-butorphanol (AB) versus dexmedetomidine-butorphanol (DB), on echocardiographic (ECHO) variables in cats following sedation and blood donation.

DESIGN

Experimental randomized, blinded crossover study.

SETTING

University teaching hospital.

ANIMALS

Eleven client-owned healthy cats.

INTERVENTIONS

Cats received a baseline ECHO without sedation prior to their first donation. Cats were sedated intramuscularly with AB (alfaxalone, 2 mg/kg, and butorphanol, 0.2 mg/kg) for 1 donation and DB (dexmedetomidine, 10 μg/kg, and butorphanol 0.2, mg/kg) for another, with a minimum 6 weeks between donations. A post-sedation, post-donation ECHO was performed after each blood donation.

MEASUREMENTS AND MAIN RESULTS

Eight cats completed the study. Compared to baseline, DB combined with blood donation decreased heart rate (-84/min; P < 0.0001), fractional shortening (-16.5%; P < 0.0001), ejection fraction (-21.0%; P = 0.0002), and cardiac output (-292 mL/min, P = 0.0001); AB combined with blood donation increased heart rate (+45/min; P = 0.0003) and decreased left ventricular end diastolic volume (-1.57 mL; P < 0.0001). Compared to AB, DB decreased heart rate (-129/min; P < 0.0001) and fractional shortening (-21.6%; P < 0.0001) and increased left ventricular end-systolic (+1.14 mL; P = 0.0004) and diastolic volumes (+1.93 mL; P < 0.0002). Cats administered DB had a significant increase in regurgitant flow across mitral, aortic, and pulmonic valves following blood donation (P < 0.05). One cat administered DB developed spontaneous echo contrast in the left ventricle following donation.

CONCLUSIONS AND CLINICAL RELEVANCE

Compared to AB, DB had more pronounced effects on ECHO variables in cats following IM sedation and blood donation. Due to its minimal impact on ECHO variables, AB may be a more desirable sedation protocol in this population of cats.

Feline procedural sedation and analgesia: When, why and how

PRACTICAL RELEVANCE

Procedural sedation and analgesia (PSA) describes the process of depressing a patient's conscious state to perform unpleasant, minimally invasive procedures, and is part of the daily routine in feline medicine. Maintaining cardiopulmonary stability is critical while peforming PSA.

CLINICAL CHALLENGES

Decision-making with respect to drug choice and dosage regimen, taking into consideration the cat's health status, behavior, any concomitant diseases and the need for analgesia, represents an everyday challenge in feline practice. While PSA is commonly perceived to be an uneventful procedure, complications may arise, especially when cats that were meant to be sedated are actually anesthetized.

AIMS

This clinical article reviews key aspects of PSA in cats while exploring the literature and discussing complications and risk factors. Recommendations are given for patient assessment and preparation, clinical monitoring and fasting protocols, and there is discussion of how PSA protocols may change blood results and diagnostic tests. An overview of, and rationale for, building a PSA protocol, and the advantages and disadvantages of different classes of sedatives and anesthetics, is presented in a clinical context. Finally, injectable drug protocols are reported, supported by an evidence-based approach and clinical experience.

Anesthetic Effects of Intramuscular Alfaxalone-Ketamine in Naked Mole Rats (Heterocephalus glaber)

In this study, adult intact male and female (n = 10) naked mole rats (Heterocephalus glaber) were anesthetized by using a combination of ketamine (20 mg/kg IM), and alfaxalone (4.0 mg/kg IM). Induction and recovery times were recorded. Vital parameters, including heart rate, respiratory rate, and reflexes, were monitored every 5 min during the anesthetic period. Anesthetic induction was smooth and rapid. Induction time was significantly longer in male rats (median, 325 s; range, 180 to 385 s) than in females (median, 145 s; range, 118 to 180 s). In addition, overall duration of loss of righting reflex was shorter in male mole rats (median, 50 min; range, 36 to 65 min) than females (median, 70 min; range, 60 to 85 min). Males largely had intact withdrawal reflexes, whereas females showed variable loss of both forelimb and hindlimb withdrawal reflexes. Neither recovery time (mean ± 1 SD, 16 ± 13 min) nor vital parameters differed between sexes. None of animals showed any anesthesia-related adverse responses. According to these findings, intramuscular AK is a safe and effective protocol that provides brief, light anesthesia in male naked mole rats and deeper anesthesia in females. We recommend adding analgesics when this AK protocol is used for pain-inducing or invasive procedures, and further studies evaluating higher doses and different combinations are indicated.

Anesthetic Effects of Alfaxalone-Ketamine, Alfaxalone-Ketamine-Dexmedetomidine, and Alfaxalone-Butorphanol-Midazolam Administered Intramuscularly in Five striped Palm Squirrels ( Funambulus pennantii)

Injectable anesthesia protocols for five striped palm squirrels (Funambulus pennantii) are poorly described in the literature. In this study, male intact squirrels received intramuscular injections of either alfaxalone (6 mg/kg) and ketamine (40 mg/ kg; AK group, n = 8); alfaxalone (6 mg/kg), ketamine (20 mg/kg), and dexmedetomidine (0.1 mg/kg; AKD group, n = 8); or alfaxalone (8 mg/kg), butorphanol (1 mg/kg), and midazolam (1 mg/kg; ABM group, n = 8). Atipamezole (0.15 mg/kg IM) and flumazenil (0.1 mg/kg IM) were administered 40 min after anesthesia induction (defined as loss of the righting reflex) with AKD and ABM, respectively. Heart rate, respiratory rate, rectal temperature, and reflexes were recorded every 5 min during anesthesia. Anesthetic induction was rapid in all groups (AK: median, 49 s; range, 33 to 60 s; AKD, 60 s; 54 to 70 s; and ABM, 15 s; 5 to 58 s). The anesthetic duration (from induction to full recovery) for the AK group was 62 ± 3 min (mean ± 1 SD). There was no statistically significant difference between the ABM and AKD groups regarding recovery time after partial antagonist administration and was 51 ± 5 and 48 ± 5 min, respectively. All AK animals showed twitching and abnormal vocalization during recovery. The righting reflex was absent in all squirrels for 20 min in the AK treatment group and throughout the 40 min anesthetic period in the AKD and ABM groups. The frontlimb withdrawal response was absent in all squirrels for the 40 min anesthetic period in the AKD and ABM groups, with variable responses for the AK treatment. All tested protocols in this study provided safe and effective immobilization in five striped palm squirrels, but oxygen and thermal support were indicated. Anesthetic depth must be determined before surgical procedures are performed in palm squirrels anesthetized by using these regimens.

Intramuscular alfaxalone and methadone with or without ketamine in healthy cats: effects on sedation and echocardiographic measurements

OBJECTIVE

To evaluate the effect of alfaxalone and methadone administered intramuscularly (IM), with or without ketamine, on sedation and echocardiographic measurements in healthy cats.

STUDY DESIGN

A randomized, blinded, clinical study.

ANIMALS

A group of 24 client-owned cats.

METHODS

Baseline echocardiographic evaluation (bEchoCG) was performed. Cats were given IM alfaxalone (2 mg kg^-1) and methadone (0.3 mg kg^-1) with (AMK group) or without (AM group) ketamine (1 mg kg^-1). A sedation score (0-5, indicating none to good sedation) was assigned at 5 (T5), 10 (T10) and 15 (T15) minutes after IM injection. At T15, a second echocardiographic evaluation (sEchoCG) was performed. Data are shown as median (range). Significance was p < 0.05.

RESULTS

Finally, 21 cats were included. Sedation score was significantly higher in the AMK (11 cats) than in the AM group (10 cats): 4 (1-5) versus 0.5 (0-4) at T5 (p = 0.003); 4 (1-5) versus 1.5 (0-5) at T10 (p = 0.043); and 4 (1-5) versus 2 (0-5) at T15 (p = 0.024). All echocardiographic measurements obtained were within reference ranges. Between the groups, aortic root area (p = 0.009) and end-diastolic aortic dimension (p = 0.011) were significantly higher in the AM group at bEchoCG and sEchoCG, respectively. Within each group, values at bEchoCG and sEchoCG showed no significant differences, except for pulmonary peak velocity (0.85 m second^-1; p = 0.028) in the AMK group and ejection time (154 m second; p = 0.03) in the AM group; both variables decreased after sedation.

CONCLUSIONS AND CLINICAL RELEVANCE

In this population of healthy cats, neither protocol produced clinically meaningful effects on the echocardiographic variables evaluated. Alfaxalone with methadone produced mild sedation, whereas the addition of 1 mg kg^-1 ketamine induced adequate sedation for diagnostic procedures.

Comparison of intramuscular administration of alfaxalone-ketamine-dexmedetomidine and alfaxalone-butorphanol-midazolam in naked mole-rats (Heterocephalus glaber)

OBJECTIVE

To compare anesthetic effects of alfaxalone-ketamine-dexmedetomidine (AKD) and alfaxalone-butorphanol-midazolam (ABM) in naked mole-rats (Heterocephalus glaber).

ANIMALS

20 naked mole-rats.

PROCEDURES

Naked mole-rats received AKD (alfaxalone, 2 mg/kg; ketamine, 20 mg/kg; and dexmedetomidine, 0.02 mg/kg; n = 10) or ABM (alfaxalone, 2 mg/kg; butorphanol, 2 mg/kg; and midazolam, 1 mg/kg; 9) IM; 1 animal was removed from the study. Atipamezole (I mg/kg) and flumazenil (0.1 mg/kg) were administered 40 minutes after anesthetic induction (defined as loss of the righting reflex) with AKD and ABM, respectively. Heart rate, respiratory rate, oxygen saturation, and reflexes were recorded every 5 minutes.

RESULTS

The ABM group had significantly longer median times for induction and recovery than the AKD group. Administration of ABM resulted in significantly lower respiratory rates than administration of AKD from time of anesthetic induction to 10 minutes after induction. Respiratory rate significantly decreased in the AKD group from I0 minutes after induction through the end of the anesthetic period but did not change over time in the ABM group. Males had higher respiratory rates in both groups. Loss of the righting reflex was still evident 40 minutes after induction in both groups. In the AKD group, all tested reflexes were absent from I0 to 40 minutes after induction; the ABM group had variable reflexes that recovered within individual animals over time.

CONCLUSIONS AND CLINICAL RELEVANCE

Both AKD and ABM provided effective immobilization in naked mole-rats, but AKD appeared to provide more consistent and deeper anesthesia, compared with administration of ABM.

Pharmacologic Methods: An Update on Optimal Presedation and Euthanasia Solution Administration

Pre-euthanasia sedation or anesthesia offers many benefits. It allows the owners to spend time with their pet before euthanasia, improves safety for the person performing euthanasia and others who are present, decreases stress for the patient, reduces or eliminates the need for physical restraint for intravenous injection. Under anesthesia, non-intravenous routes may be used for administration of euthanasia solutions. Some drugs that do not require injection; the oral transmucosal route is noninvasive and suitable for several drugs or drug combinations. The oral route also is feasible, but there are fewer data available on suitable drugs and doses.

Effects of oral trazodone on echocardiographic and hemodynamic variables in healthy cats

OBJECTIVES

The purpose of this study was to evaluate the effects of oral trazodone on echocardiographic variables, heart rate (HR) and blood pressure (BP) in healthy cats.

METHODS

Client-owned domestic cats between 2 and 8 years of age were recruited. Cats were considered healthy based on physical examination, complete blood count, blood chemistry profile, urinalysis, total thyroxine concentration, non-invasive BP measurement by Doppler method and a screening transthoracic echocardiogram with simultaneous electrocardiogram. Echocardiographic variables assessed pre-trazodone and 90-120 mins post-trazodone (50 mg PO) included left ventricular internal diameter in systole and diastole, interventricular septal and left ventricular free-wall thickness in systole and diastole, left atrial size, left auricular function and left ventricular diastolic function assessed by spectral Doppler transmitral and pulmonary venous flow velocities, and tissue Doppler profiles. Mean echocardiographic and hemodynamic variables were calculated for pre- and post-trazodone examinations for each cat. Pre- and post-trazodone variables were analyzed with a paired t-test with significance set at P <0.05.

RESULTS

Twelve healthy cats were evaluated. Trazodone was administered to all cats and a sedative effect was observed. There were no clinically significant differences in any echocardiographic variables post-trazodone administration. Systolic BP was significantly decreased after trazodone (P = 0.001) with no significant change in HR.

CONCLUSIONS AND RELEVANCE

Trazodone did not alter echocardiographic variables, in a clinically relevant manner, in this group of healthy cats. Trazodone may aid in obtaining transthoracic echocardiograms without affecting HR or echocardiographic variables but may significantly lower BP in healthy cats.

Comparison of two high doses of subcutaneous buprenorphine in cats undergoing ovariohysterectomy

Objectives:

The aim of the study was to evaluate the analgesia and recovery effects of two doses (0.12 mg/kg and 0.24 mg/kg) of subcutaneous buprenorphine in cats undergoing ovariohysterectomy.

Methods:

This was an assessor-blinded, randomised, clinical study. A total of 83 cats were recruited and randomly allocated to receive 0.12 mg/kg buprenorphine or 0.24 mg/kg buprenorphine subcutaneously, followed 30 minutes later by 40 μg/kg medetomidine intramuscularly. Anaesthesia was induced with intravenous alfaxalone to effect and maintained with isoflurane in oxygen. All cats received meloxicam before surgery. Temperament score, quality of sedation, induction of anaesthesia, dose of alfaxalone and recovery were scored using simple descriptive scales. Atipamazole was administered following surgery. Physiological variables during anaesthesia were recorded. Cats were assessed postoperatively by the same blinded observer at 2, 4 and 24 hours using a modified Colorado Feline Acute Pain scale. The presence or absence of mydriasis was noted.

Results:

No significant differences were identified between groups. Three cats in the 0.12 mg/kg group and four in the 0.24 mg/kg group required rescue analgesia. Mydriasis persisting for at least 24 hours was evident in 75 cats.

Conclusions and relevance:

No differences in analgesia were detected between groups with these protocols; mydriasis was common in both groups.

Intranasal dexmedetomidine in healthy beagles: An echocardiographic and pharmacokinetic/pharmacodynamic study

The aim of this study was to compare the sedative and cardiovascular effects of dexmedetomidine (DEX) administrated via intranasal (IN) and intramuscular (IM) routes. This masked, randomised, crossover study used six male beagle dogs, receiving 0.02 mg/kg dexmedetomidine either IN (DEX-IN) or IM (DEX-IM), and an equal volume of saline by the alternative route. Dexmedetomidine plasma concentration was measured before (TB) and at time points (T) 2, 5, 10, 15, 30, 45, 60, 90 and 120 min after drug administration (T0). Physiological variables, sedation scores and sedation times were recorded until recovery. Echocardiography was performed at TB and between T20-T40. Repeated data over time were analysed using a Scheirer-Ray-Hare test. Other data were compared using a Wilcoxon or Student's t test. Times from T0 to sternal position and from lateral to sternal position were longer for DEX-IN than DEX-IM (P = 0.018 and P = 0.009, respectively). Time from sternal to standing position was shorter for DEX-IN than DEX-IM (P = 0.03). Dexmedetomidine plasma concentrations were significantly lower for DEX-IN than DEX-IM from T10 to T120. Heart rate was significantly lower for DEX-IM than DEX-IN from T5 to T20. Echocardiography showed a decrease in systolic function and calculated cardiac output in DEX-IM as compared to baseline. The DEX concentration-sedation curve for DEX-IN as compared to DEX-IM was leftward shifted, whereas the IN and IM DEX concentration-variation-in-heart-rate curves overlapped. Although reaching lower plasma concentrations, IN dexmedetomidine produced similar sedation to IM dexmedetomidine without affecting cardiovascular function.

Effects of Intramuscular Alfaxalone/Acepromazine on Echocardiographic, Biochemical, and Blood Gas Measurements in Healthy Cats

The effects of intramuscular injection of alfaxalone ([ALF] 5 mg/kg), acepromazine ([ACE] 0.05 mg/kg), and an ALF-ACE combination ([AA] 0.025 mg/kg ACE followed by 2.5 mg/kg ALF) on the sedation, echocardiographic, biochemical, and blood gas indexes and recovery were evaluated in seven cats. No sedation was obtained with ACE, and sedation scores were higher with ALF than with AA treatment. Compared with baseline, an increase in heart rate occurred after ACE, and all treatments caused a decrease in systemic arterial pressure. Decreased left ventricular internal dimension in diastole, end-diastolic volume of the left ventricle, stroke volume, and left atrial dimension were identified after AA. There were minimal changes in echocardiographic variables after ALF. Biochemical and blood gas analysis showed no significant changes after all treatments. Although the difference in quality of recovery between the AA and ALF treatment groups was insignificant, all cats treated with AA or ALF showed ataxia. The AA combination did not change the recovery score, and tremor and twitching were identified more frequently with AA than ALF. ALF had no significant effects on echocardiographic, biochemical, or blood gas variables. ALF could be considered a useful sedative option for diagnostic procedures and echocardiography in cats.

Comparison of two intramuscular sedation protocols on sedation, recovery and ease of venipuncture for cats undergoing blood donation

OBJECTIVES

The aim of this study was to compare the quality of sedation and recovery, and ease of venipuncture following sedation for feline blood donation using two intramuscular (IM) sedation protocols: alfaxalone/butorphanol (AB) and dexmedetomidine/butorphanol (DB).

METHODS

This was an experimental randomized, blinded, crossover study. Ten client-owned healthy cats were recruited to participate in the study. Cats were sedated with AB (alfaxalone 2 mg/kg and butorphanol 0.2 mg/kg) for one donation and DB (dexmedetomidine 10 μg/kg and butorphanol 0.2 mg/kg) for another. Reaction to injection, quality of sedation and quality of recovery were assessed by a blinded observer. Time to lateral recumbency, number of venipuncture attempts, time required for blood collection and time to return to sternal recumbency were recorded. Cats were monitored for evidence of gastrointestinal distress. Each donation consisted of a maximum of 53 ml whole blood drawn over 3-22 mins. Donors received 100 ml subcutaneous lactated Ringer's solution in recovery. Owners, unaware of sedation protocol, were asked to complete a questionnaire evaluating their cat's behavior following sedation.

RESULTS

IM injections were well tolerated by both treatment groups. There was no significant difference between treatment groups in sedation scores for posture ( P = 0.30) or behavior ( P = 0.06). Cats sedated with DB had significantly higher muscle relaxation scores ( P = 0.03) compared with AB. There was no significant difference between treatment groups in time to lateral recumbency ( P = 0.12), number of venipuncture attempts ( P = 0.91) and time for blood draw ( P = 0.29). There was no difference in quality of recoveries between treatment groups based on simple descriptive scores ( P = 0.18) and owner evaluation 24 h following sedation. One cat vomited following administration of DB.

CONCLUSIONS AND RELEVANCE

Alfaxalone is a suitable alternative to dexmedetomidine when combined with butorphanol and used as part of an IM sedation protocol for cats undergoing blood donation.

Electrocardiography-gated cardiac CT angiography can differentiate brachycephalic dogs with and without pulmonary valve stenosis and findings differ from transthoracic echocardiography

Pulmonary valve stenosis (PS) is one of the most commonly diagnosed congenital heart defects in dogs. Currently, transthoracic echocardiography (TTE) is the standard modality used to evaluate PS. Image acquisition by TTE can be challenging in some brachycephalic breeds of dogs. The use of echocardiographic-gated CT angiography (ECG-gated CTA) in veterinary medicine is limited. This retrospective method comparison study investigated right and left ventricular outflow diameters by sedated ECG-gated CTA and unsedated TTE in 14 brachycephalic dogs with PS and 12 brachycephalic dogs without PS. Measurements of ventricular outflow structures were made in early systole and end diastole for both modalities and then compared for significance between systolic and diastolic phases, as well as between the two modalities. Ratios of the pulmonary trunk diameter to the aorta at different locations (aortic valve, aortic annulus, and ascending aorta) and in different planes (transverse, sagittal) were compared between dogs with PS and without PS, as well as within dogs, by both TTE and ECG-gated CTA. Transthoracic echocardiography and ECG-gated CTA both detected significantly greater pulmonary trunk to aorta ratios in dogs with PS at all aortic locations (P < 0.05). Pulmonary valve to aortic valve ratios were significantly smaller in dogs with PS (P < 0.05). Pulmonary trunk to aorta and pulmonary valve to aorta ratios were achieved with good anatomic detail using ECG-gated CTA. Ratios of the pulmonary trunk and pulmonary valve relative to the aorta may be useful to evaluate for PS using a modality that is underutilized for cardiac assessment.

Pharmacokinetics of intramuscular alfaxalone and its echocardiographic, cardiopulmonary and sedative effects in healthy dogs

The pharmacokinetics and the effects of a single intramuscular (IM) dose of alfaxalone on sedation and cardiopulmonary and echocardiographic variables was studied in dogs. Twelve healthy adult Beagles (3 females, 9 males) were used in this prospective controlled cross-over trial. Echocardiography was performed with and without 4 mg kg-1 alfaxalone IM with a week wash-out interval. Sedation (19-point scale; 0 = no sedation), cardiopulmonary parameters, blood gas analysis and plasma concentration of alfaxalone were assessed every 5 minutes following the injection (T0). The influence of the alfaxalone plasma concentration and time on physiological variables was tested using a linear model whereas echocardiographic measurements were compared between conscious and alfaxalone-administered dogs using paired t-tests. Compared to baseline, alfaxalone administration was followed by an increase in heart rate (HR) from T5 to T30 and a decrease in mean arterial pressure (MAP) at T10, T25 and T30, in stroke volume (SV; 15 ± 5 to 11 ± 3 ml; P<0.0001), and end-diastolic volume (EDV; 24.7 ± 5.7 to 19.4 ± 4.9 ml). Cardiac output (CO) and blood gas analysis did not change significantly throughout. Mean plasma half-life was 29 ± 8 minutes, volume of distribution was 1.94 ± 0.63 L kg-1, and plasma clearance was 47.7 ± 14.1 ml kg-1 minute-1. Moderate to deep sedation was observed from T5 to T35. Ten dogs showed paddling, trembling, nystagmus and strong reaction to sound during the procedure. Although there were no significant changes in CO and oxygenation, the impact of HR, MAP, SV, EDV alterations requires further investigations in dogs with cardiac disease.

Evaluation of an intramuscular butorphanol and alfaxalone protocol for feline blood donation: a pilot study

Objectives The purpose of this pilot study was to evaluate the use of an intramuscular (IM) sedation protocol with butorphanol and alfaxalone in cats undergoing blood donation. We hypothesized that this drug combination would provide sufficient sedation to perform phlebotomy without causing hypotension or significant changes in heart rate. Methods Six purpose-bred, healthy adult cats were sedated using IM butorphanol (0.4 mg/kg) and alfaxalone (2-3 mg/kg). Pulse and Doppler blood pressure (BP) were recorded at baseline, after sedation and immediately following phlebotomy. Once laterally recumbent, 12 ml/kg blood was collected from the jugular vein. Sedation scores, duration of lateral recumbency and the ability to successfully perform phlebotomy were recorded. Results There was no significant change in heart rate post-sedation (median 190 beats per min [bpm], range 160-224 bpm) or post-phlebotomy (median 200 bpm, range 180-220 bpm) compared with baseline values (median 200 bpm, range 180-220 bpm) ( P = 0.395). A statistically significant change in BP was detected ( P = 0.029), attributed to a difference between post-sedation (median 113.3 mmHg, range 110.7-130.0) and baseline (median 133.3 mmHg, range 130.0-183.3) measurements. Hypotension was not observed in any cat. Collection of at least 80% of the target volume was achieved in 5/6 cats, although all were adequately sedated to allow jugular venous phlebotomy. Median recumbency time was 53 mins (range 43-83 mins). Phlebotomy duration lasted a median of 13 mins (range 5-21 mins). Conclusions and relevance The administration of IM alfaxalone and butorphanol provided sufficient restraint for blood donation without causing hypotension or significant changes in heart rate before or after phlebotomy.

AAFP Feline Anesthesia Guidelines

AIM

The overarching purpose of the AAFP Anesthesia Guidelines (hereafter referred to as the 'Guidelines') is to make anesthesia and sedation safer for the feline patient. Scope and accessibility: It is noteworthy that these are the first exclusively feline anesthesia guidelines authored by an expert panel, making them particularly useful as an extensively referenced, practical resource for veterinary practice teams. Because much of the key content is presented in tabular or visual format, the Guidelines have a high level of accessibility and convenience that invites regular usage. While the recommendations in the Guidelines focus primarily on client-owned cats, the content is also applicable to community-sourced animals with an unknown medical history.

Effects of sedation with dexmedetomidine and buprenorphine on echocardiographic variables, blood pressure and heart rate in healthy cats

Objectives Sedative agents are occasionally used to enable echocardiographic examination when screening cats for heart disease, such as hypertrophic cardiomyopathy (HCM). Owing to their haemodynamic effects, sedative agents may alter echocardiographic measurements. The aim of the study was to evaluate the effects of the sedative combination dexmedetomidine and buprenorphine on echocardiographic variables, blood pressure (BP) and heart rate (HR) in healthy cats. Methods Fifty healthy, client-owned cats were prospectively recruited and included after physical examination. Cats were sedated intramuscularly with dexmedetomidine and buprenorphine, according to body weight. Blood pressure and HR measurements, echocardiographic and Doppler examinations were performed prior to sedation and repeated once cats had achieved acceptable sedation. Results Left ventricular internal diameter at end-diastole and systole, right ventricular internal diameter at end-diastole, left atrium (LA), pulmonary artery (PA) deceleration time, and systolic, diastolic and mean arterial blood pressure increased after sedation ( P ⩽0.022). Aortic and PA maximum velocity, fractional shortening, PA acceleration/deceleration time and HR decreased after sedation ( P <0.0001). Interventricular septum at end-diastole and systole, left ventricular posterior wall at end-diastole and systole, aortic diameter (Ao), left atrial/aortic diameter (LA/Ao) and pulmonic acceleration time did not change. Conclusions and relevance Blood pressure increased and HR decreased post-sedation. While wall thickness and LA/Ao were not affected by sedation, indices of LA and left ventricular size increased. Further studies are needed using cats with HCM to assess the effect of this sedative combination on HCM screening results.

Assessing analgesia equivalence and appetite following alfaxalone- or ketamine-based injectable anesthesia for feline castration as an example of enhanced recovery after surgery

Objectives The primary study objective was to assess two injectable anesthetic protocols, given to facilitate castration surgery in cats, for equivalence in terms of postoperative analgesia. A secondary objective was to evaluate postoperative eating behavior. Methods Male cats presented to a local clinic were randomly assigned to receive either intramuscular ketamine (5 mg/kg, n = 26; KetHD) or alfaxalone (2 mg/kg, n = 24; AlfHD) in combination with dexmedetomidine (25 μg/kg) and hydromorphone (0.05 mg/kg). All cats received meloxicam (0.3 mg/kg SC) and intratesticular lidocaine (2 mg/kg). Species-specific pain and sedation scales were applied at baseline, 1, 2 and 4 h postoperatively. Time taken to achieve sternal recumbency and begin eating were also recorded postoperatively. Results Pain scale scores were low and showed equivalence between the treatment groups at all time points (1 h, P = 0.38, 95% confidence interval [CI] of the difference between group scores 0-0; 2 h, P = 0.71, 95% CI 0-0; 4 h, P = 0.97, 95% CI 0-0). Four cats crossed the threshold for rescue analgesia (KetHD, n = 1; AlfHD, n = 3). At 1 h, more cats in the KetHD (65%) group than in the AlfHD (42%) group were sedated, but statistical significance was not detected ( P = 0.15, 95% CI -1 to 0). Most AlfHD cats (88%) began eating by 1 h vs 65% of KetHD cats ( P = 0.039). Time to recover sternal recumbency did not differ between groups ( P = 0.86, 95% CI -14.1 to 11.8). Conclusions and relevance These results show that AlfHD and KetHD provide equivalent analgesia as part of a multimodal injectable anesthetic protocol. Alfaxalone is associated with an earlier return to eating.

A survey of dog and cat anaesthesia in a sample of veterinary practices in New Zealand

AIMS

To survey current anaesthesia practices for dogs and cats in small and mixed animal practices in New Zealand in order to improve anaesthesia education.

METHODS

A questionnaire was sent to 440 small and mixed animal practices, including questions regarding the type of practice, preanaesthetic examination, anaesthetic drugs and management, anaesthetic machines, monitoring and topics of interest for continuing professional development.

RESULTS

Responses were obtained from 113/440 (26%) practices, with 78 (69%) respondents from small and 35 (31%) from mixed animal practices. A preanaesthetic physical examination was carried out by >95% of respondents and premedication was usually given to dogs (112/113; 99%) and cats (95/113; 85%). Acepromazine was the preferred sedative for dogs and cats, with morphine or buprenorphine. Propofol and alfaxalone were the preferred induction agents, and isoflurane was preferred for maintenance in both dogs and cats. A venous catheter was usually placed for anaesthesia in dogs (59/113; 52%), but less so in cats (39/113; 35%). Perioperative fluid was administered at 10 mL/kg/hour by 62/110 (56%) respondents. Intubation was usually used for anaesthesia in dogs (111/112; 99%), and cats (87/112; 78%). Almost 40% of respondents usually administered supplementary oxygen if patients were not intubated. Local analgesia was used by 69/111 (88%) respondents sometimes or always if applicable. Morphine or buprenorphine, and meloxicam were common choices for post-operative analgesia after neuter surgery in dogs and cats. A semiclosed (non-rebreathing) system was used in animals weighing <10 kg, and a Mapleson E or F non-rebreathing circuit was used by 66/109 (61%) practices. Only 15/111 (14%) practices had a ventilator in their practice. A dedicated anaesthetist was usually used by 104/113 (92%) practices, and apnoea alarms, pulse oximeters, thermometers and oesophageal stethoscopes were the main monitoring devices available in practices. Loco-regional block, pain management, and anaesthetic drugs were the main topics of interest for continuing education.

CONCLUSIONS AND CLINICAL RELEVANCE

Responses by the veterinarians taking part in this survey indicated that they had a reasonably good standard of anaesthetic practice. A physical examination was carried out preanaesthesia, and premedication including analgesia was routinely administered to most patients. A dedicated anaesthetist usually monitored patients and most respondents reported they had access to basic anaesthetic monitoring equipment. Areas where changes could lead to improved anaesthetic practice were increased use of I/V catheterisation, endotracheal intubation, and supplementary oxygen, and reduced I/V fluid rates.

Comparison of intramuscular alfaxalone and ketamine combined with dexmedetomidine and butorphanol for castration in cats

Objectives Cardiorespiratory parameters and anaesthesia quality in cats anaesthetised with either intramuscular (IM) alfaxalone or ketamine both combined with dexmedetomidine and butorphanol for castration were evaluated. Methods Thirty-two client-owned cats were randomly assigned to receive either alfaxalone (A; 3 mg/kg IM) or ketamine (K; 5 mg/kg IM), combined with dexmedetomidine (10 μg/kg) and butorphanol (0.2 mg/kg). Heart rate (HR), respiratory rate (RR) and rectal temperature (T°) were recorded prior to drug administration. Pulse rate (PR) and RR were recorded 10 (T10) and 15 (T15) mins after injection (T0). Cardiorespiratory values (PR, RR, SPO2, blood pressure, PE'CO2) were recorded every 5 mins for the duration of the procedure. Pain at injection, intubation and recovery were evaluated with simple descriptive scores. Feasibility of anaesthesia was evaluated by the number of top-ups of anaesthetic needed. Cat attitude, ability to walk and presence of ataxia were assessed several times after extubation (Texmin) and the time between injection and extubation recorded. Pain was assessed at Tex120 and Tex240 with the 4Avet-pain score. Results The RR was significantly lower in group K at T10 (RRK = 28 ±13.35 breaths per minute [brpm], RRA= 43.24 ±7.04 brpm) and T15 (RRK = 28 ±11.53 brpm vs RRA = 43 ±12.18 brpm). Time to extubation was significantly longer in group A (TA = 62 ±14.6 mins, TK = 45.13 ± 7.38 mins). Cats in group K needed more top-ups, were more ataxic at Tex120, had a worse recovery score at Tex60 and were less willing to walk at Tex30. Conclusions and relevance Cats receiving alfaxalone had a longer but better quality recovery. Cardiorespiratory parameters were stable and within clinically acceptable values following IM injection of either alfaxalone or ketamine in healthy cats. Intramuscular alfaxalone is a suitable alternative to ketamine for short procedures requiring anaesthesia when used in combination with dexmedetomidine and butorphanol.