The objective of this study was to develop baseline topographical data of landmarks for locating and generating sonographic calliper measurements along with dynamic parameters of caecum and colon in 50 native adult healthy unsedated Spiti horses and Himalayan Hill mules of either sex. The wall thickness, contractility, character and echo-architecture of caecum and colon were recorded. Caecum was found from 15th to 17th inter costal space (ICS). Right dorsal colon (RDC), right ventral colon (RVC), left ventral colon (LVC) and left dorsal colon (LDC) were found from 6th to 14th, 9th to 17th, 9th to 14th and 6th to 15th ICS, respectively. Descending colon was found in the left paralumbar fossa upto tuber-coxae in both horses as well as mules. The corresponding values of horses and mules for wall thickness (in mm) was 2.1±0.05 and 1.4±0.05 for the caecum, 2.16±0.05 and 1.32±0.02 for the right dorsal colon, 2.1±0.03 and 1.32 ±0.02 for the right ventral colon, 2.12±0.03 and 1.32±0.02 for the left dorsal colon, 2.1±0.03 and 1.32±0.02 for the right dorsal colon and 2.04±0.02 for the descending colon. Prominent sacculations were observed on ventral colon and absent on dorsal colon. Detailed ultrasonographic examination of caecum and colon generated baseline data, which will be useful for management of the affections of caecum and colon. [ABSTRACT FROM AUTHOR]