Effect of Pimobendan on Echocardiographic Values in Dogs with Asymptomatic Mitral Valve Disease

Background: Pimobendan (PIMO) is a novel inodilator that has shown promising results in the treatment of advanced mitral valve disease (MVD), but little is known about its hemodynamic effects, especially regarding the mitral regurgitant volume in naturally occurring MVD.
Hypothesis: The addition of pimobendan to treatment decreases the regurgitant fraction (RF) in dogs with asymptomatic MVD.
Animals: Twenty-four client-owned dogs affected by International Small Animal Cardiac Health Council class Ib MVD.
Methods: Prospective, blinded, and controlled clinical trial. Dogs were assigned to a PIMO treatment group (n = 19) (0.2–0.3 mg/kg q12h) or a control group (n = 5). Echocardiographic evaluations were performed over a 6-month period.
Results: The addition of PIMO to treatment did not decrease the RF of dogs affected by asymptomatic class 1b MVD over the study period ( P = .85). There was a significant increase in the ejection fraction of the PIMO treated dogs at 30 days (80.8 ± 1.42 versus 69.0 ± 2.76, corrected P = .0064), and a decrease in systolic left ventricular diameter (corrected P = .011) within the PIMO group compared with baseline. However, this improvement in systolic function was not sustained over the 6-month trial period.
Conclusion and Clinical Importance: This study did not identify beneficial long-term changes in the severity of mitral regurgitation after addition of PIMO to angiotensin converting enzyme inhibitor treatment of dogs with asymptomatic MVD.     

Serum Cardiac Troponin I Concentration in Retired Racing Greyhounds

Background: Cardiac troponin I (cTnI) is a polypeptide found specifically in cardiac muscle tissue that has been used as a diagnostic and prognostic indicator of cardiomyopathy. Increases in cTnI are associated with myocardial pathologic processes. However, high serum cTnI concentrations have been observed in normal Greyhounds.
Hypothesis: We hypothesized that Greyhounds have cTnI concentrations higher than non-Greyhound dogs, and that a separate reference range should be established for Greyhounds.
Animals: Blood samples were collected from the jugular vein from a group of 20 healthy Greyhound blood donors.
Methods: Analysis of serum cTnI was performed with an immunoassay system with a detection level of 0.01 ng/mL, as described previously. The Greyhound values were compared with 2 groups of Boxers with and without arrhythmogenic right ventricular cardiomyopathy (ARVC), and to a group of non-Boxer control dogs from a previous study.
Results: The mean cTnI concentration in Greyhounds was significantly higher ( P < .0001) than that in non-Greyhound control dogs, although not significantly different from normal Boxers ( P = .50), or Boxers with ARVC ( P = .58). Greyhound serum cTnI concentrations were in the range found in Boxers with ARVC. The proposed reference range for cTnI in Greyhounds is 0.05–0.16 ng/mL.
Conclusions and Clinical Importance: Greyhounds have a reference range for serum cTnI concentrations that differs from that of other previously published reference ranges for dogs of other breeds. Until a broader database and more precise reference range can be established, caution should be exercised in interpreting serum cTnI concentrations in Greyhounds with suspected cardiac disease.     

Left Ventricular Radial and Circumferential Wall Motion Analysis in Horses Using Strain, Strain Rate, and Displacement by 2D Speckle Tracking

Background: Noninvasive assessment of left-ventricular (LV) function is clinically relevant, but is incompletely studied in horses.
Objectives: To document the feasibility, describe the techniques, and determine the reliability of 2D speckle tracking (2DST) for characterization of LV radial and circumferential wall motion in horses.
Animals: Three Standardbreds, 3 Thoroughbreds; age 8–14 years; body weight 517–606 kg.
Methods: Observational study. Repeated 2-dimensional echocardiographic examinations were performed in unsedated horses by 2 observers and subsequently analyzed by 2DST. Test reliability was determined for segmental and for averaged 2DST indices (including strain, strain rate, displacement, and rotation) by estimating measurement variability, within-day interobserver variability, between-day interobserver variability, and between-day intraobserver variability. Variability was expressed as coefficient of variation (percent) and the absolute value below which the difference between 2 measurements will lie with 95% probability.
Results: 2DST analyses were feasible in 16 of 18 echocardiographic studies. The automated tracking was accurate during systole but inaccurate during diastole. Reliability was higher for radial compared to circumferential measurements. For radial strain, radial systolic strain rate, and radial systolic displacement, the test-retest variabilities ranged between 2.4 and 33.1% for segmental and between 4.1 and 16.1% for averaged measurements.
Conclusions and Clinical Importance: Systolic radial motion of the LV at the chordal level could be reliably characterized in horses by 2DST. Circumferential measurements were less reliable. Diastolic measurements were invalid because of inaccurate tracking. The clinical value of LV wall motion analysis by 2DST in horses requires further investigation.     

Total bilirubin is an independent predictor of death in dogs with degenerative valvular disease and dilated cardiomyopathy

IntroductionThere is little published regarding the association between canine cardiovascular disease and the hepatic system. The objective of the study was to evaluate the relationship between hepatic parameters, survival, and disease stages of dogs with either dilated cardiomyopathy (DCM) or degenerative valvular disease (DVD).Animals, materials, and methodsRetrospective study analyzing hepatic parameters in dogs with DVD or DCM in American College of Veterinary Internal Medicine stage B or C and healthy control dogs. Associations between liver parameters, type and stage of disease, and survival were investigated.ResultsNinety-nine dogs were included in the study: 61 DVD, 22 DCM, and 16 controls. Differences in liver parameter concentrations between DCM, DVD, and disease stages were found. Univariate analysis identified alanine aminotransferase (P < 0.001), aspartate aminotransferase (P = 0.02), and total bilirubin (P = 0.005) as predictors of mortality. In the multivariate analysis, total bilirubin remained an independent predictor of mortality.ConclusionsThe observed differences between DCM, DVD, and disease stages are likely consistent with disease-specific hemodynamics and progression of disease. This and the role of total bilirubin as an independent predictor for mortality indicate that in dogs with DVD and DCM the cardiovascular–hepatic interaction might be of relevance for disease progression and outcome, as reported for humans with cardiac disease. Further studies into the role of hepatic function in canine cardiac disease are required.     

Comparison of three two-dimensional echocardiographic methods of assessing left ventricular size in Doberman Pinschers

IntroductionCompare three methods of obtaining linear left ventricular dimensions within the same Doberman Pinscher (DP).AnimalsOne hundred and thirty-nine client-owned DP.Materials and MethodsLinear left ventricular dimensions were measured using two-dimensional short-axis (Sx-2D), motion-mode short-axis (Sx-MM), and motion-mode long-axis (Lx-MM) methods, then left ventricular volumes were obtained using monoplane Simpson's method of discs (SMOD). A Friedman test with Dunn's multiple comparisons was used to compare differences between methods. Bias and correlation were evaluated via Bland-Altman and Spearman's correlation. Sensitivity and specificity for diagnosing occult dilated cardiomyopathy (DCM) compared to SMOD were determined. Coefficients of variation (CVs) were calculated for intra- and inter-observer measurement variability.ResultsThere were significant differences between all linear dimensions in diastole and systole. Short-axis 2D measurements had significant bias compared with Sx-MM (diastole +1.19 mm, systole +1.65 mm) and Lx-MM (diastole +4.36 mm, systole +3.87 mm) as did Sx-MM compared with Lx-MM (diastole +3.17 mm, systole +2.22 mm). All linear dimensions had a moderate positive correlation with SMOD. The sensitivity and specificity of linear measurements to detect DCM were: Sx-2D (sensitivity 72.0%, specificity 88.5%), Sx-MM (sensitivity 52.0%, specificity 92.0%), and Lx-MM (sensitivity 37.5%, specificity 99.1%). All methods had acceptably low CV for intra- and inter-observer measurement variability.ConclusionsResults of this study suggest that linear measurements are repeatable and correlate with reference standard; however, there is a significant bias between measurements, and they should not be used interchangeably.