Evaluation of echocardiography indicators of cows and calves with myocardial dystrophy

Abstract

Echocardiography is the most informative non‐invasive method of heart disease diagnosis, which makes it possible to determine the structural and functional state of the heart through visualization using reflected ultrasound wave. The purpose of this study is to analyze echocardiograms of the cows and calves with myocardial dystrophy. The studies were carried out in of the Agricultural production cooperative “Gridino” (Russia, Kostroma region) on highly productive cows of the Kostroma breed 20 days after calving (3‐4 lactation) and 2‐month‐old calves obtained from these cows. Four experimental groups of animals were formed: group 1 ‐ clinically healthy cows (n=15), group 2 ‐ cows with symptoms of myocardial dystrophy (n=15), group 3 ‐ calves obtained from clinically healthy cows (n=15), group 4 ‐ calves obtained from cows with symptoms of myocardial dystrophy (n=15). An ultrasonic veterinary machine AcuVista VT98C with a convex scanning transducer with a frequency of 3.5 MHz was used to get the echocardiograms. Access points for the study were prepared according to the heart anatomy; echocardiography was performed in B‐ and M‐modes. The following indices were determined: left ventricular end‐diastolic size (LVd), right ventricular end‐diastolic size (RVd), left ventricular end‐systolic size (LVs), right ventricular end‐systolic size (RVs), thickness of the interventricular septum in diastole (VSd), thickness of left ventricular posterior wall in diastole (LVWd), left ventricular posterior wall thickness in systole (LVWs), left atrial diameter (LA), and aortic root diameter (AO).According to the results of echocardiography, cows with symptoms of myocardial dystrophy had RVs 16.0±1.15 mm, which was 16.79% higher than in clinically healthy cows. At the same time, calves obtained from sick mothers, had a higher value of RVs (11.3±0.65 mm) by 4.63% in comparison with calves from clinically healthy mothers. A lower LA was determined among sick cows and their calves by 13.29% (P<0.001) and 5.29%, respectively, compared with the indices of clinically healthy animals. Cows of both groups did not have significant differences in LVs: for clinically healthy animals, this indicator was 38.1±1.51 mm, for unhealthy ‐ 39.88±0.96 mm. Calves obtained from cows with signs of myocardial dystrophy showed LVs within 23.6±0.72 mm, which was 10.94% less (P<0.05) compared with calves from clinically healthy cows. The VSd index did not have significant differences in comparison for the corresponding groups. The indices of LVWd and LVWs did not differ significantly in the groups of cows. Calves obtained from unhealthy mothers had a tendency to lower values of LVWd and LVWs respectively, by 7.5% and 2.13% in comparison with young calves from clinically healthy cows. Among the cows with symptoms of myocardial dystrophy, the AO index was lower by 14.77% (P<0.001) compared with healthy animals and amounted to 50.2±1.23 mm. Among the calves of both groups, there was no significant difference in AO data.The revealed changes characterized the development of dystrophic processes in the myocardium and the initial stage of heart remodeling in high‐yielding cows in presence of high physiological stress. A similar tendency of the structural and functional myocardium disturbance was observed in calves obtained from cows with symptoms of myocardial dystrophy.