A serial study of heart function during pregnancy, lactation and the dry period in dairy goats using echocardiography

Echocardiography and Doppler measurements mere performed to investigate cha nges in heart dimensions and function during pregnancy, lactation and the n on-pregnant, non-lactating (dry) period in dairy goats. Eight Swedish domes tic goats (Capra hircus) mere studied with two-dimensional (2DE), M-mode an d continuous wave Doppler measurements. Cardiac dimensions did not differ b etween periods. The mean cardiac outputs were 35 and 28 % greater during pr egnancy and lactation, respectively, vs. the dry period. Arterial blood pre ssure (measured by telemetry) did not differ between reproductive periods b efore echocardiographic measurements, but became elevated during the measur ements, with the smallest rise during lactation. Heart rate was elevated du ring pregnancy and increased further during echocardiographic measurements, but was not elevated during the other periods. The cranial location of the heart influenced the selection of examination window and caused some diffi culties in positioning the ultrasound transducer. This may have led to unde restimation of the velocity trace integral and therefore to underestimation of cardiac output. However, our values mere within the range of these obta ined with dye- and thermodilution methods. The goats tolerated the investig ations well during lactation and the dry period, but showed increased blood pressure and heart rate during pregnancy. Therefore, the non-invasive and safe echocardiographic-Doppler method appears to be a good alternative for studies of heart dimensions and function during lactation and the dry perio d in the dairy goat.