This literature review addresses the morphological variations in the stomach of domestic animals by associating them with their diet. The stomach is an important organ located between the esophagus and the small intestine. It is an enlarged portion of the digestive system, where partial digestion occurs, as well as absorptive processes and secretion of hormones and enzymes. The organ has great diversity among mammals, this condition being associated with the eating habits assumed by the representatives of the class. Scientific articles and books on anatomy, histology, veterinary medical clinic, animal management and nutrition were used as a basis for textual structuring of this work. The stomach can be classified as unicavitary, when it consists of a single saculiform dilation, being described in carnivores as the dog and the cat, herbivores as the horses and omnivores as the pigs. The latter two being characterized by a glandular and aglandular stomach lining, while in the first two the lining tissue is entirely glandular. The stomach is said to be pluricavitary, when it is formed by compartments, as in ruminants, in which the constituent chambers are predominantly aglandular, being a glandular one. Knowledge of the subject in question is of great relevance, especially for veterinarians, so that these professionals can effectively identify possible changes that may affect the stomach, favoring the care of sick animals.