Ultrasonography of the reticulum in cows.

The reticulum and adjacent organs were examined ultrasonographically in 51 cows by use of a 3.5-MHz linear transducer applied to the ventral aspect of the thorax over the sixth and seventh intercostal spaces. Examination included assessment of the contour of the reticulum, of reticular contractions, and of the organs adjacent to the reticulum. The normal reticulum appeared as a half-moon-shaped structure with a smooth contour; it contracted at regular intervals and was situated immediately adjacent to the diaphragm and ventral portion of the abdominal wall when relaxed. Contents of the reticulum could not normally be imaged because of its partly gaseous composition. The ruminoreticular groove, craniodorsal blind sac of the rumen, and the ventral sac of the rumen were observed caudally. The distal aspect of the spleen and parts of the omasum, abomasum, and liver could be imaged. Reticular motility was characterized by a biphasic contraction pattern. Four biphasic reticular contractions usually were observed during a 4-minute period. During the first (incomplete) contraction, the reticulum contracted by a mean of 7.2 +/- 2.30 cm. There was then low-grade, incomplete relaxation of the reticulum, followed immediately by the second reticular contraction, during which the reticulum usually disappeared from the 17.5-cm-deep screen. The reticulum then reappeared in its normal position. The first reticular contraction lasted a mean of 2.6 +/- 0.33 seconds and the second contraction lasted 3.9 +/- 0.55 seconds. The mean interval between 2 biphasic contractions was 44.9 +/- 10.53 seconds. The speed of the first reticular contraction was 5.4 +/- 1.32 cm/s.(ABSTRACT TRUNCATED AT 250 WORDS)