Abstract: Pathological changes along the alimentary tract (oral cavity, oesophagus and stomach with cardia, fundus and pylorus sections) were examined along with their frequency and roles in mortality among canines. This study was performed to determine the pathological changes, the incidence and the definition (macroscopic and microscopic) of these lesions in the alimentary tract of dogs. It also examined whether or not these lesions caused pathogenesis of secondary diseases or death. Total 100 dogs of various breeds aged from 1 week to 114 months (9 and a half years) were studied. For histopathological examinations, lesions in the organs were scored in detail as mild, moderate and severe. The macroscopic lesions identified were the types of infections generally found in the gastrointestinal system. Included in these observations were focal, greyish-red and white erosions in the tongue; hyperemia and haemorrhage in the oesophagus and hyperemia, bleeding, mucosal thickening, foreign bodies (in 3 dogs) and ascarids (in 5 dogs) in the stomach. On a microscopic level, severe histopathological observations included bacterial colonies, degeneration, desquamation and necrosis in the epithelium; hyperemia, haemorrhage and fibrosis in propria; degeneration, desquamation, dilatation and hyperplasia in glands and depletion in lymphoid tissue were observed and scored. Immunohistochemistry revealed the positive staining for Canine Parvovirus-2 (CPV-2) in 90 dogs, Canine Distemper Virus (CDV) in 27 dogs and 24 dogs with both of these viruses. Parasitological investigations revealed 5 dogs with ascarids. Results from pathoanatomical diagnoses demonstrated oesophagitis in 10 cases, acute gastritis in 11 cases, chronic gastritis in 17 cases and eosinophilic gastroenteritis in 1 case. Thus, the collective results suggest that primarily parvoviral enteritis but also other lesions and diseases in the gastrointestinal tract cause death in these dogs.