OBJECTIVE To evaluate accuracy of quantification of right ventricle volume (RVV) by use of 3-D echocardiography (3DE) and ECG-gated multidetector CT (MDCT).
ANIMALS 6 healthy hound-cross dogs.
PROCEDURES ECG-gated MDCT and complete 3DE examinations were performed on each dog. Right ventricular end-diastolic volumes (EDVs), end-systolic volumes (ESVs), stroke volume (SV), and ejection fraction (EF) were measured for 3DE and MDCT data sets by use of software specific for RVV quantification. Correlation and level of agreement between methods were determined. Intraobserver and interobserver variability were assessed for 3DE.
RESULTS No significant differences were detected between SV and EF obtained with MDCT and 3DE. Significant differences were detected between right ventricular EDV and ESV obtained with MDCT and 3DE. No significant difference in heart rate was detected between methods. The correlation between MDCT and 3DE was very good (r = 0.87) for EDV and ESV, moderate (r = 0.60) for EF, and poor (r = 0.31) for SV. Bland-Altman analysis revealed a systematic underestimation of RVV derived by use of 3DE, compared with the RVV derived by use of MDCT (mean bias, 15 and 10.3 mL for EDV and ESV, respectively). Intraobserver (EDV, 12%; ESV, 18%) and interobserver (EDV, 14%; ESV, 11%) variability were acceptable for 3DE.
CONCLUSIONS AND CLINICAL RELEVANCE There was substantial variance for RVV measured by use of 3DE in healthy dogs and a significant underestimation of volumes, compared with results for MDCT, despite the fact there were no significant differences in SV and EF.
Objective—To validate the use of a human enzyme immunoassay (EIA) kit for measurement of plasma antidiuretic hormone (ADH) concentration in dogs and evaluate plasma ADH concentrations in dogs with congestive heart failure (CHF) attributable to acquired cardiac disease, compared with findings in healthy dogs.
Animals—6 healthy dogs and 12 dogs with CHF as a result of chronic degenerative valve disease or dilated cardiomyopathy.
Procedures—Plasma samples from the 6 healthy dogs were pooled and used to validate the EIA kit for measurement of plasma ADH concentration in dogs by assessing intra-assay precision, dilutional linearity, and spiking recovery. Following validation, plasma ADH concentrations were measured in the 6 healthy dogs and in the 12 dogs with CHF for comparison.
Results—The EIA kit measured ADH concentrations in canine plasma samples with acceptable intra-assay precision, dilutional linearity, and spiking recovery. The intra-assay coefficient of variation was 11%. By use of this assay, the median plasma concentration of ADH in dogs with CHF was 6.15 pg/mL (SD, 3.2 pg/mL; range, 4.18 to 15.47 pg/mL), which was significantly higher than the median concentration in healthy dogs (3.67 pg/mL [SD, 0.93 pg/mL; range, 3.49 to 5.45 pg/mL]).
Conclusions and Clinical Relevance—Plasma ADH concentrations in dogs can be measured with the tested EIA kit. Plasma ADH concentrations were higher in dogs with CHF induced by acquired cardiac disease than in healthy dogs. This observation provides a basis for future studies evaluating circulating ADH concentrations in dogs with developing heart failure.
To compare left atrial volume (LAV) and right atrial volume (RAV) determined by 2-D and 3-D echocardiographic methods with the LAV and RAV determined by ECG-gated multidetector CT (MDCT) for healthy dogs.
11 healthy purpose-bred young adult hound-type dogs.
Each dog was anesthetized and underwent MDCT and a complete echocardiographic examination. Modality-specific software was used to measure the respective atrial volumes at ventricular end systole, and LAV and RAV measurements were subsequently indexed to body weight and compared among imaging modalities.
The LAV determined by echocardiographic methods did not differ significantly from the LAV determined by MDCT. However, the RAV determined by 3-D echocardiography and 2-D echocardiography via the left apical and left cranial windows differed significantly from the RAV determined by MDCT. Bland-Altman analyses indicated that the indexed LAV and RAV determined by echocardiographic methods were systematically underestimated, compared with MDCT measurements, but the bias was much smaller for LAV than for RAV.
CONCLUSIONS AND CLINICAL RELEVANCE
Results suggested that, for dogs, echocardiography might be an acceptable alternative to MDCT for measurement of LAV but not for measurement of RAV. However, the study population was small and homogenous in terms of breed, age, and weight. These findings need to be validated in a larger, more varied population of dogs with and without cardiac disease.
To investigate associations between short-term treatment with a previously described compounded transdermal formulation of atenolol and heart rate in cats.
11 healthy adult cats.
Cats received the atenolol gel formulation (gradually increased from 12.5 mg/cat, q 24 h to 25 mg/cat, q 12 h) by application to the pinnae at home over a 10-day period in a prospective, experimental study. On day 10, cats were hospitalized for measurement of serum atenolol concentrations 3, 6, and 12 hours after the morning treatment. Mean heart rate measured at the 3- and 6-hour time points was compared with a baseline value (measured at enrollment).
All cats completed the study; 4 were excluded from analyses after an apparent formulation error was detected in 1 batch. Two cats had minor adverse effects (localized erythema of the pinna). Five of 7 cats had serum atenolol concentrations ≥ 260 ng/mL (considered therapeutic) at ≥ 1 time point. Heart rate had a strong negative correlation (r =–0.87) with serum atenolol concentration. A 90-day drug stability investigation of 4 formulations (identical to the intended study treatment except for pH [range, 6.5 to 7.7]) revealed an apparent decrease in atenolol concentration at a pH of 7.7.
CONCLUSIONS AND CLINICAL RELEVANCE
Topical administration of the formulation as described resulted in targeted serum atenolol concentrations in most cats, with attendant HR reduction. Validation of these preliminary results in a larger sample and investigation of the treatment in cats with structural heart disease is needed. Verification of appropriate pH (target, 7.0) is likely essential for the compound's stability.
OBJECTIVE To evaluate the accuracy of cardiac output (CO) estimated by use of ECG-gated multidetector CT (MDCT) and 1-, 2-, and 3-D echocardiography and by use of thermodilution.
ANIMALS 6 healthy hound-cross dogs.
PROCEDURES Electrocardiogram-gated contrast-enhanced 64-slice MDCT and 1-, 2-, and 3-D echocardiography were performed on each dog. The CO for ECG-gated MDCT was calculated as volumetric measurements of stroke volume multiplied by mean heart rate. Echocardiographic left ventricle end-diastolic volumes and end-systolic volumes were measured by use of the Teichholz method (1-D echocardiography) and a single-plane method of disks (2-D echocardiography). Real-time 3-D echocardiographic left ventricle volumes were measured with 3-D functional analysis software on right long-axis and left apical views. The CO of each dog was measured in triplicate by use of thermodilution. Mean CO values, correlations, and limits of agreement for MDCT, echocardiographic modalities, and thermodilution were compared.
RESULTS CO measured by use of MDCT, 2-D echocardiography, and 3-D echocardiography had the strongest correlations with CO measured by use of thermodilution. No significant difference in CO was detected between MDCT, any echocardiographic method, and thermodilution. Bland-Altman analysis revealed a systematic underestimation of CO derived by use of MDCT, 2-D echocardiography, and 3-D echocardiography.
CONCLUSIONS AND CLINICAL RELEVANCE Use of MDCT, 2-D echocardiography, and 3-D echocardiography to measure CO in healthy dogs was feasible. Measures of CO determined by use of 3-D echocardiography on the right long-axis view were strongly correlated with CO determined by use of thermodilution, with little variance and slight underestimation.
OBJECTIVE To compare left ventricle (LV) volume and function variables obtained by use of 1-D, 2-D, and real-time 3-D echocardiography versus ECG-gated multidetector row CT (MDCT) angiography, which was considered the criterion-referenced standard.
ANIMALS 6 healthy, purpose-bred dogs.
PROCEDURES Dogs were anesthetized and administered a constant rate infusion of esmolol, and 1-D, 2-D, and 3-D echocardiography and ECG-gated, contrast-enhanced MDCT were performed. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume, and ejection fraction (EF) were calculated by use of the Teichholz method for 1-D echocardiography, single-plane and biplane modified Simpson method of disks (MOD) and area-length method for 2-D echocardiography, and real-time biplane echocardiography (RTBPE) and real-time 3-D echocardiography (RT3DE) for 3-D echocardiography. Volumes were indexed to body surface area and body weight. Median values, correlations, and limits of agreement were compared between echocardiographic modalities and MDCT.
RESULTS EDV and ESV measured by use of RTBPE and RT3DE had the strongest correlations with results for MDCT. Values obtained for EDV, ESV, stroke volume, and EF did not differ significantly between echocardiographic methods and MDCT. Use of RT3DE and RTBPE slightly underestimated EDV, ESV, and EF, compared with values for MDCT, as determined with Bland-Altman analysis.
CONCLUSIONS AND CLINICAL RELEVANCE Values for EDV and ESV obtained by use of 3-D echocardiography, including RTBPE and RT3DE, had the highest correlation with slight underestimation, compared with values obtained by use of MDCT. This was similar to results for 3-D echocardiography in human medicine.
OBJECTIVE To compare effects of tiletamine-zolazepam, alfaxalone, ketamine-diazepam, and propofol for anesthetic induction on cardiorespiratory and acid-base variables before and during isoflurane-maintained anesthesia in healthy dogs.
ANIMALS 6 dogs.
PROCEDURES Dogs were anesthetized with sevoflurane and instrumented. After dogs recovered from anesthesia, baseline values for cardiorespiratory variables and cardiac output were determined, and arterial and mixed-venous blood samples were obtained. Tiletamine-zolazepam (5 mg/kg), alfaxalone (4 mg/kg), propofol (6 mg/kg), or ketamine-diazepam (7 and 0.3 mg/kg) was administered IV in 25% increments to enable intubation. After induction (M0) and at 10, 20, 40, and 60 minutes of a light anesthetic plane maintained with isoflurane, measurements and sample collections were repeated. Cardiorespiratory and acid-base variables were compared with a repeated-measures ANOVA and post hoc t test and between time points with a pairwise Tukey test.
RESULTS Mean ± SD intubation doses were 3.8 ± 0.8 mg/kg for tiletamine-zolazepam, 2.8 ± 0.3 mg/kg for alfaxalone, 6.1 ± 0.9 mg/kg and 0.26 ± 0.04 mg/kg for ketamine-diazepam, and 5.4 ± 1.1 mg/kg for propofol. Anesthetic depth was similar among regimens. At M0, heart rate increased by 94.9%, 74.7%, and 54.3% for tiletamine-zolazepam, ketamine-diazepam, and alfaxalone, respectively. Tiletamine-zolazepam caused higher oxygen delivery than propofol. Postinduction apnea occurred in 3 dogs when receiving alfaxalone. Acid-base variables remained within reference limits.
CONCLUSIONS AND CLINICAL RELEVANCE In healthy dogs in which a light plane of anesthesia was maintained with isoflurane, cardiovascular and metabolic effects after induction with tiletamine-zolazepam were comparable to those after induction with alfaxalone and ketamine-diazepam.
OBJECTIVE To compare rates of major intraoperative complications and survival to hospital discharge between surgical ligation (SL) and canine ductal occluder (CDO) implantation for treatment of dogs with left-to-right shunting patent ductus arteriosus (PDA).
DESIGN Retrospective cohort study.
ANIMALS 120 client-owned dogs with left-to-right shunting PDA (62 treated by SL and 58 treated by CDO implantation).
PROCEDURES Data were retrieved from medical records of included dogs regarding signalment, medical history, vertebral heart scale, preoperative echocardiographic findings, complications encountered during surgery, and durations of anesthesia and surgery (SL or CDO implantation). Data were compared between dogs treated by SL and those treated by CDO implantation.
RESULTS Dogs treated by CDO implantation were significantly older and heavier than dogs treated by SL and had more pathological cardiac remodeling (as indicated by mitral regurgitation scores, left atrial-to-aortic root diameter ratios, and fractional shortening values). Durations of anesthesia and surgery were also significantly longer for CDO implantation versus SL. The major complication rate for dogs treated by SL (6/62 [10%]) was significantly greater than that for dogs treated by CDO implantation (0/58 [0%]). One dog in the SL group died during surgery. Overall rate of survival to hospital discharge was 99% (119/120).
CONCLUSIONS AND CLINICAL RELEVANCE Both SL and CDO implantation were viable methods for PDA attenuation in the evaluated dogs. Although a greater proportion of dogs had major complications during the SL procedure, the 2 procedures had comparable rates of survival to hospital discharge.