The objective of the present study was to examine if heart murmurs in adult cattle can be objectively diagnosed using phonocardiography. The examinations were conducted using phonocardiograms (PCG) and required a scheme for evaluation. Twenty cattle older than two years of age that were hospitalised at the Clinic for Ruminants, Oberschleissheim, were used for the study. In all of them, heart murmurs were detected during auscultation. The Meditron Analyzer 4.0 (Welch Allyn GmbH & Co KG, Jungingen) allowed the simultaneous recording of electrocardiogram (ECG) and PCG. The ECG using a thoracic lead served as a timeline for the PCG. In a pre-test (n = 20) so called threshold values were established which marked the division between the “background noise” (amplitudes between the heart sounds) and murmurs. These threshold values (for positive and negative range) were established for four different locations per side of the body (in the third and fourth intercostals spaces (ICS), dorsally and ventrally, re-spectively), as well as for the presentation of the PCG with use of a 50, 100 Hz filter, respectively. In the subsequent main study twenty animals were examined clinically and according to the results of auscultation assigned to the heart murmur grades (HM) 0-6 and categorised into groups: HM “faint” (HM grade 0-2), HM “moderately loud” (HM grade 3-4) and HM “loud” (HM grade 5-6). PCG were recorded on all eight locations mentioned above. The quality and number of acceptable PCGs of the right body side was very low, thus these recordings were not used in the analysis. For the PCG evaluation certain selected heart actions were presented in a larger scale and printed on graph paper. Systole and diastole were marked using the ECG and the threshold values were drawn in manually. In addition, systole and diastole were divided into 10 and 20 equal intervals for the 50 Hz and 100 Hz presentations, respectively. At these determined points the amplitudes were measured and recorded if they were above/below the threshold values or if no values could be measured at these points. For amplitudes that were outside the threshold values relative frequency at each point of measurement for each location and for 50 and 100 Hz presentations was calculated. Comparing the sum of the amplitudes outside the threshold values between the groups “faint” and “loud” significant differences were found for the location 1 (third ICS, dorsally, left side) in the systole at 50 Hz and for the loca-tion 2 (third ICS, ventrally, left side) in the systole at 100 Hz (p = 0.041 and p = 0.034). A significant difference between the groups “faint” and “loud” was found for the loca-tion 1 in the systole at 50 Hz (p = 0.042) concerning the area under the curve using the amplitudes measured at these 10 and 20 points of measurement, respectively. In addition, the mean values of the amplitudes that were outside the threshold values were calculated. Comparing the groups “faint” and “loud” a significant difference was also found for the location 1 in the systole at 50 Hz in the positive range (p = 0.034) as well as for location 2 in the systole at 50 Hz in the negative range (p = 0.045). Further investigations could confirm the tendencies found in the present study. Additional investigations with a larger number of animals could help to classify heart murmurs. Besides, they might help to increase the chances of obtaining usable measurements from the right side. Also, an algorithm for automatic evaluation of PCGs based on the data of the present study would be very helpful.
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