Technical note: The use of a sonomicrometry system for monitoring uterine involution in postpartum dairy cows

Abstract

Sonomicrometry allows the measurement of the distance between 2 piezoelectric crystals and has been widely used to investigate the contractility of the heart and gastrointestinal tract. The objective of this study was to determine whether this method can be used to quantify the reduction in uterine size in cows postpartum. Seven healthy pluriparous Holstein Friesian cows (3.7±0.7 yr old, parity 2.4±0.5, mean±SD) were used. Three weeks before calving, 4 piezoelectric crystals were implanted via laparotomy in the myometrium of the greater curvature of the pregnant uterine horn in a longitudinal direction. Sonometric measurements were conducted daily from 2 d before parturition until 14 d after calving, followed by measurements every other day until d 28. Changes in the distance between neighboring crystals were presented as relative changes (%) from baseline values before parturition. The diameter of the previously pregnant uterine horn was measured using transrectal B-mode sonography from d 10 to 28 after calving. The cows were slaughtered 39±6 d postpartum and the uterus was evaluated for fixation of the crystals. The distances between neighboring crystals underwent changes with a reduction of greater than 50% until d 1 postpartum, but no further changes were recorded from d 1 to 7. In the second week, changes in all distances were affected by day postpartum. One distance was affected by day postpartum in wk 3 and 4. There was a positive correlation between the diameter of the previously pregnant horn and the distances between the crystals. Examination of the uterus after slaughter of the cows revealed that 8 crystals (29%) were no longer fixed in the myometrium. Seven of these (25%) could be evaluated completely or partially and 1 (4%) could not be analyzed. Sonomicrometry seems to be suitable for the objective measurement of reduction in uterine length in cows.

The effect of metritis and subclinical hypocalcemia on uterine involution in dairy cows evaluated by sonomicrometry

“…The sonomicrometry system (Sonometrics, London, ON, Canada), the surgery for implantation of the piezoelectric crystals and the sonometric measurements and analysis have been described in detail [ 25 ]. In brief, the sonomicrometry system consisted of 4 piezoelectric crystals connected to a sonomicrometer (TRX8), a channel selector box and a Sonometrics data acquisition computer.…”

“…Sonomicrometry has been used experimentally for continuous measurement of cardiac and skeletal muscle contractility [ 22 , 23 , 24 ], and a technique using sonomicrometry was recently established to examine reduction of uterine size in dairy cows. In a study involving seven Holstein Friesian cows, sonomicrometry was found to be suitable for assessment of the reduction in uterine length in the puerperium, and currently, it is the only practical technique available for this purpose [ 25 ].…”