Pulsed tissue Doppler imaging of the left ventricular septal mitral annulus in healthy dogs

An echocardiographic study of breed-specific reference ranges in healthy French Bulldogs

Echocardiography is a standard diagnostic tool for assessment of cardiac functions and cardiovascular diseases in dogs, however published echocardiographic measurements have varied widely based on dog breeds. The objective of this prospective reference interval study was to provide breed-specific echocardiographic values for healthy French Bulldogs. A total of 42 healthy French Bulldogs of both sexes (23 females and 19 males) were sampled. Furthermore, measurements for a control group (n = 16) were also conducted in four other dog breeds (Cocker Spaniel [n = 2], Cavalier King Charles Spaniel [n = 4], Terrier [n = 5], and Crossbreed [n = 5]). Standard M-mode, two-dimensional (2D), pulse wave (PW) Doppler, and tissue Doppler imaging (TDI) echocardiographic measurements were obtained from healthy French Bulldogs. The M-mode echocardiographic data obtained from French Bulldogs were compared to the data obtained from the control group. The left ventricular internal dimension at end-diastole (LVIDd; cm)/body surface area (BSA) (m² ) ratio for the study group was 3.35/0.53 = 6.32. Left ventricular measurements for French bulldogs and internal dimension at end-systole (21.23 ± 3.50 mm) and at end-diastole (33.50 ± 4.12 mm) were found to be significantly higher (P < .001) compared to control group values (left ventricular internal dimension at end-systole [LVIDs]; 17.46 ± 2.85 mm, LVIDd; 27.16 ± 4.20 mm, respectively). A significantly positive correlation in the French Bulldog group was noted between body weight and M-mode measurements (EPSS, IVSd, IVSs, LVIDd, LVIDs, and LVPWd). French bulldogs had a greater systolic and diastolic left ventricular volume than the control group. As a result, values reported in this study could be used as specific reference ranges in French Bulldogs.

Long-term administration of prednisolone: Effects on the myocardial tissue of healthy beagle dogs

This study aimed to assess the structural and functional effects of long-term hyperglucocorticoidemia on canine myocardium and compare these parameters with histopathological changes. Twelve healthy male beagle dogs were enrolled and assigned to the high-dose prednisolone (P; n=6) and control (C; n=6) groups. The P group was treated with 2 mg/kg of prednisolone BID for 84 days. Clinical parameters were measured using echocardiography and non-invasive systolic blood pressure (SBP) measured before the initiation of synthetic corticosteroids and at 7, 28, 56, and 84 days after the start of medication. For histological evaluation, cardiovascular tissue was harvested from dogs in groups P (at the end of the medication period) and C (scheduled to be euthanized for unrelated reasons). In the P group, clinical changes including thickening of the left ventricular free wall (LVFW) and interventricular septum (IVS), decreased left ventricular (LV) diastolic function, and increased SBP were observed after the start of medication. During histological evaluation, fibrosis was observed in the LVFW and IVS in the P group. Furthermore, decreased glucocorticoid receptor (GCR) levels were observed in the LVFW, right ventricular free wall (RVFW), and IVS and increased mineralocorticoid receptor (MCR) levels were observed in the LVFW and RVFW in the P group compared with those in the C group. In conclusion, fibrosis may cause LV structural and functional abnormalities in dogs with hyperadrenocorticism. Furthermore, GCR downregulation and upregulated MCR might influence the myocardial fibrosis.

Inotropic and chronotropic effects of sotalol in healthy dogs

INTRODUCTION

Sotalol is an anti-arrhythmic drug commonly used for the treatment of pathologic tachyarrhythmias in dogs. The β-adrenergic blockade associated with sotalol administration may result in reduced myocardial contractility, which is clinically relevant for treating dogs with arrhythmias and concurrent myocardial dysfunction. The inotropic properties of sotalol are not well characterized in dogs.

ANIMALS, MATERIALS, AND METHODS

Ten healthy, adult, large breed dogs were prospectively enrolled. All dogs underwent physical examination, blood pressure measurement, electrocardiography, 24-h Holter monitoring, and echocardiography including three-dimensional left ventricular volume measurements. Dogs were subsequently administered sotalol (1-2 mg/kg) orally twice daily for 12-16 days, and the same diagnostic tests were performed. Paired statistical analysis was used to compare parameters at baseline and after treatment with sotalol.

RESULTS

Standard echocardiographic parameters of systolic function were reduced on sotalol compared to baseline, including ejection fraction via Simpson's method of disks which was 5.8% (95% confidence interval [CI]: 2.77-8.83%, p = 0.002) lower post-treatment. Maximum heart rate on Holter monitor was 17 bpm (95% CI: 9-37 bpm, p = 0.002) lower post-treatment than at baseline.

CONCLUSIONS

Sotalol has a mild negative inotropic effect in healthy dogs based on standard echocardiographic measurements. There is also a negative chronotropic effect at higher heart rates based on 24-h Holter monitoring.