Effects of Eplerenone on Blood Pressure and Echocardiographic and Serum Biochemical Variables in Five Healthy Dogs: A Pilot Study.

Eplerenone (EP), an aldosterone antagonist, is reported to produce renal and cardiac protective effects in noncanine species. However, there are no detailed reports available on cardiovascular effects of EP in dogs. This study aimed to determine effect of EP on echocardiographic parameters, blood pressures, and biochemical variables in healthy dogs. Five healthy Beagle dogs were randomly divided and repeatedly used in each of 3 dose groups, receiving 2.5, 5, or 10 mg/kg BW EP orally q24 h for 4 wks. Serum biochemical test, blood pressure, and Doppler echocardiography measurements were performed before EP administration and at 1, 2, and 4 weeks after EP administration. Treatment with EP reduced mean blood pressure in a dose-dependent manner and significantly (but in a dose-independent manner) decreased left atrium/aorta ratio, early diastolic transmitral flow, early diastolic transmitral flow/late diastolic transmitral flow, peak velocity of early diastolic transmitral flow/peak velocity of early diastolic mitral annular motion, left ventricle and right ventricle Tei indices, stroke volume, cardiac output, and mid systole myocardial velocity gradient 1 to 4 weeks after administration. Deceleration time of early diastolic transmitral flow significantly increased after EP administration. No significant changes were observed in serum biochemical variables. The results indicated that EP might reduce preload, thereby decreasing left atrial size. In addition, reduction of left ventricular stiffness may have theoretically taken place but this could not be tested using the present study design. It is suggested that EP administration within the dose range used in this study is safe for administration to healthy dogs. Further studies are needed to explore both safety and efficacy, as well as to seek a recommended dose range of EP treatment in client-owned dogs with heart disease.

Effect of pravastatin on echocardiographic circulation parameters in dogs.

The purpose of this study was to determine the effect of pravastatin (PS) on hemodynamic parameters in healthy dogs. Five beagle dogs were repeatedly used in each of the 4 groups. One group was not medicated (control). Dogs in other groups received 0.5, 1.0 or 2.0 mg/kg PS orally q24hr, for 4 weeks. Physical examination, blood biochemical tests, blood pressure measurements and Doppler echocardiography were performed before and 1, 2 and 4 weeks after PS administration in all dogs. PS significantly reduced the left atrial-to-aortic diameter ratio (LA/Ao), early diastolic transmitral flow (E) wave, E/early diastolic mitral annulus motion velocity (Em) ratio, left ventricular (LV) fractional shortening, LV ejection fraction, mid systolic myocardial velocity gradient, stroke volume (SV), cardiac output (CO), right and left ventricular Tei indices and elevated Em and early diastolic myocardial velocity gradient. Heart rate was not significantly altered during PS administration, but mean blood pressure decreased slightly. The hematological and blood biochemical values were within normal limits during PS administration. These results revealed that PS administration increases LV expansion capacity and decreases LV constriction and left atrial pressure. It has been suggested that PS may be effective in improving heart failures with LV diastolic dysfunction or elevated left atrial pressure in dogs.

Therapeutic effect of low-dose imatinib on pulmonary arterial hypertension in dogs.

This was a pilot study to determine the effectiveness of low-dose imatinib therapy for hemodynamic disturbances, including pulmonary arterial hypertension (PAH), and clinical manifestations caused by chronic heart failure in dogs. Six client-owned dogs with PAH were administered imatinib mesylate orally, 3 mg/kg body weight q24h, for 30 d. Physical examination, blood biochemical tests, radiography, and Doppler echocardiography were performed prior to imatinib administration and again 30 days after administration. Clinical scores were significantly reduced after imatinib treatment. Systolic pulmonary arterial pressure, heart rate, maximum tricuspid regurgitation velocity, left atrium/aorta ratio, right and left ventricular Tei indexes, early diastolic transmitral flow wave/mitral annulus velocity ratio, and plasma atrial natriuretic peptide concentration decreased significantly after therapy. Diastolic blood pressure, stroke volume, cardiac output, and left ventricular fractional shortening increased significantly after therapy. These results indicate that low-dose imatinib therapy was effective for heart failure in dogs with PAH.

Effet thérapeutique de faibles doses d'imatinib sur l'hypertension artérielle pulmonaire chez les chiens. Cette étude pilote visait à déterminer l'efficacité d'une thérapie à l'aide de faibles doses d'imatinib pour les perturbations hémodynamiques incluant l'hypertension artérielle pulmonaire (HAP) et les manifestations cliniques causées par une insuffisance cardiaque chronique chez les chiens. On a administré le mésylate d'imatinib oralement, 3 mg/kg de poids corporel, q24h, pendant 30 jours, à six chiens atteints de HAP appartenant à des clients. Un examen physique, des tests sanguins biochimiques, une radiographie et une échographie par Doppler ont été réalisés avant l'administration d'imatinib, puis de nouveau 30 jours après l'administration. Les cotes cliniques ont été significativement réduites après le traitement à l'imatinib. La pression artérielle pulmonaire systolique, la fréquence cardiaque, la vélocité de régurgitation tricuspidienne maximale, le rapport oreillette gauche/aorte, les index Tei ventriculaires gauche et droit, le rapport de vélocité diastolique précoce du débit transmitral/annulus mitral et la concentration de peptides natriurétiques du plasma atrial ont baissé significativement après la thérapie. La pression artérielle diastolique, le volume d'éjection systolique, le débit cardiaque et le raccourcissement fractionnel ventriculaire gauche ont augmenté significativement après la thérapie. Ces résultats indiquent que le traitement à faibles doses d'imatinib a été efficace pour l'insuffisance cardiaque chez les chiens atteints de HAP.(Traduit par Isabelle Vallières).