Sedative and echocardiographic effects of dexmedetomidine combined with butorphanol in healthy dogs

The impact of intravenous medetomidine and vatinoxan on echocardiographic evaluation of dogs with stage B1 mitral valve disease

INTRODUCTION/OBJECTIVE

The purpose of this study was to investigate the echocardiographic effects of intravenous medetomidine and vatinoxan in dogs with stage B1 mitral valve disease. We hypothesised medetomidine-vatinoxan would reduce the need for manual restraint during echocardiography without producing detrimental cardiovascular effects or echocardiographic changes.

ANIMALS

Twelve client-owned dogs with stage B1 mitral valve disease.

METHODS

A transthoracic echocardiographic examination was performed before and after sedation with intravenous medetomidine (10 μg/kg) and vatinoxan (200 μg/kg). Vital parameters were also recorded, and the level of sedation was assessed subjectively. The data were analysed with Student's t-tests with an alpha level of <0.05.

RESULTS

End-systolic volume and left ventricular systolic diameter increased (from 0.89 ± 0.19 mL/kg to 1.13 ± 0.29 mL/kg and 0.96 ± 0.12 cm to 1.10 ± 0.10 cm, respectively) and ejection fraction (from 66.33 ± 4.0% to 56.23 ± 9.54%) and fractional shortening (from 36.13 ± 5.42% to 27.24 ± 5.6%) decreased significantly after sedation. End diastolic volume, left ventricular diastolic diameter, and left atrial size remained statistically unchanged, while aortic (from 1.34 ± 0.2 m/s to 0.99 ± 0.14 m/s) and pulmonic (from 0.94 ± 0.16 m/s to 0.66 ± 0.15 m/s) velocities decreased significantly. No dogs had a mean arterial pressure below 65 mmHg. Sedation enabled echocardiographic examination without manual restraint. No adverse effects were observed with the dose studied.

CONCLUSIONS

Echocardiographic parameters were not completely comparable with the baseline values, which should be taken into consideration when evaluating dogs sedated with intravenous medetomidine-vatinoxan.

Effect of dexmedetomidine constant rate infusion on the analgesic duration of peripheral nerve blocks in dogs: a randomized clinical study

The aim of this study was to evaluate whether a constant rate infusion of dexmedetomidine could prolong the analgesic effect of peripheral nerve blocks. Twenty client-owned dogs were enrolled and randomly divided into 2 groups. The DEX group received dexmedetomidine infusion at 1 mcg kg-1 h-1, and the NaCl group received an equivalent volume infusion of saline. Infusions were started after securing vascular access and continued for 10 min, after which intravenous (IV) methadone at 0.2 mg kg-1 and propofol to effect were administered. All animals were maintained with isoflurane in 70% oxygen. Sciatic, saphenous and obturator nerve blocks were performed using 0.1 mL kg-1 0.5% ropivacaine/block. Intraoperative fentanyl was administered if the heart rate and/or mean arterial pressure (MAP) increased > 15% from the previous measurement, and vasopressors were administered if MAP was ≤ 70 mmHg. Postoperative pain was assessed every hour using the Glasgow Composite Pain Scale (GCPS) until the first rescue analgesia administration. Postoperative rescue analgesia (methadone (0.2 mg kg-1 IV) and carprofen (2 mg kg-1 IV)) was administered if the pain score was higher than 6/24 or 5/20. Duration of analgesia was defined as the time between the nerve block procedure and initial postoperative rescue analgesia. Ambulation, proprioception, and skin sensitivity were evaluated to assess the duration of the motor and sensory block. A Student T and chi-square test were used to compare groups for duration of postoperative analgesia and intraoperative fentanyl and vasopressor use, respectively (p values ≤ 0.5 considered significant). A greater number of dogs in the NaCl group required fentanyl (5/10 p = 0.03) and vasopressors (8/10, p = 0.02) than did those in the DEX group (0/10 and 2/10, respectively). The duration of postoperative analgesia was significantly longer (604 ± 130 min) in the DEX group than in the NaCl group (400 ± 81 min, p = 0.0005).Dexmedetomidine infusion at 1 mcg kg-1 h-1 delays the time to first administration of rescue analgesia and reduces intraoperative analgesic and vasopressor requirements during Tibial Tuberosity Advancement surgery.

Effect of Butorphanol-Medetomidine and Butorphanol-Dexmedetomidine on Echocardiographic Parameters during Propofol Anaesthesia in Dogs

This study compared the effects of butorphanol-medetomidine and butorphanol-dexmedetomidine combinations on echocardiographic parameters during propofol anaesthesia in dogs. The dogs were randomly divided into two groups. In the butorphanol-medetomidine (BM) group, butorphanol (0.2 mg/kg) and medetomidine (15 μg/kg) were intravenously administered; in the butorphanol-dexmedetomidine (BD) group, butorphanol (0.2 mg/kg) and dexmedetomidine (7.5 μg/kg) was used. Anaesthesia was induced with propofol and maintained with a constant-rate infusion of propofol (0.2 mg/kg/min). The echocardiographic parameters were assessed in conscious dogs (T0). Echocardiography was conducted again at 10 min post premedication (T1), followed by assessments at 30 (T2), 60 (T3), and 90 (T4) mins. The dogs were subjected to diagnostic procedures (radiography, computed tomography) under anaesthesia. A significant reduction in heart rate and cardiac output was noted in both groups at T1. There was no significant difference in the stroke volume between the BM and BD groups. The application of butorphanol-dexmedetomidine caused a significant increase in the left ventricular internal diameter in diastole and the diameter of the left atrium compared to that caused by butorphanol-medetomidine. This study documented that butorphanol-medetomidine and butorphanol-dexmedetomidine combinations caused similar reductions in heart rate and cardiac output in both groups. 'New´ valvular regurgitation occurred following their administration.

Pharmacokinetics and pharmacodynamics of intravenous dexmedetomidine (2 μg∙kg-1) in dogs

This study assessed the pharmacokinetics and pharmacodynamics of low-dose dexmedetomidine after IV bolus in dogs. Six healthy adult dogs (6.8 ± 3.0 kg) received dexmedetomidine (2 μg.kg-1 IV) over 2 min, using an infusion pump. Blood samples were collected totaling 5 h of monitoring. A validated UHPLC-MS/MS method was used to determine the plasma concentration of dexemedetomidine. For pharmacodynamics, HR, RR, oscillometric MBP, Grint END sedation score were evaluated at baseline (T0), every 3 min (T3 to T21), and after 30 (T30) and 60 (T60) minutes, with p < 0.05. T1/2 was 28.28 ± 6.14 min; the area under the curve was 467.44 ± 60.42 ng/mL/min. The total clearance was 5.46 ± 0.41 mL/min/kg, the Vdss was 146.19 ± 21.04 mL/kg, and the C max was 3.13 ± 1.15 ng/mL. HR (bpm) decreased significantly from T6 (79 ± 21) to T21 (78 ± 31) compared to T0 (116 ± 28). RR(mpm) decreased from T3 (43 ± 44) to T60 (41 ± 23), with T0 being 70 ± 48. The MBP (mmHg) increased at T18 (151 ± 34), T21 (152 ± 35), and T30 (140 ± 27), compared to T0 (111 ± 22). Sedation occurred at all times post-bolus, with a maximum peak at T12 (END 8 ± 6). The low dose of dexmedetomidine provided sedation in all animals, characterizing rapid metabolization and elimination. However, cardiovascular effects still may have negative repercussions in dogs with hemodynamic comorbidities, highlighting the caution and individualization of its use in certain patients.

Determination of a safe sedative combination of dexmedetomidine, ketamine and butorphanol for minor procedures in dogs by use of a stepwise optimization method

BACKGROUND

In veterinary practice, most minor procedures such as radiographs, skin biopsies, and wound treatments require sedation. The combination of butorphanol, ketamine, and dexmedetomidine is commonly used, but the ideal dosages for this combination have not been defined. This randomized prospective clinical 3-phases trial initially tested eight clinically relevant combinations of intramuscular administration in 50 dogs (phase 1). The quality of each combination was rated using a purposefully developed negative score (NS; 0-21.5, the lower the NS the better the quality of sedation) to judge the quality of sedation, the occurrence of side effects, and the need for additional anaesthetics. Based on the results of the NS, the eight combinations were divided into "promising" and "unsatisfactory" subgroups. In phase 2, a new combination (N) was calculated and tested in six dogs replacing the worst of the eight initial combinations. This procedure was repeated until the NS could not be improved any further. In phase 3, the best combination was tested in 100 adult dogs undergoing diagnostic or therapeutic procedures.

RESULTS

The optimal combination established was dexmedetomidine 0.005 mg/kg, ketamine 1 mg/kg, and butorphanol 0.3 mg/kg with a median NS of 1.5 (interquartile range 1.5-2.4). In all 112 dogs receiving this combination, the quality of sedation was satisfactory and no severe side effects were detected.

CONCLUSIONS

The application of this optimization method allowed the calculation of an optimal drug combination to sedate cardiovascularly healthy dogs. After having being tested in 112 animals, this combination can consequently be considered safe. Therefore, this combination can now be used in daily clinical practice for cardiovascularly healthy adult dogs undergoing minor procedures.

M-Mode Echocardiography in Canine Veterinary Practice: A Comprehensive Review of Left Ventricular Measurements in 44 Different Dog Breeds

This review article focuses on the use of canine M-mode in veterinary medicine, specifically in assessing the left ventricle measurements in several breeds. It traces the historical development of echocardiography techniques, including A-mode, B-mode, and motion mode (M-mode), which provide accurate unidimensional records of cardiac structures. This article highlights the significance of M-mode measurements in diagnosing stage B2 of MMVD, where left ventricular end-diastolic internal diameter corrected with body weight (LVIDdN) is essential for identifying cardiac enlargement. It also explains the role of M-mode in diagnosing DCM, outlining criteria such as left ventricular dilatation. The authors emphasize the importance of breed-specific reference values for echocardiographic measurements due to variations in somatotype among dogs. This review provides a comprehensive table summarizing M-mode measurements of the left ventricle for 44 different dog breeds, including interventricular septum thickness, left ventricular internal diameter, and left ventricular posterior wall thickness during systole and diastole. This review's methodology involves compiling data from various scientific literature sources, providing an extensive tabular representation of M-mode measurements for different breeds, ages, and sexes. Overall, this review highlights the critical role of M-mode echocardiography in diagnosing and managing cardiac diseases in dogs, underscores the importance of breed-specific reference values, and presents a comprehensive summary of M-mode measurements for various dog breeds, aiding both clinicians and researchers.

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.

Use of a novel shockwave trode results in better patient acceptance in awake canine patients treated for musculoskeletal disease

Introduction

Extracorporeal shockwave therapy (ESWT) is used as a treatment option for several musculoskeletal pathologies in dogs. When performing ESWT using electrohydraulic devices, sedation is commonly recommended due to the noise and discomfort associated with the treatment. The aim of this study was to compare the tolerance of ESWT delivered by a standard or novel trode in awake canine patients with musculoskeletal disease.

Materials and methods

This was a prospective, blinded clinical trial in which dogs with musculoskeletal disease received awake treatment with ESWT with a gradually increasing energy protocol using both standard and novel trodes with an electrohydraulic generator in a randomized fashion. Noise reactivity and tolerance to treatment as measured in number of shocks and energy level achieved were recorded.

Results

Forty client-owned dogs with pathology affecting the hips, stifles, elbows, or shoulders were enrolled. Thirty-three dogs completed all three treatment sessions, three dogs completed two sessions, and four dogs completed one session. There was evidence of improved patient tolerability with the novel trode, based on an increased average number of shocks delivered (n ± SD = 848 ± 334 for novel trode; n ± SD = 767 ± 358 for standard trode; p = 0.0384) and higher average treatment energy level achieved (E ± SD = 6.5 ± 2.5 for novel trode; E ± SD = 5.3 ± 2.8 for standard trode; p = < 0.001). Decreased noise reactivity was found to be positively correlated with tolerability of shockwave treatment (energy level: p = 0.0168; number of shocks: p = 0.0097).

Discussion

Administration of electrohydraulic ESWT is feasible in select awake patients using a gradually increasing energy protocol, and the tested novel shockwave trode is better tolerated than the standard trode. Further studies are required to determine the efficacy of the novel trode, and if gradually increasing energy protocols are clinically equivalent to current standard protocols that employ a consistent energy level.

Multiple uses of dexmedetomidine in small animals: a mini review

Dexmedetomidine is an alpha-2 adrenergic agonist, which use had an exponential increase in human and veterinary medicine in the last 10 years. The aim of this mini review is to summarize the various uses of dexmedetomidine underlining its new applications and capabilities in the small animals' clinical activity. While this drug was born as sedative in veterinary medicine, some studies demonstrated to be effective as an analgesic both in single administration and in continuous infusion. Recent studies have also shown the role of dexmedetomidine as an adjuvant during locoregional anesthesia, increasing the duration of the sensitive block and consequently decreasing the demand for systemic analgesics. The various analgesic properties make dexmedetomidine an interesting drug for opioid-free analgesia. Some studies highlighted a potential neuroprotective, cardioprotective and vasculoprotective role of dexmedetomidine, thus conferring it a place in critical care medicine, such as trauma and septic patients. Dexmedetomidine has demonstrated to be a multitasking molecule and it is ready to face new challenges.

Sedative effects and changes in cardiac rhythm with intravenous premedication of medetomidine, butorphanol and ketamine in dogs

OBJECTIVE

To determine the sedative effects and characteristics of cardiac rhythm with intravenous (IV) premedication of medetomidine, butorphanol and ketamine in dogs.

STUDY DESIGN

Prospective, blinded, randomized clinical trial.

ANIMALS

A total of 116 client-owned healthy dogs undergoing elective surgery.

METHODS

Dogs were randomly allocated one of four groups: group M, medetomidine 5 μg kg^-1; group B, butorphanol 0.2 mg kg^-1; group MB, medetomidine 5 μg kg^-1 and butorphanol 0.2 mg kg^-1; or group MBK, medetomidine 5 μg kg^-1, butorphanol 0.2 mg kg^-1 and ketamine 1 mg kg^-1 IV. Sedation was assessed using a numerical descriptive scale. Heart rate (HR) and rhythm were monitored; propofol dose (mg kg^-1 IV) to allow orotracheal intubation was documented. Data were analysed using anova, accounting for multiple testing with the Tukey honest significant difference test.

RESULTS

Sedation scores varied significantly between all groups at all time points, except between groups MB and MBK at four time points. HR decreased in all groups: most in groups M and MB, least in group B. HR was initially higher in group MBK than in groups M and MB. Arrhythmias occurred in all groups: group B showed second-degree atrioventricular blocks occasionally, all other groups showed additionally ventricular escape complexes and bundle branch blocks. Dose of propofol required for orotracheal intubation was significantly higher in group B (5.0 ± 2.0 mg kg^-1) than in group M (2.6 ± 0.6 mg kg^-1). Although no difference could be demonstrated between groups MB (1.4 ± 0.6 mg kg^-1) and MBK (0.9 ± 0.8 mg kg^-1), both groups required significantly less propofol than group M.

CONCLUSION AND CLINICAL RELEVANCE

Medetomidine-based premedication protocols led to various bradyarrhythmias. Addition of subanaesthetic doses of ketamine to medetomidine-based protocols resulted in higher HRs, fewer bradyarrhythmias and fewer animals that required propofol for intubation without causing side effects in healthy dogs.

Conventional and advanced echocardiographic assessment of systolic function in dogs sedated with dexmedetomidine or acepromazine

Dexmedetomidine and acepromazine, sedatives commonly used in dogs have opposite vascular effects, resulting in afterload increase and decrease, respectively. This could variably affect systolic myocardial function. Previous echocardiographic studies assessing the cardiovascular effects of these drugs used conventional echocardiography, while advanced techniques such as speckle tracking echocardiography (STE) and tissue Doppler imaging (TDI), which are known to provide a more accurate assessment of systolic function, have been rarely used for this aim. Moreover, in the few studies using advanced techniques, the drugs where combined with opioids. Therefore, the main objective of this prospective study was to assess systolic myocardial function by conventional and advanced echocardiography (STE and TDI), in dogs sedated exclusively with dexmedetomidine or acepromazine not combined with other drugs. Twenty healthy dogs were randomly divided into two groups, Group A (acepromazine, 20 μg/kg IM), and Group D (dexmedetomidine, 5 μg/kg IM), cardiovascular parameters were assessed before sedation (T0), and thirty minutes afterwards (T1). Systolic arterial pressure and heart rate decreased in both groups at T1 as compared to T0. Only one conventional echocardiographic raw variable (left ventricular internal dimension in systole) and three out of five advanced echocardiographic variables (radial TDI systolic velocities at the epicardial region of the left ventricular free wall, longitudinal TDI systolic velocities of the septal mitral valve annulus and the STE-derived left ventricular global strain), were affected in Group D. A systolic impairment was observed in Group D and better estimated by advanced echocardiography. In Group A, only the end diastolic voume index (conventional echocardiography) was decreased. Both protocols seem to induce echocardiographic changes more likely secondary to their vascular action.

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.

Echocardiographic assessment of dilated cardiomyopathy in dogs

Dilated cardiomyopathy (DCM) is a frequent cause of cardiac disability, congestive heart failure (CHF), and arrhythmic death in dogs. The etiology of DCM is usually idiopathic/genetic, but some causes of a DCM phenotype are reversible. The disease is classified into preclinical (occult) and clinical (overt) stages; the latter stems from heart failure with reduced ejection fraction. DCM is further characterized by clinical, electrocardiographic, circulating biomarker, and imaging abnormalities. The diagnosis of clinical DCM with CHF is straightforward; however, identification of the preclinical stage can be challenging. Echocardiography is central to the diagnosis of both stages and characterized by left ventricular (LV) systolic dysfunction with progressive chamber dilation and variable enlargements of the left atrium and right-sided chambers. Left ventricular dilation is defined by increased LV end-diastolic volumes, areas, and internal dimensions normalized to body size or indexed to the aorta. Systolic dysfunction is characterized by decreased LV ejection fraction, increased end-systolic volume, and reduced shortening across minor and longitudinal LV axes. Dyssynchrony can confound the interpretation of linear indices of systolic function. A comprehensive echocardiogram in DCM includes two-dimensional and M-mode studies, spectral and tissue Doppler imaging, and potentially three-dimensional echocardiography and myocardial strain imaging. Echocardiographic findings should be interpreted within the context of identifiable risks and comorbidities, physical diagnosis, complementary diagnostic testing, and limitations of current reference intervals. Ambiguous examinations should be repeated. Specific echocardiographic criteria for the diagnosis of DCM are proposed to encourage discussion and additional outcome and breed-specific echocardiographic studies of canine DCM.

TRANSTHORACIC ECHOCARDIOGRAPHIC EVALUATION AND SERUM CARDIAC TROPONIN VALUES IN ANESTHETIZED HEALTHY FEMALE SOUTHERN SEA OTTERS (ENHYDRA LUTRIS NEREIS)

Information about antemortem cardiac evaluation in sea otters (Enhydra lutris) is limited, despite well-established clinical care and rehabilitation procedures and a reported elevated risk of cardiac disease for this species. Serum cardiac troponin I (cTnI) concentration and echocardiographic assessment are two ways of screening for and diagnosing cardiac disease. However, no baseline data or reference intervals for either evaluation are published for sea otters. The objectives of this prospective study were to establish serum cTnI concentrations and echocardiographic technique and quantitative measurements in anesthetized healthy female southern sea otters (Enhydra lutris nereis) (n=15). Serum cTnI values were assessed by a high-sensitivity assay. Serum cTnI concentration ranged from <0.006 to 0.038 ng/ml. A complete echocardiogram, including two-dimensional and M-mode modalities, was performed. Echocardiographic measurements for left atrial size, aorta size, left ventricular structure, and left ventricular function were reported. The median left atrial size to aorta ratio was 1.22 (range 0.80-1.59) in short-axis and 1.70 (range 1.39-2.15) in long-axis. The median left ventricular internal dimension was 3.53 cm (range 2.87-4.92 cm) when assessed in two dimensions and 3.58 cm (range 2.80-4.48 cm) by M-mode. Serum concentrations of cTnI and transthoracic echocardiography may represent valuable tools for the antemortem diagnosis of cardiac disease in sea otters.

Echocardiographic Assessment of Healthy Midazolam/Butorphanol or Midazolam/Morphine-Sedated Dogs

The purpose of this study was to assess the effects of midazolam combined with morphine or butorphanol on echocardiographic variables of healthy dogs. Twenty-four dogs of various breeds aged 34.33 ± 23.41 months and weighing 8.1 ± 4.7 kg were enrolled in the study. Subjects were randomly allocated in one of two experimental groups of sedation with intramuscular midazolam (0.3 mg/kg) combined with butorphanol (0.2 mg/kg) (G_B, n = 12) or morphine (0.3 mg/kg) (G_M, n = 12). Transthoracic echocardiographic examinations comprised B-Mode, M-Mode, spectral Doppler and pulsed tissue Doppler assessment. Data were recorded before sedation (T_B) and 20 minutes following intramuscular administration of either sedation protocol (T_S). Data were analyzed using repeated measures ANOVA followed by Tukey's posthoc test. Shortening fraction, ejection fraction, left ventricular diameter and volume did not differ among groups and time points. The A and E' waves were decreased in G_M at T_S compared to T_B. Isovolumic relaxation time, Ae/Ao ratio, aortic and pulmonary flows and S' wave did not differ among time points and groups. These sedation protocols did not cause clinically relevant changes in echocardiographic variables, therefore can be used for sedation of uncooperative dogs during echocardiographic evaluation.

ECHOCARDIOGRAPHIC VARIABLES IN THE AFRICAN PAINTED DOG (LYCAON PICTUS)

The aim of this study was to screen for cardiac disease and report normal echocardiographic variables from a managed population of the African painted dog (Lycaon pictus; APD). The study included six male adult APDs under managed care with no evidence of significant structural cardiac disease. Echocardiography was performed with APD maintained under anesthesia with a combination of midazolam, butorphanol, and inhaled isoflurane. All animals underwent a full physical examination and two-dimensional (2D), M-mode, and Doppler echocardiography using standard views. Left ventricular volumes were calculated using the Simpson's method of discs. Medians with ranges were reported for the echocardiographic variables. No valvular structural abnormalities were noted. Trace mitral regurgitation was documented in five of six APD, trace tricuspid regurgitation in three of six, and mild pulmonic regurgitation in all APD. No aortic regurgitation was noted. Standard M-mode measurements fell within the normal ranges for allometrically scaled M-mode cardiac measurements for normal adult domestic dogs (Canis familiaris). Two-dimensional measurements were comparable with that of domestic dogs with similar body weight. The study demonstrates a similarity in cardiac size and function compared with normal adult domestic dogs and provides baseline echocardiographic variables for investigation of cardiac health in other populations of APDs in the future.

Angiostrongylus vasorum in a Red Panda (Ailurus fulgens): Clinical Diagnostic Trial and Treatment Protocol

PURPOSE

The literature refers that Angiostrongylus vasorum should always be considered in the differential diagnosis of respiratory diseases in captive red panda (Ailurus fulgens) from endemic areas, and the importance of undertaking a careful diagnostic process and timely medical treatment are crucial when the disease is suspected. The authors think that the description of this clinical case can help other colleagues in the deworming, clinical and anesthesiologic management of infected subjects.

METHODS

A red panda was referred to the Veterinary Teaching Hospital of the University of Milan in Lodi, due to a diagnosis of A. vasorum formulated in May 2015. The diagnosis was made after the detection of both first-stage larvae by Baermann technique and antigens by serological rapid in-clinic assay. In addition, haemochromocytometric and blood chemistry tests, echocardiography and a CT examination were carried out.

RESULTS

The subject was successfully treated by oral administration of milbemycin oxime and praziquantel (Milbemax, Novartis, Italy), respectively, at the weekly dose of 12.5 mg/subject and 125 mg/subject for three consecutive weeks, alternated with 20 days of suspension. Treatment continued with the same scheme until clinical examination carried out in Lodi in December 2018.

CONCLUSION

The follow-up of the described clinical case demonstrates how appropriate management of the infection and the subsequent prophylaxis can correctly eliminate the parasite, thus avoiding the spread of the nematode and the onset of severe and lethal lung forms as described in the literature.

Chylopericardium Effusion in a Lac Alaotra Bamboo Lemur (Hapalemur alaotrensis)

Simple Summary

The clinical staff of the Veterinary Teaching Hospital of the University of Milan in Lodi have worked closely with veterinarians operating in a famous zoological park in Northern Italy. Thanks to this collaboration it has been possible to properly manage the clinical case reported in this brief communication. In veterinary medicine, clinical cases of chylopericardium in the species Hapalemur alaotrensis have never been described in the literature. Even in more common species, such as dogs and cats, it is a very rare pathology. The description of this clinical case and its diagnostic management can be a valid clinical and anatomopathological support for other colleagues who face a similar case, so that they can focus on diagnostic investigations useful for diagnosis. A new anesthesiologic protocol, allowing the optimal management of the patient throughout the clinical procedure, is also reported in detail, as well as the detailed description of the lymphoCT examination. For all these reasons the authors think that the description of this clinical case can help other colleagues in the management of infested subjects.

Abstract

An 11-year-old female Hapalemur alaotrensis was evaluated following a history of dyspnea of 15 days’ duration. Thoracic radiography performed by the referring veterinarian revealed a large cardiac silhouette and dorsal deviation of the trachea. Heart sounds were muffled. Echocardiographic findings were indicative of severe pericardial effusion without cardiac tamponade. No pleural effusion was identified. A computed tomography (CT) exam confirmed the presence of severe pericardial effusion and allowed identification of a parenchymatous mediastinal lesion sited at the level of the left hemithorax. To delineate the thoracic duct, lymphoCT was also performed by injection of iodinated contrast medium in the perianal subcutaneous tissue. Pericardiocentesis yielded a considerable amount of effusion with chylous biochemical and cytological properties. A diagnosis of chylopericardium with absence of pleural effusion was made. Initially, the chylopericardium was managed conservatively with two centesis and oral treatment with prednisolone. Medical treatment did not result in complete resolution of effusion and clinical signs; therefore, subtotal pericardiectomy and thoracic duct ligation were recommended. After the second pericardiocentesis, the subject died and the pericardiectomy could not be performed. To the authors’ knowledge, this is the first report of the development of chylopericardium in a Hapalemur alaotrensis.

Echocardiographic reference intervals with allometric scaling of 823 clinically healthy rhesus macaques (Macaca mulatta)

BACKGROUND

Echocardiography is commonly used for assessing cardiac structure and function in various species including non-human primates. A few previous studies reported normal echocardiographic reference intervals of clinically healthy rhesus macaques under sedation. However, these studies were under-powered, and the techniques were not standardized. In addition, body weight, age, and sex matched reference intervals should be established as echocardiographic measurements are commonly influenced by these variables. The purpose of this study was to establish reference intervals for complete echocardiographic parameters based on a large cohort of clinically healthy rhesus macaques with wide ranges of weight and age distributions using allometric scaling.

RESULTS

A total of 823 rhesus macaques (ages 6 months to 31 years old; body weights 1.4 to 22.6 kg) were enrolled. Of these rhesus macaques, 421 were males and 402 were females. They were assessed with a complete echocardiographic examination including structural and functional evaluation under sedation with ketamine hydrochloride. The reference intervals of the key echocardiographic parameters were indexed to weight, age, and sex by calculating the coefficients of the allometric eq. Y = aM^b. On correlation matrix, body weight, age, sex, and heart rate were significantly correlated with various echocardiographic parameters and some of the parameters were strongly correlated with body weight and age. Multiple regression analysis revealed that heart rate and body weight statistically significantly predicted several echocardiographic parameters. Valve regurgitation including tricuspid, aortic, pulmonic, and mitral regurgitations without other cardiac structural and functional abnormalities are common in clinically healthy rhesus macaques under ketamine sedation.

CONCLUSIONS

In this study, the reference intervals of echocardiographic parameters were established by performing complete echocardiographic examinations on a large number of clinical healthy rhesus macaques. In addition, allometric scaling was performed based on their weight, and further indexed to age and sex. These allometrically scaled reference intervals can be used to accurately evaluate echocardiographic data in rhesus macaques and diagnose structural and functional evidence of cardiac disease.

Development of Spontaneous Echocardiographic Contrast After Transarterial Occlusion of a Patent Ductus Arteriosus in an Adult Dog With Concurrent Pulmonary Hypertension

An 8-year-old intact female Chihuahua was presented for evaluation and possible occlusion of a previously diagnosed patent ductus arteriosus (PDA). Transthoracic echocardiography revealed left ventricular and left atrial enlargement, enlargement of the main pulmonary artery, and a PDA with bidirectional shunting. Tricuspid regurgitant velocities suggested moderate pulmonary hypertension. The PDA was occluded with an Amplatz® Canine Duct Occluder using a transarterial approach on the following day. No immediate complications were observed other than an acute decrease in left ventricular systolic function. One day after the PDA occlusion transthoracic echocardiography revealed no residual ductal flow, but there was spontaneous echocardiographic contrast in the left ventricle. The patient was discharged with sildenafil, pimobendan, and clopidogrel. Five weeks later when the patient was presented for a recheck examination, the previously documented spontaneous echocardiographic contrast was no longer present. Finding spontaneous echocardiographic contrast in the dog has not previously been reported in association with PDA occlusion.

GREAT APE HEART PROJECT GUIDELINES FOR THE ECHOCARDIOGRAPHIC ASSESSMENT OF GREAT APES

Cardiovascular disease (CVD) has been identified as a major cause of mortality in all four great ape taxa in zoologic institutions. In an effort to better understand and treat CVD in captive great apes, a program called the Great Ape Heart Project (GAHP), based at Zoo Atlanta, collects and maintains a database of echocardiograms and other relevant medical information relating to the cardiac health status of great apes. Cardiac health assessments have become standard practice among North American zoos that house great apes and are recommended by all four great ape Species Survival Plans (SSP) for the assessment of CVD in captive great apes. As of December 31, 2017, more than 70 ape-holding institutions have submitted approximately 1,100 cardiac examinations of great apes to the GAHP, information from which is stored in the GAHP database. Transthoracic echocardiography is one of the most practical and cost-effective diagnostic imaging techniques for the evaluation of cardiac function in great apes. Standardization of echocardiographic measurements is critical for maximizing the diagnostic value of an echocardiographic exam and for utilization of stored information in comparative studies within and between the great ape taxa. The following manuscript offers suggestions for standardization of nomenclature, imaging technique, echocardiographic measurements, data storage, and reporting of cardiac exams for submission into the GAHP database with the goal of promoting consistency and quality in data collection.

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.

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.

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.

LC-MS/MS Method for Simultaneous Quantification of Dexmedetomidine, Dezocine, and Midazolam in Rat Plasma and Its Application to Their Pharmacokinetic Study

A simple, sensitive, and accurate LC-MS/MS method was established and validated for the simultaneous quantification of dexmedetomidine, dezocine, and midazolam in rat plasma. Chromatographic separation was achieved on a C18 column (50 mm × 2.1 mm, 3 µm) using a mobile phase composed of water (containing 0.1% formic acid) and acetonitrile. The lower limits of quantification were 0.1, 0.1, and 0.2 ng/mL for dexmedetomidine, dezocine, and midazolam in rat plasma, respectively. The analytes were determined with selected reaction monitoring under positive ionization mode. The intra- and interday precision and accuracy were all within acceptable limits during the entire validation, and the stability of analytes was acceptable under various storage conditions. The validated method was successfully applied in pharmacokinetic studies of dexmedetomidine, dezocine, and midazolam following intravenous injection.