The flexible gastrointestinal endoscopy is a noninvasive modality for the assessment, diagnosis of gastro-intestinal disorders and analysis of the tissues, cells and mucosa of the gastro-intestinal tract. The utilization of this technique is for esophagoscopy, gastroscopy, duodensocopy and even colonoscopy in conjunction with the corresponding anatomical relations. The present investigation was conducted on the apparently healthy three mongrel dogs that were brought to the surgery unit of the faculty of veterinary medicine, Cairo University and three other dogs were kept for normal anatomical dissection. This work illustrated the usage of anatomy, endoscopy and radiography in order to ob- tain an endoscopic image and simultaneously, take an x-ray film along the different parts of the colon. The study revealed that the colon of the dog has the simplest form, being divided into ascending, transverse, and descending parts and extending from the ceco- colic opening to the cranial end of the rectum. Different angulations and directional changes in the colon of dog supported by the anatomical interpretations, the overall form and directions of the insertion tube during the colon examination were mentioned. This work aimed to presen a clear and detailed data of the normal endoscopy and the anatomy of the colon in addition to, providing an educational model for practical application of the endoscopic examination of the lower part of the gastrointestinal tract of the dog.