Equine Gastric Ulcer Syndrome (EGUS) occurs with variable prevalence in horses, donkeys, and mules. Due to the particularities of the mucous membranes, the syndrome is made up of Squamous Gastric Disease (ESGD) and Glandular Gastric Disease (EGGD). Given the multifactorial nature and multiple classification systems of the syndrome, significant differences have been reported between prevalence studies performed ante mortem, which are even more remarkable when compared with postmortem evaluations. This study aimed to perform a postmortem evaluation of the stomachs from these three different types of equids to characterize similarities and differences in the dynamics of ESGD presentation. A total of 300 equid stomachs, 100 from each group (horses, donkeys and mules), were obtained immediately after slaughter. The postmortem examination considered the inspection of the squamous region (cardia, dorsal fundus, and Margo Plicatus [MP]) and the classification of the observed lesions. The global presence of EGUS in the entire population of study was 92% (85%, 95%, and 96% for horses, donkeys, and mules, respectively), with 83,3% being affected by ESGD (78%, 89%, and 83% for horses, donkeys, and mules, respectively), compromising the MP in all cases. The occurrence of ESGD was evidenced in horses, donkeys, and mules subjected to similar handling conditions prior to slaughter, including long-distance traveling, fasting, and stress factors.