RESUMO
The study was conducted to establish the ultrasonographic features of the healthy and impacted omasum in cows and buffaloes. Scanning was done using a 3.5 MHz microconvex transducer. In healthy buffaloes, the omasum could be scanned at the eighth to ninth intercostal space as a round or oval structure having thick echogenic wall with echogenic leaves. Gradual slow movements of omasal leaves could also be seen in real-time B-mode. The omasum appeared to be very clear, large, and close to the transducer at the start of the omasal contraction, and as the contraction progressed the omasum retracted away from the transducer and became very small. In healthy cows the omasum was seen as a crescent-shaped structure with an echogenic wall. The contents of the omasum or omasal leaves could not be visualized. Omasal contractility was not as prominent as in buffaloes. In buffaloes, the impacted omasum appeared amotile, the omasal leaves were not visible, and the omasum as a whole gave a prominent distal acoustic shadow. In cows, the impaction could be diagnosed based on amotile omasum covering a large area on the right side. Ultrasonography was found to be helpful in subjective assessment of omasal impaction but could not aid in diagnosing the severity of impaction.
