Ultrasonography of the omasum in 30 Saanen goats

Ultrasonography was carried out in standing, non-sedated goats using a 5.0 MHz linear transducer. The location and size of the omasum, thickness of the omasal wall and visualisation of the abomasal laminae, contents and contractions were assessed. The omasum was visible from the 9th intercostal space (ICS) in all the goats, and from the 8th and 10th ICSs in 29 and 24 goats, respectively. The omasum was seen medial to the liver, but only the omasal wall closest to the transducer was visible. The dorsal omasal limit formed a dorsally convex curve running from cranioventral to caudodorsal and was furthest from the dorsal midline in the 6th ICS. The ventral omasal limit formed a ventrally convex curve. The size of the omasum was largest (10.2 ± 3.1 cm) in the 9th ICS and decreased cranially and caudally from this position. Active omasal motility was recorded in 20 goats with 0.3 to 2.0 contractions per minute.The findings of this study provide reference ranges for the interpretation of the location and size of the omasum in goats with suspected omasal abnormalities. Ultrasonography is an ideal diagnostic tool for evaluation of the omasum, which is not accessible to conventional examination techniques, such as inspection, palpation, percussion and auscultation.The caprine omasum is located in the ventral aspect of the cranial part of the abdomen between the rumen and liver [1]. The omasum has 80 to 100 laminae, which vary in size and serve to absorb water, minerals and short-chain fatty acids [2]. Although the omasum is involved in various gastrointestinal disorders, primary diseases of the omasum are uncommon and occur chiefly in cattle [3,4]. They include omasal impaction and inflammation as well as paresis, which is characterised by cessation of influx of ingesta from the reticulum leading to anterior functional stenosis. Peritonitis may result in secondary inflammatory changes of the omasum, and retrograde flow of ingesta into the omasum may occur in cattle with ileu