The aim ofthis study isto investigate the correlation between the incidence ofspontaneous tumours ofvarious origins and the localisation indogs with sex, breed, and age factors. Atotal of360tumours with various localisation were studied pathomorphologically. Histopathologic data sets from 360dog tissue samples were processed and statistically examined. Achi-square test ofindependence was conducted toexamine the relationships among the various levels ofthe specified variables. Logistic regression models were employed for dichotomous outcomes toascertain the influence ofcertain explanatory variables onthe tumour types. Characteristic pathomorphological changes observed during examination ofdogs with oncologic diseases were determined. The most common neoplasms were mammary tumours, accounting for 43% ofthe cases. The mammary gland tumours were most common inmongrel dogs (25%), with German Shepherds (17.3%), Poodles, Dachshunds, Central Asian Shepherds (6.7% each), and Rottweilers (5.7%) following. The highest frequency ofthese tumours appeared at8years ofage, predominantly originating from the ductal epithelium, which represented 46.4% ofall the malignant cases.