ABSTRACT
Background and Aim: Vasovagal tonus index (VVTI) serves as a straightforward assessment tool for autonomic function during both physiological and pathological conditions, including pregnancy, in horses. Obtaining VVTI through a modified base apex lead system could be a practical and comfortable solution. In this study, we assessed VVTI in horses with respect to training status and electrocardiographic measurements utilizing a novel modified base apex lead technique. Materials and Methods: A total of 12 Thai native crossbred horses and 12 Arabian horses, all free of cardiac abnormalities, were enrolled in the study. Animals underwent electrocardiogram (ECG) and VVTI using both the base-apex lead method and its modified version. 25 mm/s and 10 mm/mV ECG recordings provided standard bipolar limb leads. The amplitudes and durations of P waves, QRS complexes, PR interval, QT interval, and T duration were assessed. The T wave's shape was examined. Each recording's R-R interval was utilized to assess heart rate. Twenty consecutive beats were used to compute the variability of heart rate (VVTI). Results: The P wave amplitude was the only significant difference (p < 0.05) between the base apex lead method and the modified base apex lead method, with no variations in heart rate, P duration, PR interval, T duration, and QRS duration and amplitude. Both methods showed mainly biphasic T wave patterns. The VVTI values of all horses did not differ significantly between the base apex and modified base apex methods. There was no significant difference in VVTI between Thai crossbred horses and Arabian horses in either method. Conclusion: This study provided the first evidence that VVTI can be evaluated using the modified base apex lead system and may be useful for cardiovascular function monitoring in horses.
ABSTRACT
Background and Aim: Pregnancy affects maternal hemodynamics. The changes in autonomic nervous system activity for hemodynamics adaptation in pregnant horses are still unclear. Thus, this study aimed to examine the effect of pregnancy on electrocardiographic, vasovagal tonus index, and echocardiographic variables in horses. Materials and Methods: A total of 23 Thai native crossbred mares without any cardiac abnormalities were included in this study. The animals were assigned into two groups, a non-pregnant mare group (n =12) and a pregnant mare group (n = 11). Electrocardiogram recordings (paper speed = 25 mm/s and calibration = 10 mm/mV) were performed to obtain six limb leads (leads I, II, III, aVR, aVL, and aVF). The vasovagal tonus index (VVTI) was calculated to assess variability in heart rate over short periods using just 20 consecutive beats. Cardiac structure and function were evaluated by echocardiography. Results: Heart rate, P wave duration, PR interval, QRS duration, QT interval, and T wave duration were significantly different between non-pregnant and pregnant horses (p < 0.05). Pregnant horses had significantly lower VVTI than non-pregnant (p < 0.05). There were no significant differences in cardiac structures including % interventricular septum (IVS), % left ventricular posterior wall (LVPW), IVS in diastole, left ventricular internal diameter at end-diastole, LVPW thickness at end-diastole, IVS in systole, left ventricular internal diameter at end-systole, LVPW thickness at end-systole, and left atrium/aortic roots ratio between the two groups. However, the pregnant horses had a significantly higher cardiac output and % ejection fraction than non-pregnant horses (p < 0.05). Conclusion: This study provided the first evidence that hemodynamic adaptations during pregnancy modified cardiac conduction, vasovagal tonus index, and echocardiographic variables in horses.
ABSTRACT
BACKGROUND AND AIM: Ovariohysterectomy (OHE) is a common procedure for sterilization of female dogs. However, knowledge of changes in pain stress, oxidative stress, and total antioxidant power status before, during, and after OHE is limited. The objective of this experiment was to study the effect of duration on pain stress, oxidative stress, and total antioxidant power status in female dogs undergoing OHE. MATERIALS AND METHODS: Seven female dogs were sterilized using the OHE method. Pain scores, hematological changes, and biochemical markers were investigated during pre-operative, 3 h after starting OHE, and on days 3, 7, 10, and 14 of an experimental period. Data were analyzed using one-way analysis of variance. RESULTS: At 3 days after OHE, pain score was higher than on days 7-14 of the experimental period; percentage of neutrophil, 3 h after starting OHE, was higher than during pre-operative and on days 3-14 of the experimental period; percentage of lymphocyte on days 10-14 was lower than during pre-operative, 3 h after starting OHE, and on days 3-7 of the experimental period; neutrophil/lymphocyte ratio, 3 h after starting OHE, was higher than during pre-operative and on days 3-14 of the experimental period; plasma malondialdehyde on day 3 was higher than during pre-operative, 3 h after starting OHE, and on days 3-14 of the experimental period; and total antioxidant power on day 14 was higher than during pre-operative, 3 h after starting OHE, and on days 3-10 of the experimental period, respectively. CONCLUSION: This experiment indicated that OHE caused pain stress, oxidative stress, and reduction of total antioxidant power in female dogs. Finally, female dogs needed antioxidant for 7 days after OHE.
ABSTRACT
Heart rate variability (HRV) and echocardiography were performed in 14 dogs with mitral regurgitation (MR) before and after 14 days of 0.5mg/kg/day of enalapril treatment. All dogs were in heart failure stages B1 and B2. After enalapril treatment, left ventricular end diastolic diameter (LVEDd), left ventricular end diastolic diameter normalized for body weight (LVEDdN) and percent mitral regurgitant jet decreased (P<0.05). The diastolic blood pressure decreased (P<0.05). Increased time domain parameters of HRV were found. For frequency domain analysis, the total frequency (TF) increased significantly (P<0.05). The normalized low frequency (LF norm) decreased while normalized high frequency (HF norm) increased causing significant reduction in LF/HF (P<0.05). Before enalapril treatment, LF was correlated with end diastolic volume (EDV) (P<0.01) and LVEDd (P<0.05). In conclusion, MR dogs receiving enalapril treatment for 14 days had increased cardiac parasympathetic tone while sympathetic tone was suppressed. The decreased sympathetic activity corresponded to the reduction in cardiac preload and afterload.